Near-infrared observations of the carbon stars TU Geminorum and SS Virginis at milliarcsecond resolution

¹ European Southern Observatory, Karl-Schwarzschildstr. 2, 85748 Garching bei München, Germany e-mail: arichich@eso.org
² Physical Research Laboratory, Navrangpura, 380009 Ahmedabad, India e-mail: chandra@prl.res.in

Received: 9 December 2005
Accepted: 5 February 2006

Abstract

Aims.High-angular resolution investigations of carbon stars.

Methods. Milliarcsecond resolution observations in the near infrared K band by the method of lunar occultations are presented for the carbon stars TU Gem and SS Vir.

Results. Although a companion to TU Gem is known from the Tycho catalogue, we were not able to detect it so we place limits on its K-band brightness. For both stars, we determined accurate values of the angular diameters at the phase of the observation, namely mas and mas for SS Vir and TU Gem. Using distance estimates from the literature, we found that the two stars have radii of about 500 and 250 , respectively. We also computed their effective temperatures.

Conclusions. The result for SS Vir ( K) is in good agreement with estimates, but in the case of TU Gem our value of K requires reconsidering currently available models.