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9 results on '"Achim Weiss"'

1. The Complete Redshift Distribution of Dusty Star-forming Galaxies from the SPT-SZ Survey

Author

Ryley Hill, Daniel P. Marrone, Manuel Aravena, Matthew A. Malkan, M. Strandet, Sreevani Jarugula, W. B. Everett, Antony A. Stark, Scott Chapman, Yashar D. Hezaveh, Christopher C. Hayward, Cassie Reuter, Kedar A. Phadke, Thomas R. Greve, Matthieu Béthermin, Joaquin Vieira, M. Archipley, Justin Spilker, Katrina C. Litke, C. De Breuck, Chenxing Dong, Desika Narayanan, J. Fu, Achim Weiss, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Observational cosmology, 010504 meteorology & atmospheric sciences, Distribution (number theory), Early universe, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Star (graph theory), Astronomy & Astrophysics, 01 natural sciences, Atomic, Particle and Plasma Physics, Galaxy evolution, 0103 physical sciences, Galaxy formation and evolution, Nuclear, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Molecular, Astronomy and Astrophysics, Interstellar molecules, Astrophysics - Astrophysics of Galaxies, Galaxy, Redshift, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), High-redshift galaxies, Astrophysics::Earth and Planetary Astrophysics, Astronomical and Space Sciences, Physical Chemistry (incl. Structural)
Abstract

The South Pole Telescope (SPT) has systematically identified 81 high-redshift, strongly gravitationally lensed, dusty star-forming galaxies (DSFGs) in a 2500 square degree cosmological mm-wave survey. We present the final spectroscopic redshift survey of this flux-limited ($S_{870\, \mathrm{\mu m}} > 25\, \mathrm{mJy}$) sample, initially selected at $1.4$ mm. The redshift survey was conducted with the Atacama Large Millimeter/submillimeter Array across the $3$ mm spectral window, targeting carbon monoxide line emission. By combining these measurements with ancillary data, the SPT sample is now spectroscopically complete, with redshifts spanning $1.9$$$$5$, making this the largest sample of high-redshift DSFGs to-date, and enabling the "high-redshift tail" of extremely luminous DSFGs to be measured. Though galaxy formation models struggle to account for the SPT redshift distribution, the larger sample statistics from this complete and well-defined survey will help inform future theoretical efforts., Comment: 56 pages, 25 figures, accepted for publication in ApJ

Published
2020

2. Dense cores and star formation in the giant molecular cloud Vela C

Author

Frederic Schuller, Fabrizio Massi, Davide Elia, T. Hill, Frédérique Motte, Achim Weiss, Timea Csengeri, E. Schisano, Friedrich Wyrowski, M. De Luca, Luca Olmi, Francesco Strafella, Dario Lorenzetti, Teresa Giannini, Karl M. Menten, Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], Max Planck Institute for Radio Astronomy, Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Institute of Hydrology, INAF - Osservatorio Astronomico di Roma (OAR), Antarctic Research a European Network for Astrophysics (ARENA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Sciences pour l'environnement (SPE), Centre National de la Recherche Scientifique (CNRS)-Université Pascal Paoli (UPP), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Max-Planck-Institut für Radioastronomie (MPIFR), ITA, FRA, DEU, FORMATION STELLAIRE 2020, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Massi, F., Weiss, A., Elia, D., Csengeri, T., Schisano, E., Giannini, T., Hill, T., Lorenzetti, D., Menten, K., Olmi, L., Schuller, F., Strafella, F., De Luca, M., Motte, F., Wyrowski, F., Università degli Studi di Roma 'La Sapienza' [Rome], Osservatorio di Astrofisica di Roma (OAR), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Pascal Paoli (UPP)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), and École normale supérieure - Paris (ENS-PSL)

Subjects
Initial mass function, FOS: Physical sciences, Context (language use), Astrophysics, Vela, 01 natural sciences, 0103 physical sciences, protostar [Stars], individual objects: Vela Molecular Ridge [ISM], 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), formation [Stars], ComputingMilieux_MISCELLANEOUS, O-type star, Physics, [PHYS]Physics [physics], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, Molecular cloud, ISM [Submillimeter], Astronomy and Astrophysics, Galactic plane, Astrophysics - Astrophysics of Galaxies, Galaxy, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), structure [ISM], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Context The Vela Molecular Ridge is one of the nearest (700 pc) giant molecular cloud (GMC) complexes hosting intermediate-mass (up to early B, late O stars) star formation, and is located in the outer Galaxy, inside the Galactic plane. Vela C is one of the GMCs making up the Vela Molecular Ridge, and exhibits both sub-regions of robust and sub-regions of more quiescent star formation activity, with both low- and intermediate(high)-mass star formation in progress. Aims We aim to study the individual and global properties of dense dust cores in Vela C, and aim to search for spatial variations in these properties which could be related to different environmental properties and/or evolutionary stages in the various sub-regions of Vela C. Methods We mapped the submillimetre (345 GHz) emission from vela C with LABOCA (beam size 19.2", spatial resolution ~0.07 pc at 700 pc) at the APEX telescope. We used the clump-finding algorithm CuTEx to identify the compact submillimetre sources. We also used SIMBA (250 GHz) observations, and Herschel and WISE ancillary data. The association with WISE red sources allowed the protostellar and starless cores to be separated, whereas the Herschel dataset allowed the dust temperature to be derived for a fraction of cores. The protostellar and starless core mass functions (CMFs) were constructed following two different approaches, achieving a mass completeness limit of 3.7 Msun. Results We retrieved 549 submillimetre cores, 316 of which are starless and mostly gravitationally bound (therefore prestellar in nature). Both the protostellar and the starless CMFs are consistent with the shape of a Salpeter initial mass function in the high-mass part of the distribution. Clustering of cores at scales of 1--6 pc is also found, hinting at fractionation of magnetised, turbulent gas., Comment: 21 pages, 19 figures, to be published in Astronomy & Astrophysics

Published
2019

3. The ATLASGAL survey: distribution of cold dust in the Galactic plane. Combination with Planck data

Author

Silvia Leurini, Nicola Schneider, Henrik Beuther, Th. Henning, Achim Weiss, Friedrich Wyrowski, Leonardo Bronfman, Timea Csengeri, Sylvain Bontemps, James Urquhart, Frederic Schuller, Karl M. Menten, University of Edinburgh, Mars Desert Research Station (MDRS), Max-Planck-Institut für Radioastronomie (MPIFR), FORMATION STELLAIRE 2016, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Departamento de Astronomia (DAS)

Subjects
Milky Way, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, symbols.namesake, 0103 physical sciences, Planck, 10. No inequality, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, Degree (graph theory), 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, Galactic plane, Astrophysics - Astrophysics of Galaxies, Galaxy, Dust lane, Projection (relational algebra), Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), symbols, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA]
Abstract

Sensitive ground-based submillimeter surveys, such as ATLASGAL, provide a global view on the distribution of cold dense gas in the Galactic plane. Here we use the 353 GHz maps from the Planck/HFI instrument to complement the ground-based APEX/LABOCA observations with information on larger angular scales. The resulting maps reveal the distribution of cold dust in the inner Galaxy with a larger spatial dynamic range. We find examples of elongated structures extending over angular scales of 0.5 degree. Corresponding to >30 pc structures in projection at a distance of 3 kpc, these dust lanes are very extended and show large aspect ratios. Furthermore, we assess the fraction of dense gas ($f_{\rm DG}$), and estimate 2-5% (above A$_{\rm{v}}>$7 mag) on average in the Galactic plane. PDFs of the column density reveal the typically observed log-normal distribution for low- and exhibit an excess at high column densities. As a reference for extragalactic studies, we show the line-of-sight integrated N-PDF of the inner Galaxy, and derive a contribution of this excess to the total column density of $\sim2.2$%, above $N_{\rm H_2} = 2.92\times10^{22}$ cm$^{-2}$. Taking the total flux density, we provide an independent estimate of the mass of molecular gas in the inner Galaxy of $\sim1\times10^9\,M_{\odot}$, which is consistent with previous estimates using CO emission. From the mass and $f_{\rm DG}$ we estimate a Galactic SFR of $\dot M = 1.3\,M_{\odot}$ yr$^{-1}$. While the distribution of diffuse gas is homogenous in the inner Galaxy, the CMZ stands out with a higher dense gas fraction. The low star formation efficiency of the Milky Way is well explained by the low $f_{\rm DG}$ in the Galactic ISM, while the high $f_{\rm DG}$ towards the CMZ, despite its low star formation activity, suggests that, in that particular region of our Galaxy, high-density gas is not the bottleneck for star formation., Accepted for publication in A&A. 10 pages, 10 figures, abstract is shortened

Published
2016

4. Molecular depletion times and the CO-to-H 2 conversion factor in metal-poor galaxies

Author

Francoise Combes, Achim Weiss, Andreas Lundgren, V. Casasola, L. K. Hunt, Leonardo Testi, Paola Caselli, Santiago García-Burillo, Karl M. Menten, Roberto Maiolino, Christian Henkel, Observatorio Astronomico Nacional, Madrid, Istituto Nazionale di Astrofisica (INAF), INAF - Osservatorio Astrofisico di Arcetri (OAA), RTM - Alpes de Haute Provence - Digne les Bains, ONF - RTM - Alpes de Haute Provence - Digne les Bains, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Collège de France - Chaire Galaxies et cosmologie, Collège de France (CdF (institution)), Institut für Physik (Institut für Physik), University of Potsdam = Universität Potsdam, Observatorio Astronómico Nacional (OAN), oan, École normale supérieure - Paris (ENS Paris), Chaire Galaxies et cosmologie, and Universität Potsdam

Subjects
Physics, [PHYS]Physics [physics], Metallicity, Conversion factor, Local Group, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, 3. Good health, Baryon, chemistry.chemical_compound, chemistry, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Low Mass, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS, Dwarf galaxy, Carbon monoxide
Abstract

Tracing molecular hydrogen content with carbon monoxide in low-metallicity galaxies has been exceedingly difficult. Here we present a new effort, with IRAM 30-m observations of 12CO(1-0) of a sample of 8 dwarf galaxies having oxygen abundances ranging from 12+logO/H=7.7 to 8.4. CO emission is detected in all galaxies, including the most metal-poor galaxy of our sample (0.1 Zsun); to our knowledge this is the largest number of 12CO(1-0) detections ever reported for galaxies with 12+logO/H, 18 pages, 15 figures, accepted for publication in A&A

Published
2015

5. HIGH-RESOLUTION IMAGING OF PHIBSS z ∼ 2 MAIN-SEQUENCE GALAXIES IN CO J = 1 → 0

Author

Alberto D. Bolatto, N. M. Förster Schreiber, Linda J. Tacconi, Andreas Burkert, David Fisher, Steven R. Warren, Amélie Saintonge, Stijn Wuyts, Achim Weiss, Reinhard Genzel, F. Bournaud, Francoise Combes, Adam Leroy, Santiago García-Burillo, M. C. Cooper, Nicolas Bouché, Amiel Sternberg, Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Max-Planck-Institut für Extraterrestrische Physik (MPE), Departamento de Ciência do Solo, Universidade de São Paulo (USP), Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Chaire Galaxies et cosmologie, Collège de France (CdF (institution)), Observatorio Astronomico Nacional [Madrid] (OAN), Instituto Geografico Nacional (IGN), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), 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), Institut of Physics - Riga, Latvian Academy of Sciences, École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Universidade de São Paulo = University of São Paulo (USP), École normale supérieure - Paris (ENS-PSL), Collège de France - Chaire Galaxies et cosmologie, Observatorio Astronomico Nacional, Madrid, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, [PHYS]Physics [physics], Star formation, Sigma, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Redshift, Projection (relational algebra), Space and Planetary Science, Brightness temperature, Astrophysics of Galaxies (astro-ph.GA), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Excitation, ComputingMilieux_MISCELLANEOUS, Line (formation)
Abstract

We present Karl G. Jansky Very Large Array observations of the CO J=1-0 transition in a sample of four $z\sim2$ main sequence galaxies. These galaxies are in the blue sequence of star-forming galaxies at their redshift, and are part of the IRAM Plateau de Bure HIgh-$z$ Blue Sequence Survey (PHIBSS) which imaged them in CO J=3-2. Two galaxies are imaged here at high signal-to-noise, allowing determinations of their disk sizes, line profiles, molecular surface densities, and excitation. Using these and published measurements, we show that the CO and optical disks have similar sizes in main-sequence galaxies, and in the galaxy where we can compare CO J=1-0 and J=3-2 sizes we find these are also very similar. Assuming a Galactic CO-to-H$_2$ conversion, we measure surface densities of $\Sigma_{mol}\sim1200$ M$_\odot$pc$^{-2}$ in projection and estimate $\Sigma_{mol}\sim500-900$ M$_\odot$pc$^{-2}$ deprojected. Finally, our data yields velocity-integrated Rayleigh-Jeans brightness temperature line ratios $r_{31}$ that are approximately unity. In addition to the similar disk sizes, the very similar line profiles in J=1-0 and J=3-2 indicate that both transitions sample the same kinematics, implying that their emission is coextensive. We conclude that in these two main sequence galaxies there is no evidence for significant excitation gradients or a large molecular reservoir that is diffuse or cold and not involved in active star-formation. We suggest that $r_{31}$ in very actively star-forming galaxies is likely an indicator of how well mixed the star formation activity and the molecular reservoir are., Comment: To appear in ApJ

Published
2015

6. VERIFYING ASTEROSEISMICALLY DETERMINED PARAMETERS OF KEPLER STARS USING HIPPARCOS PARALLAXES: SELF-CONSISTENT STELLAR PROPERTIES AND DISTANCES

Author

V. Silva Aguirre, Marc H. Pinsonneault, Achim Weiss, Kamal Uddin, Timothy R. Bedding, Dennis Stello, Travis S. Metcalfe, Joseph D. Twicken, Tiago L. Campante, Sarbani Basu, Andrea Miglio, Peter Tenenbaum, Saskia Hekker, Daniel Huber, Hans Kjeldsen, Savita Mathur, Benoit Mosser, Jérôme Ballot, Aldo Serenelli, Ronald L. Gilliland, Luca Casagrande, Mário J. P. F. G. Monteiro, Y. P. Elsworth, O. L. Creevey, Joergen Christensen-Dalsgaard, Rafael A. García, William J. Chaplin, Kavli Institute for Theoretical Physics [Santa Barbara] (KITP), University of California [Santa Barbara] (UC Santa Barbara), University of California (UC)-University of California (UC), Research School of Astronomy and Astrophysics [Canberra] (RSAA), Australian National University (ANU), 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), Stellar Astrophysics Centre [Aarhus] (SAC), Aarhus University [Aarhus], Institute of Space Sciences [Barcelona] (ICE-CSIC), Spanish National Research Council [Madrid] (CSIC), 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), Observatoire de Haute-Provence (OHP), Institut Pythéas (OSU PYTHEAS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS), 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), School of Physics and Astronomy, University of Birmingham [Birmingham], National Center for Atmospheric Research [Boulder] (NCAR), Department of Physics and Astronomy [Aarhus], Space Science Institute [Boulder] (SSI), Differenciation Thymique et Physiologie des Lymphocytes T (U591), Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), 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), Departments of Astronomy and Chemistry, The Ohio State University, Ohio State University [Columbus] (OSU), School of Physics [UNSW Sydney] (UNSW), University of New South Wales [Sydney] (UNSW), SLAC National Accelerator Laboratory (SLAC), Stanford University, Low Energy Astrophysics (API, FNWI), University of California [Santa Barbara] (UCSB), University of California-University of California, 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), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD), and Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Field (physics), Stellar population, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Kepler, Asteroseismology, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, [PHYS]Physics [physics], 010308 nuclear & particles physics, Astronomy and Astrophysics, Observable, Astrophysics - Astrophysics of Galaxies, Galaxy, Photometry (astronomy), Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Accurately determining the properties of stars is of prime importance for characterizing stellar populations in our Galaxy. The field of asteroseismology has been thought to be particularly successful in such an endeavor for stars in different evolutionary stages. However, to fully exploit its potential, robust methods for estimating stellar parameters are required and independent verification of the results is mandatory. With this purpose, we present a new technique to obtain stellar properties by coupling asteroseismic analysis with the InfraRed Flux Method. By using two global seismic observables and multi-band photometry, the technique allows us to obtain masses, radii, effective temperatures, bolometric fluxes, and hence distances for field stars in a self-consistent manner. We apply our method to 22 solar-like oscillators in the Kepler short-cadence sample, that have accurate Hipparcos parallaxes. Our distance determinations agree to better than 5%, while measurements of spectroscopic effective temperatures and interferometric radii also validate our results. We briefly discuss the potential of our technique for stellar population analysis and models of Galactic Chemical Evolution., Comment: 28 pages, 5 figures, ApJ, accepted

Published
2012

7. The age of the Milky Way halo stars from the Sloan Digital Sky Survey

Author

Achim Weiss, Paula Jofre, M2A 2011, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Max-Planck-Institut für Astrophysik (MPA), and Max-Planck-Gesellschaft

Subjects
[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Milky Way, Metallicity, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Blue straggler, Galactic halo, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, diffusion, Astronomy and Astrophysics, stars: population II, Horizontal branch, Astrophysics - Astrophysics of Galaxies, Galaxy, Galaxy: halo, Stars, Space and Planetary Science, Globular cluster, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics
Abstract

We determined the age of the stellar content of the Galactic halo by considering main-sequence turn-off stars. From the large number of halo stars provided by Sloan Digital Sky Survey, we could accurately detect the turn-off as a function of metallicity of the youngest dominant population, which was done by looking at the hottest (bluest) stars of a population. Using the turn-off temperature of a population of a given metallicity, we looked for the isochrones with that turn-off temperature and metallicity and found no age gradient as a function of metallicity. This would mean that this dominating population of the Galactic halo formed rapidly, probably during the collapse of the proto-Galactic gas. Moreover, we could find a significant number of stars with hotter temperatures than the turn-off, which might be blue horizontal branch (BHB) stars, blue stragglers, or main sequence stars that are younger than the dominant population and were probably formed in external galaxies and accreted later on to our Milky Way. Motivated by the current debate about the efficiency of gravitational settling (atomic diffusion) in the interior of old solar-type stars, we used isochrones with and without settling to determine the ages. When ignoring diffusion in the isochrones we obtained ages of 14-16 Gyr. This result is a strong argument against inhibited diffusion in old halo field stars, since it results in a serious conflict with the age of the Universe of 13.7 Gyr. The age obtained including diffusion in the isochrones was 10-12 Gyr, which agrees with the absolute age of the old globular clusters in the inner halo., Comment: Astronomy and Astrophysics -- in press

Published
2011

8. Solar-like Oscillations in Low-luminosity Red Giants: First Results from Kepler

Author

M. D. Suran, S. Deheuvels, Lars Bildsten, H. L. Preston, Savita Mathur, Søren Frandsen, Derek Buzasi, Anne-Marie Broomhall, Aliz Derekas, Dennis Stello, Günter Houdek, Thomas Kallinger, Achim Weiss, Timothy Brown, William J. Borucki, David G. Koch, Jørgen Christensen-Dalsgaard, Michael J. Ireland, Timothy R. Bedding, Tiago L. Campante, J. De Ridder, Vinothini Sangaralingam, Hans Kjeldsen, Hans Bruntt, Daniel Huber, Michael Gruberbauer, Kevin Belkacem, Yvonne Elsworth, Jérôme Ballot, N. J. Tarrant, Ian W. Roxburgh, Chen Jiang, Jon M. Jenkins, Artie P. Hatzes, Marc-Antoine Dupret, László L. Kiss, C. Barban, Steven J. Hale, Rafael A. García, Marie-Jo Goupil, Benoit Mosser, William J. Chaplin, Alfred F. Noels, Andrea Miglio, Ian R. Stevens, Ronald L. Gilliland, Saskia Hekker, Josefina Montalbán, Christoffer Karoff, Yveline Lebreton, Sydney Institute for Astronomy (SIfA), The University of Sydney, School of Physics and Astronomy, University of Birmingham [Birmingham], Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Indian Institute of Astrophysics (IIA), 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), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-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), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), 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), Danish AsteroSeismology Centre (DASC), Aarhus University [Aarhus], NASA Ames Research Center (ARC), Las Cumbres Observatory Global Telescope, Space Telescope Science Institute (STSci), Département des Sciences et Gestion de l'Environnement/Océanologie [Liège], Université de Liège, Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto, Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Department of Computer Science (Queen Mary University of London), Queen Mary University of London (QMUL), Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, 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), Astrophysique Interprétation Modélisation (AIM (UMR7158 / 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 Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Universidade do Porto = University of Porto, Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), 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)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, and Universidade do Porto [Porto]

Subjects
FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 7. Clean energy, Asteroseismology, Photometry (optics), 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Solar-like oscillations, 010303 astronomy & astrophysics, Red clump, Scaling, Stellar evolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, Light curve, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, stars: oscillations
Abstract

We have measured solar-like oscillations in red giants using time-series photometry from the first 34 days of science operations of the Kepler Mission. The light curves, obtained with 30-minute sampling, reveal clear oscillations in a large sample of G and K giants, extending in luminosity from the red clump down to the bottom of the giant branch. We confirm a strong correlation between the large separation of the oscillations (Delta nu) and the frequency of maximum power (nu_max). We focus on a sample of 50 low-luminosity stars (nu_max > 100 muHz, L, Comment: accepted by ApJ Letters, to appear in special Kepler issue. Updated references

Published
2010

9. Detection of Solar-like Oscillations from Kepler Photometry of the Open Cluster NGC 6819

Author

Yveline Lebreton, Charles S. Baldner, Jørgen Christensen-Dalsgaard, Juan Carlos Suárez, Andrea Miglio, J. Molenda-Zakowicz, Nada Jevtic, Achim Weiss, Savita Mathur, Marie-Jo Goupil, L. Esch, Saskia Hekker, William J. Borucki, Caroline Barban, Hans Bruntt, Rafael A. García, Daniel Huber, Aldo Serenelli, Ian R. Stevens, Victor Silva Aguirre, Frank Grundah, Vinothini Sangaralingam, Katia Biazzo, Hans Kjeldsen, Torben Arentoft, Christiaan Sterken, Søren Meibom, Ian W. Roxburgh, Jérôme Ballot, Yvonne Elsworth, Karsten Brogaard, Francesca D'Antona, Dennis Stello, Ning Gai, Josefina Montalbán, Christoffer Karoff, Biwei Jiang, Timothy R. Bedding, Sarbani Basu, William J. Chaplin, Ronald L. Gilliland, Timothy M. Brown, B. Mosser, Kevin Belkacem, Róbert Szabó, Jon M. Jenkins, Pierre Demarque, Arlette Noels, Teodoro Roca Cortés, Peter Stine, Reza Samadi, David G. Koch, Sydney Institute for Astronomy (SIfA), The University of Sydney, Department of Astronomy, Yale University [New Haven], Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), 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), 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), School of Physics and Astronomy, University of Birmingham [Birmingham], Las Cumbres Observatory Global Telescope, Danish AsteroSeismology Centre (DASC), Aarhus University [Aarhus], Space Telescope Science Institute (STSci), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-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), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Indian Institute of Astrophysics (IIA), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Département des Sciences et Gestion de l'Environnement/Océanologie [Liège], Université de Liège, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), INAF - Osservatorio Astronomico di Roma (OAR), Beijing Normal University (BNU), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Engineering Technology, Bloomsburg University, Astronomical Institute [Wroclaw], University of Wrocław [Poland] (UWr), Instituto de Astrofisica de Canarias (IAC), Departmento de Astrofísica, Universidad de La Laguna [Tenerife - SP] (ULL), Department of Computer Science (Queen Mary University of London), Queen Mary University of London (QMUL), Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Vrije Universiteit Brussel (VUB), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), NASA Ames Research Center (ARC), 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)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Beijing Normal University, University of Wrocław [Poland], Vrije Universiteit [Brussels] (VUB), Astrophysique Interprétation Modélisation (AIM (UMR7158 / 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 Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), 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), Harvard University-Smithsonian Institution, and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, stars: interiors, 01 natural sciences, Asteroseismology, Luminosity, open clusters and associations: individual: NGC 6819, techniques: photometric, Frequency separation, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Solar-like oscillations, 010303 astronomy & astrophysics, Stellar evolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Radial velocity, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, stars: fundamental parameters, stars: oscillations, Open cluster
Abstract

Asteroseismology of stars in clusters has been a long-sought goal because the assumption of a common age, distance and initial chemical composition allows strong tests of the theory of stellar evolution. We report results from the first 34 days of science data from the Kepler Mission for the open cluster NGC 6819 -- one of four clusters in the field of view. We obtain the first clear detections of solar-like oscillations in the cluster red giants and are able to measure the large frequency separation and the frequency of maximum oscillation power. We find that the asteroseismic parameters allow us to test cluster-membership of the stars, and even with the limited seismic data in hand, we can already identify four possible non-members despite their having a better than 80% membership probability from radial velocity measurements. We are also able to determine the oscillation amplitudes for stars that span about two orders of magnitude in luminosity and find good agreement with the prediction that oscillation amplitudes scale as the luminosity to the power of 0.7. These early results demonstrate the unique potential of asteroseismology of the stellar clusters observed by Kepler., Comment: 5 pages, 4 figures, accepted by ApJ (Lett.)

Published
2010

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