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VLT Observations of the Ultraluminous X-ray Source NGC 1313 X-2

P. Mucciarelli·L. Zampieri·R. Falomo·R. Turolla·A. Treves
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Abstract

We present archive ESO VLT photometric and spectroscopic data of the Ultraluminous X-ray source NGC 1313 X-2. The superb quality of the VLT images reveals that two distinct objects, with R magnitudes 23.7 and 23.6, are visible inside the Chandra error box. The two objects, separated by 0.75 arcsec, were unresolved in our previous ESO 3.6 m+EFOSC image. We show that both are stars in NGC 1313, the first a B0-O9 main sequence star of ~20 Msun, while the second a G supergiant of ~10 Msun. Irrespectively of which of the two objects the actual counterpart is, this implies that NGC 1313 X-2 is a high mass X-ray binary with a very massive donor.

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P. Mucciarelli, L. Zampieri, R. Falomo, R. Turolla, A. Treves. 2005-10-13. VLT Observations of the Ultraluminous X-ray Source NGC 1313 X-2. https://doi.org/10.1086/498448

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