Red-Eye Astronomy: 15 Years of V-band and Near-IR Tio Photometry of the Red Supergiants Alpha Orionis And TV Geminorum.

Details Red-Eye Astronomy: 15 Years of V-band and Near-IR Tio Photometry of the Red Supergiants Alpha Orionis And TV Geminorum. Red-Eye Astronomy: 15 Years of V-band and Near-IR Tio Photometry of the Red Supergiants Alpha Orionis And TV Geminorum.

May 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011aas...21832205w&link_type=abstract

American Astronomical Society, AAS Meeting #218, #322.05; Bulletin of the American Astronomical Society, Vol. 43, 2011

Astronomy and Astrophysics

Astronomy

Scientific paper

V-band and narrow to intermediate-band Wing TiO-band (719 nm, 754 nm), and near-IR 1024 nm pseudo-bolometric photometric observations of the SRc M2 Iab supergiants Alpha Orionis and TV Geminorum have been conducted for the past 15 years. The goals are to monitor brightness and temperature-dependent TiO-band variations, ascertain any resulting periodicities and amplitudes, and estimate variations of basic stellar parameters such as temperature, luminosity, and radius.
Preliminary results for both stars indicate similar long-term V-mag periods of 6.5 years with imposed shorter-term V-mag periods of 1.2 years. The V-magnitude amplitudes were 0.8 for Alpha Ori and 1.3 for TV Gem. For both stars the temperature and luminosity variations correlate well with the V-mag changes.
However, inverse radii correlations with respect to temperature and luminosity variations were not seen in either star. In Alpha Ori the the radii changes were approximately in direct correlation with the temperature and luminosity changes. In TV Gem there was a combination of correlation/inverse correlation effects. Causes for these variations are speculative, but may be due to highly convective super-granulations occurring at irregular intervals rather than fundamental mode pulsation or harmonic oscillations. Based in part on an updated RSG temperature scale and a new VLA/Hipparchos distance estimate (197 PC), the Alpha Ori temperatures ranged from 3550 K to 3730 K, with ranges in solar luminosities and radii of L = 90,000 to 115,000 and R = 760 to 820, respectively. The slightly more dynamical TV Gem underwent temperature variations from 3500 K to 3850 K with ranges in solar luminosity and radii of L = 65,000 to 90,000 and R = 620 to 720 respectively. Discussions of the observations, data reduction methods, and analysis of the data will be presented.
This research is supported by NASA grant NNX10AI85G and NSF grants AST 10-09903 and AST 05-07542.

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