منابع مشابه
Measuring the Rotation Speed of Giant Stars From Gravitational Microlensing
During some gravitational lensing events, the lens transits the face of the star. This causes a shift in the apparent radial velocity of the star which is proportional to its rotation speed. It also changes the magnification relative to what would be expected for a point source. By measuring both effects, one can determine the rotation parameter v sin i. The method is especially useful for K gi...
متن کاملFirst signatures of strong differential rotation in A-type stars
We reanalyzed high quality spectra of 158 stars of spectral types A0–F1 and v sin i between 60 and 150 km s−1. Using a Least Squares Deconvolution technique we extracted high S/N broadening profiles and determined the loci of the Fourier transform zeros q1 and q2 where the S/N-ratio was high enough. The values of v sin i were redetermined and found to be consistent with the values derived by Ro...
متن کاملRotation In Young Stars
The smallest molecular cores observed to date have at least ∼6 orders of magnitude greater angular momentum per unit mass than the Sun, suggesting that they would greatly exceed the breakup velocity if no angular momentum was lost during the star formation process. Therefore, an angular momentum regulation mechanism must be at work in the pre-main-sequence phase, and disks are often invoked as ...
متن کاملDifferential Rotation in F Stars
Differential rotation can be detected in single line profiles of stars rotating more rapidly than about v sin i = 10 km s with the Fourier transform technique. This allows to search for differential rotation in large samples to look for correlations between differential rotation and other stellar parameters. I analyze the fraction of differentially rotating stars as a function of color, rotatio...
متن کاملThe First Stars
■ Abstract We review recent theoretical results on the formation of the first stars in the universe, and emphasize related open questions. In particular, we discuss the initial conditions for Population III star formation, as given by variants of the cold dark matter cosmology. Numerical simulations have investigated the collapse and the fragmentation of metal-free gas, showing that the first s...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 2011
ISSN: 0035-8711
DOI: 10.1111/j.1365-2966.2010.18152.x