Publications (2)0 Total impact
ABSTRACT: We report on the identification of the optical/IR counterpart of the 29.5-s transient X-ray pulsar GS 1843+009. We re-analysed an archival ROSAT HRI observation of GS 1843+009, obtaining a new refined position. The optical and IR follow-up observations carried out for the new error circle allowed us to find a relatively faint (V=20.9) and variable early type reddened star (V-R=2.1). The optical spectra show the Balmer and Paschen series in emission, while the IR observations confirm the presence of a flux excess (H=13.2, J-H=0.54), suggesting that the star is surrounded by a circumstellar envelope. Spectroscopic and photometric data together indicate a B0-B2 IV-Ve spectral-type star located at a distance of > 10kpc confirming the Be-star/X-ray binary nature of GS 1843+009. Comment: 6 pages (3 figures included). Accepted for publication in A&A
ABSTRACT: OAO1657-415 is only the seventh eclipsing X-ray pulsar known and therefore has the potential to yield only the seventh mass of a neutron star in an X-ray binary. Here we report photometric and spectroscopic observations of candidates for the optical counterpart to the system and identify a B6V or B5III star as a possible companion to the neutron star. We measure the observational parameters of the star and suggest reasons why OAO1657-415 may be unlike other high mass X-ray binaries.