Volume 453, Number 1, July I 2006
|Page(s)||295 - 299|
|Section||Stellar structure and evolution|
|Published online||09 June 2006|
M-type giants as optical counterparts of X-ray sources 4U 1700+24 and 4U 1954+319
INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, via Gobetti 101, 40129 Bologna, Italy (formerly IASF/CNR, Bologna) e-mail: email@example.com
2 Dipartimento di Fisica, Università di Ferrara, via Saragat 1, 44100 Ferrara, Italy
Accepted: 9 March 2005
We observed with Chandra two peculiar galactic X-ray sources, 4U 1700+24 and 4U 1954+319, which are suspected to have a M-type giant star as optical counterpart, in order to get a high-precision astrometric position for both of them. The peculiarity of these sources lies in the fact that these are the only two cases among low-mass X-ray binaries (LMXBs), besides the confirmed case of GX 1+4, for which the companion can possibly be a M-type giant. We found that in both cases the field M-type giant star is indeed the counterpart of these X-ray sources. We also determined the distance to 4U 1954+319 to be ~1.7 kpc. This result suggests that a number of faint ( erg s-1) Galactic X-ray sources are “symbiotic X-ray binaries”, that is, wide-orbit LMXBs composed of a compact object, most likely a neutron star, accreting from the wind of a M-type giant.
Key words: astrometry / stars: binaries: general / X-rays: binaries / stars: neutron / stars: individuals: 4U 1700+24 / stars: individual: 4U 1954+319
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.