Optical spectroscopic observations of MXB 0656-072
ATel #1303; Jingzhi Yan, Qingzhong Liu and Hui Li (PMO)
on 24 Nov 2007; 07:29 UT
Credential Certification: Jingzhi Yan (jzyan@pmo.ac.cn)
Subjects: Optical, X-ray, Binary, Neutron Star, Star, Transient, Variables
A recent X-ray outburst of MXB 0656-072 was detected by INTEGRAL (ATEL #1281), Swift and RXTE (ATEL #1293). We carried out our optical spectroscopic observations of MXB 0656-072 just before (JD 2454402-2454406) and during (JD 2454421) the outburst using 2.16m telescope at Xinglong station, National Astronomical Observatories, Chinese Academy of Sciences. EWs of Halpha line during our 2007 observational run are nearly two times of those during our 2005 and 2006 observational runs. The lines of He I 5875, Hbeta also have the same variability. In addition, He I 6678 in the 2007 spectra was obviously in emission, comparing to the weak He I 6678 in the 2005 and 2006 spectra. The EWs of Halpha emission line during our 2005, 2006 and 2007 runs are listed in the following table:
JD-2450000 EW(-A)
3667.377 14.1
3667.389 13.8
3668.381 14.1
3668.393 14.2
4007.353 16.9
4008.354 16.1
4010.376 17.1
4011.380 17.0
4402.410 25.7
4404.382 25.2
4405.352 25.5
4406.368 25.5
4421.267 23.8
4421.336 24.3
The further analysis combining with our synchronous photometric observations is under discussion.
