Other
Scientific paper
Dec 1996
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996aas...18911905o&link_type=abstract
American Astronomical Society, 189th AAS Meeting, #119.05; Bulletin of the American Astronomical Society, Vol. 28, p.1432
Other
Scientific paper
I describe spectroscopic techniques for studying starspots on late-type active stars. I develop an empirical spectral synthesis technique that independently measures starspot filling factor and temperature by fitting TiO absorption bands of different temperature sensitivities. Spectra of inactive G and K stars are used as proxies for the unspotted photospheres of the active stars, and spectra of M stars represent the spots. The set of TiO bands beginning at 7055 Angstroms and the band at 8860 Angstroms are most useful for this procedure; the starspots must be cooler than 4000 K. I apply this technique to spectra of seven RS CVn systems and one FK Comae star. Measured spot filling factors range from below the detection threshold ( ~ 8%) to nearly 60%. By comparing our measurements with contemporaneous photometry, we find, for some active stars, that the unspotted brightness of the star is significantly brighter than historical light maximum, and conclude that some starspot coverage has always been present. In some cases we find much higher spot filling factors than measured using other techniques, implying a uniform component to the starspot coverage. I extend this technique into the H band (where starspots contribute much more to the overall stellar spectrum than in the visible) by observing a pair of OH lines near 1.563mu m in three RS CVn systems. In inactive stars the equivalent width of these lines increases approximately linearly as temperature decreases from 5000 K to 3000 K; the OH lines greatly extend the temperature range over which starspots can be studied through molecular absorption features. Also, I apply TiO-band spectroscopy to the problem of Doppler imaging. Doppler imaging better constrains the sizes and shapes of starspots than their temperatures. TiO-band spectroscopy can supply the needed temperature constraint; the Doppler image is made to reproduce the observed depths of the TiO bands as well as the atomic line profiles. For the star II Pegasi, a Doppler image constrained by TiO-band spectroscopy yields a starspot temperature ~ 350 K cooler than that given by Doppler imaging alone.
No associations
LandOfFree
Spectroscopic Measurements of Starspot Area and Temperature on Magnetically Active Stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Spectroscopic Measurements of Starspot Area and Temperature on Magnetically Active Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spectroscopic Measurements of Starspot Area and Temperature on Magnetically Active Stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-818553