11
11
Jun 30, 2018
06/18
Jun 30, 2018
by
Gaia Collaboration; F. van Leeuwen; A. Vallenari; C. Jordi; L. Lindegren; U. Bastian; T. Prusti; J. H. J. de Bruijne; A. G. A. Brown; C. Babusiaux; C. A. L. Bailer-Jones; G. Jasniewicz; S. Jordan; M. Kontizas; A. J. Korn; A. C. Lanzafame; M. Manteiga; A. Moitinho; K. Muinonen; J. Osinde; E. Pancino; M. Biermann; T. Pauwels; J. -M. Petit; A. Recio-Blanco; A. C. Robin; L. M. Sarro; C. Siopis; M. Smith; K. W. Smith; A. Sozzetti; W. Thuillot; D. W. Evans; W. van Reeven; Y. Viala; U. Abbas; A. Abreu...
texts
eye 11
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Context. The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS). This is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are calculated using Hipparcos and Tycho-2 positions in 1991.25 as prior information. Aims. We investigate the scientific potential and limitations of the TGAS component by means of the astrometric data for open clusters. Methods. Mean cluster parallax and proper motion values are...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1703.01131
6
6.0
Jun 30, 2018
06/18
Jun 30, 2018
by
L. Eyer; N. Mowlavi; D. W. Evans; K. Nienartowicz; D. Ordonez; B. Holl; I. Lecoeur-Taibi; M. Riello; G. Clementini; J. Cuypers; J. De Ridder; A. C. Lanzafame; L. M. Sarro; J. Charnas; L. P. Guy; G. Jevardat de Fombelle; L. Rimoldini; M. Süveges; F. Mignard; G. Busso; F. De Angeli; F. van Leeuwen; P. Dubath; M. Beck; J. J. Aguado; J. Debosscher; E. Distefano; J. Fuchs; P. Koubsky; T. Lebzelter; S. Leccia; M. Lopez; A. Moitinho; S. Regibo; V. Ripepi; M. Roelens; L. Szabados; B. Tingley; V....
texts
eye 6
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The ESA Gaia mission provides a unique time-domain survey for more than one billion sources brighter than G=20.7 mag. Gaia offers the unprecedented opportunity to study variability phenomena in the Universe thanks to multi-epoch G-magnitude photometry in addition to astrometry, blue and red spectro-photometry, and spectroscopy. Within the Gaia Consortium, Coordination Unit 7 has the responsibility to detect variable objects, classify them, derive characteristic parameters for specific...
Topics: Solar and Stellar Astrophysics, Instrumentation and Methods for Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.03295
3
3.0
Jun 30, 2018
06/18
Jun 30, 2018
by
B. Mosser; O. Benomar; K. Belkacem; M. J. Goupil; N. Lagarde; E. Michel; Y. Lebreton; D. Stello; M. Vrard; C. Barban; T. R. Bedding; S. Deheuvels; W. J. Chaplin; J. De Ridder; Y. Elsworth; J. Montalban; A. Noels; R. M. Ouazzani; R. Samadi; T. R. White; H. Kjeldsen
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eye 3
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The detection of oscillations with a mixed character in subgiants and red giants allows us to probe the physical conditions in their cores. With these mixed modes, we aim at determining seismic markers of stellar evolution. Kepler asteroseismic data were selected to map various evolutionary stages and stellar masses. Seismic evolutionary tracks were then drawn with the combination of the frequency and period spacings. We measured the asymptotic period spacing for more than 1170 stars at various...
Topics: Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1411.1082
4
4.0
Jun 30, 2018
06/18
Jun 30, 2018
by
T. Kallinger; J. De Ridder; S. Hekker; S. Mathur; B. Mosser; M. Gruberbauer; R. A. Garcia; C. Karoff; J. Ballot
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eye 4
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The long and almost continuous observations by Kepler show clear evidence of a granulation background signal in a large sample of stars, which is interpreted as the surface manifestation of convection. It has been shown that its characteristic timescale and rms intensity fluctuation scale with the peak frequency (\nu_{max}) of the solar-like oscillations. Various attempts have been made to quantify the observed signal, to determine scaling relations, and to compare them to theoretical...
Topics: Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1408.0817
3
3.0
Jun 30, 2018
06/18
Jun 30, 2018
by
P. G. Beck; E. Kambe; M. Hillen; E. Corsaro; H. Van Winckel; E. Moravveji; J. De Ridder; S. Bloemen; S. Saesen; P. Mathias; P. Degroote; T. Kallinger; T. Verhoelst; H. Ando; F. Carrier; B. Acke; R. Oreiro; A. Miglio; P. Eggenberger; B. Sato; K. Zwintz; P. I. Pápics; P. Marcos-Arenal; S. A. Sans Fuentes; V. S. Schmid; C. Waelkens; R. Østensen; J. M. Matthews; M. Yoshida; H. Izumiura; H. Koyano; S. Nagayama; Y. Shimizu; N. Okada; K. Okita; A. Sakamoto; T. Yamamuro; C. Aerts
texts
eye 3
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Red giants are evolved stars which exhibit solar-like oscillations. Although a multitude of stars have been observed with space telescopes, only a handful of red-giant stars were targets of spectroscopic asteroseismic observing projects. We search for solar-like oscillations in the two bright red-giant stars $\gamma$ Psc and $\theta^1$ Tau from time series of ground-based spectroscopy and determine the frequency of the excess of oscillation power $\nu_{max}$ and the mean large frequency...
Topics: Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1407.6352
5
5.0
Jun 30, 2018
06/18
Jun 30, 2018
by
P. Marcos-Arenal; W. Zima; J. De Ridder; C. Aerts; R. Huygen; R. Samadi; J. Green; G. Piotto; S. Salmon; C. Catala; H. Rauer
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eye 5
favorite 0
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Many aspects of the design trade-off of a space-based instrument and its performance can best be tackled through simulations of the expected observations. The complex interplay of various noise sources in the course of the observations make such simulations an indispensable part of the assessment and design study of any space-based mission. We present a formalism to model and simulate photometric time series of CCD images by including models of the CCD and its electronics, the telescope optics,...
Topics: Instrumentation and Methods for Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1404.1886
3
3.0
Jun 30, 2018
06/18
Jun 30, 2018
by
V. Silva Aguirre; G. R. Ruchti; S. Hekker; S. Cassisi; J. Christensen-Dalsgaard; A. Datta; A. Jendreieck; J. Jessen-Hansen; A. Mazumdar; B. Mosser; D. Stello; P. G. Beck; J. de Ridder
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eye 3
favorite 0
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About 1% of giant stars have been shown to have large surface Li abundances, which is unexpected according to standard stellar evolution models. Several scenarios for lithium production have been proposed, but it is still unclear why these Li-rich giants exist. A missing piece in this puzzle is the knowledge of the exact stage of evolution of these stars. Using low-and-high-resolution spectroscopic observations, we have undertaken a survey of lithium-rich giants in the Kepler field. In this...
Topics: Astrophysics of Galaxies, Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1402.6339
7
7.0
Jun 30, 2018
06/18
Jun 30, 2018
by
P. Marcos-Arenal; W. Zima; J. De Ridder; R. Huygen; C. Aerts
texts
eye 7
favorite 0
comment 0
The preparation of a space-mission that carries out any kind of imaging to detect high-precision low-amplitude variability of its targets requires a robust model for the expected performance of its instruments. This model cannot be derived from simple addition of noise properties due to the complex interaction between the various noise sources. While it is not feasible to build and test a prototype of the imaging device on-ground, realistic numerical simulations in the form of an end-to-end...
Topics: Instrumentation and Methods for Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1402.2582
5
5.0
Jun 29, 2018
06/18
Jun 29, 2018
by
J. De Ridder; G. Molenberghs; L. Eyer; C. Aerts
texts
eye 5
favorite 0
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Context. The Kepler space mission led to a large amount of high-precision time series of solar-like oscillators. Using a Bayesian analysis that combines asteroseismic techniques and additional ground-based observations, the mass, radius, luminosity, and distance of those stars can be estimated with good precision. This has given a new impetus to the research field of galactic archeology. Aims. The first data release of the Gaia space mission contains the TGAS catalog with parallax estimates for...
Topics: Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1609.08945
6
6.0
Jun 29, 2018
06/18
Jun 29, 2018
by
G. Clementini; V. Ripepi; S. Leccia; N. Mowlavi; I. Lecoeur-Taibi; M. Marconi; L. Szabados; L. Eyer; L. P. Guy; L. Rimoldini; G. Jevardat de Fombelle; B. Holl; G. Busso; J. Charnas; J. Cuypers; F. De Angeli; J. De Ridder; J. Debosscher; D. W. Evans; P. Klagyivik; I. Musella; K. Nienartowicz; D. Ordonez; S. Regibo; M. Riello; L. M. Sarro; M. Suveges
texts
eye 6
favorite 0
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We present an overview of the Specific Objects Study (SOS) pipeline developed within the Coordination Unit 7 (CU7) of the Gaia Data Processing and Analysis Consortium (DPAC), the coordination unit charged with the processing and analysis of variable sources observed by Gaia, to validate and fully characterise Cepheids and RR Lyrae stars observed by the spacecraft. We describe how the SOS for Cepheids and RR Lyrae stars (SOS Cep&RRL) was specifically tailored to analyse Gaia's G-band...
Topics: Astrophysics, Solar and Stellar Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1609.04269
4
4.0
Jun 29, 2018
06/18
Jun 29, 2018
by
F. Perez Hernandez; R. A. Garcia; E. Corsaro; S. A. Triana; J. De Ridder
texts
eye 4
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Frequencies of acoustic and mixed modes in red giant stars are now determined with high precision thanks to the long continuous observations provided by the NASA Kepler mission. Here we consider the eigenfrequencies of nineteen low-luminosity red giant stars selected by Corsaro et al. (2015) for a detailed peak-bagging analysis. Our objective is to obtain stellar parameters by using individual mode frequencies and spectroscopic information. We use a forward modelling technique based on a...
Topics: Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1605.01567
4
4.0
Jun 29, 2018
06/18
Jun 29, 2018
by
R. Lombaert; L. Decin; P. Royer; A. de Koter; N. L. J. Cox; E. González-Alfonso; D. Neufeld; J. De Ridder; M. Agúndez; J. A. D. L. Blommaert; T. Khouri; M. A. T. Groenewegen; F. Kerschbaum; J. Cernicharo; B. Vandenbussche; C. Waelkens
texts
eye 4
favorite 0
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Context. The recent detection of warm H$_2$O vapor emission from the outflows of carbon-rich asymptotic giant branch (AGB) stars challenges the current understanding of circumstellar chemistry. Two mechanisms have been invoked to explain warm H$_2$O vapor formation. In the first, periodic shocks passing through the medium immediately above the stellar surface lead to H$_2$O formation. In the second, penetration of ultraviolet interstellar radiation through a clumpy circumstellar medium leads to...
Topics: Astrophysics, Solar and Stellar Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1601.07017
17
17
Jun 28, 2018
06/18
Jun 28, 2018
by
M. Jerzykiewicz; G. Handler; J. Daszynska-Daszkiewicz; A. Pigulski; E. Poretti; E. Rodriguez; P. J. Amado; Z. Kolaczkowski; K. Uytterhoeven; T. N. Dorokhova; N. I. Dorokhov; D. Lorenz; D. Zsuffa; S. -L. Kim; P. -O. Bourge; B. Acke; J. De Ridder; T. Verhoelst; R. Drummond; A. I. Movchan; J. -A. Lee; M. Steslicki; J. Molenda-Zakowicz; R. Garrido; S. -H. Kim; G. Michalska; M. Paparo; V. Antoci; C. Aerts
texts
eye 17
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A multisite photometric campaign for the Beta Cephei and eclipsing variable 16 Lacertae is reported. 749 h of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with ten telescopes during 185 nights. After removing the pulsation contribution, an attempt was made to solve the resulting eclipse light curve by means of the computer program EBOP. Although a unique solution was not obtained, the range of solutions could be constrained by...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1508.05250
18
18
Jun 27, 2018
06/18
Jun 27, 2018
by
E. Corsaro; J. De Ridder; R. A. García
texts
eye 18
favorite 0
comment 0
High-precision frequencies of acoustic modes in red giant stars are now available thanks to the long observing length and high-quality of the light curves provided by the NASA Kepler mission, thus allowing to probe the interior of evolved cool low-mass stars with unprecedented level of detail. We characterize the acoustic signature of the helium second ionization zone in a sample of 18 low-mass low-luminosity red giants by exploiting new mode frequency measurements derived from more than four...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1504.04674
12
12
Jun 27, 2018
06/18
Jun 27, 2018
by
E. Corsaro; J. De Ridder; R. A. García
texts
eye 12
favorite 0
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The currently available Kepler light curves contain an outstanding amount of information but a detailed analysis of the individual oscillation modes in the observed power spectra, also known as peak bagging, is computationally demanding and challenging to perform on a large number of targets. Our intent is to perform for the first time a peak bagging analysis on a sample of 19 low-mass low-luminosity red giants observed by Kepler for more than four years. This allows us to provide high-quality...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1503.08821
55
55
Sep 23, 2013
09/13
Sep 23, 2013
by
G. Handler; M. Jerzykiewicz; E. Rodriguez; K. Uytterhoeven; P. J. Amado; T. N. Dorokhova; N. I. Dorokhov; E. Poretti; J. -P. Sareyan; L. Parrao; D. Lorenz; D. Zsuffa; R. Drummond; J. Daszynska-Daszkiewicz; T. Verhoelst; J. De Ridder; B. Acke; P. -O. Bourge; A. I. Movchan; R. Garrido; M. Paparo; T. Sahin; V. Antoci; S. N. Udovichenko; K. Csorba; R. Crowe; B. Berkey; S. Stewart; D. Terry; D. E. Mkrtichian; C. Aerts
texts
eye 55
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We report a multisite photometric campaign for the Beta Cephei star 12 Lacertae. 750 hours of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with 9 telescopes during 190 nights. Our frequency analysis results in the detection of 23 sinusoidal signals in the light curves. Eleven of those correspond to independent pulsation modes, and the remainder are combination frequencies. We find some slow aperiodic variability such as that...
Source: http://arxiv.org/abs/astro-ph/0510326v1
53
53
Sep 23, 2013
09/13
Sep 23, 2013
by
B. Mosser; C. Barban; J. Montalban; P. G. Beck; A. Miglio; K. Belkacem; M. J. Goupil; S. Hekker; J. De Ridder; M. A Dupret; Y. Elsworth; A. Noels; F. Baudin; E. Michel; R. Samadi; M. Auvergne; A. Baglin; C. Catala
texts
eye 53
favorite 0
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The CoRoT mission has provided thousands of red-giant light curves. The analysis of their solar-like oscillations allows us to characterize their stellar properties. Up to now, the global seismic parameters of the pressure modes remain unable to distinguish red-clump giants from members of the red-giant branch. As recently done with Kepler red giants, we intend to analyze and use the so-called mixed modes to determine the evolutionary status of the red giants observed with CoRoT. We also aim at...
Source: http://arxiv.org/abs/1105.6113v2
91
91
Sep 23, 2013
09/13
Sep 23, 2013
by
M. P. Di Mauro; D. Cardini; G. Catanzaro; R. Ventura; C. Barban; T. R. Bedding; J. Christensen-Dalsgaard; J. De Ridder; S. Hekker; D. Huber; T. Kallinger; A. Miglio; J. Montalban; B. Mosser; D. Stello; K. Uytterhoeven; K. Kinemuchi; H. Kjeldsen; F. Mullally; M. Still
texts
eye 91
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We present the results of the asteroseismic analysis of the red-giant star KIC 4351319 (TYC 3124-914-1), observed for 30 days in short-cadence mode with the Kepler satellite. The analysis has allowed us to determine the large and small frequency separations, and the frequency of maximum oscillation power. The high signal-to-noise ratio of the observations allowed us to identify 25 independent pulsation modes whose frequencies range approximately from 300 to 500 muHz. The observed oscillation...
Source: http://arxiv.org/abs/1105.1076v1
63
63
Sep 23, 2013
09/13
Sep 23, 2013
by
S. Hekker; C. Barban; T. Kallinger; W. Weiss; J. De Ridder; A. Hatzes; CoRoT team
texts
eye 63
favorite 0
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Asteroseismic observations from space can provide us with long time series of uninterrupted high quality data for many stars at the same time. The CoRoT satellite (Convection Rotation and planetary Transits) was launched successfully in December 2006 and provides high precision photometery for a large number of stars. Here we present our research on (late G and K) red giant stars observed during the first long run (150 days) of CoRoT with the 'eye' dedicated to exo-planet research.
Source: http://arxiv.org/abs/0810.2797v1
38
38
Sep 23, 2013
09/13
Sep 23, 2013
by
J. Cuypers; C. Aerts; P. De Cat; J. De Ridder; K. Goossens; C. Schoenaers; K. Uytterhoeven; B. Acke; G. Davignon; J. Debosscher; L. Decin; W. De Meester; P. Deroo; R. Drummond; K. Kolenberg; K. Lefever; G. Raskin; M. Reyniers; S. Saesen; B. Vandenbussche; R. Van Malderen; T. Verhoelst; H. Van Winckel; C. Waelkens
texts
eye 38
favorite 0
comment 0
Gamma Doradus stars are excellent targets for asteroseismology since the gravity modes present in these stars probe the deep stellar interiors. Mode identification will improve the knowledge of these stars considerably. A selected group of Gamma Doradus stars and some candidates were observed with the Mercator telescope to find and/or confirm the periodicities in the light variations and to derive reliable amplitude ratios in different pass bands. A frequency analysis was performed on all new...
Source: http://arxiv.org/abs/0903.5213v1
55
55
Sep 23, 2013
09/13
Sep 23, 2013
by
B. Mosser; Y. Elsworth; S. Hekker; D. Huber; T. Kallinger; S. Mathur; K. Belkacem; M. J. Goupil; R. Samadi; C. Barban; T. R. Bedding; W. J. Chaplin; R. A. Garcia; D. Stello; J. De Ridder; C. K. Middour; R. L. Morris; E. V Quintana
texts
eye 55
favorite 0
comment 0
We aim to describe the oscillation power excess observed in Kepler red giants, and to investigate empirical scaling relations governing these parameters. From these scalings relations, we derive new physical properties of red giant oscillations. Various different methods were compared in order to validate the processes and to derive reliable output values. For consistency, a single method was then used to determine scaling relations for the relevant global asteroseismic parameters: mean mode...
Source: http://arxiv.org/abs/1110.0980v1
53
53
Sep 23, 2013
09/13
Sep 23, 2013
by
S. Mathur; S. Hekker; R. Trampedach; J. Ballot; T. Kallinger; D. Buzasi; R. A. Garcia; D. Huber; A. Jimenez; B. Mosser; T. R. Bedding; Y. Elsworth; C. Regulo; D. Stello; W. J. Chaplin; J. De Ridder; S. J. Hale; K. Kinemuchi; H. Kjeldsen; F. Mullaly; S. E. Thompson
texts
eye 53
favorite 0
comment 0
More than 1000 red giants have been observed by NASA/Kepler mission during a nearly continuous period of ~ 13 months. The resulting high-frequency resolution ( < 0.03 muHz) allows us to study the granulation parameters of these stars. The granulation pattern results from the convection motions leading to upward flows of hot plasma and downward flows of cooler plasma. We fitted Harvey-like functions to the power spectra, to retrieve the timescale and amplitude of granulation. We show that...
Source: http://arxiv.org/abs/1110.0117v1
52
52
Sep 23, 2013
09/13
Sep 23, 2013
by
S. Hekker; C. Barban; F. Baudin; J. De Ridder; T. Kallinger; T. Morel; W. J. Chaplin; Y. Elsworth
texts
eye 52
favorite 0
comment 0
Long timeseries of data increase the frequency resolution in the power spectrum. This allows for resolving stochastically excited modes with long mode lifetimes, as well as features that are close together in frequency. The CoRoT fields observed during the initial run and second long run partly overlap, and stars in this overlapping field observed in both runs are used to create timeseries with a longer timespan than available from the individual runs. We aim to measure the mode lifetimes of...
Source: http://arxiv.org/abs/1006.4284v2
48
48
Sep 23, 2013
09/13
Sep 23, 2013
by
F. Baudin; C. Barban; M. J. Goupil; R. Samadi; Y. Lebreton; H. Bruntt; T. Morel; L. Lefèvre; E. Michel; B. Mosser; F. Carrier; J. De Ridder; A. Hatzes; S. Hekker; T. Kallinger; M. Auvergne; A. Baglin; C. Catala
texts
eye 48
favorite 0
comment 0
The G6 giant HR\,2582 (HD\,50890) was observed by CoRoT for approximately 55 days. Mode frequencies are extracted from the observed Fourier spectrum of the light curve. Numerical stellar models are then computed to determine the characteristics of the star (mass, age, etc...) from the comparison with observational constraints. We provide evidence for the presence of solar-like oscillations at low frequency, between 10 and 20\,$\mu$Hz, with a regular spacing of $(1.7\pm0.1)\mu$Hz between...
Source: http://arxiv.org/abs/1111.6543v1
58
58
Sep 23, 2013
09/13
Sep 23, 2013
by
C. Aerts; P. De Cat; J. De Ridder; H. Van Winckel; G. Raskin; G. Davignon; K. Uytterhoeven
texts
eye 58
favorite 0
comment 0
We perform a seismic study of the young massive $\beta $Cephei star HD 203664 with the goal to constrain its interior structure. Our study is based on a time series of 328 new Geneva 7-colour photometric data of the star spread over 496.8 days. The data confirm the frequency of the dominant mode of the star which we refine to $f_1=6.02885 $c d$^{-1}$. The mode has a large amplitude of 37 mmag in V and is unambiguously identified as a dipole mode ($\ell=2$) from its amplitude ratios and...
Source: http://arxiv.org/abs/astro-ph/0511306v1
46
46
Sep 23, 2013
09/13
Sep 23, 2013
by
P. De Cat; K. Goossens; F. Bouckaert; L. Eyer; J. Cuypers; J. De Ridder; C. Aerts; M. -A. Dupret; A. Grigahcene; many observers
texts
eye 46
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We report on observational results obtained for 78 objects originally classified as bona-fide or candidate gamma Doradus stars. For the southern objects, we gathered echelle spectra with the CORALIE spectrograph attached to the Euler telescope in 1998-2003 and/or Johnson-Cousins B,V,Ic observations with the MODULAR photometer attached to the 0.5-m SAAO telescope in 1999-2000. For the northern objects, we obtained Geneva U,B,B1,B2,V,V1,G observations with the P7 photometer attached to the 1.2-m...
Source: http://arxiv.org/abs/astro-ph/0511208v1
50
50
Sep 23, 2013
09/13
Sep 23, 2013
by
S. Mathur; S. Hekker; R. Trampedach; J. Ballot; T. Kallinger; D. Buzasi; R. A. Garcia; D. Huber; A. Jimenez; B. Mosser; T. R. Bedding; Y. Elsworth; C. Regulo; D. Stello; W. J. Chaplin; J. De Ridder; S. J. Hale; K. Kinemuchi; H. Kjeldsen; F. Mullally; S. E. Thompson
texts
eye 50
favorite 0
comment 0
The granulation pattern that we observe on the surface of the Sun is due to hot plasma from the interior rising to the photosphere where it cools down, and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones and more extended atmospheres than the Sun, we cannot a priori assume that granulation in red giants is a scaled version of...
Source: http://arxiv.org/abs/1109.1194v1
78
78
Sep 23, 2013
09/13
Sep 23, 2013
by
S. Hekker; R. L. Gilliland; Sarbani Basu; J. De Ridder; W. J. Chaplin; Y. Elsworth
texts
eye 78
favorite 0
comment 0
The successful launches of the CoRoT and Kepler space missions have led to the detections of solar-like oscillations in large samples of red-giant stars. The large numbers of red giants with observed oscillations make it possible to investigate the properties of the sample as a whole: ensemble asteroseismology. In this article we summarise ensemble asteroseismology results obtained from data released by the Kepler Science Team (~150,000 field stars) as presented by Hekker et al. (2011b) and for...
Source: http://arxiv.org/abs/1109.0144v1
56
56
Sep 23, 2013
09/13
Sep 23, 2013
by
D. Huber; T. R. Bedding; D. Stello; S. Hekker; S. Mathur; B. Mosser; G. A. Verner; A. Bonanno; D. L. Buzasi; T. L. Campante; Y. P. Elsworth; S. J. Hale; T. Kallinger; V. Silva Aguirre; W. J. Chaplin; J. De Ridder; R. A. Garcia; T. Appourchaux; S. Frandsen; G. Houdek; J. Molenda-Zakowicz; M. J. P. F. G. Monteiro; J. Christensen-Dalsgaard; R. L. Gilliland; S. D. Kawaler; H. Kjeldsen; A. M. Broomhall; E. Corsaro; D. Salabert; D. T. Sanderfer; S. E. Seader; J. C. Smith
texts
eye 56
favorite 0
comment 0
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,...
Source: http://arxiv.org/abs/1109.3460v1
47
47
Sep 23, 2013
09/13
Sep 23, 2013
by
E. Corsaro; H. -E. Fröhlich; A. Bonanno; D. Huber; T. R. Bedding; O. Benomar; J. De Ridder; D. Stello
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We investigate different amplitude scaling relations adopted for the asteroseismology of stars that show solar-like oscillations. Amplitudes are among the most challenging asteroseismic quantities to handle because of the large uncertainties that arise in measuring the background level in the star's power spectrum. We present results computed by means of a Bayesian inference on a sample of 1640 stars observed with Kepler, spanning from main sequence to red giant stars, for 12 models used for...
Source: http://arxiv.org/abs/1212.1156v2
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74
Sep 22, 2013
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Sep 22, 2013
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W. Zima; T. Arentoft; J. De Ridder; S. Salmon; C. Catala; H. Kjeldsen; C. Aerts
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The PLATO satellite mission project is a next generation ESA Cosmic Vision satellite project dedicated to the detection of exo-planets and to asteroseismology of their host-stars using ultra-high precision photometry. The main goal of the PLATO mission is to provide a full statistical analysis of exo-planetary systems around stars that are bright and close enough for detailed follow-up studies. Many aspects concerning the design trade-off of a space-based instrument and its performance can best...
Source: http://arxiv.org/abs/1004.0738v1
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47
Sep 22, 2013
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Sep 22, 2013
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B. Mosser; K. Belkacem; M. J. Goupil; A. Miglio; T. Morel; C. Barban; F. Baudin; S. Hekker; R. Samadi; J. De Ridder; W. Weiss; M. Auvergne; A. Baglin
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The CoRoT 5-month long observation runs give us the opportunity to analyze a large variety of red-giant stars and to derive fundamental stellar parameters from their asteroseismic properties. We perform an analysis of more than 4\,600 CoRoT light curves to extract as much information as possible. We take into account the characteristics of the star sample and of the method in order to provide asteroseismic results as unbiased as possible. We also study and compare the properties of red giants...
Source: http://arxiv.org/abs/1004.0449v1
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33
Sep 22, 2013
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Sep 22, 2013
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S. Saesen; A. Pigulski; F. Carrier; G. Michalska; C. Aerts; J. De Ridder; M. Briquet; G. Handler; Z. Kolaczkowski; B. Acke; E. Bauwens; P. G. Beck; Y. Blom; J. Blommaert; E. Broeders; M. Cherix; G. Davignon; J. Debosscher; P. Degroote; L. Decin; S. Dehaes; W. De Meester; P. Deroo; M. Desmet; R. Drummond; J. R. Eggen; J. Fu; K. Gazeas; G. A. Gelven; C. Gielen; R. Huygen; X. Jiang; B. Kalomeni; S. -L. Kim; D. H. Kim; G. Kopacki; J. -H. Kwon; D. Ladjal; C. -U. Lee; Y. -J. Lee; K. Lefever; A....
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As a result of the variability survey in Chi Persei and NGC6910, the number of Beta Cep stars that are members of these two open clusters is increased to twenty stars, nine in NGC6910 and eleven in Chi Persei. We compare pulsational properties, in particular the frequency spectra, of Beta Cep stars in both clusters and explain the differences in terms of the global parameters of the clusters. We also indicate that the more complicated pattern of the variability among B type stars in Chi Persei...
Source: http://arxiv.org/abs/1004.2853v1
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41
Sep 22, 2013
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Sep 22, 2013
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T. R. Bedding; D. Huber; D. Stello; Y. P. Elsworth; S. Hekker; T. Kallinger; S. Mathur; B. Mosser; H. L. Preston; J. Ballot; C. Barban; A. M. Broomhall; D. L. Buzasi; W. J. Chaplin; R. A. Garcia; M. Gruberbauer; S. J. Hale; J. De Ridder; S. Frandsen; W. J. Borucki; T. Brown; J. Christensen-Dalsgaard; R. L. Gilliland; J. M. Jenkins; H. Kjeldsen; D. Koch; K. Belkacem; L. Bildsten; H. Bruntt; T. L. Campante; S. Deheuvels; A. Derekas; M. -A. Dupret; M. -J. Goupil; A. Hatzes; G. Houdek; M. J....
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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...
Source: http://arxiv.org/abs/1001.0229v2
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47
Sep 22, 2013
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Sep 22, 2013
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S. Hekker; J. De Ridder; F. Baudin; C. Barban; F. Carrier; A. P. Hatzes; T. Kallinger; W. W. Weiss
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Observations of red (G-K)-giant stars with the CoRoT satellite provide unprecedented information on the stochastically excited oscillations in these stars. The long time series of nearly uninterrupted high-cadence and high-precision photometry revealed the presence of non-radial modes with long lifetimes, which opens the possibility to perform asteroseismology on these stars. Also, the large number of red giants, for which solar-like oscillations are now observed, allows for a more statistical...
Source: http://arxiv.org/abs/1001.4543v1
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57
Sep 22, 2013
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Sep 22, 2013
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J. Blomme; J. Debosscher; J. De Ridder; C. Aerts; R. L. Gilliland; J. Christensen-Dalsgaard; H. Kjeldsen; T. M. Brown; W. J. Borucki; D. Koch; J. M. Jenkins; D. W. Kurtz; D. Stello; I. R. Stevens; M. D. Suran; A. Derekas
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We present the first results of the application of supervised classification methods to the Kepler Q1 long-cadence light curves of a subsample of 2288 stars measured in the asteroseismology program of the mission. The methods, originally developed in the framework of the CoRoT and Gaia space missions, are capable of identifying the most common types of stellar variability in a reliable way. Many new variables have been discovered, among which a large fraction are eclipsing/ellipsoidal binaries...
Source: http://arxiv.org/abs/1001.0507v2
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52
Sep 22, 2013
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Sep 22, 2013
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Ronald L. Gilliland; T. M. Brown; J. Christensen-Dalsgaard; H. Kjeldsen; C. Aerts; T. Appourchaux; S. Basu; T. R. Bedding; W. J. Chaplin; M. S. Cunha; P. De Cat; J. De Ridder; J. A. Guzik; G. Handler; S. Kawaler; L. Kiss; K. Kolenberg; D. W. Kurtz; T. S. Metcalfe; M. J. P. F. G. Monteiro; R. Szabó; T. Arentoft; L. Balona; J. Debosscher; Y. P. Elsworth; P. - O. Quirion; D. Stello; J. C. Suárez; W. J. Borucki; J. M. Jenkins; D. Koch; Y. Kondo; D. W. Latham; J. F. Rowe; J. H. Steffen
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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...
Source: http://arxiv.org/abs/1001.0139v1
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51
Sep 22, 2013
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Sep 22, 2013
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S. Hekker; J. Debosscher; D. Huber; M. G. Hidas; J. De Ridder; C. Aerts; D. Stello; T. R. Bedding; R. L. Gilliland; J. Christensen-Dalsgaard; T. M. Brown; H. Kjeldsen; W. J. Borucki; D. Koch; J. M. Jenkins; H. Van Winckel; P. G. Beck; J. Blomme; J. Southworth; A. Pigulski; W. J. Chaplin; Y. P. Elsworth; I. R. Stevens; S. Dreizler; D. W. Kurtz; C. Maceroni; D. Cardini; A. Derekas; M. D. Suran
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Oscillating stars in binary systems are among the most interesting stellar laboratories, as these can provide information on the stellar parameters and stellar internal structures. Here we present a red giant with solar-like oscillations in an eclipsing binary observed with the NASA Kepler satellite. We compute stellar parameters of the red giant from spectra and the asteroseismic mass and radius from the oscillations. Although only one eclipse has been observed so far, we can already determine...
Source: http://arxiv.org/abs/1001.0399v1
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58
Sep 22, 2013
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Sep 22, 2013
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F. Carrier; J. De Ridder; F. Baudin; C. Barban; A. P. Hatzes; S. Hekker; T. Kallinger; A. Miglio; J. Montalban; T. Morel; W. W. Weiss; M. Auvergne; A. Baglin; C. Catala; E. Michel; R. Samadi
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Convection in red giant stars excites resonant acoustic waves whose frequencies depend on the sound speed inside the star, which in turn depends on the properties of the stellar interior. Therefore, asteroseismology is the most robust available method for probing the internal structure of red giant stars. Solar-like oscillations in the red giant HR7349 are investigated. Our study is based on a time series of 380760 photometric measurements spread over 5 months obtained with the CoRoT satellite....
Source: http://arxiv.org/abs/1001.1655v1
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65
Sep 22, 2013
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Sep 22, 2013
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T. Kallinger; W. W. Weiss; C. Barban; F. Baudin; F. Carrier; C. Cameron; J. De Ridder; M. -J. Goupil; M. Gruberbauer; A. Hatzes; S. Hekker; R. Samadi; M. Deleuil
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Context. Observations and analysis of solar-type oscillations in red-giant stars is an emerging aspect of asteroseismic analysis with a number of open questions yet to be explored. Although stochastic oscillations have previously been detected in red giants from both radial velocity and photometric measurements, those data were either too short or had sampling that was not complete enough to perform a detailed data analysis of the variability. The quality and quantity of photometric data as...
Source: http://arxiv.org/abs/0811.4674v2
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49
Sep 22, 2013
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Sep 22, 2013
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S. Hekker; T. Kallinger; F. Baudin; J. De Ridder; C. Barban; F. Carrier; A. P. Hatzes; W. W. Weiss; A. Baglin
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eye 49
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Observations during the first long run (~150 days) in the exo-planet field of CoRoT increase the number of G-K giant stars for which solar-like oscillations are observed by a factor of 100. This opens the possibility to study the characteristics of their oscillations in a statistical sense. We aim to understand the statistical distribution of the frequencies of maximum oscillation power (nu_max) in red giants and to search for a possible correlation between nu_max and the large separation...
Source: http://arxiv.org/abs/0906.5002v1
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63
Sep 22, 2013
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Sep 22, 2013
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S. Hekker; R. L. Gilliland; Y. Elsworth; W. J. Chaplin; J. De Ridder; D. Stello; T. Kallinger; K. A. Ibrahim; T. C. Klaus; J. Li
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The first public release of long-cadence stellar photometric data collected by the NASA Kepler mission has now been made available. In this paper we characterise the red-giant (G-K) stars in this large sample in terms of their solar-like oscillations. We use published methods and well-known scaling relations in the analysis. Just over 70% of the red giants in the sample show detectable solar-like oscillations, and from these oscillations we are able to estimate the fundamental properties of the...
Source: http://arxiv.org/abs/1103.0141v1
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49
Sep 22, 2013
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Sep 22, 2013
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T. Morel; A. Miglio; N. Lagarde; J. Montalban; M. Rainer; E. Poretti; S. Hekker; T. Kallinger; B. Mosser; M. Valentini; F. Carrier; M. Hareter; L. Mantegazza; J. De Ridder
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A precise characterisation of the red giants in the seismology fields of the CoRoT satellite is a prerequisite for further in-depth seismic modelling. The optical spectra obtained for 19 targets have been used to accurately estimate their fundamental parameters and chemical composition. The extent of internal mixing is also investigated through the abundances of Li, CNO and Na (as well as 12C/13C in a few cases).
Source: http://arxiv.org/abs/1210.2982v1
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81
Sep 22, 2013
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Sep 22, 2013
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D. Huber; M. J. Ireland; T. R. Bedding; I. M. Brandão; L. Piau; V. Maestro; T. R. White; H. Bruntt; L. Casagrande; J. Molenda-Żakowicz; V. Silva Aguirre; S. G. Sousa; T. Barclay; C. J. Burke; W. J. Chaplin; J. Christensen-Dalsgaard; M. S. Cunha; J. De Ridder; C. D. Farrington; A. Frasca; R. A. García; R. L. Gilliland; P. J. Goldfinger; S. Hekker; S. D. Kawaler; H. Kjeldsen; H. A. McAlister; T. S. Metcalfe; A. Miglio; M. J. P. F. G. Monteiro; M. H. Pinsonneault; G. H. Schaefer; D. Stello; M....
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We present results of a long-baseline interferometry campaign using the PAVO beam combiner at the CHARA Array to measure the angular sizes of five main-sequence stars, one subgiant and four red giant stars for which solar-like oscillations have been detected by either Kepler or CoRoT. By combining interferometric angular diameters, Hipparcos parallaxes, asteroseismic densities, bolometric fluxes and high-resolution spectroscopy we derive a full set of near model-independent fundamental...
Source: http://arxiv.org/abs/1210.0012v1
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47
Sep 22, 2013
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Sep 22, 2013
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P. Dubath; L. Rimoldini; M. Süveges; J. Blomme; M. López; L. M. Sarro; J. De Ridder; J. Cuypers; L. Guy; I. Lecoeur; K. Nienartowicz; A. Jan; M. Beck; N. Mowlavi; P. De Cat; T. Lebzelter; L. Eyer
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We present an evaluation of the performance of an automated classification of the Hipparcos periodic variable stars into 26 types. The sub-sample with the most reliable variability types available in the literature is used to train supervised algorithms to characterize the type dependencies on a number of attributes. The most useful attributes evaluated with the random forest methodology include, in decreasing order of importance, the period, the amplitude, the V-I colour index, the absolute...
Source: http://arxiv.org/abs/1101.2406v2
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Sep 22, 2013
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Sep 22, 2013
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J. Blomme; L. M. Sarro; F. T. O'Donovan; J. Debosscher; T. Brown; M. Lopez; P. Dubath; L. Rimoldini; D. Charbonneau; E. Dunham; G. Mandushev; D. R. Ciardi; J. De Ridder; C. Aerts
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We present a novel automated methodology to detect and classify periodic variable stars in a large database of photometric time series. The methods are based on multivariate Bayesian statistics and use a multi-stage approach. We applied our method to the ground-based data of the TrES Lyr1 field, which is also observed by the Kepler satellite, covering ~26000 stars. We found many eclipsing binaries as well as classical non-radial pulsators, such as slowly pulsating B stars, Gamma Doradus, Beta...
Source: http://arxiv.org/abs/1101.5038v1
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Sep 22, 2013
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Sep 22, 2013
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A. Miglio; J. Montalban; F. Baudin; P. Eggenberger; A. Noels; S. Hekker; J. De Ridder; W. Weiss; A. Baglin
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The detection with CoRoT of solar-like oscillations in nearly 800 red giants in the first 150-days long observational run paves the way for detailed studies of populations of galactic-disk red giants. We investigate which information on the observed population can be recovered by the distribution of the observed seismic constraints: the frequency of maximum oscillation power (nu_max) and the large frequency separation (Deltanu). We propose to use the observed distribution of nu_max and of...
Source: http://arxiv.org/abs/0908.0210v1
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47
Sep 21, 2013
09/13
Sep 21, 2013
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L. Eyer; A. Jan; P. Dubath; K. Nienartowicz; J. Blomme; J. Debosscher; J. De Ridder; M. Lopez; L. Sarro
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eye 47
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The classification of time series from photometric large scale surveys into variability types and the description of their properties is difficult for various reasons including but not limited to the irregular sampling, the usually few available photometric bands, and the diversity of variable objects. Furthermore, it can be seen that different physical processes may sometimes produce similar behavior which may end up to be represented as same models. In this article we will also be presenting...
Source: http://arxiv.org/abs/0901.2835v1
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57
Sep 21, 2013
09/13
Sep 21, 2013
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S. Hekker; S. Basu; D. Stello; T. Kallinger; F. Grundahl; S. Mathur; R. A. Garcia; B. Mosser; D. Huber; T. R. Bedding; R. Szabo; J. De Ridder; W. J. Chaplin; Y. Elsworth; S. J. Hale; J. Christensen-Dalsgaard; R. L. Gilliland; M. Still; S. McCauliff; E. V. Quintana
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Context: Four open clusters are present in the Kepler field of view and timeseries of nearly a year in length are now available. These timeseries allow us to derive asteroseismic global oscillation parameters of red-giant stars in the three open clusters NGC 6791, NGC 6819 and NGC 6811. From these parameters and effective temperatures, we derive mass, radii and luminosities for the clusters as well as field red giants. Aims: We study the influence of evolution and metallicity on the observed...
Source: http://arxiv.org/abs/1104.4393v1
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75
Sep 21, 2013
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Sep 21, 2013
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S. Hekker; Y. Elsworth; J. De Ridder; B. Mosser; R. A. Garcia; T. Kallinger; S. Mathur; D. Huber; D. L. Buzasi; H. L. Preston; S. J. Hale; J. Ballot; W. J. Chaplin; C. Regulo; T. R. Bedding; D. Stello; W. J. Borucki; D. G. Koch; J. Jenkins; C. Allen; R. L. Gilliland; H. Kjeldsen; J. Christensen-Dalsgaard
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The large number of stars for which uninterrupted high-precision photometric timeseries data are being collected with \textit{Kepler} and CoRoT initiated the development of automated methods to analyse the stochastically excited oscillations in main-sequence, subgiant and red-giant stars. Aims: We investigate the differences in results for global oscillation parameters of G and K red-giant stars due to different methods and definitions. We also investigate uncertainties originating from the...
Source: http://arxiv.org/abs/1008.2959v1
