GCIRS 16SW: A Massive Eclipsing Binary in the Galactic Center

We report on the spectroscopic monitoring of GCIRS 16SW, an Ofpe/WN9 star and LBV candidate in the central parsec of the Galaxy. SINFONI observations show strong daily spectroscopic changes in the K band. Radial velocities are derived from the He I 2.112 μm line complex and vary regularly with a period of 19.45 days, indicating that the star is most likely an eclipsing binary. Under various assumptions, we are able to derive a mass of ~50 M☉ for each component.

[1]  Reinhard Genzel,et al.  Variable and Embedded Stars in the Galactic Center , 1999 .

[2]  Ralf Bender,et al.  The universe in 3D : First observations with SPIFFI, the infrared integral field spectrometer for the VLT , 2003 .

[3]  James E. Larkin,et al.  High Spectral Resolution Observations of the Massive Stars in the Galactic Center , 2005, astro-ph/0510028.

[4]  Kris Davidson,et al.  THE LUMINOUS BLUE VARIABLES: ASTROPHYSICAL GEYSERS , 1994 .

[5]  H. Levato,et al.  Separation of composite spectra: the spectroscopic detection of an eclipsing binary star , 2006 .

[6]  I. McLean,et al.  The Pistol Star , 1998 .

[7]  H Germany,et al.  GCIRS34W : an irregular variable in the Galactic Centre , 2005, astro-ph/0510478.

[8]  S. Owocki,et al.  On the Role of Continuum-driven Eruptions in the Evolution of Very Massive Stars and Population III Stars , 2006, astro-ph/0606174.

[9]  Kris Davidson,et al.  Eta carinae and its environment , 1997 .

[10]  C. Leitherer,et al.  O Stars in Transition. II. Fundamental Properties and Evolutionary Status of Ofpe/WN9 Stars from HST Ultraviolet Observations , 1997 .

[11]  E. Dorfi,et al.  Where Are the Regularly Pulsating Massive Stars? , 2000 .

[12]  G. Meynet,et al.  Stellar evolution with rotation XI. Wolf-Rayet star populations at different metallicities , 2005 .

[14]  R. Lenzen,et al.  The Stellar Cusp around the Supermassive Black Hole in the Galactic Center , 2003, astro-ph/0305423.

[15]  T. Paumard,et al.  The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics, and Formation , 2006, astro-ph/0601268.

[16]  Modern Astrophysics , 1925, Nature.

[17]  Norbert Hubin,et al.  SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light-Month , 2005 .