Bibcode
Cseh, D.; Grisé, F.; Corbel, S.; Kaaret, P.
Bibliographical reference
The Astrophysical Journal Letters, Volume 728, Issue 1, article id. L5 (2011).
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2
2011
Citations
23
Refereed citations
22
Description
High-resolution optical spectra of the ultra-luminous X-ray source (ULX)
NGC 5408 X-1 show a broad component with a width of ~750 km
s-1 in the He II and Hβ lines in addition to the narrow
component observed in these lines and [O III]. Reanalysis of
moderate-resolution spectra shows a similar broad component in the He II
line. The broad component likely originates in the ULX system itself,
probably in the accretion disk. The central wavelength of the broad He
II line is shifted by 252 ± 47 km s-1 between the two
observations. If this shift represents motion of the compact object,
then its mass is less than ~1800 M sun.