Discovery of a Luminous Blue Variable with an Ejection Nebula Near the Quintuplet Cluster

J.C. Mauerhan(1), M.R. Morris(2), A. Cotera(3), H. Dong(4), Q.D. Wang(4), S.R. Stolovy(1), C. Lang(5), I.S. Glass(6)

(1) Spitzer Science Center, California Institute of Technology, Mail Code 220-6, 1200 East California Blvd., Pasadena, CA 91125, USA;
(2) Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA
(3) SETI Institute, 515 North Whisman Road, Mountain View, CA 94043, USA
(4) Department of Astronomy, University of Massachusetts, Amherst, MA 01003, USA
(5) Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52245, USA
(6) South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa

Paper: ApJL, February 2010, accepted

EPrint Server: 1002.3379


We report the discovery of a Luminous Blue Variable (LBV) lying 7 pc in projection from the Quintuplet cluster. This source, which we call LBV G0.120-0.048, was selected for spectroscopy owing to its detection as a strong source of Paschen-alpha excess in a recent narrow-band imaging survey of the Galactic center region with HST/NICMOS. The K-band spectrum is similar to that of the Pistol Star and other known LBVs. The new LBV was previously cataloged as a photometric variable star, exhibiting brightness fluctuations of up to 1 magnitude between 1994 and 1997, with significant variability also occurring on month-to-month time scales. The luminosity of LBV G0.120-0.048, as derived from 2MASS photometry, is approximately equivalent to that of the Pistol Star. However, the time-averaged brightness of LBV G0.120-0.048 between 1994 and 1997 exceeded that of the Pistol Star; LBV G0.120-0.048 also suffers more extinction, which suggests that it was intrinsically more luminous in the infrared than the Pistol Star between 1994 and 1997. Paschen-alpha images reveal a thin circular nebula centered on LBV G0.120-0.048 with a physical radius of 0.8 pc. We suggest that this nebula is a shell of ejected material launched from a discrete eruption that occurred between 5000 and 10,000 years ago. Because of the very short amount of time that evolved massive stars spend in the LBV phase, and the close proximity of LBV G0.120-0.048 to the Quintuplet cluster, we suggest that this object might be coeval with the cluster, and may have once resided within it.

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