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361. NGC 6334 Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/ngc6334cxo
Title:: NGC 6334 Chandra X-Ray Point Source Catalog
Short Name:: NGC6334CXO
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: The full stellar population of NGC 6334, one of the most spectacular regions of massive star formation in the nearby Galaxy, has not been well sampled in past studies. The authors have analyzed a mosaic of two Chandra X-ray Observatory images of the region using sensitive data analysis methods, giving a list of 1607 faint X-ray sources with arcsecond positions and approximate line-of-sight absorption. About 95% of these are expected to be cluster members, most lower mass pre-main-sequence stars. Extrapolating to low X-ray levels, the total stellar population is estimated to be 20,000 - 30,000 pre-main-sequence stars. The X-ray sources show a complicated spatial pattern with ~10 distinct star clusters. The heavily obscured clusters are mostly associated with previously known far-infrared sources and radio H II regions. The lightly obscured clusters are mostly newly identified in the X-ray images. Dozens of likely OB stars are found, both in clusters and dispersed throughout the region, suggesting that star formation in the complex has proceeded over millions of years. A number of extraordinarily heavily absorbed X-ray sources are associated with the active regions of star formation. This table was created by the HEASARC in August 2009 based on the electronic version of table 1 from the above reference which were obtained from the AJ web site. This is a service provided by NASA HEASARC .

362. NGC 2264 Chandra X-Ray Point Source Catalog 2

ID:: ivo://nasa.heasarc/ngc2264cx2
Title:: NGC 2264 Chandra X-Ray Point Source Catalog 2
Short Name:: NGC2264CX2
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: With the goal of improving the member census of the NGC 2264 star-forming region and studying the origin of X-ray activity in young pre-main sequence (PMS) stars, the authors analyzed a deep, 100 ks long, Chandra ACIS observation covering a 17' x 17' field in the 3 Myr old star-forming region (SFR) NGC 2264. The preferential detection in X-rays of low-mass PMS stars gives strong indications of their membership. The authors study X-ray activity as a function of stellar and circumstellar characteristics by correlating the X-ray luminosities, temperatures, and absorptions with optical and near-infrared (NIR) data from the literature. The authors detected 420 X-ray point sources in the observation above a 4.6-sigma significance threshold using the PWDetect software. Optical and NIR counterparts were found in the literature for 85% of the sources. The authors argue that more than 90% of these counterparts are NGC 2264 members, thereby significantly increasing the known low-mass cluster population by about 100 objects. Among the sources without counterpart, about 50% are probably associated with members, several of which are expected to be previously unknown protostellar objects. With regard to activity, several previous findings are confirmed: X-ray luminosity is related to stellar mass, although with a large scatter; Lx/Lbol is close to, but almost invariably below, the saturation level of 10-3, especially when considering the quiescent X-ray emission. A comparison between classical T Tauri stars (CTTS) and weak-line T Tauri stars (WTTS) shows several differences: CTTS have, at any given mass, activity levels that are both lower and more scattered than WTTS; emission from CTTS may also be more time variable and is on average slightly harder than for WTTS. However, there is evidence in some CTTS of extremely cool, ~0.1 - 0.2 keV, plasma which the authors speculate is due to plasma heated by accretion shocks. The X-ray spectra of the 199 sources with more than 50 detected photons were analyzed by the authors. Spectral fits were performed with XSPEC 11.3 and with several shell and TCL scripts to automate the process. For each source, they fit the data in the [0.5 - 7.0] keV energy interval with several model spectra: one and two isothermal components (APEC), subject to photoelectric absorption from interstellar and circumstellar material (WABS). Plasma abundances for one-temperature (1T) models were fixed at 0.3 times the solar abundances, while they were both fixed at that value and treated as a free parameter for the two-temperature (2T) models. The absorbing column densities, NH, were both left as a free parameter and fixed at values corresponding to the optically/NIR determined extinctions, when available: NH = 1.6 x 1021 AV. This table contains the X-ray, optical and NIR data for the 420 detected X-ray sources; it does not contain the master catalog of 1598 optical/NIR sources within the ACIS FOV which was presented in Table 3 of the reference paper, available at <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/455/903/table3.dat">https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/455/903/table3.dat</a> This table was created by the HEASARC in March 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/455/903">CDS Catalog J/A+A/455/903</a> files table1.dat, table4.dat and table6.dat. This is a service provided by NASA HEASARC .

363. NGC 3115 Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/ngc3115cxo
Title:: NGC 3115 Chandra X-Ray Point Source Catalog
Short Name:: NGC3115CXO
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: This table contains some of the results from an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115 using the Megasecond Chandra X-ray Visionary Project observation (total exposure time 1.1 Ms). In total the authors found 136 candidate LMXBs in the field and 49 in globular clusters (GCs) above 2-sigma detection, with 0.3-8 keV luminosity LX ~ 1036 - 1039 erg s-1. Other than 13 transient candidates, the sources overall have less long-term variability at higher luminosity, at least at LX >~ 2 x 1037 erg s-1. In order to identify the nature and spectral state of these sources, the authors compared their collective spectral properties based on single-component models (a simple power law or a multicolor disk) with the spectral evolution seen in representative Galactic LMXBs. The authors found that in the LX vs. photon index GammaPL and LX versus disk temperature kTMCD plots, most of their sources fall on a narrow track in which the spectral shape hardens with increasing luminosity below LX ~ 7 x 1037 erg s-1, but is relatively constant (GammaPL ~ 1.5 or kTMCD ~ 1.5 keV) above this luminosity, which is similar to the spectral evolution of Galactic neutron star (NS) LMXBs in the soft state in the Chandra bandpass. Therefore, the authors identified the track as the NS LMXB soft-state track and suggested sources with LX <~ 1037 erg s-1 as atolls in the soft state and those with LX >~ 1037 erg s-1 as Z sources. Ten other sources (five are transients) displayed significantly softer spectra and are probably black hole X-ray binaries in the thermal state. One of them (a persistent source) is in a metal-poor GC. The 11 Chandra observations of NGC 3115 are listed in Table 1 of the reference paper. They were made during three epochs: one in 2001,two in 2010, and nine in 2012. All observations used the imaging array of the AXAF CCD Imaging Spectrometer (ACIS). This table contains the properties of the 482 detected point sources in the merged and single Chandra ACIS observations of NGC 3115 above a 2-sigma threshold and after eliminating a number of spurious sources associated with bright streaks on the ACIS-S1 chip and (in one case) on a CCD edge. 469 of these sources (indicated by values of obs_flag = '0') have a single entry in this table, based on their properties as derived from all of the available Chandra data for that position. There are 13 transient sources (having obs_flag = 'h') for which an additional entry is provided referring to their properties in the "high state", and based on the combination of their high-state observations, as shown in Figures 3(a) - 3(d) in the reference paper. For source number 198, there is a second additional entry provided referring to its properties in the "low state", and based on the combination of its low-state observations, as shown in Figure 3(c) in the reference paper. Thus, there are 496 entries (rows) in this table, i.e., 482 + 13 + 1. This table was created by the HEASARC in August 2015 based on the union of the machine-readable versions of Table 3 (the master source catalog) and Table 4 (the source counts, fluxes and hardness ratios in the merged observations) that were obtained from the ApJ web site. It does not contain the source counts and fluxes in the individual observations which were given in Table 5 of the reference paper. This is a service provided by NASA HEASARC .

364. NGC 3293 Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/ngc3293cxo
Title:: NGC 3293 Chandra X-Ray Point Source Catalog
Short Name:: NGC3293CXO
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: NGC 3293 is a young stellar cluster at the northwestern periphery of the Carina Nebula Complex that has remained poorly explored until now. The authors wanted to characterize the stellar population of NGC 3293 in order to evaluate key parameters of the cluster population like the age and the mass function, and to test claims of an abnormal initial mass function (IMF) and a deficit of <= 2.5*Msun stars. Thus, they performed a deep (71 ksec) X-ray observation of NGC 3293 with Chandra in which they detected 1026 individual X-ray point sources. These X-ray data directly probe the low-mass (M <= 2*Msun) stellar population by means of the strong X-ray emission of young low-mass stars. The authors have identified counterparts for 74% of the X-ray sources in their deep near-infrared images. These data clearly show that NGC 3293 hosts a large population of ~ 1*Msun stars, refuting claims of a lack of M <= 2.5*Msun stars. The analysis of the color-magnitude diagram suggests an age of ~8-10 Myr for the low-mass population of the cluster. There are at least 511 X-ray detected stars with color-magnitude positions that are consistent with young stellar members within 7 arcminutes from the cluster center. The number ratio of X-ray detected stars in the 1-2 solar mass range versus the M >= 5*Msun stars (known from optical spectroscopy) is well consistent with the expectation from a normal field initial mass function. Most of the early B-type stars and ~20% of the later B-type stars are detected as X-ray sources. These data shows that NGC 3293 is one of the most populous stellar clusters in the entire Carina Nebula Complex (only excelled by Tr 14, and very similar to Tr 16 and Tr 15). The cluster has probably harbored several O-type stars, the supernova explosions of which may have had an important impact on the early evolution of the Carina Nebula Complex. The authors used the Chandra X-ray Observatory to perform a deep pointing of the cluster NGC 3293 with the Imaging Array of the Chandra Advanced CCD Imaging Spectrometer (ACIS-I). The 71-ksec observation was performed as an open time project with ObsID 16648 (PI: T. Preibisch) during Chandra Observing Cycle 15 in October 2015 (start date: 2015-10-07 T10:14:23, end date: 2015-10-08 T06:43:28). The imaging array ACIS-I provides a field of view of 17' x 17' on the sky (which corresponds to a scale of 11.3 x 11.3pc at the cluster distance of 2.3 kpc), and has a pixel size of 0.492". The aimpoint of the observation was RA(J2000) = 10h 35m 50.07s, Dec(J2000) = -58o 14' 00", which is close to the optical center of the cluster (see Fig. 1 in the reference paper). The pointing roll angle (i.e., the orientation of the detector with respect to the celestial North direction) was 140.19o. In addition to ACIS-I, one CCD detector (CCD 7 = S3) of the spectroscopic array ACIS-S was also operational during this pointing. It covers an 8.3' x 8.3' area on the sky southwest of the cluster center. While the ACIS-I chips are front-illuminated (FI), the S3 chip is back-illuminated (BI), and thus its response extends to energies below that accessible by the FI chips. This causes a substantially higher level of background in the S3 chip. Furthermore, the PSF is seriously degraded at the rather large off-axis angles of the S3 chip. These two effects led to a considerably higher detection limit for point sources in the area covered by the S3 chip compared to the region covered by the ACIS-I array. Nevertheless, the S3 data were included in the data analysis and source detection, and contributed four point sources to the total source list. At the distance of 2.3 kpc, the expected ACIS point source sensitivity limit for a three-count detection on-axis in a 71-ks observation corresponds to a minimum X-ray luminosity of Lx ~ 1029.7 erg s-1 in the 0.5-8.0 keV energy band, assuming an extinction of AV ~ 1 mag (NH ~ 2 x 1021 cm-2) typical for the stars in the central region of NGC 3293, and a thermal plasma with kT = 1 keV (which is a typical value for young stars). Using the empirical relation between X-ray luminosity and stellar mass and the temporal evolution of X-ray luminosity from the sample of young stars in the Orion Nebula Cluster, which was very well studied in the Chandra Orion Ultradeep Project (Preibisch et al. 2005, ApJS, 160, 401; Preibisch & Feigelson 2005, ApJS, 160, 390), the authors expected to detect ~90% of the ~ 1*Msun stars in the central region of the young cluster NGC 3293. The X-ray properties of the 97 B-type stars in the ACIS-I field towards the cluster (24 of which are detected as X-ray sources) are not included in this HEASARC table, but are listed in Table 3 of the reference paper, which is also reproduced below: <pre> ESL No.* Star Name X-ray Spectral Type X-ray Luminosity (Lx) log (Lx/Lbol) Src No. erg/s 49 B2.5 V < 4.33e+30 < -5.88 33 HDE 303073 B8 III < 7.15e+30 < -6.31 65 ALS 20075 B5 III-V < 2.12e+30 < -5.88 77 B6-7 V < 1.42e+30 < -5.91 96 ALS 20084 B6-7 III < 9.09e+29 < -5.96 87 47 B5 V 4.62e+30 -5.11 38 B2.5 V < 7.16e+29 < -6.94 68 78 B9 III 4.79e+30 72 B8 IIp < 6.87e+29 69 B5 V < 3.89e+29 < -6.47 22 HDE 303075 B0.5-1.5n < 6.22e+29 < -7.77 109 B5 V < 5.05e+29 < -6.06 93 B6-7 V < 5.16e+29 < -6.17 116 B6-7 V < 4.74e+29 < -5.88 73 B6-7 V < 3.87e+29 < -6.38 10 CPD-57 3500 395 B1 III 7.35e+29 -7.89 121 ALS 20096 B8: III < 4.84e+29 50 B3 Vn < 5.01e+29 < -6.71 2 HD 91943 418 B0.7 Ib 4.11e+30 -8.15 41 V438 Car B2.5 V < 3.94e+29 < -7.21 48 CPD-57 3505 461 B2.5 V 1.39e+30 -6.67 3 CPD-57 3506A 490 B1 III 5.37e+30 -7.63 125 B8 III-V < 8.62e+29 < -5.48 19 V405 Car 523 B1 V 6.77e+29 -7.88 34 CPD-57 3509 535 B2 IIIh 6.71e+29 -7.54 1 HD 91969 542 B0 Iab 2.78e+31 -7.52 106 565 B6-7 V 1.20e+30 -5.54 53 CPD-57 3512 B3 V < 3.61e+29 < -6.70 98 598 B8 III-V 1.31e+30 -5.65 30 CPD-57 3514 601 B2 V 1.99e+30 -6.64 123 604 B8 III 3.79e+30 -4.98 8 HD 91983 626 B1 III 1.36e+30 -7.78 32 CPD-57 3518 B0.5-B1.5 Vn < 1.20e+30 < -7.14 61 B5 V < 3.87e+29 < -6.56 5 CPD-57 3521 679 B1 III 3.45e+30 -7.61 28 CPD-57 3520 B2 V < 4.16e+29 < -7.46 113 B6-7 V < 4.09e+29 < -6.01 11 CPD-57 3526 703 B1: 2.29e+30 6 CPD-57 3526B 710 B1 III 2.29e+30 -7.73 84 B5 V < 3.99e+29 < -6.33 31 CPD-57 3528 B2 V < 1.50e+30 < -6.66 29 CPD-57 3531 B0.5-B1.5 Vn < 5.99e+29 < -7.56 59 B5 III-Vn < 8.23e+29 < -6.61 80 B5 V < 1.31e+30 < -5.98 13 HD 92024 831 B1 III 6.59e+29 -7.82 108 850 B6-7 V 3.65e+30 -5.09 95 884 B6-7 V 1.49e+30 -5.66 67 B3 V < 1.20e+30 < -6.42 97 B6-7 III < 6.34e+29 < -6.01 94 927 B5 V 4.42e+30 -5.35 85 B5 V < 1.47e+30 < -5.80 4 CPD-57 3523 697 B1 III 3.40e+30 -7.57 7 HD 92044 908 B1 III 2.20e+30 -7.94 14 CPD-57 3524A 704 B0.5 IIIn 5.46e+30 -7.27 </pre> * The ESL number is the source number of the star as given in Evans et al. (2005, A&A, 437, 467). This table was created by the HEASARC in September 2017 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/605/A85">CDS Catalog J/A+A/605/A85</a> files table1.dat and table2.dat. This is a service provided by NASA HEASARC .

365. NGC 2264 Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/ngc2264cxo
Title:: NGC 2264 Chandra X-Ray Point Source Catalog
Short Name:: NGC2264CXO
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: The NGC 2264 Chandra X-Ray Point Source Catalog contains the results of a Chandra observation of a field in the NGC 2264 star-forming region. The observation was made with Chandra's Advanced CCD Imaging Spectrometer imaging array (ACIS-I) on 2002 February 9, and has an exposure time of 48.1 ks. The catalog contains 263 sources, and includes X-ray luminosity, optical and infrared photometry, and X-ray variability information. The authors found 41 variable sources, 14 of which have a flare-like light curve, and two of which have a pattern of a steady increase or decrease over a 10-hr period. The optical and infrared photometry for the stars identified as X-ray sources are consistent with most of these objects being pre-main sequence stars with ages younger than 3 Myr. The authors found that 213 (81%) of the 263 X-ray sources have optical and/or infrared counterparts, most, but probably not all, of which are likely to be member stars of NGC 2264. There are 51 X-ray sources that lack optical or infrared counterparts: the authors believe that these are most likely extragalactic objects (active galaxies). This table was created by the HEASARC in February 2007 based on CDS table J/AJ/127/2659, files table1.dat, table4.dat and table5.dat. This is a service provided by NASA HEASARC .

366. NGC 4278 Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/ngc4278cxo
Title:: NGC 4278 Chandra X-Ray Point Source Catalog
Short Name:: NGC4278CXO
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: This table lists some of the properties of the discrete X-ray sources detected in the authors' monitoring program of the globular cluster (GC)-rich elliptical galaxy, NGC 4278, observed with Chandra ACIS-S in six separate pointings, resulting in a co-added exposure of 458 ks. From this deep observation, 236 sources have been detected within the region overlapped by all observations, 180 of which lie within the D25 ellipse angular diameter of the galaxy. These 236 sources range in X-ray luminosity LX from 3.5 x 1036 erg s-1 (with 3-sigma upper limit <= 1 x 1037 erg s-1) to ~2 x 1040 erg s-1, including the central nuclear source which has been classified as a LINER. From optical data, 39 X-ray sources have been determined to be coincident with a GC, these sources tend to have high X-ray luminosity, with 10 of these sources exhibiting LX > 1 x 1038 erg s-1. From X-ray source photometry, it has been determined that the majority of the 236 point sources that have well-constrained colors have values that are consistent with typical low-mass X-ray binary spectra, with 29 of the sources expected to be background objects from the log N-log S relation. There are 103 sources in this population that exhibit long-term variability, indicating that they are accreting compact objects. Three of these sources have been identified as transient candidates, with a further three possible transients. Spectral variations have also been identified in the majority of the source population, where a diverse range of variability has been identified, indicating that there are many different source classes located within this galaxy. This HEASARC table contains the master source list (Table 3 of the reference paper) and the X-ray properties of the sources in the co-added observations (Table 4 of the reference paper), but not the X-ray properties of the sources in the 6 individual observations (Tables 5-10 of the reference paper). The details of the six individual pointings used in this study, e.g., the Chandra ObsIDs, dates, exposure times and cleaned exposure times, are given in Table 1 of the reference paper, and repeated here: <pre> Obs. No.OBSID Date Exposure (s) Cleaned Exposure (s) 1 4741 2005 Feb 3 37462.0 37264.5 2 7077 2006 Mar 16 110303.8 107736.7 3 7078 2006 Jul 25 51433.2 48076.2 4 7079 2006 Oct 24 105071.7 102504.6 5 7081 2007 Feb 20 110724.0 107564.5 6 7080 2007 Apr 20 55824.8 54837.5 Total Co-added 470819.5 457984.0 </pre> Notes. The pointing OBSID 7181 was taken before OBSID 7080, so to maintain the time sequence of the exposures these observation numbers have been labeled as above in the reference paper. The details of the energy bands and X-ray colors used in this study are given in Table 2 of the reference paper, and repeated here: <pre> Band/Color Energy Range/Definition Broad (B) 0.3-8 keV Soft (S) 0.3-2.5 keV Hard (H) 2.5-8 keV Soft 1 (S1) 0.3-0.9 keV Soft 2 (S2) 0.9-2.5 keV Conventional broad (Bc) 0.5-8 keV Conventional soft (Sc) 0.5-2 keV Conventional hard (Hc) 2-8 keV Hardness ratio HR (Hc-Sc)/(Hc+Sc) X-ray color C21 -log(S2) + log(S1) = log(S1/S2) X-ray color C32 -log(H) + log(S2) = log(S2/H) </pre> This table was created by the HEASARC in April 2009 based on machine-readable versions of Tables 3 and 4 from the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .

367. NGC 55 Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/ngc55cxo
Title:: NGC 55 Chandra X-Ray Point Source Catalog
Short Name:: NGC55CXO
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: This table contains a comprehensive X-ray point source catalog of the SB(s)m galaxy NGC 55, a member of the nearby Sculptor group of galaxies, as part of the Chandra Local Volume Survey. The combined archival observations of this galaxy have an effective exposure time of 56.5 ks. When combined with the catalogs of sources in NGC 2403 and NGC 4214 given in this same reference paper, and the authors' previously published catalogs for NGC 300 (Binder et al. 2012, ApJ, 758, 15) and NGC 404 (Binder et al. 2013, ApJ, 763, 128), the CLVS contains 629 high-significance X-ray sources total down to a limiting unabsorbed luminosity of ~ 5 x 1035 erg s-1 in the 0.35-8.0 keV band in each of the five galaxies. In the reference paper, the authors present X-ray hardness ratios, spectral analysis, radial source distributions, and an analysis of the temporal variability for the X-ray sources detected at high significance. To constrain the nature of each X-ray source, they carried out cross-correlations with multi-wavelength data sets. They searched overlapping Hubble Space Telescope observations for optical counterparts to their X-ray detections to provide preliminary classifications for each X-ray source as a likely X-ray binary, background active galactic nucleus, supernova remnant, or foreground star. The authors utilized archival X-ray observations: NGC 55 was observed by the Chandra X-Ray Observatory on 2001 September 11 for 47 ks using the ACIS-I array (Obs. ID 2255), and on 2004 June 29 for 9.5 ks using the ACIS-I array (Obs. ID 4744). The iterative source detection strategy that was used is described in Section 2.3 of Binder et al. (2012, ApJ, 758, 15). ACIS-Extract (AE) was run a final time on the source list that was produces after an initial run of wavdetect followed by several iterations of AE, and the Poisson probability of not being a source (pns) value was computed in each of the following nine energy bands: 0.5 - 8.0, 0.5 - 2.0, 2.0 - 8.0, 0.5 - 1.0, 1.0 - 2.0, 2.0 - 4.0, 4.0 - 8.0, 0.35 - 1.0 or 0.35 - 8.0 keV. To be included in the final NGC 55 catalog, a source was required to have a pns value less than 4 x 10-6 in any of the nine energy bands. The final CLVS source catalog for NGC 55 contains 154 sources. This table was created by the HEASARC in September 2015 based on machine-readable versions of those parts of Table 5 and 8 from the reference paper which pertained to the 154 high-significance (pns < 4 x 10-6) X-ray sources which were detected in NGC 55. It does not include the 76 lower-significance sources in NGC 55 which had 4 x 10-6 < pns < 1.0 x 10-3, some of which are likely to be genuine X-ray sources. This is a service provided by NASA HEASARC .

368. NGC 4649 Chandra X-Ray Point Source Catalog 2

ID:: ivo://nasa.heasarc/ngc4649cx2
Title:: NGC 4649 Chandra X-Ray Point Source Catalog 2
Short Name:: NGC4649CX2
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: This table contains the main X-ray source catalog for the Chandra monitoring observations of the 16.5-Mpc distant elliptical galaxy, NGC 4649. The galaxy has been observed with Chandra ACIS-S3 in six separate pointings, reaching a total exposure of 299 ks. There are 501 X-ray sources detected in the 0.3-8.0 keV band in the merged observation or in one of the six individual observations; 399 sources are located within the D25 ellipse. The observed 0.3-8.0 keV luminosities of these 501 sources range from 9.3 x 1036 erg s-1 to 5.4 x 1039 erg s-1. The 90% detection completeness limit within the D25 ellipse is 5.5 x 1037 erg s-1. Based on the surface density of background active galactic nuclei (AGNs) and the detection completeness, we expect ~ 45 background AGNs among the catalog sources (~ 15 within the D25 ellipse). There are nine sources with luminosities greater than 1039 erg s-1, which are candidates for ultraluminous X-ray sources. The nuclear source of NGC 4649 is a low-luminosity AGN, with an intrinsic 2.0-8.0 keV X-ray luminosity of 1.5 x 1038 erg s-1. The X-ray colors suggest that the majority of the catalog sources are low-mass X-ray binaries (LMXBs). The authors find that 164 of the 501 X-ray sources show long-term variability, indicating that they are accreting compact objects, and discover four transient candidates and another four potential transients. They also identify 173 X-ray sources (141 within the D25 ellipse) that are associated with globular clusters (GCs) based on Hubble Space Telescope and ground-based data; these LMXBs tend to be hosted by red GCs. Although NGC 4649 has a much larger population of X-ray sources than the structurally similar early-type galaxies, NGC 3379 and NGC 4278, the X-ray source properties are comparable in all three systems. This HEASARC table contains the main Chandra source catalog of the basic properties of the 501 X-ray detected sources (Table 3 in the reference paper which includes both sources detected in the merged X-ray image as well as a number only detected in the individual observations), and also the information on source counts, hardness ratios and soft and hard X-ray colors in the merged observation for the same 501 X-ray detected sources (Table 4 in the reference paper). It does not contain the information on source counts, hardness ratios and soft and hard X-ray colors for these same sources in the six individual observations that were contained in Tables 5 - 10 of the reference paper. This table was created by the HEASARC in March 2013 based on the electronic version of Tables 3 and 4 from the reference paper which were obtained from the ApJS website.. This is a service provided by NASA HEASARC .

369. NGC 1333 Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/ngc1333cxo
Title:: NGC 1333 Chandra X-Ray Point Source Catalog
Short Name:: NGC1333CXO
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: NGC 1333, a highly active star formation region within the Perseus molecular cloud complex, has been observed on 2000 July 12.96 - 13.48 with the ACIS-I detector on board the Chandra X-Ray Observatory. The aim point of the array was 3 29 06.1, +31 19 38 (J2000,0 RA and Dec), the satellite roll angle was 95.7 degrees, and the effective exposure time after removing time intervals contaminated by background flaring was 37.8 ks. In this image with a sensitivity limit in luminosity of ~1028 erg/s for X-ray sources at the 318 pc distance of NGC 1333, 127 X-ray sources were detected, most with sub-arcsecond positional accuracy. While 32 of these sources appear to be foreground stars and extragalactic background objects, 95 X-ray sources are identified with known cluster members. The X-ray luminosity function of the discovered young stellar object (YSO) population spans a range of log LX ~= 28.0 - 31.5 erg s-1 in the 0.5 - 8 keV band, and the absorption column densities range from log NH ~=20 to 23 cm-2. Most of the sources have plasma temperatures between 0.6 and 3 keV, but a few sources show higher temperatures up to ~7 keV. Comparison with K-band source counts indicates that all of the known cluster members with K < 12 and about half of the members with K > 12 were detected. (K ~= 11, the peak of the K-band luminosity function, corresponds to 0.2 - 0.4 M_solar stars for a cluster age of ~1 Myr). Seven of the 20 known YSOs in NGC 1333 which are producing jets or molecular outflows were detected, as well as one deeply embedded object without outflows. No evident difference in X-ray emission of young stars with and without outflows is found. This present table contains X-ray, optical and near-infrared information on the 109 X-ray sources that were detected above a source significance threshold of 1 x 10-6 in any of 3 energy bands: soft: 0.5 - 2.0 keV, hard: 2.0 - 8.0 keV, or full: 0.5 - 8.0 keV, excluding 8 sources that were deemed to be spurious on visual examination of the images. The faintest on-axis source emerging from the wavelet detection procedure has 5 extracted counts, corresponding to a source of log LX ~ 28.0 in the total (0.5 - 8.0 keV) band for a source with negligible interstellar absorption (AV ~ 1) and a typical source spectrum of a kT ~ 1 keV thermal plasma. This limit increases to 28.6 (29.3) if the absorption is increased to AV ~ 5 (10). The sensitivity decreases by a factor of 4 at the edge of the field compared to the central regions. 80 of the significant 109 sources (73%) have counterparts in a non-X-ray band. This table does not include 18 tentative X-ray sources listed in Table 3 of the reference paper that were found by the authors by searching for concentrations of photons spatially coincident with known sources from near-IR, mm/sub-mm, and radio catalogs of this region which did not reach the detection significance given above. Most of these tentative sources are believed to be real sources. This table was created by the HEASARC in March 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/575/354">CDS catalog J/ApJ/575/354</a> files table1.dat and table2.dat. This is a service provided by NASA HEASARC .

370. NGC 2024 Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/ngc2024cxo
Title:: NGC 2024 Chandra X-Ray Point Source Catalog
Short Name:: NGC2024CXO
Date:: 09 May 2025
Publisher:: NASA/GSFC HEASARC
Description:: The NGC 2024 Chandra X-Ray Point Source Catalog contains the results of a sensitive 76 ks Chandra observation of the young stellar cluster in NGC 2024, lying at a distance of ~415 pc in the Orion B giant molecular cloud. Previous infrared observations have shown that this remarkable cluster contains several hundred embedded young stars, most of which are still surrounded by circumstellar disks. Thus, it presents a rare opportunity to study X-ray activity in a large sample of optically invisible protostars and classical T Tauri stars (CTTSs) undergoing accretion. Chandra detected 283 X-ray sources, of which 248 were identified with counterparts at other wavelengths, mostly in the near-infrared. Astrometric registration of Chandra images against the Two Micron All Sky Survey (2MASS) resulted in positional offsets of ~0.25" near field center, yielding high confidence identifications of infrared counterparts. The Chandra detections are characterized by hard, heavily absorbed spectra and specular variability. Spectral analysis of more than 100 of the brightest X-ray sources yields a mean V-band extinction of ~10.5 magnitudes and typical plasma energies <kT> ~ 3 keV. Chandra detected all but one of a sample of 27 classical T Tauri stars (CTTSs) identified from previous near- and mid-infrared photometry, and their X-ray and bolometric luminosities are correlated. IRS 2b, which is thought to be a massive embedded late O or early B star that may be the ionizing source of NGC 2024, is detected as an X-ray source. Seven millimeter-bright cores (FIR 1-7) in NGC 2024 that may be protostellar were not detected, with the possible exception of faint emission near the unusual core FIR 4. This table was created by the HEASARC in January 2007 based on CDS table J/ApJ/598/375/table1.dat. This is a service provided by NASA HEASARC .

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369. NGC 1333 Chandra X-Ray Point Source Catalog

370. NGC 2024 Chandra X-Ray Point Source Catalog

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