相关论文: Rotation of 10 Be stars through Fourier transform …
Spectroscopic monitoring of 141 southern field B type stars, 114 of them known to exhibit the Be phenomenon, allowed the estimation of their projected rotational velocities, effective temperatures and superficial gravities from…
In this paper we develop a calculation code to account for the effects carried by fast rotation on the observed spectra of early-type stars. Stars are assumed to be in rigid rotation and the grid of plane-parallel model atmospheres used to…
We argue that, in general, observational studies of Be-star rotation have paid insufficient attention to the effects of equatorial gravity darkening. We present new line-profile calculations that emphasize the insensitivity of line width to…
The Fourier Transform method is a popular tool to derive the rotational velocities of stars from their spectral line profiles. However, its domain of validity does not include line-profile variables with time-dependent profiles. We…
We present a comprehensive study that applies the Fourier transform to a sample of O and early B-type stars (either dwarfs, giants, or supergiants) to determine their projected rotational velocities, compare with previous values obtained…
We obtained high quality spectra of 135 stars of spectral types F and later and derived ``overall'' broadening functions in selected wavelength regions utilizing a Least Squares Deconvolution (LSD) procedure. Precision values of the…
Fast rotation seems to be the mayor factor to trigger the Be phenomenon. Surface fast rotation can be favored by initial formation conditions, such as abundance of metals. We have observed 118 Be stars up to the apparent magnitudes V=9 mag.…
We conduct a systematic study on the effects of rapid rotation on predicted Be star observables. We use the three-dimensional Monte Carlo radiative transfer code, \textsc{hdust}, to model a comprehensive range of Be star subtypes at varying…
We used Fourier transform techniques to determine macroturbulent velocity. The analysis is done with mictoturbulent velocity and rotation velocity as an unknown quantities. In order to distinguish the effects of rotation from…
Fast rotation seems to be the major factor to trigger the Be phenomenon. Surface fast rotation can be favored by initial formation conditions such as metal abundance. Models of fast rotating atmospheres and evolutionary tracks are used to…
Be stars are found to rotate close to their critical rotation and therefore they are considered as an important laboratory of study for stellar rotation. In this context, we obtain the projected rotational velocity of a sample of classical…
Differential rotation can be detected in single line profiles of stars rotating more rapidly than about $v \sin{i} = 10$ km s$^{-1}$ with the Fourier transform technique. This allows to search for differential rotation in large samples to…
The spin-down of Be stars due to angular momentum transport from star to disc has been considered. This has been prompted by empirical studies of observed optical and IR line profile studies indicating that the disc is rotating in a…
Mechanisms influencing absorption line profiles of fast rotating stars can be sorted into two groups; (i) intrinsic variations sensitive to temperature and pressure, and (ii) global effects common to all spectral lines. I present a detailed…
Context: Rotation plays a key role in the life cycles of stars with masses above 8 Msun. Hence, accurate knowledge of the rotation rates of such massive stars is critical for understanding their properties and for constraining models of…
The evolutionary status of Be-type stars remains unclear, with both single-star and binary pathways having been proposed. Here, VFTS spectroscopy of 73 Be-type stars, in the spectral-type range, B0--B3, is analysed to estimate projected…
We assume that stars may undergo surface differential rotation to study its impact on the interpretation of $V\!\sin i$ and on the observed distribution $\Phi(u)$ of ratios of true rotational velocities $u=V/V_\rm c$ ($V_\rm c$ is the…
Using 2D models of rotating stars, the interferometric measurements of alpha Eri and its fundamental parameters corrected for gravitational darkening effects we infer that the star might have a core rotating 2.7 times faster than the…
We continue our studies on stellar latitudinal differential rotation. The presented work is a sequel of the work of Reiners et al. who studied the spectral line broadening profile of hundreds of stars of spectral types A through G at high…
The effect of gravitational darkening on models of the thermal structure of Be star disks is systematically studied for a wide range of Be star spectral types and rotation rates. Gravitational darkening causes a reduction of the stellar…