NOAO >   Observing Info >   Approved Programs >   2016A-0156

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Program Information for 2016A-0156


PI: Rodolfo Angeloni, Gemini Observatory, rangelon@gemini.edu
Address: Gemini Observatory, Colina El Pino s/n, La Serena Chile

CoI: Pawel Pietrukowicz, Warsaw University Astronomical Observatory
CoI: Francesco Di Mille, Carnegie Institution of Washington
CoI: Andrzej Udalski, Warsaw University Astronomical Observatory

Title: Spectroscopic follow-up of puzzling OGLE sources: a new class of variable stars?

Abstract: Variable stars provide unique information on structure and evolution of stars and stellar systems in general. For example, they are widely used for measurements of distances on different scales. Amongst about 400 million stars toward the Galactic bulge monitored by the OGLE survey every night, of which hundreds of thousands have been detected and classified as variable stars of known types, we have found 14 objects with extremely short periods of 15-40 min showing stable in time, pulsation-like, high-amplitude variations of 0.2-0.4 mag in the I band, not observed in any other stars. We propose to use the GMOS-S spectrograph to determine parameters for seven selected stars, such as temperature, gravity, and chemical composition. The spectra will help to answer the following questions: how homogeneous this group of stars is, what differs them from other objects, what drives the observed photometric variations.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2016A):  GEM-SQ/GMOSS -- 5hrs band 2 (GS-2016A-Q-71)


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NOAO >   Observing Info >   Approved Programs >   2016A-0156

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