Related papers: Complex Modulation of Rapidly Rotating Young M Dwa…

We investigate the survival of dust trapped in magnetically confined cool gas clouds (or {\it prominences}) around rapidly rotating M-dwarfs exhibiting the ``scallop-shell'' light-curve morphology. Using a two-dimensional…

We used the optical and near-infrared imagers located on the Liverpool, the IAC80, and the William Herschel telescopes to monitor 18 M7$-$L9.5 dwarfs with the objective of measuring their rotation periods. We achieved accuracies typically…

The Oef category gathers rapidly rotating and evolved O-stars displaying a centrally reversed He II 4686 emission line. The origin of the variability of their photospheric and wind spectral lines is debated, with rotational modulation or…

The globular cluster Messier 80 was monitored by the Kepler space telescope for 80 days during the K2 mission. Continuous, high-precision photometry of such an old, compact cluster allows us to study its variable star population in…

Context. The Kepler mission has recently discovered a brown dwarf companion transiting one member of the M4V+M5V visual binary system LHS 6343 AB with an orbital period of 12.71 days. Aims. The particular interest of this transiting system…

Theoretical predictions suggest that the distribution of planets in very young stars could be very different to that typically observed in Gyr old systems that are the current focus of radial velocity surveys. However, the detection of…

In a previous study on gas-stellar counterrotation for a large sample of E/S0 and spiral galaxies (Kannappan & Fabricant 2001), two dwarf irregular galaxies were included, of which one was tentatively identified as a counterrotator. Here we…

Asteroseismology of bright stars has become increasingly important as a method to determine fundamental properties (in particular ages) of stars. The Kepler Space Telescope initiated a revolution by detecting oscillations in more than 500…

Circumstellar debris disks are important because of their connection to planetary systems. An efficient way to identify these systems is through their infrared excess. Most studies so far concentrated on early-type or solar-type stars, but…

Eclipsing binaries are important benchmark objects to test and calibrate stellar structure and evolution models. This is especially true for binaries with a fully convective M-dwarf component for which direct measurements of these stars'…

We present four newly validated transiting brown dwarfs identified through TESS photometry and confirmed with high-precision radial velocity measurements obtained from the FEROS and PLATOSpec spectrographs. Notably, three of these…

We present multi-telescope, ground-based, multiwavelength optical and near-infrared photometry of the variable L3.5 ultra-cool dwarf 2MASSW J0036159+182110. We present 22 nights of photometry of 2MASSW J0036159+182110, including 7 nights of…

We study variability through simultaneous optical and X-ray observations for the first time in a statistical sample of 256 M dwarfs. Such observations are required to constrain the flare frequency and energetics and to understand the…

We present results from a series of follow-up observations of a sub-sample of the representative SAURON survey elliptical (E) and lenticular (S0) galaxies using the OASIS integral-field spectrograph. These observations focus on the central…

Stellar rotation was proposed as a potential age diagnostic that is precise, simple, and applicable to a broad range of low-mass stars ($\leq$1 $M_\odot$). Unfortunately, rotation period $(P_{\rm rot})$ measurements of low-mass members of…

We present a comprehensive catalog of the dippers---young stellar objects that exhibit episodic dimming---derived from the one year's worth of data of Transiting Exoplanet Survey Satellite ($ TESS$) full-frame images. In the survey, we…

We classified the reddest ($r-J>2.2$) stars observed by the NASA $Kepler$ mission into main sequence dwarf or evolved giant stars and determined the properties of 4216 M dwarfs based on a comparison of available photometry with that of…

The photospheres of some white dwarfs are "polluted" by accretion of material from their surrounding planetary debris. White dwarfs with dust disks are often heavily polluted and high-resolution spectroscopic observations of these systems…

The extended main sequence (eMS) and extended main sequence turnoff (eMSTO) phenomena have been observed in some young and intermediate-age star clusters in the Milky Way and in the Magellanic Clouds. In this study, we conduct a survey of…

Hot subdwarf stars are mostly stripped red giants that can exhibit photometric variations due to stellar pulsations, eclipses, the reflection effect, ellipsoidal modulation, and Doppler beaming. Detailed studies of their light curves help…