New MIR Excess Sources north of the IRS 13 Complex

The ISAAC and NAOS/CONICA systems on the ESO VLT UT1 and UT4 telescopes have been used to image the central stellar cluster of the Milky Way in the MIR L and M band (3.3 μm and 4.6 μm) in order to obtain new information on the stellar populations within the central cluster. The NAOS/CONICA adaptive optics images of unprecedented sharpness and sensitivity have resulted in the detection of a small cluster (<0.13 light years) of 7 compact sources with a strong infrared excess. Our MIR imaging and spectroscopy data clearly show that this excess is due to the contribution of warm T < 500 K dust. The nature of these newly found sources is currently unclear. Three possible explanations are mentioned and briefly discussed: 1) The L band excess sources north of the IRS 13 complex may be heavily extincted luminous stars; 2) They may be hot stars that heat the more ambient environment of the local mini-spiral; 3) Finally the newly found objects may even be young stars with luminous accretion disks.

[1]  K. Menten,et al.  A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way , 2002, Nature.

[2]  P. Wizinowich,et al.  Limits on the Short-Term Variability of Sagittarius A* in the Near-Infrared , 2002, astro-ph/0208239.

[3]  Eugene Serabyn,et al.  Massive Stars in the Arches Cluster , 2002, astro-ph/0208145.

[4]  A. Fuente,et al.  The history of mass dispersal around Herbig Ae/Be stars , 2002 .

[5]  P. Wizinowich,et al.  Spatially Resolved Observations of the Galactic Center Source IRS 21 , 2002, astro-ph/0204372.

[6]  Gerard Rousset,et al.  NAOS + CONICA at YEPUN : First VLT Adaptive Optics System Sees First Light , 2001 .

[7]  A. Eckart,et al.  Stellar orbits near Sagittarius A , 2002, astro-ph/0201031.

[8]  Fulvio Melia,et al.  An Accretion-induced X-Ray Flare in Sagittarius A* , 2001, astro-ph/0110564.

[9]  Peter L. Biermann,et al.  The Nature of the 10 kilosecond X-ray flare in Sgr A* , 2001 .

[10]  Caltech,et al.  Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre , 2001, Nature.

[11]  Francois Rigaut,et al.  Adaptive optics L-band observations of the Galactic Center region , 2001 .

[12]  T. Paumard,et al.  New results on the helium stars in the galactic center using BEAR spectro-imagery , 2000, astro-ph/0011215.

[13]  E. Becklin,et al.  The accelerations of stars orbiting the Milky Way's central black hole , 2000, Nature.

[14]  Ortwin Gerhard,et al.  The Galactic Center He I Stars: Remains of a Dissolved Young Cluster? , 2000 .

[15]  C. Pichon,et al.  Stellar dynamics in the Galactic centre: Proper motions and anisotropy , 2000, astro-ph/0001428.

[16]  T. Nagata,et al.  A Survey of Dust Features in the 3 Micron Spectra of YSO Candidates , 1998 .

[17]  E. Becklin,et al.  High Proper-Motion Stars in the Vicinity of Sagittarius A*: Evidence for a Supermassive Black Hole at the Center of Our Galaxy , 1998, astro-ph/9807210.

[18]  F. Yusef-Zadeh,et al.  Proper Motions of Ionized Gas at the Galactic Center: Evidence for Unbound Orbiting Gas , 1998, astro-ph/9803231.

[19]  Reinhard Genzel,et al.  On the nature of the dark mass in the centre of the Milky Way , 1997 .

[20]  A. Nota,et al.  Luminous Blue Variables: Massive Stars in Transition , 1997 .

[21]  Alfred Krabbe,et al.  The Dark Mass Concentration in the Central Parsec of the Milky Way , 1996 .

[22]  A. Eckart,et al.  Observations of stellar proper motions near the Galactic Centre , 1996, Nature.

[23]  K. Sellgren,et al.  Really Cool Stars at the Galactic Center , 1996, astro-ph/9608107.

[24]  Michael G. Burton,et al.  The Discovery of Hot Stars near the Galactic Center Thermal Radio Filaments , 1996 .

[25]  Alfred Krabbe,et al.  The Nuclear Cluster of the Milky Way: Star Formation and Velocity Dispersion in the Central 0.5 Parsec , 1995 .

[26]  Frederick J. Vrba,et al.  Herbig Ae/Be Stars: Intermediate-Mass Stars Surrounded by Massive Circumstellar Accretion Disks , 1992 .