- ID:
- ivo://nasa.heasarc/newmdwarfs
- Title:
- New M Dwarfs in the Solar Neighborhood
- Short Name:
- NEWMDWARFS
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the results from a spectroscopic study of 1080 nearby active M dwarfs, selected by correlating the Two Micron All Sky Survey (2MASS) and ROSAT catalogs at galactic latitudes greater than 15 degrees above or below the Galactic Plane and using a matching radius of 20 arcseconds, as well as color cuts (J-H < 0.75, H-K > 0.15 and 0.8 < J-K < 1.1) designed to select M dwarfs. The authors have derived the spectral types and estimated distances for all of their stars. The spectral types range between K5 and M6. Nearly half of the stars lie within 50 pc. The authors have measured the equivalent width of the H-alpha emission line. Their targets show an increase in chromospheric activity from early to mid-spectral types, with a peak in activity around M5. Using the count rate and hardness ratios obtained from the ROSAT catalog,the authors have derived the stellar X-ray luminosities. Their stars display a "saturation-type" relation between the chromospheric and coronal activity. The relation is such that log L<sub>X</sub>/L<sub>bol</sub> remains "saturated" at a value of approximately -3 for varying H-alpha equivalent width. The authors have found 568 matches in the USNO-B catalog and have derived the tangential velocities v<sub>tan</sub> for these stars. There is a slight trend of decreasing chromospheric activity with age, such that the stars with higher v<sub>tan</sub> values have lower H-alpha equivalent widths. The coronal emission, however, remains saturated at a value of log L<sub>X</sub>/L<sub>bol</sub> ~ -3 for varying tangential velocities, suggesting that the coronal activity remains saturated with age. The authors do not find any break in the saturation-type relation at the spectral type at which stars become fully convective (~M3.5). Most of the stars in their sample show more coronal emission than the dMe stars in the Hyades and Praesepe clusters and have v<sub>tan</sub> < 40 km s<sup>-1</sup>, suggesting that they belong to a young population. This table was created by the HEASARC in March 2010 based on the (corrected) electronic version of Table 1 from the reference paper which was obtained from the Astronomical Journal web site. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/openclust
- Title:
- New Optically Visible Open Clusters and Candidates Catalog
- Short Name:
- OpenCluster
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This is a new catalog of open clusters in the Galaxy which updates the previous catalogs of Lynga (1987, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/92">CDS Cat. VII/92</a>, the HEASARC Browse table now called LYNGACLUST) and of Mermilliod (1995, in Information and On-Line Data in Astronomy, ed. D. Egret & M. A. Albrecht (Dordrecht: Kluwer), 127) (included in the WEBDA database, <a href="http://www.univie.ac.at/webda/">http://www.univie.ac.at/webda/</a>). New objects and new data, in particular, data on kinematics (proper motions) that were not present in the old catalogs, have been included. Virtually all of the clusters presently known are included, which represents a large increase in the number of objects (almost 1,000) relative to the Lynga Catalog. In total, 99.7% of the objects have estimates of their apparent diameters, and 74.5% have distance, E(B-V) and age determinations. Concerning the data on kinematics, 54.7% have their mean proper motions listed, 25% their mean radial velocities, and 24.2% have both information simultaneously. Acknowledgments: Extensive use has been made by the authors of the SIMBAD and WEBDA databases. This project is supported by FAPESP (grant number 03/12813-4) and CAPES (CAPES-GRICES grant number 040/2008). This database table was originally created by the HEASARC in September 2002 based on the CDS version of the catalog. In March 2006, the HEASARC updated the table to use instead the following file obtained from the authors' web site: <a href="http://www.astro.iag.usp.br/ocdb/file/clusters.txt">http://www.astro.iag.usp.br/ocdb/file/clusters.txt</a>. In August 2017, the HEASARC reverted to using the CDS version of this catalog, available as the file clusters.dat at <a href="http://cdsarc.u-strasbg.fr/ftp/cats/B/ocl/">http://cdsarc.u-strasbg.fr/ftp/cats/B/ocl/</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc2403cxo
- Title:
- NGC 2403 Central 3-kpc Region Chandra Source Catalog
- Short Name:
- NGC2403CXO
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Archival Chandra observations are used to study the X-ray emission associated with star formation in the central region of the nearby (D = 3.2 Mpc, 1 arcminute = 1 kpc) SAB(s)cd galaxy NGC 2403. The distribution of X-ray emission is compared to the morphology visible at other wavelengths using complementary Spitzer, Galaxy Evolution Explorer, and ground-based H-alpha imagery. In general, the brightest X-ray emission is associated with H II regions and to other star-forming structures, but is more pervasive, existing also in regions devoid of strong H-alpha and UV emission. NGC 2403 was observed in full-frame mode with the Chandra ACIS-S on four occasions for a total of ~ 180 ks, on 2001 Apr 17, 2004 Aug 13, 2004 Oct 03 and 2004 Dec 22. The source-finding tool described by Tennant (2006, AJ, 132, 1372) was applied to all 4 individual data sets and to the merged data set in order to search for discrete X-ray sources. The search was limited to the cnetral 6' x 6' (6 kpc x 6 kpc) region and to events within the full Chandra energy range 0.3-8.0 keV. Fifty eight point sources were detected in the merged data set with a signal-to-noise ratio (S/N) above 2.8 and with a minimum of 5 sigma above background uncertainty (corresponding to a detection limit of 8-10 counts for a typical on-axis source). These sources were listed in Table 2 of the reference paper and and are contained in the present HEASARC table. They can be selected by specifying source_type = 'Point Source'. The X-ray data were also examined to see if there was emission from known SNRs and H II regions after masking out the afore-mentioned X-ray point sources (see Section 2.1 of the reference paper for full details). Events falling within the areas defined by 24 optically identified SNRs that were imaged on the S3 chip in the first three observations were used to construct a composite spectrum. This stacked spectrum was fit by an absorbed 1-T APEC model with the hydrogen column density as a free parameter in XSPEC which was then used to translate the observed net count rates into X-ray luminosities. Only 4 or 5 of these SNRs are likely to be 'truely' detected X-ray sources. The SNRs can be selected in the present HEASARC table by specifying source_type ='SNR'. A similar procedure was used to search the X-ray data for the presence of X-ray emission at the locations of 47 H II regions in NGC 2403. Events falling within the areas defined by 47 H II regiuons that were imaged on the S3 chip in the first three observations were used to construct a composite spectrum. This stacked spectrum was fit by an absorbed 2-T APEC model with the hydrogen column density as a free parameter in XSPEC which was then used to translate the observed net count rates into X-ray luminosities. Only the most X-ray-luminous H II regions are likely to be 'truely' detected X-ray sources. The H II regions can be selected in the present HEASARC table by specifying source_type ='HII Region'. This table was created by the HEASARC in June 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/139/1066">CDS Catalog J/AJ/139/1066</a> files table2.dat, table5.dat and table7.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc2903cxo
- Title:
- NGC 2903 Central Region Chandra X-Ray Point Source Catalog
- Short Name:
- NGC2903CXO
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from a deep Chandra observation of the central regions of the late-type barred spiral galaxy NGC 2903. The Chandra data reveal soft (kT<sub>e</sub> ~ 0.2 - 0.5 keV) diffuse emission in the nuclear starburst region and extending ~ 2' (~ 5 kpc) to the north and west of the nucleus. Much of this soft hot gas is likely to be from local active star-forming regions; however, besides the nuclear region, the morphology of hot gas does not strongly correlate with the bar or other known sites of active star formation. The central ~ 650 pc radius starburst zone exhibits much higher surface brightness diffuse emission than the surrounding regions and a harder spectral component in addition to a soft component similar to the surrounding zones. The authors interpret the hard component as also being of thermal origin with kT<sub>e</sub> ~ 3.6 keV and to be directly associated with a wind fluid produced by supernovae and massive star winds similar to the hard diffuse emission seen in the starburst galaxy M82. The inferred terminal velocity for this hard component, ~ 1100 km/s, exceeds the local galaxy escape velocity suggesting a potential outflow into the halo and possibly escape from the galaxy gravitational potential. Morphologically, the softer extended emission from nearby regions does not display an obvious outflow geometry. However, the column density through which the X-rays are transmitted is lower in the zone to the west of the nucleus compared to that from the east and the surface brightness is relatively higher suggesting some of the soft hot gas originates from above the disk: viewed directly from the western zone but through the intervening disk of the host galaxy along sight lines from the eastern zone. There are several point-like sources embedded in the strong diffuse nuclear emission zone. Their X-ray spectra show them to likely be compact binaries. None of these detected point sources are coincident with the mass center of the galaxy and the authors place an upper limit on the luminosity from any point-like nuclear source o < 2 x 10<sup>38</sup> erg/s in the 0.5 - 8.0keV band, which indicates that NGC 2903 lacks an active galactic nucleus. Heating from the nuclear starburst and a galactic wind may be responsible for preventing cold gas from accreting onto the galactic center. NGC 2903, a nearby (8.9 Mpc, 1" = 43 pc) late-type barred SAB(rs)bc galaxy with strong circumnuclear star formation, was observed with Chandra using the ACIS-S instrument in imaging mode on 2010 March 7 (ObsID 11260). The source finding tool in lextrct (Tennant 2006, AJ, 132, 1372) was applied in the energy range of 0.5 - 8.0 keV in order to detect point sources inside the D<sub>25</sub> isophote. A total of 92 point-like sources were detected with a signal-to-noise ratio (S/N) above 2.4 (see Tennant 2006) and with a minimum of 5 counts above the background uncertainty. This table contains this list of point-like sources. This table was created by the HEASARC in September 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/758/105">CDS Catalog J/ApJ/758/105</a> file table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc4365cxo
- Title:
- NGC 4365 Chandra LMXB Catalog
- Short Name:
- NGC4365CXO
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors used the Chandra X-Ray Observatory ACIS-S3 to image the X-ray-faint elliptical galaxy NGC 4365 and the lenticular galaxy NGC 4382. This table presents only the NGC 4365 results; however, the results for NGC 4382 are also available in <a href="ngc4382cxo.html">a separate table</a>. NGC 4365 was observed on 2001 June 23 with a live exposure of 40429 s. The observations resolved much of the X-ray emission into 99 sources for NGC 4365, most of which are low-mass X-ray binaries (LMXBs) associated with the galaxy. Within one effective radius of NGC 4365, about 45% of the counts were resolved into sources, 30% were attributed to unresolved LMXBs, and 25% were attributed to diffuse gas. The authors identified 18 out of the 37 X-ray sources in a central field in NGC 4365 with globular clusters. The authors defined two hardness ratios: HR21 = (M - S)/(M + S) and HR31 = (H - S)/(H + S), where S, M, and H are the total counts in the soft (0.3 - 1 keV), medium (1 - 2 keV), and hard (2 - 10 keV) bands, respectively. This table was created by the HEASARC in June 2018 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/599/218">CDS Catalog J/ApJ/599/218</a> file table1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc4382cxo
- Title:
- NGC 4382 Chandra LMXB Catalog
- Short Name:
- NGC4382CXO
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors used the Chandra X-Ray Observatory ACIS-S3 to image the X-ray-faint elliptical galaxy NGC 4365 and the lenticular galaxy NGC 4382. This table presents only the NGC 4382 results; however, the results for NGC 4365 are also available in <a href="ngc4365cxo.html">a separate table</a>. NGC 4382 was observed on 2001 May 29-30 for 39749 s. The observations resolved much of the X-ray emission into 58 sources for NGC 4382, most of which are low-mass X-ray binaries (LMXBs) associated with the galaxy. Within two effective radii of NGC 4382, about 22% of the counts were resolved into sources, 33% were attributed to unresolved LMXBs, and 45% were attributed to diffuse gas. The authors defined two hardness ratios: HR21 = (M - S)/(M + S) and HR31 = (H - S)/(H + S), where S, M, and H are the total counts in the soft (0.3 - 1 keV), medium (1 - 2 keV), and hard (2 - 10 keV) bands, respectively. This table was created by the HEASARC in June 2018 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/599/218">CDS Catalog J/ApJ/599/218</a> file table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc6530oid
- Title:
- NGC 6530 Chandra Point Source Optical/IR Identifications Catalog
- Short Name:
- NGC6530OID
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors have obtained astrometry and BVI photometry, down to a V magnitude of ~22, of the very young open cluster NGC 6530, from observations taken with the Wide Field Imager (WFI) camera at the MPG/ESO 2.2m Telescope. They have positionally matched their optical catalog with the list of X-ray sources found in a Chandra-ACIS observation of this cluster (Damiani et al. 2004, ApJ, 608, 781: available in Browse both via links from this table and also as the NGC6530CXO table), finding a total of 828 stars in common, 90% of which are pre-main sequence stars in NGC 6530. The data used in this work come from the combination of optical BVI images taken with the WFI camera made on 27-28 July 2000, a 60 ks Chandra ACIS X-ray observation, and public near-infrared data from the All-Sky Catalog of Point Sources of the Two Micron All Sky Survey (2MASS, CDS Cat. <II/24>). The total number of optical sources falling in the Chandra FOV is 8956, while the Damiani et al. (2004, ApJ, 608, 781) Catalog contains 884 X-ray sources, who concluded that at least 90% of the X-ray sources are very probable cluster members. To cross-correlate the X-ray and optical catalogs, the authors used a matching distance of < 4 sigmaX, where sigmaX is the the X-ray positional error, or 1.5", whichever is smaller, after a systematic shift between the X-ray and WFI positions of 0.2" in RA and -0.26" in Dec had been included. This resulted in a number of multiple identifications, among which 4 turned into unique identifications when a reduced distance of 1.5" was used. This finally resulted in 721 single, 44 double, and 3 triple identifications in the optical catalog; in addition, one X-ray source has 4 optical identifications, and another has 6 optical identifications. The total number of X-ray sources with WFI counterparts is therefore 770; of them, only 15 X-ray identified stars come from the Sung et al. (2000, AJ, 120, 333) Catalog and are not in the WFI Catalog. The total number of optical sources with an X-ray counterpart is 828. The agreement between X-ray and WFI optical positions is excellent in most cases, with offsets below 1". This database table was created by the HEASARC in February 2007, based on CDS table J/A+A/430/941/table5.dat This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc1332cxo
- Title:
- NGC 1332 Chandra X-Ray Compact Source Catalog
- Short Name:
- NGC1332CXO
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Chandra ACIS-S3 (Advanced CCD Imaging Spectrometer) observations of the nearby S0 galaxy NGC 1332 resolve much of the X-ray emission into 73 point sources, of which 37 lie within the D<sub>25</sub> isophote. The remaining galaxy emission comprises hot, diffuse gas and unresolved sources and is discussed in two companion papers. The point-source X-ray luminosity function (XLF) shows the characteristic break seen in other early-type galaxies at ~2 x 10<sup>38</sup> ergs s<sup>-1</sup>. After applying corrections for detection incompleteness at low luminosities due to source confusion and contamination from diffuse galactic emission, the break vanishes and the data are well described as a single power law. This result casts further doubt on there being a "universal" XLF break in early-type galaxies, marking the division between neutron star and black hole systems. The logarithmic slope of the differential XLF (dN/dL), beta = 2.7 +/- 0.5, is marginally (~2.5 sigma) steeper than has been found for analogous completeness-corrected fits of other early-type galaxies but closely matches the behavior seen at high luminosities in these systems. Two of the sources within D<sub>25</sub> are ultraluminous X-ray sources (ULXs), although neither have LX > 2 x 10<sup>39</sup> ergs s<sup>-1</sup>. The absence of very luminous ULXs in early-type galaxies suggests a break in the XLF slope at ~1-2 x 10<sup>39</sup> ergs s<sup>-1</sup>, although the data were not of sufficient quality to constrain such a feature in NGC 1332. The sources have a spatial distribution consistent with the optical light and display a range of characteristics that are consistent with an LMXB population. The general spectral characteristics of the individual sources, as well as the composite source spectra, are in good agreement with observations of other early-type galaxies, although a small number of highly absorbed sources are seen. Two sources have very soft spectra, two show strong variability, indicating compact binary nature, and one source shows evidence of an extended radial profile. The authors do not detect a central source in NGC 1332, but find a faint (L<sub>X</sub> = 2 +/- 1 x 10<sup>38</sup> ergs s<sup>-1</sup>) point source coincident with the center of the companion dwarf galaxy NGC 1331. The region of sky containing NGC 1332 was observed with the ACIS instrument aboard Chandra between 2002 September 19 10:39 and September 20 02:59 UTC for a nominal ~60 ksec exposure.. This table contains the 73 bona fide X-ray compact sources detected in this observation, excluding one source centered within 1" of the galaxy centroid that is actually the central part of the diffuse galactic emission, one source within the D<sub>25</sub> isophote of the neighboring galaxy NGC 1331, and one source with no photons within the 0.5-7.0 keV band which is likely to be spurious. The spatial extent of 72 of the 73 sources is consistent with the instrumental PSF. One source (number 14) is clearly more extended than the PSF. This table was created by the HEASARC in May 2018 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/612/848">CDS Catalog J/ApJ/612/848</a> file table1.dat, the list of detected X-ray sources in the Chandra observation of NGC 1332. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc1068cxo
- Title:
- NGC 1068 Chandra X-Ray Compact Source Catalog
- Short Name:
- NGC1068CXO
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from a study of the compact X-ray source population in the Seyfert 2 galaxy NGC 1068, imaged with a 50-ks Chandra observation. The authors find a total of 84 compact sources on the ACIS-S3 chip, of which 66 are located within the 25.0 B-mag/arcsec<sup>2</sup> isophote of the galactic disk of NGC 1068. In the reference paper, the spectra of the 21 X-ray sources with at least 50 counts were modeled with both multicolor disk blackbody and power-law models. The power-law model provides the better description of the spectrum for 18 of these sources. For fainter sources, the spectral index was estimated from the hardness ratio. Five sources have 0.4-8 keV intrinsic luminosities greater than 10<sup>39</sup> ergs s<sup>-1</sup>, assuming that their emission is isotropic and that they are associated with NGC 1068. The authors refer to these sources as intermediate-luminosity X-ray objects (IXOs). If these five sources are X-ray binaries accreting with luminosities that are both sub-Eddington and isotropic, then the implied source masses are >~7 solar masses, and so they are inferred to be black holes. Most of the spectrally modeled sources have spectral shapes similar to Galactic black hole candidates. However, the brightest compact source in NGC 1068 has a spectrum that is much harder than that found in Galactic black hole candidates and other IXOs. The brightest source also shows large amplitude variability on both short-term and long-term timescales, with the count rate possibly decreasing by a factor of 2 in ~2 ks during this Chandra observation, and the source flux decreasing by a factor of 5 between this observation and the grating observations taken just over 9 months later. The ratio of the number of sources with luminosities greater than 2.1 x 10<sup>38</sup> ergs s<sup>-1</sup> in the 0.4-8 keV band to the rate of massive (>5 solar masses) star formation is the same, to within a factor of 2, for NGC 1068, the Antennae, NGC 5194 (the main galaxy in M51), and the Circinus galaxy. This suggests that the rate of production of X-ray binaries per massive star is approximately the same for galaxies with currently active star formation, including "starbursts." The authors were concerned with the study of the discrete X-ray source population in NGC 1068, imaged within the 8.4 arcmin x 8.4 arcmin (35.3 kpc x 35.3 kpc) field of view of the ACIS S3 chip. Images were extracted from the reprocessed level 2 events file in soft (0.4-1.5 keV), hard (1.5-5.0 keV) and full (0.4-5.0 keV) energy bands. The authors used the CIAO program wavdetect to search the images in the three energy bands for discrete sources of X-ray emission. They analyzed the images using wavelet scales in the range from 1 pixel (0.492 arcsec) to 16 pixels (7.87 arcsec), separated by a factor of sqrt(2). The wavelet source detection threshold was set to 10<sup>-6</sup>, which gives approximately one false source for the whole S3 chip. The total number of sources detected by wavdetect in the soft, hard, and full energy band images was 115, 67, and 138, respectively. Each of these sources was examined carefully by eye, and only those 84 sources that appear compact to the eye are included in this source list. This table was created by the HEASARC in August 2015 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/591/138">CDS Catalog J/ApJ/591/138</a> file table1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc4649cxo
- Title:
- NGC 4649 Chandra X-Ray Discrete Source Catalog
- Short Name:
- NGC4649CXO
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors performed a Chandra X-ray observation of the X-ray bright E2 elliptical galaxy NGC 4649 (M 60). In addition to bright diffuse emission, they resolved 165 discrete sources, most of which are presumably low-mass X-ray binaries (LMXBs). As found in previous studies, the luminosity function of the resolved sources is well-fitted by a broken power law. In NGC 4697 and NGC 1553, the break luminosity was comparable to the Eddington luminosity of a 1.4 solar mass neutron star. One possible interpretation of this result is that those sources with luminosities above the break are accreting black holes and those below are mainly accreting neutron stars. The total X-ray spectrum of the resolved sources is well fitted by a hard power law. NGC 4649 was observed on 2000 April 20 on the ACIS-S3 CCD operated at a temperature of -120 C and with a frame time of 3.2 s. In addition to the S3 chip, the ACIS chips I2, I3, S1, S2, and S4 were also turned on for the duration of the observation. Although a number of serendipitous sources were seen on the other chips, the analysis of NGC 4649 in this paper was based on data from the S3 chip alone. The total exposure for the S3 chip was 36,780 s. The discrete X-ray source population on the ACIS S3 image was determined using a wavelet detection algorithm in the 0.3 - 10.0 keV band, and they were confirmed with a local cell detection method. The authors used the CIAO, WAVDETECT, and CELLDETECT programs. The high spatial resolution of Chandra implies that the sensitivity to point sources is not affected very strongly by the background. Thus, the source detection was done using the entire exposure of 36,780 s, including periods with background flares. The wavelet source detection significance threshold was set at 10<sup>-6</sup>, which implies that less than 1 false source (due to a statistical fluctuation in the background) would be detected in the entire S3 image. This significance threshold approximately corresponds to requiring that the source flux be determined to better than 3 sigma. This table was created by the HEASARC in April 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/600/729">CDS catalog J/ApJ/600/729</a> file table1.dat. This is a service provided by NASA HEASARC .
