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Astron. Astrophys. 329, 186-189 (1998)


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SIGMA observations of X-ray Nova Velorum 1993 (GRS 1009-45)

P. Goldoni 1, M. Vargas 1, A. Goldwurm 1, P. Laurent 1, J.-P. Roques 2, E. Jourdain 2, J. Malzac 2, G. Vedrenne 2, M. Revnivtsev 3, E. Churazov 3, 4, M. Gilfanov 3, 4, R. Sunyaev 3, 4, A. Dyachkov 3, N. Khavenson 3, I. Tserenin 3 and N. Kuleshova 3

1 CEA/DSM/DAPNIA, SAp, CEA-Saclay, F-91191 Gif-sur-Yvette, France ([paolo,mv,ag,fil]@mir.saclay.cea.fr)
2 Centre d'Etude Spatiale des Rayonnements, 9 Avenue du Colonel Roche, BP 4346, F-31029 Toulouse Cedex, France
3 Space Research Institute, Profsouznaya 84/32, Moscow 117810, Russia
4 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85740 Garching bei München, Germany

Received 17 July 1997 / Accepted 21 August 1997

Abstract

We report on hard X-ray observations of X-ray Nova Velorum 1993 (GRS 1009-45) performed with the SIGMA coded mask X-ray telescope in January 1994. The source was clearly detected with a flux of about 60 mCrab in the 40-150 keV energy band during the two observations with a hard spectrum ( [FORMULA] ) extending up to [FORMULA] 150 keV. These observations confirm the duration of the activity of the source in hard X-rays over 100 days after the first maximum and suggest a spectral hardening which has already been observed in Nova Muscae. These and other characteristics found in these observations strengthen the case for this Nova to be a black hole candidate similar to Nova Muscae.

Key words: Black hole physics – gamma rays: observations – novae – stars: Nova Vel 1993=GRS 1009-45 close

© European Southern Observatory (ESO) 1998

Online publication: November 24, 1997
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