NOAO >   Observing Info >   Approved Programs >   2012A-0592

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Proposal Information for 2012A-0592


PI: Jon Mauerhan, UA Steward Observatory, mauerhan@ipac.caltech.edu
Address: 933 North Cherry Ave, Rm. N204, Tucson, Arizona 85721, USA

CoI: Schuyler Van Dyk, SSC/Caltech
CoI: Stefanie Wachter, IPAC/Caltech

Title: Photometric Monitoring of a New Sample of Candidate Luminous Blue Variables

Abstract: Luminous Blue Variables (LBV) are evolved massive stars in transition from the main-sequence to the Wolf-Rayet phase. They are characterized by extreme luminosities, large photometric variations, and circumstellar nebulae. LBV variability is believed to be linked with the enigmatic processes driving recurrent outbursts of mass which liberate these stars of their hydrogen envelopes. Because of the small sample of 10 Galactic LBVs, progress toward understanding the physics of these processes has been very limited. Fortunately, the \textitSpitzer/MIPSGAL survey revealed a population of ~100 circular nebulae surrounding bright central stars that are heavily obscured in the optical; we have determined that ~50 of them have spectral types similar to active LBVs, such as P Cyg and the Pistol Star. We suspect many of these are LBVs, and that their circumstellar shells are the result of recent mass eruptions. If they are active LBVs, we expect them to exhibit large-amplitude oscillations (~0.5-1 mag) on month-to-year timescales, and/or small eruptions (~1-2 mag) on year-to-decade timescales, like P Cyg and AG Car. Therefore we propose a SMARTS program to identify active LBVs within our sample of 43 candidates by monitoring their IR brightness with CT1.3+ANDICAM. Using an cadence of one month, we will probe for evidence of oscillations. Comparison with 2MASS will probe decade-long changes and potentially reveal evidence for eruptions.


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



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