Line-profile variations of stochastically excited oscillations in four evolved stars
Reads0
Chats0
TLDR
In this paper, line-profile variations in stochastically excited solar-like oscillations of four evolved stars were used to derive the azimuthal order of the observed mode and the surface rotational frequency.Abstract:
Context. Since solar-like oscillations were first detected in red-giant stars, the presence of non-radial oscillation modes has been debated. Spectroscopic line-profile analysis was used in the first attempt to perform mode identification, which revealed that non-radial modes are observable. Despite the fact that the presence of non-radial modes could be confirmed, the degree or azimuthal order could not be uniquely identified. Here we present an improvement to this first spectroscopic line-profile analysis. Aims. We aim to study line-profile variations in stochastically excited solar-like oscillations of four evolved stars to derive the azimuthal order of the observed mode and the surface rotational frequency. Methods. Spectroscopic line-profile analysis is applied to cross-correlation functions, using the Fourier parameter fit method on the amplitude and phase distributions across the profiles. Results. For four evolved stars, β Hydri (G2IV), � Ophiuchi (G9.5III), η Serpentis (K0III) and δ Eridani (K0IV) the line-profile variations reveal the azimuthal order of the oscillations with an accuracy of ±1. Furthermore, our analysis reveals the projected rotational velocity and the inclination angle. From these parameters we obtain the surface rotational frequency. Conclusions. We conclude that line-profile variations in cross-correlation functions behave differently for different frequencies and provide additional information about the surface rotational frequency and azimuthal order.read more
Citations
More filters
Journal ArticleDOI
Testing a predictive theoretical model for the mass loss rates of cool stars
Steven R. Cranmer,Steven H. Saar +1 more
TL;DR: In this article, a physically motivated model of the time-steady mass loss rates of cool main-sequence stars and evolved giants was developed to model the energy flux of magnetohydrodynamic turbulence from a subsurface convection zone to its eventual dissipation and escape through open magnetic flux tubes.
Journal ArticleDOI
Giant star seismology
TL;DR: In this article, the internal properties of stars in the red-giant phase undergo significant changes on relatively short timescales, and the authors anticipate that more information is still hidden in the data.
Journal ArticleDOI
The IACOB project: III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars ?
Sergio Simón-Díaz,Sergio Simón-Díaz,Mélanie Godart,Mélanie Godart,Mélanie Godart,Norberto Castro,Artemio Herrero,Artemio Herrero,Conny Aerts,Conny Aerts,Joachim Puls,John H. Telting,L. Grassitelli +12 more
TL;DR: In this article, the authors used high-resolution spectra of 430 stars with spectral types in the range O4 - B9 (all luminosity classes) compiled in the framework of the IACOB project to provide new empirical clues about macroturbulent spectral line broadening in O- and B-type stars.
Journal ArticleDOI
Giant star seismology
TL;DR: In this article, the internal properties of stars in the red-giant phase undergo significant changes on relatively short timescales, and the authors anticipate that more information is still hidden in the data.
References
More filters
Journal ArticleDOI
Non-radial oscillation modes with long lifetimes in giant stars
Joris De Ridder,C. Barban,Frédéric Baudin,Fabien Carrier,Artie P. Hatzes,Saskia Hekker,Saskia Hekker,Thomas Kallinger,Werner W. Weiss,A. Baglin,M. Auvergne,Reza Samadi,Pierre Barge,Magali Deleuil +13 more
TL;DR: The presence of radial and non-radial oscillations in more than 300 giant stars is reported, finding giant stars with equally spaced frequency peaks in the Fourier spectrum of the time series, as well as giants for which the spectrum seems to be more complex.
Journal ArticleDOI
Determining the Inclination of the Rotation Axis of a Sun-like Star
Laurent Gizon,Sami K. Solanki +1 more
TL;DR: In this paper, the authors used Monte Carlo simulations to estimate the precision of the measurement of the inclination angle between the direction of the rotation axis of a pulsating Sun-like star and the line of sight.
Journal ArticleDOI
Precise radial velocities of giant stars. III. Spectroscopic stellar parameters
Saskia Hekker,Jorge Melendez +1 more
TL;DR: In this paper, a radial velocity survey of about 380 G and K giant stars is ongoing at Lick observatory, which is used to determine spectroscopic stellar parameters, i.e. effective temperature, surface gravity, metallicity and rotational velocity.
Journal ArticleDOI
Solar-like Oscillations in Low-luminosity Red Giants: First Results from Kepler
Timothy R. Bedding,Daniel Huber,Dennis Stello,Yvonne Elsworth,Saskia Hekker,Thomas Kallinger,Thomas Kallinger,Savita Mathur,Benoit Mosser,H. L. Preston,Jérôme Ballot,C. Barban,Anne-Marie Broomhall,Derek Buzasi,William J. Chaplin,Rafael A. García,Michael Gruberbauer,Steven J. Hale,J. De Ridder,Søren Frandsen,William J. Borucki,Timothy Brown,Jørgen Christensen-Dalsgaard,Ronald L. Gilliland,Jon M. Jenkins,Hans Kjeldsen,David G. Koch,Kevin Belkacem,Lars Bildsten,Hans Bruntt,Hans Bruntt,Tiago L. Campante,Tiago L. Campante,S. Deheuvels,Aliz Derekas,Aliz Derekas,Marc-Antoine Dupret,Marie-Jo Goupil,Artie P. Hatzes,Günter Houdek,Michael J. Ireland,Chen Jiang,Christoffer Karoff,László L. Kiss,László L. Kiss,Yveline Lebreton,Andrea Miglio,Josefina Montalbán,Alfred F. Noels,Ian W. Roxburgh,Vinothini Sangaralingam,Ian R. Stevens,M. D. Suran,N. J. Tarrant,Achim Weiss +54 more
TL;DR: In this paper, the authors measured solar-like oscillations in red giants using time-series photometry from the first 34 days of science operations of the Kepler Mission and found a strong correlation between the large separation of the oscillations and the frequency of maximum power (νmax).
Journal ArticleDOI
Theoretical amplitudes and lifetimes of non-radial solar-like oscillations in red giants
Marc-Antoine Dupret,Marc-Antoine Dupret,Kevin Belkacem,Kevin Belkacem,R. Samadi,Josefina Montalbán,O. Moreira,Andrea Miglio,Mélanie Godart,Paolo Ventura,Hans-Günter Ludwig,A. Grigahcène,M. J. Goupil,Alfred F. Noels,Elisabetta Caffau +14 more
TL;DR: In this article, the authors investigated under what physical circumstances non-radial modes could be observable in red giants; what would be their amplitudes, lifetimes and heights in the power spectrum (PS).