How semiregular are irregular variables?
نویسندگان
چکیده
منابع مشابه
Mass loss rates of a sample of irregular and semiregular M-type AGB-variables
We have determined mass loss rates and gas expansion velocities for a sample of 69 M-type irregular (IRV; 22 objects) and semiregular (SRV; 47 objects) AGB-variables using a radiative transfer code to model their circumstellar CO radio line emission. We believe that this sample is representative for the mass losing stars of this type. The (molecular hydrogen) mass loss rate distribution has a m...
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We searched for the lines of Tc in the spectra of Semiregular variables (SRVs) in the wavelength region from 4180 to 4300 Å using high resolution spectroscopy. Tc as an s-process element is produced on the thermally pulsing AGB and is therefore a good indicator for the evolutionary status of Semiregular variables. Combining our results with previous investigations we get a database large enough...
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Power spectra of the light curves of semiregular variables, based on visual magnitude estimates spanning many decades, show clear evidence for stochastic excitation. This supports the suggestion by Christensen-Dalsgaard et al. (2001) that oscillations in these stars are solar-like, i.e., stochastically excited by convection, with mode lifetimes ranging from years to decades.
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ABSTRAC"T A construction method for semiregular group divisible designs is given. This method can be applied to yield many classes of (in general, non-symmetric) semiregular group divisible designs whose duals are semiregular group divisible. In particular, the method can be used to construct many classes of transversal designs whose duals are serniregular group divisible designs, but not trans...
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ژورنال
عنوان ژورنال: Astronomische Nachrichten
سال: 2009
ISSN: 0004-6337,1521-3994
DOI: 10.1002/asna.200811194