sigma Geminorum campaign
This STAROS campaign is dedicated to observing sigma Geminorum.
This STAROS campaign is dedicated to the observation of Sigma Geminorum (HD 62044), a K1 III star of magnitude 4.2. We invite you to participate by using your spectrograph in “high spectral resolution” mode to follow the temporal evolution of the Hα line, as well as the Ca II H and K lines, in order to better understand its chromospheric activity.
Sigma Gem is a relatively bright star (V = 4.2) that lends itself well to high spectral resolution observations (resolution in excess of 13,000), and is accessible with telescopes and scopes of relatively modest diameters, from 80 mm aperture upwards.
The main objective of this campaign is to observe the Hα line and its immediate surroundings. However, the chromospheric activity of this star is also visible in the center of the ultraviolet Ca II H and K lines, which constitutes a relevant secondary objective for this study. Complementary photometric observations would also be beneficial to better document these activity variations.
Let's start to observe sigma Geminorum together.
A V band light curve for Sigma Geminorum, adapted from K ̋ovári et al., Astronomy & Astrophysics, Volume 573, 2015
Sigma Geminorum is a single-lined spectroscopic binary, which means that the spectrum of only one of its components can be discerned. It is an RS Canum Venaticorum variable with a period of 19.6 days, matching the orbital period.
The stellar luminosity shows indications of ellipsoidal variation, as the primary component is partly filling its Roche lobe due to gravitational interaction between the two stars. (Source)