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Active Research At Yale |
An Asteroseismic H-R Diagram
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The mass and age of a main sequence (MS) star can be easily and
accurately determined through asteroseismology. The oscillation
frequencies of an MS star follow regular patterns on the whole. The so-called large separation, i.e., the difference
in frequency of modes of successive radial order (n), but of the same
degree (l), depends mostly on the
mass and radius of a star. On the other hand, the small separation, i.e., the
small difference in frequency of modes of nearly same order, but
different degrees, is affected by the innermost layers of the star. The
ratio of the small to the large separation is even more sensitive to the
central conditions, and hence, the stellar age. When this ratio is
plotted against the large separation for stellar models of different
mass and age, we obtain a nearly orthogonal projection of the stellar
mass and age. Since these separations can be directly derived from
the observed frequency spectrum of a star, one can estimate the stellar mass and
age from this diagram.
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May 15, 2008 - 2:00 pm
Colloquium - Prof. Stephane Courteau, Queen's University
Puzzles in Disk Galaxy Scaling Relations |
May 21, 2008 - 2:00 pm
YCAA Seminar - Ricardo Munoz, Virginia/Yale
Mapping Galactic Halo and Dwarf Spheroidal Structure with Giant Stars |
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| April 09, 2007 E. Dorrit Hoffleit (12 March 1907 - 9 April 2007)  On April 9th Dorrit Hoffleit passed away at her apartment following a brief illness. Dorrit's astronomical career spanned more than 75 years, the first 25 at Harvard and the following 50 plus years at Yale. At the time of her passing she had just celebrated her 100th birthday at a luncheon attended by 94 of her friends and colleagues (at which the accompanying photo was taken).(More)
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