Search

Your search keyword '"S. D. Kawaler"' showing total 46 results
Start Over Author "S. D. Kawaler"
46 results on '"S. D. Kawaler"'

1. Hot super-Earths stripped by their host stars

Author

M. S. Lundkvist, H. Kjeldsen, S. Albrecht, G. R. Davies, S. Basu, D. Huber, A. B. Justesen, C. Karoff, V. Silva Aguirre, V. Van Eylen, C. Vang, T. Arentoft, T. Barclay, T. R. Bedding, T. L. Campante, W. J. Chaplin, J. Christensen-Dalsgaard, Y. P. Elsworth, R. L. Gilliland, R. Handberg, S. Hekker, S. D. Kawaler, M. N. Lund, T. S. Metcalfe, A. Miglio, J. F. Rowe, D. Stello, B. Tingley, and T. R. White

Subjects
Science
Abstract

Theory predicts a deficit of super-Earth sized planets, which orbit close to their host star. Here, Lundkvist et al. use data from the NASA Kepler mission to show that this deficit is also seen in observations, thereby providing new insight into exoplanetary systems.

Published
2016
Full Text
View/download PDF

2. PLATO as it is: A legacy mission for Galactic archaeology

Author

A. Miglio, C. Chiappini, B. Mosser, G. R. Davies, K. Freeman, L. Girardi, P. Jofré, D. Kawata, B. M. Rendle, M. Valentini, L. Casagrande, W. J. Chaplin, G. Gilmore, K. Hawkins, B. Holl, T. Appourchaux, K. Belkacem, D. Bossini, K. Brogaard, M.‐J. Goupil, J. Montalbán, A. Noels, F. Anders, T. Rodrigues, G. Piotto, D. Pollacco, H. Rauer, C. Allende Prieto, P. P. Avelino, C. Babusiaux, C. Barban, B. Barbuy, S. Basu, F. Baudin, O. Benomar, O. Bienaymé, J. Binney, J. Bland‐Hawthorn, A. Bressan, C. Cacciari, T. L. Campante, S. Cassisi, J. Christensen‐Dalsgaard, F. Combes, O. Creevey, M. S. Cunha, R. S. Jong, P. Laverny, S. Degl'Innocenti, S. Deheuvels, É. Depagne, J. Ridder, P. Di Matteo, M. P. Di Mauro, M.‐A. Dupret, P. Eggenberger, Y. Elsworth, B. Famaey, S. Feltzing, R. A. García, O. Gerhard, B. K. Gibson, L. Gizon, M. Haywood, R. Handberg, U. Heiter, S. Hekker, D. Huber, R. Ibata, D. Katz, S. D. Kawaler, H. Kjeldsen, D. W. Kurtz, N. Lagarde, Y. Lebreton, M. N. Lund, S. R. Majewski, P. Marigo, M. Martig, S. Mathur, I. Minchev, T. Morel, S. Ortolani, M. H. Pinsonneault, B. Plez, P. G. Prada Moroni, D. Pricopi, A. Recio‐Blanco, C. Reylé, A. Robin, I. W. Roxburgh, M. Salaris, B. X. Santiago, R. Schiavon, A. Serenelli, S. Sharma, V. Silva Aguirre, C. Soubiran, M. Steinmetz, D. Stello, K. G. Strassmeier, P. Ventura, R. Ventura, N. A. Walton, and C. C. Worley

Published
2017
Full Text
View/download PDF

3. Kepler and TESS Observations of PG 1159-035

Author

Gabriela Oliveira da Rosa, S. O. Kepler, Alejandro H. Córsico, J. E. S. Costa, J. J. Hermes, S. D. Kawaler, Keaton J. Bell, M. H. Montgomery, J. L. Provencal, D. E. Winget, G. Handler, Bart Dunlap, J. C. Clemens, and Murat Uzundag

Subjects
Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

PG 1159-035 is the prototype of the DOV hot pre-white dwarf pulsators. It was observed during the Kepler satellite K2 mission for 69 days in 59 s cadence mode and by the TESS satellite for 25 days in 20 s cadence mode. We present a detailed asteroseismic analysis of those data. We identify a total of 107 frequencies representing 32 l=1 modes, 27 frequencies representing 12 l=2 modes, and 8 combination frequencies. The combination frequencies and the modes with very high k values represent new detections. The multiplet structure reveals an average splitting of 4.0+/-0.4 muHz for l=1 and 6.8+/-0.2 muHz for l=2, indicating a rotation period of 1.4+/-0.1 days in the region of period formation. In the Fourier transform of the light curve, we find a significant peak at 8.904+/-0.003 muHz suggesting a surface rotation period of 1.299+/-0.002 days. We also present evidence that the observed periods change on timescales shorter than those predicted by current evolutionary models. Our asteroseismic analysis finds an average period spacing for l=1 of 21.28+/-0.02 s. The l=2 modes have a mean spacing of 12.97+/-0.4 s. We performed a detailed asteroseismic fit by comparing the observed periods with those of evolutionary models. The best fit model has Teff=129600+/- 11100 K, mass M*=0.565+/-0.024 Msun, and log g=7.41+0.38-0.54, within the uncertainties of the spectroscopic determinations. We argue for future improvements in the current models, e.g., on the overshooting in the He-burning stage, as the best-fit model does not predict excitation for all the pulsations detected in PG~1159-03., 27 pages, 9 tables and 26 figures

Published
2022

4. TESS first look at evolved compact pulsators

Author

Zs. Bognár, S. D. Kawaler, K. J. Bell, C. Schrandt, A. S. Baran, P. A. Bradley, J. J. Hermes, S. Charpinet, G. Handler, S. E. Mullally, S. J. Murphy, R. Raddi, Á. Sódor, P.-E. Tremblay, M. Uzundag, W. Zong

Published
2020
Full Text
View/download PDF

5. The Asteroseismic Target List (ATL) for solar-like oscillators observed in 2-minute cadence with the Transiting Exoplanet Survey Satellite (TESS)

Author

V. Silva Aguirre, O. L. Creevey, T. L. Campante, J. Christensen-Dalsgaard, D. W. Latham, M. N. Lund, T. S. Metcalfe, H. Kjeldsen, Rasmus Handberg, S. Basu, T. Appourchaux, Warrick H. Ball, R. Vanderspek, George R. Ricker, Timothy R. Bedding, Andrea Miglio, Daniel Huber, William J. Chaplin, Rafael A. García, S. D. Kawaler, A. M. Serenelli, Guy R. Davies, D. Stello, Mathew Schofield, Department of Psychology, St John's University, Cognition, Langues, Langage, Ergonomie (CLLE-ERSS), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Toulouse - Jean Jaurès (UT2J)-Université Bordeaux Montaigne-Centre National de la Recherche Scientifique (CNRS), Département des Sciences et Gestion de l'Environnement/Océanologie [Liège], Université de Liège, Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Astronomy, Yale University [New Haven], Sydney Institute for Astronomy (SIfA), The University of Sydney, Danish AsteroSeismology Centre (DASC), Aarhus University [Aarhus], Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Research institute of Computer Vision and Robotics [Girona] (VICOROB), Universitat de Girona (UdG), Department of Physics and Astronomy [Aarhus], Department of Physics and Astronomy [Iowa City], and University of Iowa [Iowa City]

Subjects
oscillations [stars], Source code, instruments [space vehicles], media_common.quotation_subject, fundamental parameters [stars], FOS: Physical sciences, Astrophysics, 01 natural sciences, Asteroseismology, surveys, 0103 physical sciences, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), media_common, Physics, 010308 nuclear & particles physics, Subgiant, Astronomy and Astrophysics, Exoplanet, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Satellite, Cadence, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], catalogs
Abstract

We present the target list of solar-type stars to be observed in short-cadence (2-min) for asteroseismology by the NASA Transiting Exoplanet Survey Satellite (TESS) during its 2-year nominal survey mission. The solar-like Asteroseismic Target List (ATL) is comprised of bright, cool main-sequence and subgiant stars and forms part of the larger target list of the TESS Asteroseismic Science Consortium (TASC). The ATL uses Gaia DR2 and the Extended Hipparcos Compilation (XHIP) to derive fundamental stellar properties, calculate detection probabilities and produce a rank-ordered target list. We provide a detailed description of how the ATL was produced and calculate expected yields for solar-like oscillators based on the nominal photometric performance by TESS. We also provide publicly available source code which can be used to reproduce the ATL, thereby enabling comparisons of asteroseismic results from TESS with predictions from synthetic stellar populations., Comment: 13 pages, 11 figures; accepted for publication in Astrophysical Journal Supplement Series

Published
2019
Full Text
View/download PDF

6. Accurate fundamental parameters and detailed abundance patterns from spectroscopy of 93 solar-type Kepler targets★†

Author

J. Molenda-Zakowicz, Clara Régulo, T. Appourchaux, T. L. Campante, C. Catala, K. Uytterhoeven, D. T. Sanderfer, Robert L. Morris, Ian W. Roxburgh, Rasmus Handberg, H. Kjeldsen, Daniel Huber, H. Bruntt, A. O. Thygesen, Barry Smalley, S. Basu, T. R. Bedding, Yvonne Elsworth, Elisa V. Quintana, William J. Chaplin, B. Mosser, J.-C. Gazzano, D. Stello, P.-O. Quirion, R. A. Garcia, Graham A. Verner, J. Christensen-Dalsgaard, S. Mathur, T. S. Metcalfe, S. D. Kawaler, S. Hekker, and Christoffer Karoff

Subjects
Physics, 010308 nuclear & particles physics, Metallicity, Astronomy and Astrophysics, Astrophysics, Surface gravity, Light curve, 01 natural sciences, Kepler, Stars, Space and Planetary Science, 0103 physical sciences, Magnitude (astronomy), Calibration, 010303 astronomy & astrophysics, Scaling
Abstract

We present a detailed spectroscopic study of 93 solar-type stars that are targets of the NASA/Kepler mission and provide detailed chemical composition of each target. We find that the overall metallicity is well-represented by Fe lines. Relative abundances of light elements (CNO) and alpha-elements are generally higher for low-metallicity stars. Our spectroscopic analysis benefits from the accurately measured surface gravity from the asteroseismic analysis of the Kepler light curves. The log g parameter is known to better than 0.03 dex and is held fixed in the analysis. We compare our Teff determination with a recent colour calibration of V-K (TYCHO V magnitude minus 2MASS Ks magnitude) and find very good agreement and a scatter of only 80 K, showing that for other nearby Kepler targets this index can be used. The asteroseismic log g values agree very well with the classical determination using Fe1-Fe2 balance, although we find a small systematic offset of 0.08 dex (asteroseismic log g values are lower). The abundance patterns of metals, alpha elements, and the light elements (CNO) show that a simple scaling by [Fe/H] is adequate to represent the metallicity of the stars, except for the stars with metallicity below -0.3, where alpha-enhancement becomes important. However, this is only important for a very small fraction of the Kepler sample. We therefore recommend that a simple scaling with [Fe/H] be employed in the asteroseismic analyses of large ensembles of solar-type stars.

Published
2012

7. Asteroseismology of Solar-Type Stars with K2 : Detection of Oscillations in C1 Data

Author

S. Dehuevels, Tiago L. Campante, Derek Buzasi, Kuldeep Verma, Andrea Miglio, B. Mosser, William J. Chaplin, S. B. Howell, Guy R. Davies, Mia S. Lundkvist, Timothy R. White, V. Silva Aguirre, O. L. Creevey, D. Salabert, F. Marcadon, Othman Benomar, Luca Casagrande, A. M. Serenelli, G. Houdek, H. R. Coelho, Rafael A. García, Warrick H. Ball, Yvonne Elsworth, Mikkel N. Lund, T. Appourchaux, H. M. Antia, Clara Régulo, Lars A. Buchhave, Thomas Kallinger, D. W. Latham, Rasmus Handberg, Ian W. Roxburgh, Laurent Gizon, David R. Soderblom, Daniel Huber, H. Kjeldsen, Timothy R. Bedding, Sarbani Basu, S. D. Kawaler, Jørgen Christensen-Dalsgaard, Savita Mathur, Thomas Barclay, Christian A. Latham, Patrick Gaulme, Saskia Hekker, Dennis Stello, Christoffer Karoff, Department of Physics and Astronomy [Aarhus], Aarhus University [Aarhus], Groupement de Recherche et d'Etudes en Gestion à HEC (GREGH), Ecole des Hautes Etudes Commerciales (HEC Paris)-Centre National de la Recherche Scientifique (CNRS), National Space Institute [Lyngby] (DTU Space), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Institute of Space Sciences [Barcelona] (ICE-CSIC), Spanish National Research Council [Madrid] (CSIC), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Stellar Astrophysics Centre [Aarhus] (SAC), School of Physics and Astronomy [Birmingham], University of Birmingham [Birmingham], Institut de Physique du Globe de Paris (IPG Paris), Laboratoire Hippolyte Fizeau (FIZEAU), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), School of Physics and Astronomy, Institute for Astronomy [Vienna], University of Vienna [Vienna], Space Science Institute [Boulder] (SSI), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Departamento de Astrofísica [La laguna], Universidad de La Laguna [Tenerife - SP] (ULL), Kavli Institute for Theoretical Physics [Santa Barbara] (KITP), University of California [Santa Barbara] (UC Santa Barbara), University of California (UC)-University of California (UC), School of Physics [UNSW Sydney] (UNSW), University of New South Wales [Sydney] (UNSW), Institut für Informatik (LRR-TUM), Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), School of Engineering [Cardiff], Cardiff University, Technical University of Denmark [Lyngby] (DTU), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris, Université Nice Sophia Antipolis (... - 2019) (UNS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), University of California [Santa Barbara] (UCSB), and University of California-University of California

Subjects
Physics, [PHYS]Physics [physics], Stars, Amplitude, 13. Climate action, Space and Planetary Science, Oscillation, Astronomy, Astronomy and Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Asteroseismology, Noise (radio), ComputingMilieux_MISCELLANEOUS
Abstract

We present the first detections by the NASA K2 mission of oscillations in solar-type stars, using short-cadence data collected during K2 Campaign 1 (C1). We understand the asteroseismic detection thresholds for C1-like levels of photometric performance, and we can detect oscillations in subgiants having dominant oscillation frequencies around 1000 μHz. Changes to the operation of the fine-guidance sensors are expected to give significant improvements in the high-frequency performance from C3 onwards. A reduction in the excess high-frequency noise by a factor of 2.5 in amplitude would bring main-sequence stars with dominant oscillation frequencies as high as ≃2500 μHz into play as potential asteroseismic targets for K2.

Published
2015

8. A compact system of small planets around a former red-giant star

Author

Andrzej S. Baran, Suzanna K. Randall, Stéphane Charpinet, Gilles Fontaine, S. D. Kawaler, J. H. Telting, Valérie Van Grootel, Roberto Silvotti, Elizabeth M. Green, Pierre Brassard, and Roy Ostensen

Subjects
Physics, Multidisciplinary, 010308 nuclear & particles physics, Red giant, Brown dwarf, Astronomy, Astrophysics, Planetary system, 01 natural sciences, Exoplanet, Habitability of orange dwarf systems, Kepler-47, 13. Climate action, Planet, 0103 physical sciences, Binary star, 010303 astronomy & astrophysics
Abstract

Planets that orbit their parent star at less than about one astronomical unit (1 AU is the Earth-Sun distance) are expected to be engulfed when the star becomes a red giant. Previous observations have revealed the existence of post-red-giant host stars with giant planets orbiting as close as 0.116 AU or with brown dwarf companions in tight orbits, showing that these bodies can survive engulfment. What has remained unclear is whether planets can be dragged deeper into the red-giant envelope without being disrupted and whether the evolution of the parent star itself could be affected. Here we report the presence of two nearly Earth-sized bodies orbiting the post-red-giant, hot B subdwarf star KIC 05807616 at distances of 0.0060 and 0.0076 AU, with orbital periods of 5.7625 and 8.2293 hours, respectively. These bodies probably survived deep immersion in the former red-giant envelope. They may be the dense cores of evaporated giant planets that were transported closer to the star during the engulfment and triggered the mass loss necessary for the formation of the hot B subdwarf, which might also explain how some stars of this type did not form in binary systems.

Published
2011

9. The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926

Author

H. Kjeldsen, L. A. Balona, V. G. Elkin, K. Uytterhoeven, A. P. Hatzes, Søren Frimann, L. Bigot, S. D. Kawaler, J. Christensen-Dalsgaard, Hiromoto Shibahashi, M. Gruberbauer, D. W. Kurtz, M. S. Cunha, S. Frandsen, I. M. Brandão, T. Lueftinger, and Hideyuki Saio

Subjects
Physics, Rotation period, Field (physics), 010308 nuclear & particles physics, Mode (statistics), Astronomy and Astrophysics, Astrophysics, Star (graph theory), Rotation, 01 natural sciences, Stars, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Variation (astronomy), 010303 astronomy & astrophysics, Rapidly oscillating Ap star, Astrophysics::Galaxy Astrophysics
Abstract

We have discovered a new rapidly oscillating Ap star among the Kepler Mission target stars, KIC 10195926. This star shows two pulsation modes with periods that are amongst the longest known for roAp stars at 17.1 min and 18.1 min, indicating that the star is near the terminal age main sequence. The principal pulsation mode is an oblique dipole mode that shows a rotationally split frequency septuplet that provides information on the geometry of the mode. The secondary mode also appears to be a dipole mode with a rotationally split triplet, but we are able to show within the improved oblique pulsator model that these two modes cannot have the same axis of pulsation. This is the first time for any pulsating star that evidence has been found for separate pulsation axes for different modes. The two modes are separated in frequency by 55 microHz, which we model as the large separation. The star is an alpha^2 CVn spotted magnetic variable that shows a complex rotational light variation with a period of Prot = 5.68459 d. For the first time for any spotted magnetic star of the upper main sequence, we find clear evidence of light variation with a period of twice the rotation period; i.e. a subharmonic frequency of $\nu_{\rm rot}/2$. We propose that this and other subharmonics are the first observed manifestation of torsional modes in an roAp star. From high resolution spectra we determine Teff = 7400 K, log g = 3.6 and v sin i = 21 km/s. We have found a magnetic pulsation model with fundamental parameters close to these values that reproduces the rotational variations of the two obliquely pulsating modes with different pulsation axes. The star shows overabundances of the rare earth elements, but these are not as extreme as most other roAp stars. The spectrum is variable with rotation, indicating surface abundance patches.

Published
2011

10. Kepler photometry of KIC 10661783: a binary star with total eclipses and δ Scuti pulsations

Author

J. Christensen-Dalsgaard, Peter Tenenbaum, John Southworth, H. Kjeldsen, Krešimir Pavlovski, W. Zima, Andrej Prsa, J. D. Twicken, D. W. Kurtz, R. L. Gilliland, Miles T. Cote, S. L. Kim, Barry Smalley, Conny Aerts, S. D. Kawaler, H. Bruntt, and Holger Lehmann

Subjects
Physics, Frequency analysis, 010308 nuclear & particles physics, Phase (waves), Astronomy and Astrophysics, Astrophysics, Light curve, 01 natural sciences, law.invention, Photometry (optics), Stars, Amplitude, Space and Planetary Science, law, 0103 physical sciences, Binary star, Astrophysics::Solar and Stellar Astrophysics, Roche lobe, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics
Abstract

We present Kepler satellite photometry of KIC 10661783, a short-period binary star system which shows total eclipses and multi-periodic delta Scuti pulsations. A frequency analysis of the eclipse-subtracted light curve reveals at least 68 frequencies of which 55 or more can be attributed to pulsation modes. The main limitation on this analysis is the frequency resolution within the 27-day short-cadence light curve. Most of the variability signal lies in the frequency range 18 to 31 c/d, with amplitudes between 0.1 and 4 mmag. One harmonic term (2.f) and a few combination frequencies (f_i+f_j) have been detected. From a plot of the residuals versus orbital phase we assign the pulsations to the primary star in the system. The pulsations were removed from the short-cadence data and the light curve was modelled using the Wilson-Devinney code. We are unable to get a perfect fit due to the residual effects of pulsations and also to the treatment of reflection and reprocessing in the light curve model. A model where the secondary star fills its Roche lobe is favoured, which means that KIC 10661783 can be classified as an oEA system. Further photometric and spectroscopic observations will allow the masses and radii of the two stars to be measured to high precision and hundreds of delta Scuti pulsation frequencies to be resolved. This could lead to unique constraints on theoretical models of delta Scuti stars, if the evolutionary history of KIC 10661783 can be accounted for.

Published
2011

11. Kepler observations of the variability in B-type stars

Author

L. A. Balona, A. Pigulski, P. De Cat, G. Handler, J. Gutiérrez-Soto, C. A. Engelbrecht, F. Frescura, M. Briquet, J. Cuypers, J. Daszyńska-Daszkiewicz, P. Degroote, R. J. Dukes, R. A. Garcia, E. M. Green, U. Heber, S. D. Kawaler, H. Lehmann, B. Leroy, J. Molenda-Żakowicz, C. Neiner, A. Noels, J. Nuspl, R. Østensen, D. Pricopi, I. Roxburgh, S. Salmon, M. A. Smith, J. C. Suárez, M. Suran, R. Szabó, K. Uytterhoeven, null Christensen-Dalsgaard, H. Kjeldsen, D. A. Caldwell, F. R. Girouard, and D. T. Sanderfer

Subjects
Physics, Binary number, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Type (model theory), Rotation, Light curve, Instability, Spectral line, Stars, Space and Planetary Science, Modulation (music), Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The analysis of the light curves of 48 B-type stars observed by Kepler is presented. Among these are 15 pulsating stars, all of which show low frequencies characteristic of SPB stars. Seven of these stars also show a few weak, isolated high frequencies and they could be considered as SPB/beta Cep hybrids. In all cases the frequency spectra are quite different from what is seen from ground-based observations. We suggest that this is because most of the low frequencies are modes of high degree which are predicted to be unstable in models of mid-B stars. We find that there are non-pulsating stars within the beta Cep and SPB instability strips. Apart from the pulsating stars, we can identify stars with frequency groupings similar to what is seen in Be stars but which are not Be stars. The origin of the groupings is not clear, but may be related to rotation. We find periodic variations in other stars which we attribute to proximity effects in binary systems or possibly rotational modulation. We find no evidence for pulsating stars between the cool edge of the SPB and the hot edge of the delta Sct instability strips. None of the stars show the broad features which can be attributed to stochastically-excited modes as recently proposed. Among our sample of B stars are two chemically peculiar stars, one of which is a HgMn star showing rotational modulation in the light curve.

Published
2011

12. First Kepler results on compact pulsators - V. Slowly pulsating subdwarf B stars in short-period binaries

Author

Elizabeth M. Green, William J. Borucki, Conny Aerts, David G. Koch, J. Robinson, Roberto Silvotti, Gerald Handler, S. D. Kawaler, A. C. Quint, Stéphane Charpinet, Michael D. Reed, R. H. Østensen, Steven Bloemen, Jørgen Christensen-Dalsgaard, D. W. Kurtz, J. H. Telting, Andrzej S. Baran, and H. Kjeldsen

Subjects
Physics, Rotation period, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Orbital period, 01 natural sciences, Subdwarf, Tidal locking, Photometry (astronomy), Stars, Amplitude, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Multiplet, Astrophysics::Galaxy Astrophysics
Abstract

The survey phase of the Kepler Mission includes a number of hot subdwarf B (sdB) stars to search for nonradial pulsations. We present our analysis of two sdB stars that are found to be g-mode pulsators of the V1093 Her class. These two stars also display the distinct irradiation effect typical of sdB stars with a close M-dwarf companion with orbital periods of less than half a day. Because the orbital period is so short, the stars should be in synchronous rotation, and if so, the rotation period should imprint itself on the multiplet structure of the pulsations. However, we do not find clear evidence for such rotational splitting. Though the stars do show some frequency spacings that are consistent with synchronous rotation, they also display multiplets with splittings that are much smaller. Longer-duration time series photometry will be needed to determine if those small splittings are in fact rotational splitting, or caused by slow amplitude or phase modulation. Further data should also improve the signal-to-noise, perhaps revealing lower amplitude periodicities that could confirm the expectation of synchronous rotation. The pulsation periods seen in these stars show period spacings that are suggestive of high-overtone g-mode pulsations.

Published
2010

13. DQ Herculis in Profile: Whole Earth Telescope Observations and Smoothed Particle Hydrodynamics Simulations of an Edge‐on Cataclysmic Variable System

Author

M. A. Wood, J. R. Robertson, J. C. Simpson, S. D. Kawaler, M. S. O’Brien, R. E. Nather, D. E. Winget, M. H. Montgomery, T. S. Metcalfe, X. J. Jiang, E. M. Leibowitz, P. Ibbetson, D. O’Donoghue, S. Zola, J. Krzesinski, G. Pajdosz, G. Vauclair, N. Dolez, M. Chevreton, D. J. Sullivan, A. Kanaan, A. Nitta, Department of Physics and Space Sciences and SARA Observatory, Florida Institute of Technology, Melbourne, Department of Physics and Astronomy, Appalachian State University, Range Systems Design and Development Branch, NASA YA-D7, Department of Physics, Iowa State University, Department of Astronomy and McDonald Observatory, University of Texas, Austin, National Astronomical Observatoires-CAS, Department of Physics and Astronomy and Wise Observatory, South African Astronomical Observatory (SAAO), Astronomical Observatory, Jagiellonia University, Mount Suhora Observatory, Cracow Pedagogical University, Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Departement d'Astrophysique Extragalactique et de Cosmologie (DAEC), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, School of Chemical and Physical Sciences, Victoria University, Departamento de Física, Universidade Federal de Santa Catarina, and Apache Point Observatory

Subjects
novae, Physics, cataclysmic variables, Work (thermodynamics), Range (particle radiation), close [binaries], accretion disks, Phase (waves), Astronomy and Astrophysics, Function (mathematics), Astrophysics, law.invention, Smoothed-particle hydrodynamics, Telescope, accretion, Space and Planetary Science, law, hydrodynamics, Astrophysics::Solar and Stellar Astrophysics, individual (DQ Her) [stars], Degree (angle), Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Phase diagram
Abstract

International audience; The old nova DQ Herculis was the Whole Earth Telescope Northern Hemisphere target for the 1997 July campaign and was observed on four nights with the SARA 0.9 m telescope during 2003 June. We present updated ephemerides for the eclipse and 71 s timings. The Fourier transform displays power at the presumed white dwarf spin period of 71.0655 s, but no significant power at either 142 or 35.5 s. The mean pulsed light curve is obtained by folding on the orbital period modulus the mean ephemeris of the 71 s period, and from this we calculate an O-C phase diagram and amplitude versus orbital phase diagrams. In addition to the phase variations during eclipse ingress and egress, the WET data reveal significant phase variations outside of eclipse. These must result from the self-eclipse of a nonaxisymmetric disk. We simulated the disk in DQ Her using smoothed particle hydrodynamics. We improve our effective spatial signal-to-noise ratio by combining 250 snapshots of the N=20,000 phase space solution over time to obtain a 5 million particle ensemble disk. From the surface shape of the ensemble disk, the radius and vertical height above the midplane of the rim of the reprocessing region can be derived as a function of azimuthal angle. From this profile we can calculate the O-C phase and amplitude diagrams as a function of inclination angle. The calculated O-C diagrams are a remarkably good match to the observed phase and amplitude variations of the 71 s signal. The best match is for inclination angle 89.7d.

Published
2005

14. The long secondary periods in semi-regular variables

Author

S. D. Kawaler, P. R. Wood, and A. E. Olivier

Subjects
Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

About 25% of variable asymptotic giant branch stars in the LMC have light curves that are modulated by a long secondary period of length ~ 1–4 yr. Solar-vicinity analogs of these stars show radial velocity curves that are asymmetric and of small amplitude (~3–5km s−1). Possible explanations for the photometric and radial velocity variations include: eccentric motion of an orbiting companion of mass ~0.1 M⊙; radial and nonradial pulsation; rotation of an ellipsoidal-shaped red giant; episodic dust ejection; and star spot cycles. We find that there are severe difficulties with each of these models. Thus, the long secondary periods are the only unexplained type of large-amplitude stellar variability known at this time.

Published
2004

15. Whole Earth Telescope Headquarters Standard Data Formats

Author

R. L. Riddle and S. D. Kawaler

Subjects
Physics, Astronomy, data analysis, Astronomy and Astrophysics, QB1-991, law.invention, Telescope, photometric methods, Space and Planetary Science, law, Earth (chemistry), techniques, Remote sensing
Abstract

As the WET moves to CCD systems, we move away from the uniformity of the standard WET photometer into an arena where each system can be radically different. There are many possible CCD photometry systems that can fulfil the requirements of a WET instrument, but each of these will have their own unique native data format. During XCov22, it became readily apparent that the WET requires a defined data format for all CCD data that arrives at HQ. This paper describes the proposed format for the next generation of WET data; the final version will be the default format for XQED, the new photometry package discussed elsewhere in these proceedings.

Published
2003

16. Wet Observations of GD 358 in 2000

Author

J. E. Solheim, T. Sullivan, Paul A. Bradley, J. M. Gonzalez Perez, E. G. Meištas, Encarni Romero-Colmenero, E. W. Klumpe, Thorsten Nagel, G. Vauclair, Stefan Dreizler, Waldemar Ogloza, J. Xiaojun, P. Martinez, F. Johannessen, M. Chevreton, Antonio Kanaan, Matt A. Wood, Sonja Schuh, Martha L. Boyer, Nicole M. Silvestri, J. N. Fu, A. Ulla, Donald E Winget, Kazuhiro Sekiguchi, Staszek Zola, Denis J. Sullivan, T. S. Metcalfe, Jam Shaw, R. L. Riddle, Atsuko Nitta, E. R. Nather, J. L. Deetjen, Donal O'Donoghue, Souza Oliveira Kepler, A. F. Murillo Costa, S. D. Kawaler, J. E. S. Costa, Anjum S. Mukadam, J. Larrison, T. J. Ahrens, A. Kyle Jones, J. KrzesiŃski, S. J. Kleinman, R. Kalytis, R. Janulis, and A. E. Collins

Subjects
Physics, stars, lcsh:QB1-991, Stars, Space and Planetary Science, lcsh:Astronomy, evolution, Astronomy, Astronomy and Astrophysics, individual, GD 358 - stars, Astrobiology
Abstract

We report on the 323 hours of nearly uninterrupted time series photometric observations of the DBV star GD 358 acquired with the Whole Earth Telescope (WET) during May 23 to June 8, 2000. We acquired more than 232 000 independent measurements and detected the non-radial g-modes consistent with degree ℓ = 1 and radial order 8 to 20 and their linear combinations up to 6th order. We also detect, for the first time, a high amplitude ℓ = 2 mode, with a period of 796 s. In the 2000 WET data, the largest amplitude modes are similar to those detected with the WET observations of 1990 and 1994, but the highest combination order previously detected was 4th order.

Published
2003

17. Looking for Trends in the Group Properties of Pulsating Subdwarf B Stars

Author

M. D. Reed, S. D. Kawaler, and S. J. Kleinman

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics
Abstract

We examine the pulsation properties for 13 members of the pulsating subdwarf B (sdBV, or EC 14026) class of stars. By looking at the pulsation structure of an entire class of stars, it may be possible to determine the various modes of pulsations (O’Brien 1998, Kleinman 1995). Unfortunately, when we examine the ensemble of pulsation periods in EC 14026 stars, we are only able to discern a simple correlation between pulsation period and gravity, and not any structure that might help with mode identification. So we can only report on the lack of structure in the pulsation periods and present some of the work underway, which we hope will identify modes in the future.

Published
2000

18. Understanding the Cool DA White Dwarf Pulsator, G29−38

Author

S. J. Kleinman, R. E. Nather, D. E. Winget, J. C. Clemens, P. A. Bradley, A. Kanaan, J. L. Provencal, C. F. Claver, T. K. Watson, K. Yanagida, A. Nitta, J. S. Dixson, M. A. Wood, A. D. Grauer, B. P. Hine, G. Fontaine, James Liebert, D. J. Sullivan, D. T. Wickramasinghe, N. Achilleos, T. M. K. Marar, S. Seetha, B. N. Ashoka, E. Meištas, E. M. Leibowitz, P. Moskalik, J. Krzesiński, J.‐E. Solheim, A. Bruvold, D. O'Donoghue, D. W. Kurtz, B. Warner, Peter Martinez, G. Vauclair, N. Dolez, M. Chevreton, M. A. Barstow, S. O. Kepler, O. Giovannini, T. Augusteijn, C. J. Hansen, and S. D. Kawaler

Subjects
010504 meteorology & atmospheric sciences, Stellar mass, oscillations [Stars], Fotometria estelar, Astrophysics, Massa estelar, 01 natural sciences, Measure (mathematics), Instability, Asteroseismology, white dwarfs [Stars], Photometry (optics), 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, individual (G29-38) [Stars], Linear combination, 010303 astronomy & astrophysics, Stellar evolution, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, White dwarf, Astronomy and Astrophysics, Estrutura estelar, Pulsacoes estelares, Anãs brancas, Space and Planetary Science
Abstract

The white dwarfs are promising laboratories for the study of cosmochronology and stellar evolution. Through observations of the pulsating white dwarfs, we can measure their internal structures and compositions, critical to understanding post-main-sequence evolution, along with their cooling rates, which will allow us to calibrate their ages directly. The most important set of white dwarf variables to measure are the oldest of the pulsators, the cool DA variables (DAVs), which have not been explored previously through asteroseismology due to their complexity and instability. Through a time-series photometry data set spanning 10 yr, we explore the pulsation spectrum of the cool DAV, G29-38 and find an underlying structure of 19 (not including multiplet components) normal-mode, probably l=1 pulsations amidst an abundance of time variability and linear combination modes. Modeling results are incomplete, but we suggest possible starting directions and discuss probable values for the stellar mass and hydrogen layer size. For the first time, we have made sense out of the complicated power spectra of a large-amplitude DA pulsator. We have shown that its seemingly erratic set of observed frequencies can be understood in terms of a recurring set of normal-mode pulsations and their linear combinations. With this result, we have opened the interior secrets of the DAVs to future asteroseismological modeling, thereby joining the rest of the known white dwarf pulsators.

Published
1998

19. Asteroseismology of a Star Cooled by Neutrino Emission: The Pulsating Pre–White Dwarf PG 0122+200

Author

P. Ibbetson, B. N. Ashoka, Pawel Moskalik, A. Nitta, T. Thomassen, O. Giovannini, J. Bhattacharya, S. Seetha, S. Hemar, S. J. Kleinman, Matt A. Wood, Denis J. Sullivan, J. E. Solheim, Judith L. Provencal, Donald E Winget, Xue-Jian Jiang, T. K. Watson, Jurek Krzesinski, J. C. Clemens, L. van Zyl, M. S. O'Brien, R. E. Nather, T. M. K. Marar, G. Vauclair, Brian Warner, Staszek Zola, G. Pajdosz, Souza Oliveira Kepler, S. D. Kawaler, Elia M. Leibowitz, M. Chevreton, N. Dolez, and Michael H. Montgomery

Subjects
Physics, Stars, Space and Planetary Science, Astronomy, White dwarf, Astronomy and Astrophysics, Astrophysics, Neutrino, Light curve, Stellar evolution, Asteroseismology, Luminosity, Lepton
Abstract

Observation of g-mode pulsations in the variable pre-white dwarf (GW Virginis) stars provides a unique means to probe their interiors and to study the late stages of stellar evolution. Multisite campaigns have in several cases proved highly successful in decoding pre-white dwarf light curves. Three previous attempts to untangle the pulsation spectrum of the coolest GW Virginis star, PG 0122+200, confirmed the existence of multiple g-modes but left the fundamental period spacing and therefore the star's mass and luminosity in doubt. We present an analysis based on new observations of PG 0122+200 obtained during a Whole Earth Telescope (WET) campaign conducted in the fall of 1996. Although our coverage was, because of bad weather, far poorer than in previous WET campaigns, we confirm the previous result that PG 0122+200 rotates once in 1.6 ± 0.1 days. The most likely period spacing supported by the data implies a mass of 0.69±0.03 M☉. Based on the best seismology we can currently do, the cooling of PG 0122+200 is dominated by neutrino losses. This is not true for all pre-white dwarf stars and makes PG 0122+200 the prime candidate for learning useful physics. Constraints placed on the cooling rate of PG 0122+200 by future measurement of dΠ/dt could provide a unique test of the standard theory of lepton interactions in the (experimentally unexplored) region of phase-space appropriate to pre-white dwarf interiors.

Published
1998

20. Asteroseismology of the Solar Analogs 16 Cyg A and B from Kepler Observations

Author

T. Stahn, S. Mathur, T. S. Metcalfe, J. Christensen-Dalsgaard, T. Appourchaux, Martin Still, H. M. Antia, R. L. Gilliland, B. Mosser, Guy R. Davies, G. Doğan, H. Kjeldsen, P. Eggenberger, D. Stello, Yvonne Elsworth, R. A. Garcia, O. L. Creevey, S. D. Kawaler, S. Basu, Andrea Miglio, Christoffer Karoff, William J. Chaplin, T. R. Bedding, S. T. Bryson, I. M. Brandão, D. Salabert, Mutlu Yildiz, S. Hekker, Laurent Gizon, Z. Celik, Clara Régulo, O. Benomar, Khadeejah A. Ibrahim, Todd C. Klaus, Jie Li, Sébastien Deheuvels, Roger T. Howe, Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Ege Üniversitesi, and Low Energy Astrophysics (API, FNWI)

Subjects
FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, stars: interiors, 01 natural sciences, 7. Clean energy, Asteroseismology, Photometry (optics), Spitzer Space Telescope, 0103 physical sciences, Differential rotation, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Stellar evolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, Earth and Planetary Astrophysics (astro-ph.EP), 010308 nuclear & particles physics, Astronomy and Astrophysics, stars: solar-type, Orbital period, Stars, Astrophysics - Solar and Stellar Astrophysics, Convection zone, 13. Climate action, Space and Planetary Science, stars: individual (HD 186408, HD 186427), stars: fundamental parameters, stars: oscillations, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

WOS: 000301297500010, The evolved solar-type stars 16 Cyg A and B have long been studied as solar analogs, yielding a glimpse into the future of our own Sun. The orbital period of the binary system is too long to provide meaningful dynamical constraints on the stellar properties, but asteroseismology can help because the stars are among the brightest in the Kepler field. We present an analysis of three months of nearly uninterrupted photometry of 16 Cyg A and B from the Kepler space telescope. We extract a total of 46 and 41 oscillation frequencies for the two components, respectively, including a clear detection of octupole (l = 3) modes in both stars. We derive the properties of each star independently using the Asteroseismic Modeling Portal, fitting the individual oscillation frequencies and other observational constraints simultaneously. We evaluate the systematic uncertainties from an ensemble of results generated by a variety of stellar evolution codes and fitting methods. The optimal models derived by fitting each component individually yield a common age (t = 6.8 +/- 0.4 Gyr) and initial composition (Z(i) = 0.024 +/- 0.002, Y-i = 0.25 +/- 0.01) within the uncertainties, as expected for the components of a binary system, bolstering our confidence in the reliability of asteroseismic techniques. The longer data sets that will ultimately become available will allow future studies of differential rotation, convection zone depths, and long-term changes due to stellar activity cycles., NASA's Science Mission Directorate; NASANational Aeronautics & Space Administration (NASA) [NNX09AE59G]; National Science FoundationNational Science Foundation (NSF) [NSF PHY05-51164]; Science and Technology Facilities CouncilScience & Technology Facilities Council (STFC) [ST/J001163/1], Funding for this Discovery mission is provided by NASA's Science Mission Directorate. This work was supported in part by NASA grant NNX09AE59G. Computational time on Kraken at the National Institute of Computational Sciences was provided through NSF TeraGrid allocation TG-AST090107. We acknowledge the KITP staff at UCSB for their warm hospitality during the research program "Asteroseismology in the Space Age." This research was supported in part by the National Science Foundation under Grant No. NSF PHY05-51164. The authors thank Jeff Hall, Todd Henry, Dave Soderblom, and Russel White for helpful discussions, as well as the entire Kepler team, without whom these results would not be possible. We also thank all funding councils and agencies that have supported the activities of the Kepler Asteroseismic Science Consortium Working Group 1, including the Pale Blue Dot Project hosted by White Dwarf Research Corporation (http://whitedwarf.org/palebluedot/).

Published
2012

21. Ensemble asteroseismology of solar-type stars with the NASA Kepler mission

Author

Mário J. P. F. G. Monteiro, Tiago L. Campante, L. Esch, William J. Borucki, M. D. Suran, Dennis Stello, Graham A. Verner, Travis S. Metcalfe, Jon M. Jenkins, Jørgen Christensen-Dalsgaard, Alfio Bonanno, Enrico Corsaro, William J. Chaplin, Andrea Miglio, D. Salabert, Savita Mathur, Orlagh Creevey, J. Van Cleve, Joanna Molenda-Żakowicz, I. M. Brandão, Daniel Huber, Steven J. Hale, Christoffer Karoff, Jérôme Ballot, G. Houdek, D. Pricopi, Aldo Serenelli, Rafael A. García, L. Girardi, Todd C. Klaus, Yvonne Elsworth, H. Bruntt, Patrick Gaulme, S. G. Sousa, Saskia Hekker, A.-M. Broomhall, Timothy R. Bedding, Roger New, P.-O. Quirion, Ian R. Stevens, Ning Gai, T. Appourchaux, Ronald L. Gilliland, V. Silva Aguirre, Michael Thompson, Sarbani Basu, Timothy R. White, S. D. Kawaler, Clara Régulo, Marc H. Pinsonneault, G. Doğan, K. Uytterhoeven, Timothy M. Brown, Anwesh Mazumdar, Hans Kjeldsen, Karen Kinemuchi, Rasmus Handberg, B. Mosser, Antonio Jiménez, School of Physics and Astronomy, University of Birmingham [Birmingham], Aarhus University [Aarhus], Yale University [New Haven], Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Sydney Institute for Astronomy (SIfA), The University of Sydney, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Space Telescope Science Institute (STSci), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), University of Vienna [Vienna], Iowa State University (ISU), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), University of Wrocław [Poland] (UWr), Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto = University of Porto, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Catania (OACT), Universidad de La Laguna [Tenerife - SP] (ULL), Instituto de Astrofisica de Canarias (IAC), Homi Bhabha National Institute (HBNI), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Materials and Engineering Research Institute [Sheffield] (MERI), Sheffield Hallam University, Ohio State University [Columbus] (OSU), Astronomical Institute of Romanian Academy, Romanian Academy, Canadian Space Agency (CSA), Institut d'Estudis Espacials de Catalunya (IEEC-CSIC), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, NASA Ames Research Center (ARC), Las Cumbres Observatory (LCO), Low Energy Astrophysics (API, FNWI), Stellar Astrophysics Centre [Aarhus] (SAC), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Universidade do Porto, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Faculdade de Ciências

Subjects
Astronomia, Física, Física [Ciências exactas e naturais], 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Asteroseismology, Kepler Input Catalog, Kepler-47, Physical sciences [Natural sciences], Astronomy, Physical sciences, Stellar dynamics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Kepler-62, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Multidisciplinary, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Stellar collision, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Exoplanet, Astrophysics - Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Kepler-62c
Abstract

In addition to its search for extra-solar planets, the NASA Kepler Mission provides exquisite data on stellar oscillations. We report the detections of oscillations in 500 solartype stars in the Kepler field of view, an ensemble that is large enough to allow statistical studies of intrinsic stellar properties (such as mass, radius and age) and to test theories of stellar evolution. We find that the distribution of observed masses of these stars shows intriguing differences to predictions from models of synthetic stellar populations in the Galaxy., 20 pages, including on-line supporting material

Published
2011

22. Evidence for the impact of stellar activity on the detectability of solar-like oscillations observed by Kepler

Author

Rasmus Handberg, Steven J. Hale, Roger New, Rafael A. García, Fergal Mullally, Dennis Stello, Alfio Bonanno, T. S. Metcalfe, Timothy R. Bedding, D. Salabert, G. Houdek, Jørgen Christensen-Dalsgaard, Christoffer Karoff, Hans Kjeldsen, Clara Régulo, Patrick Gaulme, Graham A. Verner, Saskia Hekker, Daniel Huber, Jérôme Ballot, E. Jarvis, Tiago L. Campante, J. Molenda-Zakowicz, Savita Mathur, A.-M. Broomhall, Michael Thompson, B. Mosser, Mário J. P. F. G. Monteiro, T. Appourchaux, O. Benomar, Yvonne Elsworth, Ian W. Roxburgh, R. L. Gilliland, Sarbani Basu, S. D. Kawaler, W. Wohler, Ian R. Stevens, Enrico Corsaro, William J. Chaplin, Jie Li, School of Physics and Astronomy, University of Birmingham, Sydney Institute for Astronomy (SIfA), INAF-Osservatorio Astrofisico di Catania (INAF-OACt), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Astronomy Unit, Queen Mary, Department of Astronomy, Yale University, Institut für Astronomie, Universität Wien (IfA), High Altitude Observatory, National Center for Atmospheric Research, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Etoile, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Materials Engineering Research Institute, Faculty of Arts, Computing, Engineering and Sciences, Sheffield Hallam University, Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Danish AsteroSeismology Centre (DASC), Astronomical Institute, University of Wroclaw, Centro de Astrofísica, Universidade do Porto, Space Telescope Science Institute (STScI), Department of Physics and Astronomy, Iowa State University, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Universidad de La Laguna [Tenerife - SP] (ULL), SETI Institute, NASA Ames Research Center, Moffett Field, Orbital Sciences Corporation, NASA Ames Research Center, Moffett Field, and Low Energy Astrophysics (API, FNWI)

Subjects
Physics, Convection, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Kepler, Stars, Amplitude, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Excited state, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Solar-like oscillations, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics
Abstract

We use photometric observations of solar-type stars, made by the NASA Kepler Mission, to conduct a statistical study of the impact of stellar surface activity on the detectability of solar-like oscillations. We find that the number of stars with detected oscillations fall significantly with increasing levels of activity. The results present strong evidence for the impact of magnetic activity on the properties of near-surface convection in the stars, which appears to inhibit the amplitudes of the stochastically excited, intrinsically damped solar-like oscillations., 16 pages, 4 figures, accepted for publication in Astrophysical Journal Letters; some references updated

Published
2011

23. Constructing a One-solar-mass Evolutionary Sequence Using Asteroseismic Data from Kepler

Author

Alfio Bonanno, Axel Weiss, D. Salabert, V. Silva Aguirre, Mário J. P. F. G. Monteiro, Graham A. Verner, G. Houdek, A.-M. Broomhall, E. Corsaro, R. L. Gilliland, Jessie L. Christiansen, H. Bruntt, William J. Chaplin, J. Molenda-Zakowicz, A. M. Serenelli, S. G. Sousa, T. Appourchaux, Savita Mathur, D. A. Caldwell, J. Christensen-Dalsgaard, Timothy R. Bedding, Ralph Schönrich, Michael Thompson, B. Mosser, H. Kjeldsen, J. Ballot, S. Basu, T. S. Metcalfe, B. Wohler, Timothy R. White, Daniel Huber, R. A. Garcia, Rasmus Handberg, Andrea Miglio, Yvonne Elsworth, T. L. Campante, S. D. Kawaler, Luca Casagrande, Christoffer Karoff, S. Hekker, Patrick Gaulme, D. Stello, Laboratoire Hippolyte Fizeau (FIZEAU), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), and Low Energy Astrophysics (API, FNWI)

Subjects
Physics, Solar mass, Field (physics), 010308 nuclear & particles physics, Oscillation, FOS: Physical sciences, Astronomy and Astrophysics, Observable, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Asteroseismology, Stars, Photometry (astronomy), Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Frequency separation, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics
Abstract

Asteroseismology of solar-type stars has entered a new era of large surveys with the success of the NASA \textit{Kepler} mission, which is providing exquisite data on oscillations of stars across the Hertzprung-Russell (HR) diagram. From the time-series photometry, the two seismic parameters that can be most readily extracted are the large frequency separation ($\Delta\nu$) and the frequency of maximum oscillation power ($\nu_\mathrm{max}$). After the survey phase, these quantities are available for hundreds of solar-type stars. By scaling from solar values, we use these two asteroseismic observables to identify for the first time an evolutionary sequence of 1-M$_\odot$ field stars, without the need for further information from stellar models. Comparison of our determinations with the few available spectroscopic results shows an excellent level of agreement. We discuss the potential of the method for differential analysis throughout the main-sequence evolution, and the possibility of detecting twins of very well-known stars., Comment: 17 pages, 4 figures, accepted in ApJL

Published
2011

24. Solar-like Oscillations in KIC 11395018 and KIC 11234888 from 8 Months of Kepler Data

Author

S. D. Kawaler, J. Christensen-Dalsgaard, S. E. Seader, Mário J. P. F. G. Monteiro, Elisa V. Quintana, Timothy R. Bedding, Tiago L. Campante, Daniel Huber, H. Kjeldsen, T. S. Metcalfe, Rasmus Handberg, Graham A. Verner, Yvonne Elsworth, D. T. Sanderfer, Patrick Gaulme, O. L. Creevey, E. Corsaro, R. L. Gilliland, I. M. Brandão, S. Hekker, Michael Thompson, Timothy R. White, B. Mosser, J. Ballot, Christoffer Karoff, T. Appourchaux, G. Doğan, William J. Chaplin, Steven J. Hale, Rafael A. García, O. Benomar, J. Molenda-Zakowicz, Savita Mathur, Alfio Bonanno, D. Salabert, G. Houdek, Clara Régulo, High Altitude Observatory, National Center for Atmospheric Research, Danish AsteroSeismology Centre (DASC), Centro de Astrofísica, Universidade do Porto, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Sydney Institute for Astronomy (SIfA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), School of Physics and Astronomy, University of Birmingham, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), INAF-Osservatorio Astrofisico di Catania (INAF-OACt), Universidad de La Laguna [Tenerife - SP] (ULL), Astronomy Unit, Queen Mary, Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Institut für Astronomie, Universität Wien (IfA), Astronomical Institute, University of Wroclaw, Space Telescope Science Institute (STScI), Department of Physics and Astronomy, Iowa State University, SETI Institute, NASA Ames Research Center, Moffett Field, and Low Energy Astrophysics (API, FNWI)

Subjects
Physics, Oscillation, Stellar rotation, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Radius, Stellar classification, Stars, Laser linewidth, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Solar-like oscillations, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Solar and Stellar Astrophysics (astro-ph.SR), Envelope (waves)
Abstract

We analyze the photometric short-cadence data obtained with the Kepler Mission during the first eight months of observations of two solar-type stars of spectral types G and F: KIC 11395018 and KIC 11234888 respectively, the latter having a lower signal-to-noise ratio compared to the former. We estimate global parameters of the acoustic (p) modes such as the average large and small frequency separations, the frequency of the maximum of the p-mode envelope and the average linewidth of the acoustic modes. We were able to identify and to measure 22 p-mode frequencies for the first star and 16 for the second one even though the signal-to-noise ratios of these stars are rather low. We also derive some information about the stellar rotation periods from the analyses of the low-frequency parts of the power spectral densities. A model-independent estimation of the mean density, mass and radius are obtained using the scaling laws. We emphasize the importance of continued observations for the stars with low signal-to-noise ratio for an improved characterization of the oscillation modes. Our results offer a preview of what will be possible for many stars with the long data sets obtained during the remainder of the mission., Comment: 39 pages, 9 figures. Accepted for publication in ApJ

Published
2011

25. Kepler Asteroseismology Program: Introduction and First Results

Author

D. W. Latham, Jason F. Rowe, T. Appourchaux, Jonas Debosscher, Torben Arentoft, Jørgen Christensen-Dalsgaard, Travis S. Metcalfe, J. A. Guzik, Juan Carlos Suárez, Katrien Kolenberg, D. W. Kurtz, Yvonne Elsworth, Timothy R. Bedding, Margarida S. Cunha, Jon M. Jenkins, L. A. Balona, Hans Kjeldsen, William J. Chaplin, Jason H. Steffen, László L. Kiss, David G. Koch, P.-O. Quirion, Yoji Kondo, P. De Cat, William J. Borucki, Gerald Handler, Mário J. P. F. G. Monteiro, J. De Ridder, Conny Aerts, Sarbani Basu, S. D. Kawaler, Ronald L. Gilliland, Dennis Stello, Róbert Szabó, Timothy M. Brown, and Faculdade de Ciências

Subjects
Physics, Astronomia, Física, Física [Ciências exactas e naturais], 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Kepler, Asteroseismology, Photometry (optics), Stars, Physical sciences [Natural sciences], Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astronomy, Physical sciences, 0103 physical sciences, Solar-like oscillations, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Asteroseismology involves probing the interiors of stars and quantifying their global properties, such as radius and age, through observationsof normal modes of oscillation. The technical requirements for conducting asteroseismology include ultra-high precision measured in photometry in parts per million, as well as nearly continuous time series over weeks to years, and cadences rapid enough to sample oscillations with periods as shortas a few minutes. We report on results from the first 43 days of observations in which the unique capabilities of Kepler in providing a revolutionary advance in asteroseismology are already well in evidence. The Kepler asteroseismology program holds intrinsic importance in supporting the core planetary search program through greatly enhanced knowledge of host star properties, and extends well beyond this to rich applications in stellar astrophysics., Comment: 30 pages, 9 figures, PASP in press (Feb 2010)

Published
2010

26. Whole Earth Telescope observations of the pulsating subdwarf B star PG 0014+067

Author

M. Vučković, S. D. Kawaler, S. O’Toole, Z. Csubry, A. Baran, S. Zola, P. Moskalik, E. W. Klumpe, R. Riddle, M. S. O’Brien, F. Mullally, M. A. Wood, V. Wilkat, A.‐Y. Zhou, M. D. Reed, D. M. Terndrup, D. J. Sullivan, S.‐L. Kim, W. P. Chen, C.‐W. Chen, W.‐S. Hsiao, K. Sanchawala, H.‐T. Lee, X. J. Jiang, R. Janulis, M. Siwak, W. Ogloza, M. Paparo, Zs. Bognar, A. Sodor, G. Handler, D. Lorenz, B. Steininger, R. Silvotti, G. Vauclair, R. Oreiro, R. Ostensen, A. Bronowska, B. G. Castanheira, S. O. Kepler, L. Fraga, H. L. Shipman, J. L. Provencal, and D. Childers

Subjects
Subdwarf B star, oscillations [Stars], Subdwarfs, FOS: Physical sciences, Astrophysics, Star (graph theory), law.invention, Telescope, Observacoes astronomicas, law, Telescopios, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Astrophysics (astro-ph), High mode, Astronomy and Astrophysics, Subdwarf, Stars, Space and Planetary Science, Pulsacoes estelares, Anãs brancas, individual (PG 0014+067) [Stars], Astrophysics::Earth and Planetary Astrophysics, Longitude, Earth (classical element)
Abstract

PG 0014+067 is one of the most promising pulsating subdwarf B stars for seismic analysis, as it has a rich pulsation spectrum. The richness of its pulsations, however, poses a fundamental challenge to understanding the pulsations of these stars, as the mode density is too complex to be explained only with radial and nonradial low degree (l < 3) p-modes without rotational splittings. One proposed solution, for the case of PG 0014+067 in particular, assigns some modes with high degree (l=3). On the other hand, theoretical models of sdB stars suggest that they may retain rapidly rotating cores, and so the high mode density may result from the presence of a few rotationally-split triplet (l=1), quintuplet (l=2) modes, along with radial (l=0) p-modes. To examine alternative theoretical models for these stars, we need better frequency resolution and denser longitude coverage. Therefore, we observed this star with the Whole Earth Telescope for two weeks in October 2004. In this paper we report the results of Whole Earth Telescope observations of the pulsating subdwarf B star PG 0014+067. We find that the frequencies seen in PG 0014+067 do not appear to fit any theoretical model currently available; however, we find a simple empirical relation that is able to match all of the well-determined frequencies in this star., 19 pages, preprint of paper accepted for publication in The Astrophysical Journal

Published
2006

27. Whole Earth Telescope observations of BPM 37093: A seismological test of crystallization theory in white dwarfs

Author

A. Kanaan, A. Nitta, D. E. Winget, S. O. Kepler, M. H. Montgomery, T. S. Metcalfe, H. Oliveira, L. Fraga, A. F. M. da Costa, J. E. S. Costa, B. G. Castanheira, O. Giovannini, R. E. Nather, A. Mukadam, S. D. Kawaler, M. S. O'Brien, M. D. Reed, S. J. Kleinman, J. L. Provencal, T. K. Watson, D. Kilkenny, D. J. Sullivan, T. Sullivan, B. Shobbrook, X. J. Jiang, B. N. Ashoka, S. Seetha, E. Leibowitz, P. Ibbetson, H. Mendelson, E. G. Meištas, R. Kalytis, D. Ališauskas, D. O'Donoghue, D. Buckley, P. Martinez, F. van Wyk, R. Stobie, F. Marang, L. van Zyl, W. Ogloza, J. Krzesinski, S. Zola, P. Moskalik, M. Breger, A. Stankov, R. Silvotti, A. Piccioni, G. Vauclair, N. Dolez, M. Chevreton, J. Deetjen, S. Dreizler, S. Schuh, J. M. Gonzalez Perez, R. Østensen, A. Ulla, M. Manteiga, O. Suarez, M. R. Burleigh, M. A. Barstow, Departamento de Física (CFM), Universidade Federal de Santa Catarina, Apache Point Observatory, Department of Astronomy, University of Texas, Instituto de Física, Universidade Federal do Rio Grande do Sul, Institute of Astronomy, University of Cambridge (IoA), Harvard-Smithsonian Center for Astrophysics, Departamento de Física e Química, Universidade de Caxias do Sul, Department of Physics and Astronomy, Iowa State University, Department of Physics and Astronomy, University of Delaware, Southwestern University, South African Astronomical Observatory (SAAO), Victoria University of Wellington, Chatterton Astronomy Department, University of Sydney, Astronomical Observatory, Academy of Sciences, Indian Space Research Organization, Tel Aviv University (TAU), Institute of Theoretical Physics and Astronomy, Vilnius University, Vilnius University, Mount Suhora Observatory, Cracow Pedagogical University, Centrum Astronomiczne im. M. Kopernika, Warszawa (CAMK), Institut für Astronomie, Universität Wien (IfA), INAF-Osservatorio Astronomico di Capodimonte (INAF-OAC), Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Observatoire de Paris, Université Paris sciences et lettres (PSL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, University of Tromsø, Isaac Newton Group of Telescopes, Universidade de Vigo, and University of Leicester

Subjects
010504 meteorology & atmospheric sciences, Stellar mass, oscillations [Stars], Hidrogênio, evolution [Stars], FOS: Physical sciences, Astrophysics, Trapping, Massa estelar, 01 natural sciences, law.invention, Telescope, law, Evolucao estelar, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Crystallization, individual: BPM 37093 [Stars], 010303 astronomy & astrophysics, evolution, individual, BPM 37093, interiors, stars, oscillations, white dwarfs, 0105 earth and related environmental sciences, Physics, SIMPLE (dark matter experiment), Astrophysics (astro-ph), interiors [Stars], White dwarfs, White dwarf, Astronomy and Astrophysics, Estrelas variaveis, Core (optical fiber), Anãs brancas, Pulsacoes estelares, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Interior estelar, Instability strip, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

BPM 37093 is the only hydrogen-atmosphere white dwarf currently known which has sufficient mass (~ 1.1 M_sun) to theoretically crystallize while still inside the ZZ Ceti instability strip (T_eff ~ 12,000 K). As a consequence, this star represents our first opportunity to test crystallization theory directly. If the core is substantially crystallized, then the inner boundary for each pulsation mode will be located at the top of the solid core rather than at the center of the star, affecting mainly the average period spacing. This is distinct from the "mode trapping" caused by the stratified surface layers, which modifies the pulsation periods more selectively. In this paper we report on Whole Earth Telescope observations of BPM 37093 obtained in 1998 and 1999. Based on a simple analysis of the average period spacing we conclude that a large fraction of the total stellar mass is likely to be crystallized., Comment: 7 pages, 3 figures, 3 tables, accepted for Astronomy & Astrophysics

Published
2005

28. Pushing the ground-based limit : 14-$\mu$mag photometric precision with the definitive Whole Earth Telescope asteroseismic data set for the rapidly oscillating Ap star HR 1217

Author

K. Sekiguchi, R. R. Shobbrook, Antonio Kanaan, Jaymie M. Matthews, P. V. Birch, J. E. Solheim, B. N. Ashoka, L. Bigot, Paul A. Bradley, Souza Oliveira Kepler, Michael D. Reed, S. Seetha, R. L. Riddle, Denis J. Sullivan, S. D. Kawaler, T. K. Watson, Chris Cameron, O. Giovannini, M. Mueller, T. Sullivan, D. W. Kurtz, Anjum S. Mukadam, Donald E Winget, Donal O'Donoghue, Travis S. Metcalfe, F. Johannessen, V. Girish, E. Pallier, Matt A. Wood, S. J. Kleinman, Margarida S. Cunha, Santosh Joshi, Ana Ulla, Luciano Fraga, Atsuko Nitta, R. E. Nather, Staszek Zola, Joyce A. Guzik, G. Vauclair, Gerald Handler, Pawel Moskalik, J. M. Gonzalez Perez, Xiao-Jun Jiang, Nicole M. Silvestri, N. Dolez, and A. F. M. da Costa

Subjects
Physics, oscillations [stars], Frequency analysis, variables: other [stars], Astronomy, Perturbation (astronomy), Astronomy and Astrophysics, Observable, Astrophysics, law.invention, Magnetic field, Telescope, Stars, individual: HR 1217 [stars], Space and Planetary Science, law, Astrophysics::Solar and Stellar Astrophysics, Limit (mathematics), magnetic fields [stars], Rapidly oscillating Ap star
Abstract

HR 1217 is one of the best-studied rapidly oscillating Ap (roAp) stars, with a frequency spectrum of alternating even- and odd-� modes that are distorted by the presence of a strong, global magnetic field. Several recent theoretical studies have found that within the observable

Published
2005

29. A Strong Test of Electro-Weak Theory using Pulsating DB White Dwarf Stars as Plasmon Neutrino Detectors

Author

Don Winget, Denis J. Sullivan, T. S. Metcalfe, S. D. Kawaler, and Michael H. Montgomery

Subjects
Physics, Stellar mass, Electroweak interaction, Astrophysics (astro-ph), White dwarf, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Photon energy, Neutrino detector, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Neutrino, Instability strip, Lepton
Abstract

We demonstrate that plasmon neutrinos are the dominant form of energy loss in model white dwarf stars down to T_eff ~ 25,000 K, depending on the stellar mass. The lower end of this range overlaps the observed temperatures for the V777 Her star (DBV) instability strip. The evolution of white dwarfs at these temperatures is driven predominantly by cooling, so this directly affects the stellar evolutionary timescale in proportion to the ratio of the neutrino energy loss to the photon energy loss. This evolutionary timescale is observable through the time rate of change of the pulsation periods. Although the unified electro-weak theory of lepton interactions that is crucial for understanding neutrino production has been well tested in the high energy regime, the approach presented here should result in an interesting low-energy test of the theory. We discuss observational strategies to achieve this goal., 4 pages emulateapj, 3 figures, accepted for ApJ Letters

Published
2003

30. Amplitude and frequency variability of the pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 observed with the Whole Earth Telescope

Author

G. Handler, D. O'Donoghue, M. Muller, J.- E. Solheim, J. M. Gonzalez-Perez, F. Johannessen, M. Paparo, B. Szeidl, G. Viraghalmy, R. Silvotti, G. Vauclair, N. Dolez, E. Pallier, M. Chevreton, D. W. Kurtz, G. E. Bromage, M. S. Cunha, R. Ostensen, L. Fraga, A. Kanaan, A. Amorim, O. Giovannini, S. O. Kepler, A. F. M. Da Costa, R. F. Anderson, M. A. Wood, N. Silvestri, E. W. Klumpe, R. F. Carlton, R. H. Miller, J. P. McFarland, A. D. Grauer, S. D. Kawaler, R. L. Riddle, M. D. Reed, R. E. Nather, D. E. Winget, J. A. Hill, T. S. Metcalfe, A. S. Mukadam, M. Kilic, T. K. Watson, S. J. Kleinman, A. Nitta, J. A. Guzik, P. A. Bradley, K. Sekiguchi, D. J. Sullivan, T. Sullivan, R. R. Shobbrook, X. Jiang, P. V. Birch, B. N. Ashoka, S. Seetha, V. Girish, S. Joshi, T. N. Dorokhova, N. I. Dorokhov, M. C. Akan, E. G. Meistas, R. Janulis, R. Kalytis, D. Alisauskas, S. K. Anguma, P. C. Kalebwe, P. Moskalik, W. Ogloza, G. Stachowski, G. Pajdosz, S. Zola, Ege Üniversitesi, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
010504 meteorology & atmospheric sciences, individual: KUV 05134+2605 [Stars], oscillations [Stars], FOS: Physical sciences, Fotometria estelar, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, stars : individual : KUV 05134+2605, 01 natural sciences, stars : oscillations, law.invention, Telescope, Photometry (optics), stars : individual : PG 1654+160, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, individual: PG 1654+160 [Stars], 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Astrophysics (astro-ph), White dwarf, Astronomy and Astrophysics, stars : variables : other, Estrelas variaveis, variables: other [Stars], Stars, Amplitude, [SDU]Sciences of the Universe [physics], Pulsacoes estelares, Anãs brancas, Space and Planetary Science, Mode coupling, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

WOS: 000182039700036, We have acquired new time series photometry of the two pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 with the Whole Earth Telescope. Additional single-site photometry is also presented. We use all these data plus all available archival measurements to study the temporal behaviour of the pulsational amplitudes and frequencies of these stars for the first time. We demonstrate that both KUV 05134+2605 and PG 1654+160 pulsate in many modes, the amplitudes of which are variable in time; some frequency variability of PG 1654+160 is also indicated. Beating of multiple pulsation modes cannot explain our observations; the amplitude variability must therefore be intrinsic. We cannot find stable modes to be used for determinations of the evolutionary period changes of the stars. Some of the modes of PG 1654+160 appear at the same periods whenever detected. The mean spacing of these periods (approximate to40 s) suggests that they are probably caused by non-radial gravity-mode pulsations of spherical degree l = 1. If so, PG 1654+160 has a mass around 0.6 M.. The time-scales of the amplitude variability of both stars (down to two weeks) are consistent with theoretical predictions of resonant mode coupling, a conclusion which might however be affected by the temporal distribution of our data.

Published
2003

31. Wet Observations of PG 1159–035

Author

Howard E. Bond, Donald E Winget, Stefan Dreizler, M. S. O'Brien, J. E. S. Costa, Souza Oliveira Kepler, and S. D. Kawaler

Subjects
stars, lcsh:QB1-991, Physics, Stars, lcsh:Astronomy, Space and Planetary Science, PG 1159-035, pulsations - stars, Astronomy, Astronomy and Astrophysics, individual, Astrobiology
Abstract

PG 1159-035 has been observed with the Whole Earth Telescope on XCov3, 9, 19 and 22. In this work we present a brief summary of the campaigns.

Published
2003

32. High Precision with the Whole Earth Telescope: Lessons and Some Results from XCov20 for the roAp Star HR 1217

Author

Michael D. Reed, R. E. Nather, R. L. Riddle, Souza Oliveira Kepler, Don Winget, S. Zola, Santosh Joshi, Joyce A. Guzik, P. V. Birch, S. D. Kawaler, E. Pallier, Pawel Moskalik, Chris Cameron, Matt A. Wood, Antonio Kanaan, Margarida S. Cunha, Jaymie M. Matthews, S. Seetha, O. Giovannini, J. E. Solheim, Ana Ulla, V. Girish, M. Mueller, Denis J. Sullivan, B. N. Ashoka, J. M. Gonzalez Perez, T. Sullivan, T. K. Watson, G. Vauclair, D. W. Kurtz, Kazuhiro Sekiguchi, Atsuko Nitta, Travis S. Metcalfe, F. Johannessen, Nicole M. Silvestri, Luciano Fraga, Donal O'Donoghue, Anjum S. Mukadam, Xiao-Jun Jiang, R. R. Shobbrook, Gerald Handler, Scot Kleinman, A. F. M. da Costa, and N. Dolez

Subjects
stars, Physics, lcsh:Astronomy, Astronomy, Astronomy and Astrophysics, Astrophysics, Star (graph theory), law.invention, lcsh:QB1-991, Telescope, Stars, HR1217, Space and Planetary Science, law, roAp stars - stars, Astrophysics::Solar and Stellar Astrophysics, individual
Abstract

HR1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of nonradial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of 33.3 μHz and 34.6 μHz, with a sixth mode at a problematic spacing of 50.0 μHz (which equals 1.5 × 33.3 μHz) to the highfrequency side. Asymptotic pulsation theory allowed for a frequency spacing of 34 μHz, but hipparcos observations rule out such a spacing. Theoretical calculations of magnetoacoustic modes in Ap stars by Cunha (2001) predicted that there should be a previously undetected mode 34 μHz higher than the main group, with a smaller spacing between it and the highest one. The 20th extended coverage campaign of the Whole Earth Telescope (XCov20) has discovered this frequency as predicted by Cunha (2001). Amplitude modulation of several of the pulsation modes between the 1986 and 2000 data sets has also been discovered, while important parameters for modelling the geometry of the pulsation modes have been shown to be unchanged. With stringent selection of the best data from the WET network the amplitude spectrum shows highest peaks at only 50 μmag and formal errors on the determined amplitudes are 14 μmag. Some lessons for future use of WET for the highest precision photometry on bright stars are discussed.

Published
2003

33. WET Observations of the DAV G185-32

Author

Tsevi Mazeh, Paul A. Bradley, S. Zola, Don Winget, B. Pfeiffer, J. Krzesinski, A. V. Chernyshev, R. E. Nather, B. Serre, Matt A. Wood, G. Pajdosz, J. E. S. Costa, M. Chevreton, Anne E. Sansom, B. N. Ashoka, N. Dolez, Barbara G. Castanheira, Elia M. Leibowitz, J. E. Solheim, Souza Oliveira Kepler, S. D. Kawaler, J. N. Fu, T. K. Watson, S. J. Kleinman, E. G. Meištas, J. C. Clemens, Antonio Kanaan, T. M. K. Marar, Nicholas Achilleos, J.S. Yang, Judith L. Provencal, G. Vauclair, Pawel Moskalik, Juan Antonio Belmonte, Albert D. Grauer, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
stars, Physics, lcsh:Astronomy, Astrophysics::High Energy Astrophysical Phenomena, pulsations - stars, White dwarf, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, G185-32, lcsh:QB1-991, Stars, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, individual, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics
Abstract

The pulsating DAV white dwarf G185-32 was observed with the Whole Earth Telescope in 1992, during XCov8. We briefly report on the weighted Fourier transform of the data obtained.

Published
2003

34. The EC14026 Stars: A New Class of Pulsating Star

Author

R. S. Stobie, Darragh O'Donoghue, A. E. Lynas-Gray, D. Kilkenny, Chris Koen, and S. D. Kawaler

Subjects
Physics, Stars, T Tauri star, Stellar mass loss, K-type main-sequence star, Flare star, Astrophysics, Herbig Ae/Be star, Asteroseismology, Subdwarf
Abstract

Hot subdwarfs comprise typically 50 per cent of faint blue star surveys at high galactic latitude (e.g. the Palomar-Green (PG) survey: Green, Schmidt & Liebert 1986; the Edinburgh-Cape (EC) survey: Stobie et al. 1996a, Kilkenny et al. 1996a). In contrast to the PG survey, the EC survey has found that a large fraction (~ 15 per cent) of its hot subdwarf sample is comprised of sdB stars showing the Can K line. This implies that the hot subdwarf has a relatively luminous companion of spectral type F or G.

Published
1997

35. TESTING SCALING RELATIONS FOR SOLAR-LIKE OSCILLATIONS FROM THE MAIN SEQUENCE TO RED GIANTS USINGKEPLERDATA

Author

Steven J. Hale, Rafael A. García, Alfio Bonanno, Savita Mathur, Jeffrey C. Smith, D. Salabert, V. Silva Aguirre, Graham A. Verner, Enrico Corsaro, William J. Chaplin, G. Houdek, J. Molenda-Zakowicz, Derek Buzasi, Hans Kjeldsen, T. Appourchaux, S. E. Seader, Mário J. P. F. G. Monteiro, J. De Ridder, Tiago L. Campante, R. L. Gilliland, A.-M. Broomhall, Jørgen Christensen-Dalsgaard, D. T. Sanderfer, Yvonne Elsworth, Dennis Stello, B. Mosser, Thomas Kallinger, Daniel Huber, S. Frandsen, Timothy R. Bedding, S. D. Kawaler, Saskia Hekker, Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Low Energy Astrophysics (API, FNWI)

Subjects
Physics, Stellar mass, 010308 nuclear & particles physics, Subgiant, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Effective temperature, 01 natural sciences, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Solar-like oscillations, Instability strip, 010303 astronomy & astrophysics, Red clump, Scaling, ComputingMilieux_MISCELLANEOUS, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics
Abstract

We have analyzed solar-like oscillations in ~1700 stars observed by the Kepler Mission, spanning from the main-sequence to the red clump. Using evolutionary models, we test asteroseismic scaling relations for the frequency of maximum power (nu_max), the large frequency separation (Delta_nu) and oscillation amplitudes. We show that the difference of the Delta_nu-nu_max relation for unevolved and evolved stars can be explained by different distributions in effective temperature and stellar mass, in agreement with what is expected from scaling relations. For oscillation amplitudes, we show that neither (L/M)^s scaling nor the revised scaling relation by Kjeldsen & Bedding (2011) are accurate for red-giant stars, and demonstrate that a revised scaling relation with a separate luminosity-mass dependence can be used to calculate amplitudes from the main-sequence to red-giants to a precision of ~25%. The residuals show an offset particularly for unevolved stars, suggesting that an additional physical dependency is necessary to fully reproduce the observed amplitudes. We investigate correlations between amplitudes and stellar activity, and find evidence that the effect of amplitude suppression is most pronounced for subgiant stars. Finally, we test the location of the cool edge of the instability strip in the Hertzsprung-Russell diagram using solar-like oscillations and find the detections in the hottest stars compatible with a domain of hybrid stochastically excited and opacity driven pulsation., 11 pages, 9 figures, accepted for publication in ApJ

Published
2011

36. Kepler detected gravity-mode period spacings in a red giant star

Author

Arlette Noels, Thomas Kallinger, Josefina Montalbán, Fabien Carrier, Saskia Hekker, Hans Kjeldsen, J. De Ridder, Yvonne Elsworth, Paul G. Beck, Timothy R. Bedding, Savita Mathur, Jon M. Jenkins, Benoit Mosser, Dennis Stello, Andrea Miglio, Marc-Antoine Dupret, Rafael A. García, S. Frandsen, S. D. Kawaler, Daniel Huber, Timothy M. Brown, William J. Chaplin, Timothy R. White, Jørgen Christensen-Dalsgaard, Conny Aerts, R. L. Gilliland, Instituut voor Sterrenkunde [Leuven], Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Sydney Institute for Astronomy (SIfA), The University of Sydney, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Department of Physics and Astronomy [Vancouver], University of British Columbia (UBC), School of Physics and Astronomy, University of Birmingham [Birmingham], Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Department of Physics and Astronomy [Aarhus], Aarhus University [Aarhus], Space Telescope Science Institute (STSci), Las Cumbres Observatory Global Telescope, Department of Physics and Astronomy [Ames, Iowa], Iowa State University (ISU), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Search for Extraterrestrial Intelligence Institute (SETI), European Project: 227224,EC:FP7:ERC,ERC-2008-AdG,PROSPERITY(2009), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Low Energy Astrophysics (API, FNWI), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), and Stellar Astrophysics Centre [Aarhus] (SAC)

Subjects
Convection, Physics, Multidisciplinary, 010308 nuclear & particles physics, Oscillation, Red giant, Astronomy, Astrophysics, Giant star, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 01 natural sciences, Core (optical fiber), Solar core, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Satellite, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Envelope (waves)
Abstract

Asteroseismology Delivers Using asteroseismology—the study of stellar oscillations, it is possible to probe the interior of stars and to derive stellar parameters, such as mass and radius (see the Perspective by Montgomery ). Based on asteroseismic data from the NASA Kepler mission, Chaplin et al. (p. 213 ) detected solarlike oscillations in 500 solartype stars in our Galaxy. The distribution of the radii of these stars matches that expected from stellar evolution theory, but the distribution in mass does not, which challenges our knowledge of star formation rates, the mass of forming stars, and the models of the stars themselves. Derekas et al. (p. 216 ) report the detection of a triple-star system comprising a red giant star and two red dwarfs. The red giant star, instead of the expected solarlike oscillations, shows evidence for tidally induced oscillations driven by the orbital motion of the red dwarf pair. Finally, Beck et al. (p. 205 ) describe unusual oscillations from a red giant star that may elucidate characteristics of its core.

Published
2011

38. A Model Survey of DAV White Dwarfs

Author

S. D. Kawaler, S. J. Kleinman, and A. Bischoff

Subjects
Physics, White dwarf, Astrophysics
Abstract

We have created a grid of DAV (ZZ Ceti) pulsation models to test whether ensemble observations of DAV pulsation periods can be used to determine the nature of the DAV interiors.

Published
2000

39. Asteroseismology of the DOV star PG 1159 - 035 with the Whole Earth Telescope

Author

D. W. Kurtz, Donald E Winget, J. Brickhill, Brian Warner, S. Seetha, Marian L. Frueh, Nicholas Achilleos, J. C. Clemens, B. N. Ashoka, T. M. K. Marar, Antonio Kanaan, Carl J. Hansen, G. Vauclair, B. P. Hine, David A. H. Buckley, Dayal Wickramasinghe, D. O'Donoghue, M. Chevreton, Albert D. Grauer, Gregory W. Henry, Martin A. Barstow, Chuck Claver, Souza Oliveira Kepler, Matt A. Wood, J.-E. Solheim, Paul A. Bradley, S. D. Kawaler, Judith L. Provencal, R. E. Nather, N. Dolez, S. J. Kleinman, and Gilles Fontaine

Subjects
Rotation period, Physics, Solar mass, Dwarf star, Stellar rotation, Astronomy, White dwarf, Astronomy and Astrophysics, Astrophysics, Light curve, Asteroseismology, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Stellar pulsation
Abstract

Results are reported from 264.1 hr of nearly continuous time-series photometry on the pulsating prewhite dwarf star (DPV) PG 1159 - 035. The power spectrum of the data set is completely resolved into 125 individual frequencies; 101 of them are identified with specific quantized pulsation modes, and the rest are completely consistent with such modal assignment. It is argued that the luminosity variations are certainly the result of g-mode pulsations. Although the amplitudes of some of the peaks exhibit significant variations on the time scales of a year or so, the underlying frequency structure of the pulsations is stable over much longer intervals. The existing linear theory is invoked to determine, or strongly constrain, many of the fundamental physical parameters describing this star. Its mass is found to be 0.586 solar mass, is rotation period 1.38 days, its magnetic field less than 6000 G, its pulsation and rotation axes to be aligned, and its outer layers to be compositionally stratified.

Published
1991

40. Discovery and seismological interpretation of low-amplitude modes in the pulsating DO white dwarf PG 1707 + 427 (V817 Herculis)

Author

Don Winget, F. Wesemael, Gilles Fontaine, P. Bergeron, S. D. Kawaler, Albert D. Grauer, Pierre Brassard, and G. Vauclair

Subjects
Physics, Stellar mass, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Spherical harmonics, White dwarf, Spectral density, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Light curve, Asteroseismology, Amplitude, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Stellar pulsation
Abstract

We report the discovery of low-amplitude pulsation modes in the faint variable DO white dwarf PG 1707+427 (V817 Her). With the large aperture of the CFHT, enough modes were uncovered to allow us to derive a preliminary asteroseismological estimate of the mass of the star of approximately 0.7 M ⊙ . This assumes that the modes observed have a spherical harmonic index l=1

Published
1991

41. The EC 14026 stars - V. The pulsation periods of PB 8783

Author

M. S. O'Brien, Denis J. Sullivan, S. D. Kawaler, D. O'Donoghue, Martin A. Barstow, J. E. Solheim, J. C. Clemens, Paul Dobbie, and Chris Koen

Subjects
Physics, Rotation period, Photometry (optics), Stars, Frequency analysis, Amplitude, Space and Planetary Science, law, Astronomy and Astrophysics, Astrophysics, law.invention
Abstract

PB 8783 is a member of the newly discovered class of pulsating sdB stars, the EC 14026 stars. The potential of the pulsations of these stars as diagnostic probes of their interiors can only be realized fully by intensive campaigns of multisite time series photometry. To this end we have undertaken a campaign spanning 2 weeks and involving data from five different sites. 183 h of data were obtained. Frequency analysis yielded at least 11 pulsation periods in seven discrete groups between 94 and 136 s. Three of the periods in one specific group are equally spaced in frequency, with a spacing of 0.94 μHz. The frequency spacings amongst the members of other groups are similar to this. A rotation period of ∼12 d is implied. A general scheme for identifying the observed modes is suggested. The periods from a detailed model are in good overall agreement with the observed periods, but some difficulties remain. Three additional periods in the range 61–63 s, and with very low amplitude, were also found. No convincing interpretation of these could be devised.

42. PG 1605+072 in WET XCov22: Support for the Multi Site Spectroscopic Telescope

Author

Donal O'Donoghue, S. Dreizler, Souza Oliveira Kepler, S. D. Kawaler, Judith L. Provencal, Matthew R. Burleigh, Harry L. Shipman, Andrzej S. Baran, J. E. Solheim, Matt A. Wood, Paul A. Bradley, S. A. Good, K. Sekiguchi, Waldemar Ogloza, J. Xiaojun, Reed Riddle, S. Falter, S. L. Kim, O'Brien, O. Giovannini, Atsuko Nitta, R. Janulis, C. Akan, G. Viraghalmy, U. Heber, Maja Vučković, C. Clemens, M. Chevreton, T Laurance, Albert D. Grauer, Simon J. O'Toole, R. H. Østensen, N. Dolez, H Monteiro, Vincent M. Woolf, G. Vauclair, Ana Ulla, J. L. Deetjen, Ömür Çakırlı, Antonio Kanaan, A. V. Sergeev, Denis J. Sullivan, Roberto Silvotti, R. Crowe, Jes Costa, Mukremin Kilic, Gerald Handler, Thorsten Nagel, C. S. Jeffery, R. Rosen, Ö. Hürkal, H. Lee, Afm da Costa, S. Marinoni, Margit Paparo, Staszek Zola, E. W. Klumpe, Sonja Schuh, T. S. Metcalfe, Anjum S. Mukadam, E. Pakstiene, Jmg Perez, Fergal Mullally, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Ege Üniversitesi

Subjects
stars, lcsh:Astronomy, K-type main-sequence star, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, law.invention, lcsh:QB1-991, Telescope, law, Astrophysics::Solar and Stellar Astrophysics, individual, Astrophysics::Galaxy Astrophysics, Physics, interiors - stars, PG 1605+072, Astrophysics::Instrumentation and Methods for Astrophysics, Multi site, Astronomy, Astronomy and Astrophysics, T Tauri star, Space and Planetary Science, stars : interiors, stars : individual : PG 1605+072, Astrophysics::Earth and Planetary Astrophysics, Space Science, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

6th Whole Earth Telescope Workshop (WET) -- JUN 20-21, 2002 -- NAPLES, ITALY, WOS: 000184698800009, The Multi-site spectroscopic telescope is a virtual instrument and the name of a collaboration that opens up a new observational window by combining continuous observations of spectroscopic variations and simultaneous photometric monitoring. This constitutes an enormous observational effort, but in return promises to finally provide access to a mode identification for and an asteroseismological analysis of the pulsating sdB star PG 1605+072. Multi-Site Spectroscopic Telescope observations for this object have been secured during a large coordinated campaign in May and June of the year 2002. The frequency resolution and coverage of the photometric time series has been noticeably enhanced by a significant contribution from the Whole Earth Telescope, which was used to observe PG 1605+072 as an alternate target during the WET XCov22 campaign, also conducted in May 2002. This paper briefly outlines the motivation for the MSST project and tries to give a first assessment of the overall quality of the data obtained, with a focus on the Whole Earth Telescope observations.

43. Observations of the pulsating subdwarf B star Feige 48: Constraints on evolution and companions

Author

M. D. Reed, S. D. Kawaler, S. Zola, X. J. Jiang, S. Dreizler, S. L. Schuh, J. L. Deetjen, R. Kalytis, E. Meištas, R. Janulis, D. Ališauskas, J. Krzesiński, M. Vuckovic, P. Moskalik, W. Ogłoza, A. Baran, G. Stachowski, D. W. Kurtz, J. M. González Pérez, A. Mukadam, T. K. Watson, C. Koen, P. A. Bradley, M. S. Cunha, M. Kilic, E. W. Klumpe, R. F. Carlton, G. Handler, D. Kilkenny, R. Riddle, N. Dolez, G. Vauclair, M. Chevreton, M. A. Wood, A. Grauer, G. Bromage, J. E. Solheim, R. Østensen, A. Ulla, M. Burleigh, S. Good, Ö. Hürkal, R. Anderson, E. Pakstiene, Department of Physics, Astronomy, and Materials Science, Missouri State University, Department of Physics and Astronomy, Iowa State University, Astronomical Observatory, Jagiellonia University, National Astronomical Observatoires-CAS, Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Institute of Material Science and Applied Research of Vilnius University, Astronomical Observatory, Institute of Theoretical Physics and Astronomy, Astronomical Observatory, Mount Suhora Observatory, Cracow Pedagogical University, Centrum Astronomiczne im. M. Kopernika, Warszawa (CAMK), Centre for Astrophysics, University of Central Lancashire, Institutt for Fysikk, Universitetet i Tromsø, Department of Astronomy, University of Texas, Southwestern University, Los Alamos National Laboratory (LANL), Centro de Astrofisica da Universidade do Porto (CAUP), Department of Physics and Astronomy, Middle Tennessee State University, South African Astronomical Observatory (SAAO), Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Departement d'Astrophysique Extragalactique et de Cosmologie (DAEC), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Department of Physics and Space Sciences and SARA Observatory, Florida Institute of Technology, Melbourne, Department of Physics and Astronomy, University of Arkansas, Isaac Newton Group of Telescopes, Universidade de Vigo, Department of Physics and Astronomy, University of Leicester, Department of Astronomy and Space Sciences, Ege University, Department of Physics and Astronomy, University of North Carolina, and Ege Üniversitesi

Subjects
oscillations [stars], Subdwarf B star, stars : individual (Feige 48), FOS: Physical sciences, Astrophysics, Star (graph theory), 01 natural sciences, Stability (probability), stars : oscillations, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, individual (Feige 48) [stars], Physics, 010308 nuclear & particles physics, variables: other [stars], Astrophysics (astro-ph), Mode (statistics), Astronomy and Astrophysics, Horizontal branch, Subdwarf, stars : variables : other, Stars, Amplitude, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Since pulsating subdwarf B (sdBV or EC14026) stars were first discovered (Kilkenny et al, 1997), observational efforts have tried to realize their potential for constraining the interior physics of extreme horizontal branch (EHB) stars. Difficulties encountered along the way include uncertain mode identifications and a lack of stable pulsation mode properties. Here we report on Feige 48, an sdBV star for which follow-up observations have been obtained spanning more than four years, which shows some stable pulsation modes. We resolve the temporal spectrum into five stable pulsation periods in the range 340 to 380 seconds with amplitudes less than 1%, and two additional periods that appear in one dataset each. The three largest amplitude periodicities are nearly equally spaced, and we explore the consequences of identifying them as a rotationally split l=1 triplet by consulting with a representative stellar model. The general stability of the pulsation amplitudes and phases allows us to use the pulsation phases to constrain the timescale of evolution for this sdBV star. Additionally, we are able to place interesting limits on any stellar or planetary companion to Feige 48., accepted for publication in MNRAS

44. Evolutionary period changes in variable helium-rich white dwarfs

Author

Don Winget, S. D. Kawaler, I. Iben, and Carl J. Hansen

Subjects
Physics, Stellar mass, White dwarf, chemistry.chemical_element, Astronomy, Astronomy and Astrophysics, Astrophysics, chemistry, Space and Planetary Science, Period (geology), Variable star, Stellar evolution, Blue dwarf, Main sequence, Helium
Published
1986

45. The helium shell game - Nonradial g-mode instabilities in hydrogen-deficient planetary nebula nuclei

Author

Carl J. Hansen, S. D. Kawaler, I. Iben, and Don Winget

Subjects
Physics, Nuclear Theory, Shell (structure), White dwarf, Astronomy and Astrophysics, Astrophysics, Planetary nebula, Instability, Space and Planetary Science, Physics::Atomic and Molecular Clusters, Astrophysics::Solar and Stellar Astrophysics, Nuclear fusion, Physics::Atomic Physics, Magnetohydrodynamics, Stellar evolution, Stellar pulsation
Abstract

Preliminary results of fully nonadiabatic g-mode pulsation calculations for evolutionary models of hydrogen-deficient planetary nebula nuclei (PNNs) with active helium-burning shells are reported. Instabilities are found that are driven by the epsilon-mechanism at the position of the helium-burning shell. The periods of the unstable modes range from 50 to 214 s. In all models, the presence of an active nuclear burning shell demands that some g-modes are unstable. It is suggested that if hydrogen-deficient PNNs contain helium-burning shells, then they should show such pulsations. 23 references.

Published
1986

46. THE INTERNAL ROTATION PROFILE OF THE B-TYPE STAR KIC 10526294 FROM FREQUENCY INVERSION OF ITS DIPOLE GRAVITY MODES.

Author

S. A. Triana, E. Moravveji, P. I. Pápics, C. Aerts, S. D. Kawaler, and J. Christensen-Dalsgaard

Subjects
ANGULAR momentum (Nuclear physics), STELLAR rotation, SUPERGIANT stars, DIPOLE moments, STELLAR oscillations
Abstract

The internal angular momentum distribution of a star is the key to determining its evolution. Fortunately, stellar internal rotation can be probed through studies of rotationally split nonradial oscillation modes. In particular, the detection of nonradial gravity modes (g modes) in massive young stars has recently become feasible thanks to the Kepler space mission. Our goal is to derive the internal rotation profile of the Kepler B8V star KIC 10526294 through asteroseismology. We interpret the observed rotational splittings of its dipole g modes using four different approaches based on the best seismic models of the star and their rotational kernels. We show that these kernels can resolve differential rotation within the radiative envelope if a smooth rotational profile is assumed and if the observational errors are small. Based on Kepler data, we find that the rotation rate near the core-envelope boundary is well constrained to 163 ± 89 nHz. The seismic data are consistent with rigid rotation but a profile with counter-rotation within the envelope has a statistical advantage over constant rotation. Our study should be repeated for other massive stars with a variety of stellar parameters in order to determine the physical conditions that control the internal rotation profile of young massive stars, with the aim of improving the input physics of their models. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results