Related papers: Evidence for granulation in early A-type stars
We present results from 2D radiation-hydrodynamical simulations of fully compressible convection for the surface layers of A-type stars with the ANTARES code. Spectroscopic indicators for photospheric convective velocity fields show a…
The two pulsating pre-main sequence (PMS) stars V 588 Mon and V 589 Mon were observed by CoRoT for 23.4 days in March 2008 during the Short Run SRa01 and in 2004 and 2006 by MOST for a total of ~70 days. We present their photometric…
For the Delta Scuti star 44 Tau 13 independent frequencies have been detected in previous studies. This star is unusual among the Delta Scuti stars because of its very low v sin i value of 2 +/- 1 km/s, indicating that it is either an…
Properties of stars undergoing pulsation such as the well known root-mean-density scaling relation can be useful when trying to match the observed properties of a particular star. It is often assumed that this relation is valid for p mode…
Weak magnetic fields have recently been detected in a number of A-type stars, including Vega and Sirius. At the same time, space photometry observations of A- and late B-type stars from Kepler and TESS have highlighted the existence of…
delta Scuti stars are pulsating stars constituting the delta Scuti instability strip in the HR diagram, which consists of A and F stars of various evolutionary stages. They are in the transition region between high-mass hot stars and…
Surface gravity is one of a star's basic properties, but it is difficult to measure accurately, with typical uncertainties of 25-50 per cent if measured spectroscopically and 90-150 per cent photometrically. Asteroseismology measures…
Context: Rapid rotation is a common feature of early-type stars but which remains a challenge for the models. The understanding of its effect on stellar evolution is however imperative to interpret the observed properties of numerous stars.…
Bowman et al. (2019) reported low-frequency photometric variability in 164 O- and B-type stars observed with K2 and TESS. They interpret these motions as internal gravity waves, which could be excited stochastically by convection in the…
Using multi-site spectroscopic data collected from three sites, the frequencies and pulsational modes of the {\gamma} Doradus star HD 12901 were identified. A total of six frequencies in the range 1-2 c/d were observed, their…
Accretion from protoplanetary or debris disks can contaminate the stellar photosphere, which is detectable in stars with radiative envelopes due to relatively slower photospheric mixing. The contaminated photosphere reflects ongoing disk…
According to a recent ray-based asymptotic theory, the high-frequency p-mode spectrum of rapidly rotating stars is a superposition of frequency subsets associated with dynamically independent regions of the ray-dynamics phase space. At high…
In this paper we investigate theoretical pulsation models for the delta Scuti star 44 Tau. The star was monitored during several multisite campaigns which confirmed the presence of radial and nonradial oscillations. Moreover, its…
Surface convection is important for the presence of magnetic activity at stars. So far, this convection is thought to be a result of heating from below, where convection cells rise and break up. New models reveal that surface convection is…
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…
Hybrid $\delta$ Scuti-$\gamma$ Doradus pulsating stars show acoustic ($p$) oscillation modes typical of $\delta$ Scuti variable stars, and gravity ($g$) pulsation modes characteristic of $\gamma$ Doradus variable stars simultaneously…
We report the discovery of four rare debris disks with warm excesses around F-stars, significantly increasing the number of such systems known in the solar neighborhood. Three of the disks are consistent with the predictions of steady state…
The O9V star HD 46202, which is a member of the young open cluster NGC 2244, was observed by the CoRoT satellite in October/November 2008 during a short run of 34 days. From the very high-precision light curve, we clearly detect beta…
Based on 2-minute cadence TESS data, 20 confident independent frequencies were identified for the star TIC 120857354. The Kolmogorov-Smirnov test reveals a rotational splitting of 2.40 $\mu$Hz and a uniform frequency spacing of 74.6…
This paper examines the mode identification and presents pulsation models for FG Vir, for which 24 frequencies have been detected. Histograms of the frequency spacings show peaks which are identified with adjacent radial orders and…