The identification of the transient X-ray pulsar Cepheus X-4 with a Be/X-ray binary

Details The identification of the transient X-ray pulsar Cepheus X-4 with a Be/X-ray binary The identification of the transient X-ray pulsar Cepheus X-4 with a Be/X-ray binary

1998-01-22

arxiv.org/abs/astro-ph/9801215v1

Astronomy and Astrophysics

Astrophysics

4 pages (accepted in Astronomy & astrophysics Letters, 20 January 1998) 4 figures (fig1 in GIF format + 3 figures in Postscrip

Scientific paper

We present long slit spectral (375-725 nm) observations of the proposed identification of the transient 66s X-ray pulsar Cep X-4=GS2138+56. Spectra show features typical of Be/X-ray binaries. Superimposed on a weak emission from the IC 1396 nebula, strong H$\alpha$ (4.5 nm EW) and H$\beta$ (0.3 nm EW) lines are seen in emission with the other Balmer lines in absorption. Significant interstellar absorption features are also detected, including a strong Na I doublet (589 nm) and diffuse bands at 443, 578 and 628 nm. From the shape of the continuum as well as the lines present in the spectrum, a most probable spectral type of B1-B2V is derived with a reddening of E$_{B-V}$=1.3$\pm$0.1. The reddening value is corroborated by the measure of interstellar absorption features, except for the sodium line which appears to be in excess and may be partly from circumstellar origin. The optical absorption is fully consistent with the column density derived from X-ray spectra, therefore confirming the identification. Despite apparent spatial coincidence, the source is located much further away than the local intervening nebula IC1396. The best estimate of the distance is D=(3.8$\pm$0.6) kpc, which places the source in the outer Perseus arm of the Galaxy. At this distance, the X-ray quiescent luminosity is (3-6) 10$^{33}$ erg.s$^{-1}$, thus comparable to typical Be/X-ray binary low states.

Affiliated with

Also associated with

No associations

Rating

The identification of the transient X-ray pulsar Cepheus X-4 with a Be/X-ray binary 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 The identification of the transient X-ray pulsar Cepheus X-4 with a Be/X-ray binary, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The identification of the transient X-ray pulsar Cepheus X-4 with a Be/X-ray binary will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-210074