- ID:
- ivo://nasa.heasarc/m17cxo
- Title:
- M 17 Chandra X-Ray Point Source Catalog
- Short Name:
- M17CXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from a Chandra ACIS observation of the stellar populations in and around the M17 H II region. The field reveals 886 sources (listed in the present table) with observed X-ray luminosities (uncorrected for absorption) between ~ 29.3 erg s<sup>-1</sup> < log L<sub>X</sub> < 32.8 erg s<sup>-1</sup>, 771 of which have stellar counterparts in infrared images. Spectral analysis results for the 598 brightest X-ray sources which have photometric significance of 2.0 or greater) are also given herein. For 546 of the X-ray sources, the fits used the "wabs(apec)" thermal plasma model in XSPEC assuming scaled 0.3 times solar photospheric abundances, while for the other 52 X-ray sources for which either the thermal model poorly described the data or required nonphysical parameters and the X-ray source was not identified with a known stellar counterpart, the fits used the "wabs(powerlaw)" model in XSPEC. In addition to the comprehensive tabulation of X-ray source properties, several other results were presented in the reference paper: 1. The X-ray luminosity function is calibrated to that of the Orion Nebula Cluster population to infer a total population of roughly 8000-10,000 stars in M17, one-third lying in the central NGC 6618 cluster. 2. About 40% of the ACIS sources are heavily obscured with A<sub>V</sub> > 10 mag. Some are concentrated around well-studied star-forming regions -- IRS 5/UC1, the Kleinmann-Wright Object, and M17-North -- but most are distributed across the field. As previously shown, star formation appears to be widely distributed in the molecular clouds. X-ray emission is detected from 64 of the hundreds of Class I protostar candidates that can be identified by near- and mid-infrared colors. These constitute the most likely protostar candidates known in M17. 3. The spatial distribution of X-ray stars is complex: in addition to the central NGC 6618 cluster and well-known embedded groups, we find a new embedded cluster (designated M17-X), a 2 pc long arc of young stars along the southwest edge of the M17 H II region, and 0.1 pc substructure within various populations. These structures may indicate that the populations are dynamically young. 4. All (14/14) of the known O stars but only about half (19/34) of the known B0-B3 stars in the M17 field are detected. These stars exhibit the long-reported correlation between X-ray and bolometric luminosities of L<sub>X</sub> ~ 10<sup>-7</sup> L<sub>bol</sub>. While many O and early-B stars show the soft X-ray emission expected from microshocks in their winds or moderately hard emission that could be caused by magnetically channeled wind shocks, six of these stars exhibit very hard thermal plasma components (kT > 4 keV) that may be due to colliding wind binaries. More than 100 candidate new OB stars are found, including 28 X-ray detected intermediate- and high-mass protostar candidates with infrared excesses. 5. Only a small fraction (perhaps 10%) of X-ray selected high- and intermediate-mass stars exhibit K-band-emitting protoplanetary disks, providing further evidence that inner disks evolve very rapidly around more massive stars. This table was created by the HEASARC in December 2007 based on electronic versions of Tables 1, 2, 3, 4 and 5 of the reference paper which were obtained from the electronic ApJ web site. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/m83cxo
- Title:
- M 83 Chandra X-Ray Point Source Catalog
- Short Name:
- M83CXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors of this table have obtained a series of deep X-ray images of the nearby (4.61 Mpc) galaxy M 83 using Chandra, with a total exposure of 729 ks. Combining the new data with earlier archival observations totaling 61 ks, they find 378 point sources within the D<sub>25</sub> contour of the galaxy. The authors find 80 more sources, mostly background active galactic nuclei (AGNs), outside of the D<sub>25</sub> contour. Of the X-ray sources, 47 have been detected in a new radio survey of M 83 obtained using the Australia Telescope Compact Array (ATCA). Of the X-ray sources, at least 87 seem likely to be supernova remnants (SNRs), based on a combination of their properties in X-rays and at other wavelengths. The authors attempt to classify the point source population of M 83 through a combination of spectral and temporal analysis. As part of this effort, in the reference paper they carry out an initial spectral analysis of the 29 brightest X-ray sources. The soft X-ray sources in the disk, many of which are SNRs, are associated with the spiral arms, while the harder X-ray sources, mostly X-ray binaries (XRBs), do not appear to be. After eliminating AGNs, foreground stars, and identified SNRs from the sample, the authors construct the cumulative luminosity function (CLF) of XRBs brighter than 8 x 10<sup>35</sup> erg s<sup>-1</sup>. Despite M 83's relatively high star formation rate, the CLF indicates that most of the XRBs in the disk are low mass X-ray binaries (XRBs). The X-ray observations of M 83 in this survey were all carried out with the ACIS-S in order to maximize the sensitivity to soft X-ray sources, such as SNRs, and to diffuse emission. The nucleus of M 83 was centered in the field of the back-illuminated S3 chip to provide reasonably uniform coverage of M 83. In addition to the S3 chip, data were also obtained from chips S1, S2, S4, I2, and I3. All of the observations were made in the "very faint" mode to optimize background subtraction. Observations were spaced over a period of one year from 2010 December to 2011 December, as indicated in Table 1 of the reference paper. The only difference among observations was the roll orientation of the spacecraft and the differing exposure times. All of the observations were nominal, and yielded a total of 729 ks of useful data. In order to maximize their sensitivity and more importantly to improve their ability to identify time variable sources, the authors included in their analysis earlier Chandra observations of M 83 in 2000 and 2001 totaling 61 ks which were obtained by G. Rieke (Prop ID. 1600489) and by A. Prestwich (Prop ID. 267005758). These data were obtained in a very similar manner to that of the present survey, and increased the total exposure to 790 ks. The authors used ACIS EXTRACT (AE) to derive net count rates from the sources in various energy bands: 0.35 - 8.0 keV (total or T), 0.35 - 1.1 keV (soft or S), 1.1 - 2.6 keV (medium or M), 2.6 - 8.0 keV (hard or H), 0.5 - 2.0 keV ("normal" soft band) and 2.0 - 8.0 keV ("normal" hard band). Their choice of these bands was based on a variety of overlapping goals. The broad 0.35 - 8.0 keV band samples the full energy range accessible to Chandra observations. The three bands S, M and H provide energy ranges intended to classify sources on the basis of their hardness ratios. The boundary at 1.1 keV, in particular, is just above the region containing strong features due to Ne and Fe seen in the spectra of most SNRs. The 0.5 - 2.0 keV and 2.0 - 8.0 keV bands are needed because number counts of active galactic nuclei (AGNs) and of X-ray binary populations are normally carried out in these bands and because the 0.5 - 2.0 keV band, encompassing the peak of the response curve, provides better statistics for some purposes than S+M. The AE count rates were used to establish which of the sources in the candidate list were statistically valid. The authors retained any source that had a probability-of-no-source < 5 x 10<sup>-6</sup> in any one of these bands in the total data set. For their final run of AE, their list of source candidates had 847 potential sources. Of those, they find a total of 458 valid point sources, whose properties are listed in this table. Of the 458 point sources, 378 are located within the area defined by the D<sub>25</sub> ellipse of the galaxy (which the authors take to have a major axis diameter of 12.9 arcminutes), and the remaining 80 are outside this region. There were 43 sources in the nuclear region (defined to be any source within a projected radius of 0.5 kpc from the optical nucleus). This table was created by the HEASARC in July 2014 based on electronic versions of Tables 3, 4 and 5 from the reference paper which were obtained from the ApJS website. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/mcxc
- Title:
- MCXC Meta-Catalog of X-Ray Detected Clusters of Galaxies
- Short Name:
- MCXC
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The MCXC is the Meta-Catalog of the compiled properties of X-ray detected Clusters of galaxies. This very large catalog is based on publicly available ROSAT All Sky Survey (RASS)-based (NORAS, REFLEX, BCS, SGP, NEP, MACS, and CIZA) and ROSAT serendipitous (160SD, 400SD, SHARC, WARPS, and EMSS) cluster catalogs. Data have been systematically homogenised to an overdensity of 500, and duplicate entries from overlaps between the survey areas of the individual input catalogs have been carefully handled. The MCXC comprises 1743 clusters with virtually no duplicate entries. For each cluster, the MCXC provides three identifiers, a redshift, coordinates, membership in the original catalog, and standardised 0.1 - 2.4 keV band luminosity Lx<sub>500</sub>, total mass M<sub>500</sub>, and radius R<sub>500</sub>, where the 500 suffix means that the quantity has been calculated up to a standard characteristic radius R<sub>500</sub>, the radius within which the mean overdensity of the cluster is 500 times the critical density at the cluster redshift . The meta-catalog additionally furnishes information on overlaps between the input catalogs and the luminosity ratios when measurements from different surveys are available, and gives notes on individual objects. The MCXC is made available so as to provide maximum usefulness for X-ray, Sunyaev-Zel'dovich (SZ) and other multiwavelength studies. The catalogs and sub-catalogs included in this meta-catalog are listed in Table 1 of the reference paper, and come from the following references: <pre> Catalog Sub- Reference Title Catalog or CDS Cat. (Author) RASS IX/10 ROSAT All-Sky Bright Source Catalog (1RXS) (Voges+, 1999) BCS BCS J/MNRAS/301/881 ROSAT brightest cluster sample - I. (Ebeling+, 1998) eBCS J/MNRAS/318/333 Extended ROSAT Bright Cluster Sample (Ebeling+ 2000) CIZA X-ray clusters behind the Milky Way CIZAI ApJ, 580, 774 (Ebeling+, 2002) CIZAII J/APJ/662/224 (Kocevski+, 2007) EMSS ApJS, 72, 567 Einstein Extended Medium Sensitivity Survey (Gioia+, 1990) EMSS_1994 ApJS, 94, 583 (Gioia & Luppino, 1994) EMSS_2004 ApJ, 608, 603 (Henry 2004) MACS ApJ, 553, 668 Massive Cluster Survey (Ebeling+, 2001) MACS_MJFV ApJS, 174, 117 (Maughan+, 2008) MACS_BRIGHT MNRAS, 407, 83 (Ebeling+, 2010) MACS_DIST ApJ, 661, L33 (Ebeling+, 2007) NEP NEP J/ApJS/162/304 ROSAT NEP X-ray source catalog (Henry+, 2006) NORAS/ REFLEX NORAS J/ApJS/129/435 NORAS galaxy cluster survey. I. (Boehringer+, 2000) REFLEX J/A+A/425/367 REFLEX Galaxy Cluster Survey Cat (Boehringer+, 2004) SGP SGP J/ApJS/140/239 Clusters of galaxies around SGP (Cruddace+, 2002) SHARC SHARC_BRIGHT J/ApJS/126/209 Bright SHARC survey cluster catalog (Romer+, 2000) SHARC_SOUTH J/MNRAS/341/1093 The Southern SHARC catalog (Burke+, 2003) WARPS WARPSI J/ApJS/140/265 WARPS survey. VI. (Perlman+, 2002) WARPSII J/ApJS/176/374 WARPS-II Cluster catalog. VII. (Horner+, 2008) 160SD 160SD J/ApJ/594/154 160 square degree ROSAT Survey (Mullis+, 2003) 400SD J/ApJS/172/561 400 square degree ROSAT Cluster Survey (Burenin+, 2007) 400SD_SER Serendipitous clusters 400SD_NONSER Not entirely serendipitous clusters </pre> This table was originally ingested by the HEASARC in October 2011 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/534/A109">CDS catalog J/A+A/534/A109</a> file mcxc.dat. It was last updated in September 2023 to match the 12-Nov-2011 CDS version of the catalog. This update corrected the missing minus signs in the declinations of 6 clusters and homogenized the Abell object names. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m51cxo2
- Title:
- M 51 Deep Chandra ACIS X-Ray Point Source Catalog
- Short Name:
- M51CXO2
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors obtained a deep X-ray image of the nearby galaxy M 51 using the Chandra X-Ray Observatory. Here the catalog of X-ray sources detected in these observations is presented, while an overview of the properties of the point-source population is provided in the reference paper. The authors find 298 sources within the D<sub>25</sub> radii (the apparent major isophotal galactic radii measured at or reduced to the surface brightness level mu<sub>B</sub> = 25.0 B-mag per square arcsecond) of NGC 5194 and NGC 5195, of which 20% are variable, a dozen are classical transients, and another half dozen are transient-like sources. The typical number of active ultraluminous X-ray sources in any given observation is ~5, and only two of those sources persist in an ultraluminous state over the 12 years of observations. Given reasonable assumptions about the supernova remnant population, the luminosity function is well described by a power law with an index between 1.55 and 1.7, only slightly shallower than that found for populations dominated by high-mass X-ray binaries (HMXBs), which suggests that the binary population in NGC 5194 is also dominated by HMXBs. The luminosity function of NGC 5195 is more consistent with a low-mass X-ray binary dominated population. This deep study of M51 is composed of 107 ks of archival Chandra observations, to which the authors added another 745 ks of observations. The Chandra ObsIDs and parameters of all of the observations used in this study (which span from June 2000 to October 2012) are given in Table 2 of the reference paper. All of the observations were made with the ACIS-S array. The authors used the ACIS Extract software package (AE) to perform the photometry. For each source, AE extracted a source region whose size and shape were based on the local PSF, and a background region whose size and shape were based on the size of the local PSF and the location of nearby sources. Source properties were then calculated in a standard manner. Of particular importance in this analysis is the prob_no_source parameter, which is the probability that one could measure the observed count rate in the absence of a source. The authors took a source to be significant only if this parameter was < 5 x 10<sup>-6</sup>. At this probability threshold, one would expect a single spurious source per field, or roughly 1.5 spurious sources within the D<sub>25</sub> regions. As they used the same value in their analysis of M83 (Long et al. 2014, ApJS, 212, 21, the source catalog from which is available in the HEASARC database as the <a href="/W3Browse/chandra/m83cxo.html">M83CXO</a> table), the two catalogs are directly comparable. This table was created by the HEASARC in January 2017 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/827/46">CDS Catalog J/ApJ/827/46</a> files table4.dat, table5.dat and table6.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m33deepxmm
- Title:
- M 33 Deep XMM-Newton Survey X-Ray Source Catalog
- Short Name:
- M33DEEPXMM
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors have obtained a deep 8-field XMM-Newton mosaic of M33 covering the galaxy out to the D<sub>25</sub> isophote and beyond to a limiting 0.2-4.5 keV unabsorbed flux of 5 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> (L > 4 x 10<sup>34</sup> erg s<sup>-1</sup> at the 817 kpc distance of M33). These data allow complete coverage of the galaxy with high sensitivity to soft sources such as diffuse hot gas and supernova remnants (SNRs). In the reference paper, the authors describe the methods they used to identify and characterize 1296 point sources in the 8 fields. They compare their resulting source catalog to the literature, note variable sources, construct hardness ratios, classify soft sources, analyze the source density profile, and measure the X-ray luminosity function (XLF). As a result of the large effective area of XMM-Newton below 1 keV, the survey contains many new soft X-ray sources. The radial source density profile and XLF for the sources suggest that only ~15% of the 391 bright sources with L > 3.6 x 10<sup>35</sup> erg s<sup>-1</sup> are likely to be associated with M33, and more than a third of these are known SNRs. The log(N)-log(S) distribution, when corrected for background contamination, is a relatively flat power law with a differential index of 1.5, which suggests that many of the other M33 sources may be high-mass X-ray binaries. Finally, the authors note the discovery of an interesting new transient X-ray source, which they are unable to classify. The list of XMM-Newton observations used for this survey is given in Table 1 of the reference paper. The data reduction and source detection techniques are described in Section 3 of this same reference. The unabsorbed energy conversion factors (ECF) values for different energy bands and instruments that were used in this paper are as follows (the units are 10<sup>11</sup> counts cm<sup>2</sup> erg<sup>-1</sup>): <pre> HEASARC Energy Band MOS1 MOS2 PN band prefix (keV) Med Filter Med Filter Thin Filter sb0_ 0.2-0.5 0.5009 0.4974 2.7709 sb1_ 0.5-1.0 1.2736 1.2808 6.006 mb_ 1.0-2.0 1.8664 1.8681 5.4819 hb_ 2.0-4.5 0.7266 0.7307 1.9276 fb_ 0.2-4.5 </pre> This table was created by the HEASARC in July 2015 based on an electronic version of Table 3 of the reference paper, the list of XMM-Newton X-ray point sources detected in a deep 8-field mosaic of M33, which was obtained from the ApJS web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m31deepxmm
- Title:
- M 31 Deep XMM-Newton Survey X-Ray Source Catalog
- Short Name:
- M31DEEPXMM
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The largest Local Group spiral galaxy, M 31, has been completely imaged for the first time, with an obtained luminosity lower limit ~10<sup>35</sup>erg/s in the 0.2 - 4.5 keV band. This XMM-Newton EPIC survey combines archival observations along the major axis, from June 2000 to July 2004, with observations taken between June 2006 and February 2008 that cover the remainder of the D<sub>25</sub> ellipse. The main goal of the present paper was to study the X-ray source populations of M31. An X-ray catalog of 1897 sources was created ('the XMM LP-total catalog'), with 914 sources detected for the first time. Source classification and identification were based on X-ray hardness ratios, spatial extents of the sources, and cross correlation with catalogs in the X-ray, optical, infrared and radio wavelengths. The authors also analysed the long-term variability of the X-ray sources and this variability allowed them to distinguish between X-ray binaries and active galactic nuclei (AGN). Furthermore, supernova remnant classifications of previous studies that did not use long-term variability as a classification criterion could be validated. Including previous Chandra and ROSAT observations in the long-term variability study allowed the authors to detect additional transient or at least highly variable sources, which are good candidate X-ray binaries. Fourteen of the 30 supersoft source (SSS) candidates represent supersoft emission of optical novae. Many of the 25 supernova remnants (SNRs) and 31 SNR candidates lie within the 10 kpc dust ring and other star-forming regions in M 31. This connection between SNRs and star-forming regions implies that most of the remnants originate in type II supernovae. The brightest sources in X-rays in M 31 belong to the class of X-ray binaries (XRBs). Ten low-mass XRBs (LMXBs) and 26 LMXB candidates were identified based on their temporal variability. In addition, 36 LMXBs and 17 LMXB candidates were identified owing to correlations with globular clusters and globular cluster candidates. From optical and X-ray colour-colour diagrams, possible high-mass XRB (HMXB) candidates were selected. Two of these candidates have an X-ray spectrum as expected for an HMXB containing a neutron star primary. While this survey has greatly improved our understanding of the X-ray source populations in M 31, at this point 65% of the sources can still only be classified as "hard" sources; i.e. it is not possible to decide whether these sources are X-ray binaries or Crab-like supernova remnants in M 31 or X-ray sources in the background. Deeper observations in X-ray and at other wavelengths would help to classify these sources. This table was created by the HEASARC in October 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/534/A55">CDS Catalog J/A+A/534/A55</a> files table5.dat and table8.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m31phatsfh
- Title:
- M 31 Disk Chandra PHAT Survey: HST-Derived Star Formation History
- Short Name:
- M31PHATSFH
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The X-ray source populations within galaxies are typically difficult to identify and classify with X-ray data alone. The authors break through this barrier by combining deep new Chandra ACIS-I observations with extensive Hubble Space Telescope (HST) imaging from the Panchromatic Hubble Andromeda Treasury (PHAT) of the M 31 disk. They detect 373 X-ray sources down to 0.35-8.0keV flux of 10<sup>-15</sup>erg/cm<sup>-2</sup>/s over 0.4deg<sup>2</sup>, 170 of which are reported for the first time. The authors identify optical counterpart candidates for 188 of the 373 sources, after using the HST data to correct the absolute astrometry of our Chandra imaging to 0.1". These data are available at <a href="/W3Browse/chandra/m31phatcxo.html">M31PHATCXO</a>. For point-like counterparts, the authors examine the star formation history of the surrounding stellar populations to look for a young component that could be associated with a high-mass X-ray binary. This table presents the star formation histories for a subset of sources in the <a href="/W3Browse/chandra/m31phatcxo.html">M31PHATCXO catalog</a>. About one-third of the point sources are not physically associated with a young population, and are therefore more likely to be background galaxies. For the 40 point-like counterpart candidates associated with young populations, the authors find that their age distribution has two peaks at 15-20Myr and 40-50Myr. Considering only the 8 counterpart candidates with typical high-mass main-sequence optical star colors, their age distribution peaks mimic those of the sample of 40. Finally, the authors find that intrinsic faintness, and not extinction, is the main limitation for finding further counterpart candidates. In 2015 October, the authors observed the Panchromatic Hubble Andromeda Treasury (PHAT) footprint with Chandra with 7 pointings. The footprints are overlaid on a GALEX NUV image of M 31, along with the corresponding HST coverage, in Figure 1 of the reference paper. At each pointing they observed for about 50 ks in VF mode (Chandra ObsID 17008 to 17014 spanning 2015 Oct 06 to 2015 Oct 26). This table was created by the HEASARC in April 2020 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/239/13">CDS Catalog J/ApJS/239/13</a> file table7.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m31phatcxo
- Title:
- M 31 Disk Chandra PHAT Survey: X-Ray Source Catalog
- Short Name:
- M31PHATCXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The X-ray source populations within galaxies are typically difficult to identify and classify with X-ray data alone. The authors break through this barrier by combining deep new Chandra ACIS-I observations with extensive Hubble Space Telescope (HST) imaging from the Panchromatic Hubble Andromeda Treasury (PHAT) of the M 31 disk. They detect 373 X-ray sources down to 0.35-8.0keV flux of 10<sup>-15</sup>erg/cm<sup>-2</sup>/s over 0.4deg<sup>2</sup>, 170 of which are reported for the first time. The authors identify optical counterpart candidates for 188 of the 373 sources, after using the HST data to correct the absolute astrometry of our Chandra imaging to 0.1". While 58 of these 188 are associated with point sources potentially in M 31, over half (107) of the counterpart candidates are extended background galaxies, 5 are star clusters, 12 are foreground stars, and 6 are supernova remnants. Sources with no clear counterpart candidate are most likely to be undetected background galaxies and low-mass X-ray binaries in M 31. The hardest sources in the 1-8keV band tend to be matched to background galaxies. The 58 point sources that are not consistent with foreground stars are bright enough that they could be high-mass stars in M 31; however, all but 8 have optical colors inconsistent with single stars, suggesting that many could be background galaxies or binary counterparts. For point-like counterparts, the authors examine the star formation history of the surrounding stellar populations to look for a young component that could be associated with a high-mass X-ray binary. The associated star formation histories for sources in the catalog are available in the linked table <a href="/W3Browse/chandra/m31phatsfh.html">M31PHATSFH</a>. In 2015 October, the authors observed the Panchromatic Hubble Andromeda Treasury (PHAT) footprint with Chandra with 7 pointings. The footprints are overlaid on a GALEX NUV image of M 31, along with the corresponding HST coverage, in Figure 1 of the reference paper. At each pointing they observed for about 50ks in VF mode (Chandra ObsID 17008 to 17014 spanning 2015 Oct 06 to 2015 Oct 26). This table was created by the HEASARC in April 2020 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/239/13">CDS Catalog J/ApJS/239/13</a> file table4.dat and table6.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m16cxo
- Title:
- M 16 (Eagle Nebula) Chandra X-Ray Point Source Catalog
- Short Name:
- M16CXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Mechanisms regulating the origin of X-rays in young stellar objects and the correlation with their evolutionary stage are under debate. Studies of the X-ray properties in young clusters allow us to understand these mechanisms. One ideal target for this analysis is the Eagle Nebula (M 16), with its central cluster NGC 6611. At 1750 pc from the Sun, it harbors 93 OB stars, together with a population of low-mass stars from embedded protostars to disk-less Class III objects, with age <= 3 Myr. The authors study an archival 78 ks Chandra/ACIS-I observation of NGC 6611 and two new 80-ks observations of the outer region of M 16, one centered on the Column V and the other on a region of the molecular cloud with ongoing star formation. They detect 1755 point sources with 1183 candidate cluster members (219 disk-bearing and 964 disk-less), studying the global X-ray properties of M 16 and comparing them with those of the Orion Nebula Cluster. The authors also compare the level of X-ray emission of Class II and Class III stars and analyze the X-ray spectral properties of OB stars. Their study supports the lower level of X-ray activity for the disk-bearing stars with respect to the disk-less members. The X-ray luminosity function (XLF) of M 16 is similar to that of Orion, supporting the universality of the XLF in young clusters. Eighty-five percent of the O-type stars of NGC 6611 have been detected in X-rays. With only one possible exception, they show soft spectra with no hard components, indicating that mechanisms for the production of hard X-ray emission in O stars are not operating in NGC 6611. The determination of the absorption corrected X-ray luminosity (L<sub>X</sub>), as well as the plasma temperature (kT) and hydrogen column density (N<sub>H</sub>), requires the analysis of the X-ray spectra. The authors fit the observed spectra with thermal plasma (with both one and two temperatures) and power-law models. They use the APEC ionization-equilibrium thermal plasma code, assuming the sub-solar elemental abundances of Maggio et al. (2007, APJ, 660, 1462). The absorption was treated using the WABS model. The one-temperature (1T) thermal model was applied to all the sources with more than 25 counts, while the two-temperature (2T) thermal model was applied to each source with more than 80 counts. The power-law model has been applied to those sources with hard spectra for which the best-fit thermal model predicts a plasma temperature kT > 5 keV. When more than one model has been used for a given source, the authors chose the best model by the chi-squared probability and visual inspection of the spectrum. This table contains a description of the X-ray properties of 1754 sources (one less than stated in the abstract of the reference paper) derived from three Chandra/ACIS-I observations, together with a source classification based on the optical and infrared properties of each source. Data come from three ACIS-I observations (central or 'c', east or 'e', and north-east or 'ne') and many values are not averaged but presented for each observation as indicated by the parameter prefixes 'c_', 'e_', and 'ne_', respectively. Source detection has been performed with PWDetect, adopting a threshold corresponding to 10 spurious detections. The HEASARC eliminated the 3 parameters describing the plasma temperature of the second spectral component and its associated negative and positive errors for sources in the north-east observation, as these were blank for all entries in the original table as obtained from the CDS. This table was created by the HEASARC in March 2013 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/753/117">CDS Catalog J/ApJ/753/117</a> file xraycat.dat. Some of the values for the alt_name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/refnebulae
- Title:
- Merged Catalog of Reflection Nebulae
- Short Name:
- REFNEBULAE
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Several catalogs of reflection nebulae have been merged to create a uniform catalog of 913 objects. It contains revised coordinates, cross-identifications of nebulae and stars, as well as identifications with IRAS point sources. The HEASARC has endeavored to render all identifications of the nebulae in the various catalogs according to the styles recommended by the Dictionary of Nomenclature of Celestial Objects. This table was created by the HEASARC in October 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/399/141">CDS Catalog J/A+A/399/141</a> file table1.dat. This is a service provided by NASA HEASARC .
