1999/06/27 by C. Sánchez‐Fernández, C. Sanchez-Fernandez, A. J. Castro-Tirado +29
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9906434
Accepted for publication in Astronomy and Astrophysics Letters (4 pages, 4 figures)
arxiv created 1999/06/27 · openalex publication_date 1999/06/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We report here optical observations during the September/October 1998 outburst of the black hole candidate XTE J1550-564. CCD photometry was obtained for the optical counterpart with the 0.9m Dutch telescope at La Silla since the onset of this event. We analysed 211 U, V and i frames, from Sep 10 to Oct 23. Stochastic flaring activity was observed on Sep 11-16, but no evidence for a superhump period, as seen in other soft X-ray transients, was found. An optical flare nearly simultaneous to an X-ray flare that occurred on Sep 21 was observed in the V-band. A reddened optical spectrum showed the typical emission lines corresponding to X-ray transients in outburst. From the interstellar absorption lines, we derive E(B-V) = 0.70 +/- 0.10 and suggest a distance of about 2.5 kpc. In such case, MB = +7 mag. for the progenitor, which is consistent with the spectral type of a low-mass K0-K5 main-sequence companion.