Bibcode
Charles, P. A.; Casares, J.; Jones, D. H. P.; Broadhurst, T.; Callanan, P. J.; Carter, D.; Hacking, P.; Hassall, B. J. M.; Lawrence, A.; Naylor, T.
Bibliographical reference
In ESA, The 23rd ESLAB Symposium on Two Topics in X Ray Astronomy. Volume 1: X Ray Binaries p 103-107 (SEE N90-25711 19-89)
Advertised on:
11
1989
Citations
13
Refereed citations
11
Description
The results of optical spectroscopy and photometry from La Palma (Canary
Islands) of V404 Cyg are presented. They correspond to the optical
counterpart of the new X-ray transient GS2023+338 discovered by Ginga.
The overall light curve is similar to that of the previous optical
outburst of this object, recorded as Nova Cyg 1938 and classified as a
classical nova. It is not a classical or recurrent nova. The large range
in optical brightness and intense X-ray emission at maximum indicate
that the system must be a low-mass X-ray binary. The optical spectrum is
unlike any known LMXB or X-ray transient in that it displays strong,
broad, variable and complex emission lines of H, He I and He II. The
reddened spectrum and interstellar absorption features indicate a
problable distance in the range 1 to 3 kpc. Charged coupled device
photometry reveals that the source is variable, but gives no indication
of the orbital period, there being no eclipse or regular modulation.