The Galactic Center source IRS 13E: a star cluster

J.P. Maillard1, T. Paumard1, S. Stolovy2, F. Rigaut3

1 Institut d'Astrophysique de Paris (CNRS), 98b Blvd Arago, 75014 Paris, France
2 SIRTF Science Center, CalTech, MS 220-6, Pasadena, CA 91125, USA
3 Gemini North Headquarter, Hilo, HI 96720, USA

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We present high spatial resolution near-infrared observations of the Galactic Center source, close to SgrA, known historically as IRS13. These observations include ground-based adaptive optics images in the H, K' and L bands, HST-NICMOS observations in filters between 1.1 and 2.2m, and spectro-imaging data in the HeI 2.06mline and the Br line. Analysis of all these data provides a completely new picture of the main component, IRS 13E, which appears as a cluster of several individual stars within a projected diameter of 0.5 arcsec (0.02 pc). The main sources, 13E1, 13E2, 13E3 (a binary), and 13E4, are all of different nature. The star 13E1 is a luminous, blue object, with no detected emission line. 13E2 and 13E4 are two hot, high-mass, emission line stars, with 13E2 probably in the LBV stage and 13E4 a WR star. In contrast, 13E3a and b are extremely red objects. Few fainter sources, which become detectable only after deconvolution of the AO K'-band images are also present. An extended halo is seen around the cluster in K and more prominently in the L band, interpreted as a dust shell responsible for the red color of these embedded sources. The detection of a discrete X-ray emission (Baganoff et al.2001) at the IRS 13 position (within 1'' positional accuracy ) is examined in this new context. IRS 13E is proposed to be the remaining core of a massive, young star cluster which was disrupted in the vicinity of SgrA.

Tom Geballe