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Chandra follow-up of bursters with low persistent emission
We report on Chandra ACIS-S observations of five type I X-ray bursterswith low persistent emission: SAX J1324.5-6313, SAX J1752.3-3128, SAXJ1752.3-3128I, SAX J1324.5-6313V, and SAX J1818.7+1424. We designatecandidate persistent sources for four X-ray bursters. All candidates aredetected at a persistent luminosity level of 1032-33 ergs-1, comparable to soft X-ray transients in quiescence. Fromthe number of bursters with low persistent emission detected so far withthe Wide Field Cameras, we estimate a total of such sources in ourGalaxy between 30 and 4000.
| BeppoSAX Wide Field Cameras observations of six type I X-ray bursters
We have discovered three certain (SAX J1324.5-6313, 2S 1711-339 and SAXJ1828.5-1037) and two likely (SAX J1818.7+1424 and SAX J2224.9+5421) newthermonuclear X-ray burst sources with the BeppoSAX Wide Field Cameras,and observed a second burst ever from a sixth one (2S 0918-549). Four ofthem (excluding 2S 1711-339 and 2S 0918-549) are newly detected X-raysources from which we observed single bursts, but no persistentemission. We observe the first 11 bursts ever from 2S 1711-339;persistent flux was detected during the first ten bursts, but not aroundthe last burst. A single burst was recently detected from 2S 0918-549 byJonker et al. (2001); we observe a second burst showing radiusexpansion, from which a distance of 4.2 kpc is derived. According totheory, bursts from very low flux levels should last <~ 100 s. Suchis indeed the case for the last burst from 2S 1711-339, the single burstfrom SAX J1828.5-1037 and the two bursts from 2S 0918-549, but not forthe 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 SAXJ1324.5-6313, SAX J1818.7+1424, SAX J1828.5-1037 and SAX J2224.9+5421are members of the recently proposed class of bursters withdistinctively low persistent flux levels, and show that the galacticdistribution of this class is compatible with that of the standardlow-mass X-ray binaries.
| Mesures de vitesses radiales. VII. Accompagnement AU sol DU programme d'observation DU satellite Hipparcos. Radial velocities. VII. Ground based measurements for Hipparcos.
We publish 734 radial velocities of stars distributed in 28 fields of4x4deg. We continue the PPO series (Fehrenbach et al. 1987; Duflot etal. 1990 and 1992), using the Fehrenbach objective prism method.
| Large and kinematically unbiased samples of G- and K-type stars. V - Evolved stars in the selected areas at + 15-deg declination
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990PASP..102..242E&db_key=AST
| Photoelectric radial velocities. IV. 528 7 to 10 mag stars in the +15degree selected areas.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971MNRAS.155....1G&db_key=AST
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Observation and Astrometry data
| Constellation: | Οφιούχος |
| Right ascension: | 18h18m37.63s |
| Declination: | +14°22'44.4" |
| Apparent magnitude: | 7.609 |
| Proper motion RA: | 0.6 |
| Proper motion Dec: | -18 |
| B-T magnitude: | 8.911 |
| V-T magnitude: | 7.717 |
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