Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars

  title={Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars},
  author={Timothy R. Bedding and Beno{\^i}t Mosser and Daniel Huber and Josefina Montalb{\'a}n and Paul G. Beck and J{\o}rgen Christensen-Dalsgaard and Yvonne P. Elsworth and Rafael A. Garc{\'i}a and Andrea Miglio and Dennis Stello and Timothy R. White and Joris de Ridder and Saskia Hekker and C. Aerts and Caroline Barban and K'evin Belkacem and A-M. Broomhall and Timothy M. Brown and Derek Buzasi and Fabien Carrier and William J. Chaplin and Maria Pia di Mauro and M-A. Dupret and S{\o}ren Frandsen and Ronald L. Gilliland and Marie Jo Goupil and Jon M. Jenkins and Thomas Kallinger and Steven D. Kawaler and Hans Kjeldsen and Savita Mathur and Arlette Noels and Victor Silva Aguirre and Paolo Ventura},
Red giants are evolved stars that have exhausted the supply of hydrogen in their cores and instead burn hydrogen in a surrounding shell. Once a red giant is sufficiently evolved, the helium in the core also undergoes fusion. Outstanding issues in our understanding of red giants include uncertainties in the amount of mass lost at the surface before helium ignition and the amount of internal mixing from rotation and other processes. Progress is hampered by our inability to distinguish between red… Expand
Photospheric diagnostics of core helium burning in giant stars
Core helium burning primary red clump (RC) stars are evolved red giant stars which are excellent standard candles. As such, these stars are routinely used to map the Milky Way or determine theExpand
Astrophysics: The inner lives of red giants
Observations by the Kepler space telescope shed light on a previously untested prediction of stellar evolution theory, and Bedding et al. have used Kepler data to probe the internal structure of red giants. Expand
Fast core rotation in red-giant stars as revealed by gravity-dominated mixed modes
An increasing rotation rate from the surface of the star to the stellar core in the interiors of red giants is reported using the rotational frequency splitting of recently detected ‘mixed modes’, which confirms the theoretical prediction of a steep gradient in the rotation profile towards the deep stellar interior. Expand
Low-frequency gravity waves in blue supergiants revealed by high-precision space photometry
Almost all massive stars explode as supernovae and form a black hole or neutron star. The remnant mass and the impact of the chemical yield on subsequent star formation and galactic evolutionExpand
Evolutionary states of red-giant stars from grid-based modelling
From its surface properties it can be difficult to determine whether a red-giant star is in its helium-core-burning phase or only burning hydrogen in a shell around an inert helium core. Stars inExpand
Seismic characterization of red giants going through the helium-core flash
First-ascent red giants with masses below about $2\,M_\odot$ ignite helium in their degenerate core as a flash. Stellar evolution codes predict that the He flash consists of a series of consecutiveExpand
Amplitude and lifetime of radial modes in red giant star spectra observed by Kepler
Context: the space-borne missions CoRoT and Kepler have provided photometric observations of unprecedented quality. The study of solar-like oscillations observed in red giant stars by theseExpand
Seismic evidence for a weak radial differential rotation in intermediate-mass core helium burning stars
The detection of mixed modes that are split by rotation in Kepler red giants has made it possible to probe the internal rotation profiles of these stars, which brings new constraints on the transportExpand
Core–Envelope Coupling in Intermediate-mass Core-helium Burning Stars
Stars between two and three solar masses rotate rapidly on the main sequence, and the detection of slow core and surface rotation in the core-helium burning phase for these stars places strongExpand
The asteroseismology of evolved solar-like stars is experiencing growing interest due to the wealth of observational data from space-borne instruments such as the CoRoT and Kepler spacecraft. InExpand


Non-radial oscillation modes with long lifetimes in giant stars
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. Expand
Kepler Detected Gravity-Mode Period Spacings in a Red Giant Star
Mixed modes penetrating all the way to the core of an evolved star from 320 days of observations with the Kepler satellite are reported, which challenges knowledge of star formation rates, the mass of forming stars, and the models of the stars themselves. Expand
Solar-like Oscillations in Low-luminosity Red Giants: First Results from Kepler
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 minuteExpand
Oscillating red giants in the CoRoT exofield: asteroseismic mass and radius determination
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. AlthoughExpand
Oscillations of α UMa and other red giants
There is growing observational evidence that the variability of red giants could be caused by self-excitation of global modes of oscillation. The most recent evidence of such oscillations wasExpand
Probing populations of red giants in the galactic disk with CoRoT
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 redExpand
A secondary clump of red giant stars: why and where
Based on the results of detailed population synthesis models, Girardi et al. recently claimed that the clump of red giants in the colour–magnitude diagram (CMD) of composite stellar populationsExpand
Seismic diagnostics of red giants: first comparison with stellar models
The clear detection with CoRoT and KEPLER of radial and non-radial solar-like oscillations in many red giants paves the way for seismic inferences on the structure of such stars. We present anExpand
Evolutionary sequences for red giant stars
A set of 46 evolutionary sequences has been computed for stars ascending the red giant branch for the first time. These red giant sequences, extending from the subgiant branch to the onset of heliumExpand
Gravity modes and mixed modes as probes of stellar cores in main-sequence stars: From solar-like to β Cep stars
We investigate how the frequencies of gravity modes depend on the detailed properties of the chemical composition gradient that develops near the core of main-sequence stars and, therefore, on theExpand