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15 results on '"Konstantinova-Antova, R."'

1. Magnetism in Cool Evolved Stars: the M giants EK Bootis $\beta$ Pegasi

Author

Georgiev, S., Konstantinova-Antova, R., Lèbre, A., Aurière, M., Charbonnel, C., Palacios, Ana, Drake, N., Bogdanovski, R., Laboratoire Univers et Particules de Montpellier (LUPM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Institut de recherche en astrophysique et planétologie (IRAP), 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), and 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)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

We present a long-term spectropolarimetric study of the active M giantsEK Bootis (M5III) and β Pegasi (M2.5II-III). For each star, the variability of the diskaveraged longitudinal component of the magnetic field (Bl) is shown, along with thebehavior of different spectral activity indicators. The possible nature of the secondarycomponent of EK Boo is discussed. We compare the observed variations in the activity proxies of each of the two giants and discuss possible physical explanations for thestructure of their respective magnetic fields. For both objects, observations in linear polarisation are also presented and briefly discussed.

Published
2020

2. Theoretical convective turnover timescale and Rossby number for low- and intermediate-mass stars up to the AGB at various metallicities

Author

Charbonnel, C., Decressin, T., Lagarde, N., Gallet, F., Palacios, A., Auriere, M., Konstantinova-Antova, R., Mathis, S., Anderson, R., Dintrans, B., Université de Genève (UNIGE), Observatoire Astronomique de l'Université de Genève (ObsGE), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Unité de Génétique Moléculaire Animale (UGMA), Université de Limoges (UNILIM)-Institut National de la Recherche Agronomique (INRA), Laboratoire Univers et Particules de Montpellier (LUPM), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées (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), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), University of Sofia, 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 Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), 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 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)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2017

3. Discovery of a complex linearly polarized spectrum of Betelgeuse dominated by depolarization of the continuum

Author

Konstantinova-Antova R., Agnès Lèbre, Aurière M., Tessore B., Chiavassa A., Kervella P., Josselin E., Donati J.-F., Grunhut J. H., López Ariste A., Mathias P., Wade G. A., Fabrice Herpin, Fabas N., Perrin G., Paletou F., Montargès M., Petit P., 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), Laboratoire Univers et Particules de Montpellier (LUPM), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Cancérologie de Marseille (CRCM), Aix Marseille Université (AMU)-Institut Paoli-Calmettes, Fédération nationale des Centres de lutte contre le Cancer (FNCLCC)-Fédération nationale des Centres de lutte contre le Cancer (FNCLCC)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut de RadioAstronomie Millimétrique (IRAM), 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), Bulgarian Academy of Sciences (BAS), Cranfield University, 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), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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), and Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Betelgeuse, Physics, Brightness, 010308 nuclear & particles physics, Linear polarization, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Polarization (waves), 01 natural sciences, Spectral line, symbols.namesake, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, 0103 physical sciences, symbols, Astrophysics::Solar and Stellar Astrophysics, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Rayleigh scattering, Supergiant, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Betelgeuse is an M supergiant that harbors spots and giant granules at its surface and presents linear polarization of its continuum. We have previously discovered linear polarization signatures associated with individual lines in the spectra of cool and evolved stars. Here, we investigate whether a similar linearly polarized spectrum exists for Betelgeuse. We used the spectropolarimeter Narval, combining multiple polarimetric sequences to obtain high signal-to-noise ratio spectra of individual lines, as well as the least-squares deconvolution (LSD) approach. We have discovered the existence of a linearly polarized spectrum for Betelgeuse, detecting a rather strong signal (at a few times 10$^{-4}$ of the continuum intensity level), both in individual lines and in the LSD profiles. Studying its properties and the signal observed for the resonant \ion{Na}{i}\,D lines, we conclude that we are mainly observing depolarization of the continuum by the absorption lines. The linear polarization of the Betelgeuse continuum is due to the anisotropy of the radiation field induced by brightness spots at the surface and Rayleigh scattering in the atmosphere. We have developed a geometrical model to interpret the observed polarization, from which we infer the presence of two brightness spots and their positions on the surface of Betelgeuse. We show that applying the model to each velocity bin along the Stokes Q and U profiles allows the derivation of a map of the bright spots. We use the Narval linear polarization observations of Betelgeuse obtained over a period of 1.4 years to study the evolution of the spots. Our study of the linearly polarized spectrum of Betelgeuse provides a novel method for studying the evolution of brightness spots at its surface and complements quasi-simultaneous observations obtained with PIONIER at the VLTI., 13 pages, 10 figures, accepted for publication in Astronomy and Astrophysics

Published
2016

4. Descendants of Magnetic and non-Magnetic A-type Stars

Author

Aurière, M., Lignières, F., Konstantinova-Antova, R., Charbonnel, C., Pascal Petit, Tsvetkova, S., and Wade, G.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

We have studied the magnetic field of about 50 active and non-active single G-K-type red giants by means of spectropolarimetry with Narval and ESPaDOnS. 30 giants have been significantly Zeeman-detected. A close study of the 17 giants with known rotational periods shows that the measured magnetic field strength is correlated to the rotation, in particular to the Rossby number. 4 giants for which the magnetic field is measured to be outstandingly strong with respect to the rotational period or the evolutionary state are identified as probable Ap-star descendants. We detail their magnetic properties and propose criteria to identify Ap-star descendants., Comment: 8 pages, to appear in the proceedings of the conference "Putting A Stars into Context: Evolution, Environment, and Related Stars"

Published
2013
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5. Magnetic Field and Convection in the Cool Supergiant Betelgeuse

Author

Aurière, M., Konstantinova-Antova, R., Petit, P., Charbonnel, C., Van Eck, S., Donati, J.-F., Lignieres, F., Roudier, T., Institut de recherche en astrophysique et planétologie (IRAP), 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), University of Sofia, Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Institut d'Astronomie et d'Astrophysique, Université libre de Bruxelles (ULB), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Centre National de la Recherche Scientifique (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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2013

6. Magnetic Field and Activity of the Single Late-type Giant Beta Ceti

Author

Tsvetkova, S., Auriere, M., Konstantinova-Antova, R., Wade, G. A., Bogdanovski, R. G., and Petit, P.

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

We present the behavior of the magnetic field and activity indicators of the single late-type giant Beta Ceti in the period June 19, 2010 - December 14, 2010. We used spectropolarimetric data obtained with two telescopes - the NARVAL spectropolarimeter at Telescope Bernard Lyot, Pic du Midi, France and the ESPaDOnS spectropolarimeter at CFHT, Hawaii. The data were processed using the method of Least Square Deconvolution which enables to derive the mean photospheric profiles of Stokes I and V parameters. We measured the surface-averaged longitudinal magnetic field Bl, which varies in the interval 0.1 - 8.2 G, the line activity indicators CaII K, H_alpha, CaII IR (854.2 nm) and radial velocity. By analyzing the Bl variations, was identified a possible rotational period P = 118 days. A single, large magnetic spot which dominates the field topology is a possible explanation for the Bl and activity indicator variations of Beta Ceti., Comment: 12 pages, 10 figures, conference talk

Published
2012
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7. Magnetic field and convection in the cool supergiant Betelgeuse

Author

Petit, P., Aurière, M., Konstantinova-Antova, R., Morgenthaler, A., Perrin, G., Roudier, T., and Donati, J. -F.

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

We present the outcome of a highly-sensitive search for magnetic fields on the cool supergiant Betelgeuse. A time-series of six circularly-polarized spectra was obtained using the NARVAL spectropolarimeter at T\'elescope Bernard Lyot (Pic du Midi Observatory), between 2010 March and April. Zeeman signatures were repeatedly detected in cross-correlation profiles, corresponding to a longitudinal component of about 1 G. The time-series unveils a smooth increase of the longitudinal field from 0.5 to 1.5 G, correlated with radial velocity fluctuations. We observe a strong asymmetry of Stokes V signatures, also varying in correlation with the radial velocity. The Stokes V line profiles are red-shifted by about 9 km/s with respect to the Stokes I profiles, suggesting that the observed magnetic elements may be concentrated in the sinking components of the convective flows., Comment: Submitted to Lecture Notes in Physics (CNRS astronomy school : "From solar environment to stellar environment")

Published
2011
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8. The Synchronous Network of distant Telescopes

Author

Zhilyaev, B., Svyatogorov, O., Verlyuk, I., Andreev, M., Sergeev, A., Lovkaya, M., Antov, S., Konstantinova-Antova, R., Bogdanovski, R., Avgoloupis, S., Seiradakis, J., and Contadakis, M.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

The Synchronous Network of distant Telescopes (SNT) represents an innovative approach in observational astrophysics. Authors present the unique existing realization of the SNT-conception. It was founded within the international collaboration between astronomical observatories of Ukraine, Russia, Bulgaria and Greece. All the telescopes of the Network are equipped with standardized photometric systems (based on photomultipliers). The unified timing systems (based on GPS-receivers) synchronize all the apertures to UTC with an accuracy of 1 microsecond and better. The essential parts of the SNT are the original software for operating and data processing. Described international Network successfully works for more then 10 years. The obtained unique observational data made it possible to discover new fine-scale features and flare-triggered phenomena in flaring red dwarfs, as well as the recently found high-frequency variability in some chromospherically active stars., Comment: 7 pages, 6 figures, Bulgarian Astronomical Journal 17, 2011

Published
2011
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9. Direct detection of a magnetic field in the photosphere of the single M giant EK Bootis. How common is magnetic activity among M giants?

Author

Konstantinova-Antova, R., Aurière, M., Charbonnel, C., Drake, N. A., P Schröder, K., Stateva, I., Evelyne Alecian, Petit, P., Cabanac, R., Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2010

10. Lithium and magnetic fields in giants. HD 232862 : a magnetic and lithium-rich giant star

Author

L��bre, A., Palacios, A., Nascimento, J. D. do, Konstantinova-Antova, R., Kolev, D., Auri��re, M., de Laverny, P., and De Medeiros, J. R.

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

We report the detection of an unusually high lithium content in HD 232862, a field giant classified as a G8II star, and hosting a magnetic field. With the spectropolarimeters ESPaDOnS at CFHT and NARVAL at TBL, we have collected high resolution and high signal-to-noise spectra of three giants : HD 232862, KU Peg and HD 21018. From spectral synthesis we have inferred stellar parameters and measured lithium abundances that we have compared to predictions from evolutionary models. We have also analysed Stokes V signatures, looking for a magnetic field on these giants. HD 232862, presents a very high abundance of lithium (ALi = 2.45 +/- 0.25 dex), far in excess of the theoretically value expected at this spectral type and for this luminosity class (i.e, G8II). The evolutionary stage of HD 232862 has been precised, and it suggests a mass in the lower part of the [1.0 Msun ; 3.5 Msun ] mass interval, likely 1.5 to 2.0 solar mass, at the bottom of the Red Giant Branch. Besides, a time variable Stokes V signature has been detected in the data of HD 232862 and KU Peg, pointing to the presence of a magnetic field at the surface of these two rapidly rotating active stars., 11 pages, 9 figures ; accepted by Astronomy and Astrophysics

Published
2009

11. Rotational velocities of the giants in symbiotic stars: I. D'-type symbiotics

Author

Zamanov, R. K., Bode, M. F., Melo, C. H. F., Porter, J., Gomboc, A., and Konstantinova-Antova, R.

Subjects
Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We have measured the rotational velocities (v.sini) of the mass donors in a number of D'--type symbiotic stars, using the cross-correlation function method. Four from five D' symbiotic stars with known v.sini, appeared to be very fast rotators compared with the catalogues of v.sini for the corresponding spectral types. At least three of these stars rotate at a substantial fraction (>=0.5) of the critical velocity. This means that at least in D'-type symbiotics the cool components rotate faster than isolated giants. If these binary stars are synchronized, their orbital periods should be relatively short (4-60 days). We also briefly discuss the possible origin of the rapid rotation and its connection with mass loss and dust formation., 6 pages, to be submitted soon

Published
2005

12. Fast UBVRI colorimetry of stellar flares on EV Lacertae

Author

Zhilyaev, B., Romanyuk, Ya., Svyatogorov, O., Verlyuk, I., Alekseev, I., Lovkaya, M., Avgoloupis, S., Contadakis, M., Seiradakis, J., Antov, A., and Konstantinova-Antova, R.

Subjects
Plenary Sessions
Published
2003

14. VizieR Online Data Catalog: BCool survey of solar-type stars (Marsden+ 2014)

Author

Marsden, S. C., Petit, P., Jeffers, S. V., Morin, J., Rim Fares, Reiners, A., Do Nascimento, J. -D, Auriere, M., Bouvier, J., Carter, B. D., Catala, C., Dintrans, B., Donati, J. -F, Gastine, T., Jardine, M., Konstantinova-Antova, R., Lanoux, J., Lignieres, F., Morgenthaler, A., Ramirez-Velez, J. C., Theado, S., Grootel, V., and BCool Collaboration

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