Spectroscopic variations in Cyg X-2
Journal Article
·
· Nature (London), v. 247, no. 5437, p. 139
The x-ray source Cyg X-2 was optically identified with a fifteenth magnitude blue object. Initial spectroscopic observations showed the presence of broad Balmer absorption lines, a narrow strong Ca II K line, and a narrow He II lambda 4686 emission line. Radial velocity variations were also evident, confirmed by later spectroscopic observations. Photometric monitoring showed that the object varied erratically on a time scale of minutes. More recent spectroscopic observations showed that the He II emission had developed a P-Cygni profile, and that emission at lambda lambda 4640-50 due to C III-N III was present. The present communication reports the results of additional spectroscopic observations obtained in 1972 and 1973 with the 82 inch and 107 inch reflectors at the McDonald Observatory. The 1972 spectra obtained showed the He II and C III--N III emission features, and P-Cygni structure was evident in the He line. A strong Ca II K line was shown in the 1973 spectra, indicating a spectral type of F5 or later, although the strength of the Balmer absorption lines indicated a spectral type A5 or earlier. The C III-N III emission was no longer seen in the 1973 spectra. The He II emission was present, but with no evidence of P-Cygni structure, and it appears that Cyg X-2 no longer shows large radial velocity variations. Further optical studies are needed. (UK)
- Research Organization:
- Univ. of Texas, Austin
- NSA Number:
- NSA-29-021886
- OSTI ID:
- 4317554
- Journal Information:
- Nature (London), v. 247, no. 5437, p. 139, Journal Name: Nature (London), v. 247, no. 5437, p. 139; ISSN NATUA
- Country of Publication:
- United Kingdom
- Language:
- English
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