Related papers: Pulsations in M dwarf stars
The discovery of pulsations in some low-mass white dwarfs, including the so-called extremely low-mass white dwarfs, has opened the unprecedented opportunity of probing the internal structure of these ancient stars. We present a detailed…
We present optical high-speed photometry of three millisecond pulsars with low-mass ($< 0.3 M_{\odot}$) white dwarf companions, bringing the total number of such systems with follow-up time-series photometry to five. We confirm the…
Material accreted onto a neutron star can stably burn in steady state only when the accretion rate is high (typically super-Eddington) or if a large flux from the neutron star crust permeates the outer atmosphere. For such situations we…
PG 1159-035, a pre-white dwarf with T_eff=140,000 K, is the prototype of both two classes: the PG1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035 photometric data obtained with the Whole Earth Telescope…
We present a case study for the relevance of the r-mode instability for accreting compact stars. Our estimates are based on approximations that facilitate back-of-the-envelope calculations. We discuss two different cases: 1) For recycled…
Pulsational properties of 1.8 M$_{\odot}$ stellar models covering the latest stages of contraction toward the main sequence up to early hydrogen burning phases are investigated by means of linear nonadiabatic analyses. Results confirm that…
Observations made using TESS revealed a sample of low mass stars which show a periodic modulation on a period $<0.2$~d. Surprisingly many of these Ultra Fast Rotating (UFR) stars showed no evidence of flare activity which would be expected…
We present the detection of an energetic flare on the pre-main sequence M3 star NGTS J121939.5-355557, which we estimate as only 2 Myr old. The flare had an energy of $3.2\pm^{0.4}_{0.3}\times 10^{36}$erg and a fractional amplitude of…
Stellar activity and rotation frustrate the detection of exoplanets through the radial velocity technique. This effect is particularly of concern for M dwarfs, which can remain magnetically active for billions of years. We compile rotation…
A linear nonadiabatic analysis of the vibrational stability of population III main-sequence stars was carried out. It was demonstrated that, in the case of massive stars with $M \gtrsim 5\Mo$, helium burning (triple alpha reaction) starts…
Using linear non-adabatic pulsation analysis, we explore the radial-mode (p-mode) stability of stars across a wide range of mass (0.2 <= M <= 50 Msun), composition (0 <= X <= 0.7, Z=0.001, 0.02), effective temperature (3 000 <= T_eff <= 40…
The $\epsilon$ mechanism is a self-excitation mechanism of stellar pulsations which acts in regions inside the star where nuclear burning takes place. It has been shown that the $\epsilon$ mechanism can excite pulsations in models of hot…
We present a study of the variation timescales of the chromospheric activity indicator H$\alpha$ on a sample of 13 fully-convective, active mid-to-late M stars with masses between 0.1--0.3 solar masses. Our goal was to determine the…
The fundamental properties of low-mass stars are not as well understood as those of their more massive counterparts. The best method for constraining these properties, especially masses and radii, is to study eclipsing binary systems, but…
In this paper we describe a new class of pulsating stars, the prototype of which is the bright, early, F-type dwarf, Gamma Doradus. These stars typically have between 1 and 5 periods ranging from 0.4 to 3 days with photometric amplitudes up…
Context. M stars are preferred targets for studying terrestrial exoplanets, for which we hope to obtain their atmosphere spectra in the next decade. However, M dwarfs have long been known for strong magnetic activity and the ability to…
We have searched for short periodicities in the light curves of stars with $T_{\rm eff}$ cooler than 4000 K made from 2-minute cadence data obtained in TESS sectors 1 and 2. Herein we report the discovery of 10 rapidly rotating M-dwarfs…
The Rossi X-ray Timing Explorer has detected nearly coherent oscillations in the tails of type I X-ray bursts from 17 low-mass X-ray binaries. The oscillations are thought to be generated by brightness fluctuations associated with a surface…
Helium core white dwarfs (WDs) with mass M <~ 0.20 Msun undergo several Gyrs of stable hydrogen burning as they evolve. We show that in a certain range of WD and hydrogen envelope masses, these WDs may exhibit g-mode pulsations similar to…
We present here a detailed pulsational study applied to low-mass He-core white dwarfs, based on full evolutionary models representative of these objects. The background stellar models on which our pulsational analysis was carried out were…