Research Note

Unveiling the nature of IGR J16493-4348 with IR spectroscopy^*

¹ Observatorio Astronómico de la Universidad de Valencia, Calle Catedrático Agustín Escardino 7, 46980 Paterna, Valencia, Spain e-mail: elisa.nespoli@uv.es
² Departamento de Astronomía, Universidad de Concepción, Casilla 160-C, Concepción, Chile

Received: 3 March 2010
Accepted: 8 April 2010

Abstract

Context. The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) is discovering a large number of new hard X-ray sources, many of them being HMXBs. The identification and spectral characterization of their optical/infrared counterparts is a necessary step in undertaking a detailed study of these systems.

Aims. In a previous paper, we presented spectral analyses and classifications of six newly discovered INTEGRAL sources. In this paper, we extend the analysis to IGR J16493–4348.

Methods. We used the ESO/VLT ISAAC spectrograph to observe the proposed IR counterpart to the source, obtaining a K_s medium-resolution spectrum (R = 500) with a signal-to-noise ratio (S/N) 150. We classified the source by comparing with published atlases.

Results. We spectrally classified the source as a B0.5-1 supergiant and estimated its interstellar extinction. We compared the extinction derived from X-ray data with effective interstellar extinction obtained from our data, discussing the absorption component associated with the circumstellar environment.