Open AccessOGLE observations of four X‐ray binary pulsars in the Small Magellanic Cloud
Author(s) -
Coe M. J.,
Orosz J. A.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03047.x
Subject(s) - physics , light curve , astrophysics , neutron star , photometry (optics) , pulsar , small magellanic cloud , large magellanic cloud , astronomy , amplitude , x ray binary , x ray pulsar , binary number , mass ratio , stars , optics , arithmetic , mathematics
This paper presents analysis and interpretation of OGLE photometric data of four X‐ray binary pulsar systems in the Small Magellanic Cloud (SMC): 1WGA J0054.9‐7226, RX J0050.7‐7316, RX J0049.1‐7250 and 1SAX J0103.2‐7209. In each case, the probable optical counterpart is identified on the basis of its optical colours. In the case of RX J0050.7‐7316 the regular modulation of its optical light curve appears to reveal an ellipsoidal modulation with a period of 1.416 d. Using reasonable masses for the neutron star and the B star, we show that the amplitude and relative depths of the minima of the I ‐band light curve of RX J0050.7‐7316 can be matched with an ellipsoidal model where the B star nearly fills its Roche lobe. For mass ratios in the range of 0.12 to 0.20, the corresponding best‐fitting inclinations are about 55° or larger. The neutron star would be eclipsed by the B star at inclinations larger than ≈60° for this particular mass ratio range. Thus RX J0050.7‐7316 is a good candidate system for further study. In particular, we would need additional photometry in several colours, and most importantly, radial velocity data for the B star before we could draw more quantitative conclusions about the component masses.