This table contains some of the results from a study of the X-ray binary (XRB) populations in the bulge and ring regions of the ring galaxy NGC 1291. Utilizing the four available Chandra observations totaling an effective exposure of 179 ks, the authors detect 169 X-ray point sources in the galaxy in the full band (0.3 - 8.0 keV) with a false-positive probability threshold of 10^-6 (implying approximately 2 false detections given the size of the image). Of these sources, 75 are in the bulge and 71 are in the ring. The authors report photometric properties of these sources in a point-source catalog. There are ~ 40% of the bulge sources and ~ 25% of the ring sources showing > 3-sigma long-term variability in their X-ray count rate. The X-ray colors suggest that a significant fraction of the bulge (~ 75%) and ring (~ 65%) sources are likely low-mass X-ray binaries (LMXBs). The spectra of the nuclear source indicate that it is a low-luminosity active galactic nucleus (AGN) with moderate obscuration; spectral variability is observed between individual observations. The authors construct 0.3-8.0 keV X-ray luminosity functions (XLFs) for the bulge and ring XRB populations, taking into account the detection incompleteness and background AGN contamination. They reach 90% completeness limits of ~ 1.5 x 10³⁷ and ~ 2.2 x 10³⁷ erg s^-1 for the bulge and ring populations, respectively. Both XLFs can be fit with a broken power-law model, and the shapes are consistent with those expected for populations dominated by LMXBs. In the paper, the authors perform detailed population synthesis modeling of the XRB populations in NGC 1291, which suggests that the observed combined XLF is dominated by an old LMXB population. They compare the bulge and ring XRB populations, and argue that the ring XRBs are associated with a younger stellar population than the bulge sources, based on the relative overdensity of X-ray sources in the ring, the generally harder X-ray color of the ring sources, the overabundance of luminous sources in the combined XLF, and the flatter shape of the ring XLF. This table was created by the HEASARC in May 2012 based on an electronic version of Table 2 from the reference paper obtained from the ApJ website. This is a service provided by NASA HEASARC .

This table contains the point source catalog based on the first high spatial resolution X-ray study of NGC 2244, the 2 Myr old stellar cluster in the Rosette Nebula, using Chandra. Over 900 X-ray sources are detected within 20 arcminutes of the cluster central position (J2000.0 RA and Dec of 6 31 59.9, +4 55 36); 77% of these X-ray sources have optical or FLAMINGOS NIR stellar counterparts and are mostly previously uncataloged young cluster members. The X-ray-selected population is estimated to be nearly complete between 0.5 and 3 M_solar. A number of further results emerge from the analysis: (1) The X-ray luminosity function (XLF) and the associated K-band LF indicate a normal Salpeter IMF for NGC 2244. This is inconsistent with the top-heavy IMF reported from earlier optical studies that lacked a good census of < 4 M_solar stars. By comparing the NGC 2244 and Orion Nebula Cluster XLFs, the authors estimate a total population of ~2000 stars in NGC 2244. (2) The spatial distribution of X-ray stars is strongly concentrated around the central O5 star, HD 46150. The other early O star, HD 46223, has few companions. The cluster's stellar radial density profile shows two distinctive structures: a power-law cusp around HD 46150 that extends to ~0.7 pc, surrounded by an isothermal sphere extending out to 4 pc with core radius 1.2 pc. This double structure, combined with the absence of mass segregation, indicates that this 2 Myr old cluster is not in dynamical equilibrium. (3) The fraction of X-ray-selected cluster members with K-band excesses caused by inner protoplanetary disks is 6%, slightly lower than the 10% disk fraction estimated from the FLAMINGOS study based on the NIR-selected sample. (4) X-ray luminosities for 24 stars earlier than B4 confirm the long-standing log (L_X/L_bol) ~ -7 relation. The Rosette OB X-ray spectra are soft and consistent with the standard model of small-scale shocks in the inner wind of a single massive star. This table was created by the HEASARC in July 2008 based on electronic versions of Tables 2, 3, 4, 5 and 6 of the reference paper which were obtained from the electronic ApJ web site. This is a service provided by NASA HEASARC .

This contains some of the results from the first high spatial resolution X-ray study of the massive star-forming region NGC 6357, which were obtained in a 38 ks Chandra/ACIS observation. Inside the brightest constituent of this large H II region complex is the massive open cluster Pismis 24. It contains two of the brightest and bluest stars known, yet remains poorly studied; only a handful of optically bright stellar members have been identified. The authors have investigated the cluster extent and initial mass function and detected ~800 X-ray sources with a limiting sensitivity of ~ 10³⁰ erg s^-1: this provides the first reliable probe of the rich intermediate-mass and low-mass population of this massive cluster, increasing the number of known members from optical studies by a factor of ~ 50. The high-luminosity end (log L[2-8 keV] >= 30.3 erg s^-1) of the observed X-ray luminosity function in NGC 6357 is clearly consistent with a power-law relation as seen in the Orion Nebula Cluster and Cepheus B, yielding the first estimate of NGC 6357's total cluster population, a few times the known Orion population. The long-standing L_X ~ 10^-7 L_bol correlation for O stars is confirmed. Twenty-four candidate O stars and one possible new obscured massive YSO or Wolf-Rayet star are presented. Many cluster members are estimated to be intermediate-mass stars from available infrared photometry (assuming an age of ~ 1 Myr), but only a few exhibit K-band excess. The authors report the first detection of X-ray emission from an evaporating gaseous globule at the tip of a molecular pillar; this source is likely a B0-B2 protostar. NGC 6357 was observed on 2004 July 9 with the Imaging Array of the Advanced CCD Imaging Spectrometer (ACIS-I) on board Chandra. Four front-illuminated (FI) CCDs form the ACIS-I, which covers a field of view (FOV) of ~ 17 by 17 arcminutes. The observation was made in the standard Timed Exposure, Very Faint mode, with 3.2 s integration time and 5 pixel by 5 pixel event islands. The total exposure time was 38 ks and the satellite roll angle was 289 degrees. The aim point was centered on the O3 If star Pis 24-1, the heart of the OB association Pismis 24. The Chandra observation ID is 4477. Data reduction started with filtering the Level 1 event list processed by the Chandra X-ray Center pipeline to recover an improved Level 2 event list. To improve absolute astrometry, X-ray positions of ACIS-I sources were obtained by running the wavdetect wavelet-based source detection algorithm within the Chandra Interactive Analysis of Observations (CIAO) package on the original Level 2 event list, using only the central 8 by 8 arcminutes of the field. The resulting X-ray sources were matched to the 2MASS point source catalog. The authors calculated the position offsets between 277 X-ray sources and their NIR counterparts and applied an offset of +0.02" in right ascension (R.A.) and -0.33" in declination to the X-ray coordinates. From an initial list of 910 potential X-ray sources, the authors rejected sources with a P_B > 1% likelihood of being a background fluctuation. The trimmed source list includes 779 sources, with full-band (0.5 - 8.0 keV) net (background-subtracted) counts ranging from 1.7 to 1837 counts. The 779 valid sources were purposely divided by the authors into two lists: the 665 sources with P_B < 0.1% make up the primary source list of highly reliable sources (Table 1 in the reference paper; sources with source_type = 'M' in this table), and the remaining 114 sources with P_B >= 0.1% likelihood of being spurious background fluctuations were listed as tentative sources in Table 2 of the reference paper (source_type = 'T' in this table). The authors believe that most of these tentative sources are likely real detections. This table was created by the HEASARC in October 2007 based on the merger of the electronic versions of Tables 1 (Main Source Catalog) and 2 (Tentative Sources which were obtained from the ApJ website. To help distinguish from which original table entries in this Browse table come from, the HEASARC has created a parameter called source_type which is set to 'M' for sources from Table 1 and to 'T' for sources from Table 2. This is a service provided by NASA HEASARC .