NOAO >   Observing Info >   Approved Programs >   2006A-0300

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Proposal Information for 2006A-0300


PI: Howard E. Bond, Space Telescope Science Institute, bond@stsci.edu
Address: 3700 San Martin Dr, Baltimore, MD 21218, USA

CoI: Dianne Harmer, NOAO
CoI: Melike Afsar, Ege University, Turkey

Title: The Stellar Environment around V838 Monocerotis

Abstract: V838 Monocerotis is a unique erupting variable star that has produced a spectacular light echo. The nature of the outburst, in which the star expanded rapidly to become an extremely cool supergiant and temporarily one of the brightest stars in the entire Milky Way, remains unexplained; it is one of the leading current challenges to our understanding of stellar evolution. Using the 1.5m SMARTS/CTIO telescope, we have discovered three B-type stars within 1 arcmin of V838 Mon, and the variable itself has an unresolved B companion. Thus V838 Mon lies within a young cluster of about the age of the Pleiades, in spite of its location ~9 kpc away in the rough direction of the Galactic anticenter. Using WIYN and the multi-object Hydra spectrograph, we propose to obtain spectra of several hundred stars within several arcmin of V838 Mon, in order to identify cluster members and reject members of the rich stellar foreground in this low-latitude field. Specific goals are (a) to determine the turnoff mass and age of the cluster, and (b) to refine the distance through main-sequence fitting. Both pieces of information will help constrain explanations for the outburst mechanism.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2006A-0300

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