Access to Astronomical Catalogues

← Click to display the menu
J/ApJ/697/224     Chandra X-ray sources in ω Cen    (Haggard+, 2009)

A Chandra study of the Galactic globular cluster omega Centauri. Haggard D., Cool A.M., Davies M.B. <Astrophys. J., 697, 224-236 (2009)> =2009ApJ...697..224H
ADC_Keywords: Clusters, globular ; X-ray sources ; Cross identifications Keywords: binaries: close - globular clusters: individual (ω Centauri) - novae, cataclysmic variables - stars: neutron - X-rays: binaries Abstract: We analyze a ∼70ks Chandra Advanced CCD Imaging Spectrometer exposure of the globular cluster ω Cen (NGC 5139). The ∼17'x17' field of view fully encompasses three core radii and almost twice the half-mass radius. We detect 180 sources to a limiting flux of ∼4.3x10-16erg/cm2/s (Lx=1.2x1030erg/s at 4.9kpc). After accounting for the number of active galactic nuclei and possible foreground stars, we estimate that 45-70 of the sources are cluster members. Four of the X-ray sources have previously been identified as compact accreting binaries in the cluster - three cataclysmic variables (CVs) and one quiescent neutron star. Correlating the Chandra positions with known variable stars yields eight matches, of which five are probable cluster members that are likely to be binary stars with active coronae. Extrapolating these optical identifications to the remaining unidentified X-ray source population, we estimate that 20-35 of the sources are CVs and a similar number are active binaries. This likely represents most of the CVs in the cluster, but only a small fraction of all the active binaries. Description: We obtained two exposures of ω Cen using the imaging array of the Advanced CCD Imaging Spectrometer (ACIS-I) on 2000 January 24-25, in "very faint" mode. The total exposure time was 72.4ks. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 113 180 ω Cen X-ray sources
See also: B/chandra : The Chandra Archive Log (CXC, 1999-) J/ApJ/663/1021 : Log of ω Cen scientific images (Castellani+, 2007) J/A+A/424/1101 : Variable Stars in the field of ω Cen (Kaluzny+, 2004) J/A+A/400/521 : Omega Cen XMM observations (Gendre+, 2003) J/ApJ/578/405 : Neutron stars in NGC 5139 (Rutledge+, 2002) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 A4 --- ID Source identification in this work 6- 24 A19 --- CXOHCD IAU name (JHHMMSS.ss+DDMMSS.s) 26- 29 F4.2 --- Offset Radial offset from the cluster center in units of core radii 31- 33 I3 ct Mcts Medium band raw source counts (0.5-4.5keV) 35- 39 F5.1 ct Mctsc Medium band corrected source counts (0.5-4.5keV) 41- 43 I3 ct Scts Soft band raw source counts (0.5-1.5keV) 45- 49 F5.1 ct Sctsc Soft band corrected source counts (0.5-1.5keV) 51- 53 I3 ct Hcts Hard band raw source counts (1.5-6.0keV) 55- 59 F5.1 ct Hctsc Hard band corrected source counts (1.5-6.0keV) 61- 63 I3 ct Cts Raw X-ray counts in the Chandra Deep Field South (CDFS) soft X-ray band (0.5-2.0keV) 65- 69 F5.1 ct Ctsc Corrected X-ray counts in the Chandra Deep Field South (CDFS) soft X-ray band (0.5-2.0keV) 71- 76 F6.3 --- S/H ? Hardness ratio 78- 84 E7.2 mW/m2 Fx X-ray flux derived from the medium counts values 86-104 A19 --- OName Previous X-ray ID references (1) 105-113 A9 --- OptID Optical ID (2)
Note (1): X-ray ID references abbreviations are: PSPC = Johnston et al. 1994A&A...289..763J (<[JVH94] NGC 5139 NN> in Simbad) HRI = Verbunt & Johnston, 2000A&A...358..910V (<[JVH94] NGC 5139 NNa> in Simbad) ACIS = Rutledge et al. 2002, Cat. J/ApJ/578/405 (<[RBB2002b] NN> in Simbad) XMM = Gendre et al. 2003, Cat. J/A+A/400/521 (<[GBW2003] NNN> in Simbad) Note (2): Optical ID references abbreviations are: HD = Hog et al. 1998, Cat. I/250; Perryman et al. 1997, Cat. I/239; CV = Carson et al. 2000ApJ...532..461C, Haggard et al. 2002AAS...201.0718H, 2003AAS...203.5203H; qNS = Haggard et al. 2004ApJ...613..512H; V,NV = Kaluzny et al. 2004, Cat. J/A+A/424/1101 (<Cl* NGC 5139 SAW VNNN> in Simbad)
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 18-May-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

catalogue service

© UDS/CNRS

Contact