New clues on outburst mechanisms and improved spectroscopic elements of the black-hole binary V4641 Sagittarii

Details New clues on outburst mechanisms and improved spectroscopic elements of the black-hole binary V4641 Sagittarii New clues on outburst mechanisms and improved spectroscopic elements of the black-hole binary V4641 Sagittarii

2005-08-03

arxiv.org/abs/astro-ph/0508095v1

Mon.Not.Roy.Astron.Soc.363:882-890,2005

Astronomy and Astrophysics

Astrophysics

9 pages, 8 figures, accepted for publication in MNRAS

Scientific paper

10.1111/j.1365-2966.2005.09483.x

We present spectroscopic observations of the black-hole binary V4641 Sagittarii, obtained between 4th July 2004 and 28th March 2005, which cover the minor outburst of the star in early July 2004 and quiescence variations on 19 nights scattered over six months. During the outburst, the star peaked approximately 3 magnitudes brighter than usual, and our spectra were dominated by broad hydrogen, helium and iron emission lines. The very first spectra showed P Cygni profiles, which disappeared within a few hours, indicating rapid changes in matter ejection. The H-alpha line had multiple components, one being a broad blue-shifted wing exceeding 5000 km/s. During a simultaneously observed 10-min photometric flare-up, the equivalent width of the H-alpha line temporarily decreased, implying that it was a flare of the continuum. The overall spectral appearance was similar to that observed in the 1999 September active phase, which suggests that similar mass-ejection processes were associated with both eruptions. In quiescence, the spectra were those of the early-type secondary star showing its orbital motion around the primary. By measuring cross-correlation radial velocities, we give an improved set of spectroscopic elements. Whereas we measure the same velocity amplitude (K_2=211.3+/-1.0 km/s), within errors, as Orosz et al. (2001), our centre-of-mass velocity (v_gamma=72.7+/-3.3 km/s) differs significantly from the previously published value (107.4+/-m2.9 km/s). However, we find evidence that the difference is caused by a systematic error in data reduction in the previous study, rather than by gravitational effects of an invisible third component.

Affiliated with

Also associated with

No associations

Rating

New clues on outburst mechanisms and improved spectroscopic elements of the black-hole binary V4641 Sagittarii does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with New clues on outburst mechanisms and improved spectroscopic elements of the black-hole binary V4641 Sagittarii, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and New clues on outburst mechanisms and improved spectroscopic elements of the black-hole binary V4641 Sagittarii will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-39448