OPTICAL AND INFRARED OBSERVATIONS OF THE SUSPECTED BE X-RAY TRANSIENT4U-0728-25/

Authors
NEGUERUELA I ROCHE P BUCKLEY DAH CHAKRABARTY D COE MJ FABREGAT J REIG P
Citation
I. Negueruela et al., OPTICAL AND INFRARED OBSERVATIONS OF THE SUSPECTED BE X-RAY TRANSIENT4U-0728-25/, Astronomy and astrophysics, 315(1), 1996, pp. 160-165
Citations number
25
Categorie Soggetti
Astronomy & Astrophysics
Journal title
Astronomy and astrophysics → ACNP
ISSN journal
00046361
Volume
315
Issue
1
Year of publication
1996
Pages
160 - 165
Database
ISI
SICI code
0004-6361(1996)315:1<160:OAIOOT>2.0.ZU;2-4
Abstract
We present new optical spectra and photometry plus the first infrared photometry of the optical counterpart to the X-ray transient system 4U 0728-25. Our spectral and photometrical analysis lead us to conclude that the primary is an O8-9Ve star with E(B - V) = 0.75 +/- 0.02. This revised spectral classification places the star at a distance of 6.1/-0.3 kpc, We also present evidence for an unusual faint, blue state t hat may represent a diskless phase in late 1991.