ASCA observation of the X-ray transient GRS 1009-45

Aya Kubota, Y. Tanaka, K. Makishima, Y. Ueda, H. Inoue, K. Yamaoka, T. Dotani

Research output: Contribution to journalArticle


We report on the result of the X-ray observation of X-ray Nova Velorum 1993 (GRS 1009-45), made with ASCA on November 10-11, 1993. The energy spectrum was extremely soft and accompanied by a hard tail, characteristics of the Galactic black-hole binaries in the soft state. It is well represented by a two component model consisting of a multicolor disk model or a general relativistic accretion disk model, both describing emission from an optically-thick accretion disk, and a power-law component with a photon index of ∼ 2.5. Spectral analysis of the soft component allows estimation of the mass of the central object. For the optically-estimated distance (> 1 kpc) and inclination (> 37°), the mass is estimated to be > 3.1 M. These results strongly support that the compact object is a black hole.

Original languageEnglish
Pages (from-to)449-452
Number of pages4
JournalAdvances in Space Research
Issue number3-4
Publication statusPublished - 2000
Externally publishedYes


ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Kubota, A., Tanaka, Y., Makishima, K., Ueda, Y., Inoue, H., Yamaoka, K., & Dotani, T. (2000). ASCA observation of the X-ray transient GRS 1009-45. Advances in Space Research, 25(3-4), 449-452.