Bibcode
Cornelisse, R.; Verbunt, F.; in't Zand, J. J. M.; Kuulkers, E.; Heise, J.; Remillard, R. A.; Cocchi, M.; Natalucci, L.; Bazzano, A.; Ubertini, P.
Bibliographical reference
Astronomy and Astrophysics, v.392, p.885-893 (2002)
Advertised on:
9
2002
Journal
Citations
79
Refereed citations
69
Description
We have discovered three certain (SAX J1324.5-6313, 2S 1711-339 and SAX
J1828.5-1037) and two likely (SAX J1818.7+1424 and SAX J2224.9+5421) new
thermonuclear X-ray burst sources with the BeppoSAX Wide Field Cameras,
and observed a second burst ever from a sixth one (2S 0918-549). Four of
them (excluding 2S 1711-339 and 2S 0918-549) are newly detected X-ray
sources from which we observed single bursts, but no persistent
emission. We observe the first 11 bursts ever from 2S 1711-339;
persistent flux was detected during the first ten bursts, but not around
the last burst. A single burst was recently detected from 2S 0918-549 by
Jonker et al. (2001); we observe a second burst showing radius
expansion, from which a distance of 4.2 kpc is derived. According to
theory, bursts from very low flux levels should last <~ 100 s. Such
is indeed the case for the last burst from 2S 1711-339, the single burst
from SAX J1828.5-1037 and the two bursts from 2S 0918-549, but not for
the bursts from SAX J1324.5-6313, SAX J1818.7+1424 and SAX J2224.9+5421.
The bursts from the latter sources all last ~ 20 s. We suggest that SAX
J1324.5-6313, SAX J1818.7+1424, SAX J1828.5-1037 and SAX J2224.9+5421
are members of the recently proposed class of bursters with
distinctively low persistent flux levels, and show that the galactic
distribution of this class is compatible with that of the standard
low-mass X-ray binaries.