- ID:
- ivo://CDS.VizieR/J/A+A/646/A46
- Title:
- Chamaeleon DANCe. Stellar population with Gaia-DR2
- Short Name:
- J/A+A/646/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kinematic properties and stellar parameters of the Chamaeleon stars selected in our membership analysis using Gaia-DR2 data. We provide for each star its identifier, position, proper motion, parallax, radial velocity, distance, spatial velocity, SED classification, age and membership probability. We also provide the membership probabilities for all sources in the fields surveyed by our study and the empirical isochrone of the Cha I and Cha II subgroups.
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- ID:
- ivo://CDS.VizieR/J/A+A/535/A2
- Title:
- Chamaeleon III 870um sources maps
- Short Name:
- J/A+A/535/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nearby Chamaeleon molecular cloud complex is a good laboratory for studying the process of low-mass star formation because it consists of three clouds with very different properties. Chamaeleon III does not show any sign of star formation, while star formation has been very active in Chamaeleon I and may already be finishing. Our goal is to determine whether star formation can proceed in Cha III by searching for prestellar cores, and to compare the results to our recent survey of Cha I.
- ID:
- ivo://nasa.heasarc/chainthcxo
- Title:
- Chamaeleon I North Cloud Chandra X-Ray Point Source Catalog
- Short Name:
- CHAINTHCXO
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Chamaeleon (Cha) I North Cloud Chandra X-Ray point source catalog. Sensitive X-ray imaging surveys provide a new and effective tool to establish the census of pre-main-sequence (PMS) stars in nearby young stellar clusters. A deep Chandra X-Ray Observatory (CXO) observation of PMS stars in the Chamaeleon I North cloud achieved a limiting total-band X-ray luminosity of log L<sub>t</sub> ~ 10<sup>27</sup> ergs/s (0.5 - 8 keV band) in a 0.8 x 0.8 pc<sup>2</sup> region. Of the 107 X-ray sources, 37 are associated with Galactic stars, of which 27 are previously recognized cloud members. These include 3 PMS brown dwarfs: the protostellar brown dwarf ISO 192 has a particularly high level of magnetic activity. Follow-up optical photometry and spectroscopy establish that 9-10 of the Chandra sources are probably magnetically active background stars. No new X-ray-discovered stars were confidently found despite the high sensitivity of the Chandra observation. From these findings, the authors argue that the sample of 27 PMS cloud members in the Chandra field is uncontaminated and complete down to K = 12 or a stellar mass of about 0.1 solar masses. A 16'x 16' region of the Cha I North cloud was observed with the imaging array of the Advanced CCD Imaging Spectrometer (ACIS-I) detector on board the Chandra X-Ray Observatory. The observation took place on 2001 July 2.25-3.04 UT with the detector aimpoint set at 11 10 00.0, -76 35 00 (J2000.0 RA and Declination). The effective exposure was 66.3 ksec. The authors also obtained VI-band CCD images of most of the ACIS field with the 1m telescope and CCD detector at the South African Astronomical Observatory (SAAO) during 2002 February. This table was created by the HEASARC in February 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/614/267">CDS catalog J/ApJ/614/267</a> files table1.dat, table2.dat and table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJ/602/816
- Title:
- Chamaeleon I star-forming region census
- Short Name:
- J/ApJ/602/816
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I present a new census of the members of the Chamaeleon I star-forming region. Optical spectroscopy has been obtained for 179 objects that have been previously identified as possible members of the cluster, that lack either accurate spectral types or clear evidence of membership, and that are optically visible (I<~18). I have used these spectroscopic data and all other available constraints to evaluate the spectral classifications and membership status of a total sample of 288 candidate members of Chamaeleon I that have appeared in published studies of the cluster. The latest census of Chamaeleon I now contains 158 members, eight of which are later than M6 and thus are likely to be brown dwarfs. I find that many of the objects identified as members of Chamaeleon I in recent surveys are actually field stars. Meanwhile, seven of nine candidates discovered by Carpenter and coworkers are confirmed as members, one of which is the coolest known member of Chamaeleon I at a spectral type of M8 (~0.03M_{sun}_). I have estimated extinctions, luminosities, and effective temperatures for the members and used these data to construct an H-R diagram for the cluster. Chamaeleon I has a median age of ~2Myr according to evolutionary models and hence is similar in age to IC 348 and is slightly older than Taurus (~1Myr). The measurement of an initial mass function for Chamaeleon I from this census is not possible because of the disparate methods with which the known members were originally selected and must await an unbiased, magnitude-limited survey of the cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/527/A145
- Title:
- Chamaeleon I 870um sources
- Short Name:
- J/A+A/527/A145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chamaeleon I is the most active region in terms of star formation in the Chamaeleon molecular cloud complex. Although it is one of the nearest low-mass star forming regions, its population of prestellar and protostellar cores is not known and a controversy exists concerning its history of star formation. Our goal is to search for prestellar and protostellar cores and characterize the earliest stages of star formation in this cloud.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A99
- Title:
- Chamaeleon-MMS1 NH_3_ (1,1) and (2,2) maps
- Short Name:
- J/A+A/564/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this study is to investigate the structure and kinematics of the nearby candidate first hydrostatic core Cha-MMS1. Cha-MMS1 was mapped in the NH_3_(1,1) line and the 1.2cm continuum using the Australia Telescope Compact Array, ATCA. The angular resolution of the ATCA observations is 7" (~1000AU), and the velocity resolution is 50m/s. The core was also mapped with the 64-m Parkes telescope in the NH_3_(1,1) and (2,2) lines. Observations from Herschel Space Observatory and Spitzer Space telescope were used to help interpretation. The ammonia spectra were analysed using Gaussian fits to the hyperfine structure. A two-layer model was applied in the central parts of the core where the ATCA spectra show signs of self-absorption.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A126
- Title:
- Cha-MMS1 CO 3-2 and ^13^CO 3-2 datacubes
- Short Name:
- J/A+A/633/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of its low luminosity, its chemical composition, and the absence of a large-scale outflow, the dense core Cha-MMS1 located in the Chamaeleon I molecular cloud was proposed as a first hydrostatic core (FHSC) candidate a decade ago. Our goal is to test this hypothesis by searching for a slow, compact outflow driven by Cha-MMS1 that would match the predictions of MHD simulations for this short phase of star formation. We use the Atacama Large Millimeter/submillimeter Array (ALMA) to map Cha-MMS1 at high angular resolution in CO 3-2 and ^13^CO 3-2 as well as in continuum emission. We report the detection of a bipolar outflow emanating from the central core, along a (projected) direction roughly parallel to the filament in which Cha-MMS1 is embedded and perpendicular to the large-scale magnetic field. The morphology of the outflow indicates that its axis lies close to the plane of the sky. We measure velocities corrected for inclination of more than 90km/s which is clearly incompatible with the expected properties of a FHSC outflow. Several properties of the outflow are determined and compared to previous studies of Class 0 and Class I protostars. The outflow of Cha-MMS1 has a much smaller momentum force than the outflows of other Class0 protostars. In addition, we find a dynamical age of 200-3000yr indicating that Cha-MMS1 might be one of the youngest ever observed Class 0 protostars. While the existence of the outflow suggests the presence of a disk, no disk is detected in continuum emission and we derive an upper limit of 55au to its radius. We conclude that Cha-MMS1 has already gone through the FHSC phase and is a young Class 0 protostar, but it has not brought its outflow to full power yet.
- ID:
- ivo://nasa.heasarc/champhxagn
- Title:
- CHAMP (Chandra Multiwavelength Project) Hard X-Ray Emitting AGN
- Short Name:
- CHAMPHXAGN
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the results from an X-ray and optical analysis of 188 active galactic nuclei (AGN) identified from 497 hard X-ray (observed flux in the (2.0 - 8.0 keV) band > 2.7 x 10<sup>-15</sup> erg/cm<sup>2</sup>/s) sources in 20 Chandra fields (1.5 square degrees) forming part of the Chandra Multiwavelength Project (ChaMP). These medium-depth X-ray observations enable the detection of a representative subset of those sources responsible for the bulk of the 2 - 8 keV cosmic X-ray background. Brighter than the survey's optical spectroscopic limit, the authors achieve a reasonable degree of completeness (77% of X-ray sources with counterparts r' < 22.5 have been classified): broad emission-line AGNs (62%), narrow emission-line galaxies (24%), absorption-line galaxies (7%), stars (5%), or clusters (2%). To construct a pure AGN sample, the authors required the rest-frame 2.0-8.0 keV luminosity (uncorrected for intrinsic absorption) to exceed 10<sup>42</sup> erg s<sup>-1</sup>, thereby excluding any sources that may contain a significant stellar or hot ISM component. The most luminous known star-forming or elliptical galaxies attain at most L<sub>X</sub> = 10<sup>42</sup> erg s<sup>-1</sup>. Since many of the traditional optical AGN signatures are not present in obscured sources, high X-ray luminosity becomes the authors' single discriminant for supermassive black hole accretion. They believe that almost all of the NELGs and ALGs harbor accreting SMBHs based on their X-ray luminosity. They find that 90% of the identified ChaMP sources have luminosities above this threshold. These selection criteria yield a sample of 188 AGNs from 20 Chandra fields with f(2-8 keV) > 2.7 x 10<sup>-15</sup> erg cm<sup>-2</sup> s<sup>-1</sup>, r' < 22.5, and L<sub>X</sub> > 10<sup>42</sup> erg s<sup>-1</sup>. The authors removed five objects identified as clusters based on their extended X-ray emission. This table was created by the HEASARC in March 2007 based on the CDS table J/ApJ/618/123, file table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJS/178/339
- Title:
- ChaMP extended stellar survey (ChESS)
- Short Name:
- J/ApJS/178/339
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 348 X-ray-emitting stars identified from correlating the Extended Chandra Multiwavelength Project (ChaMP), a wide-area serendipitous survey based on archival X-ray images, with the Sloan Digital Sky Survey (SDSS-DR6). We use morphological star/galaxy separation, matching to an SDSS quasar catalog, an optical color-magnitude cut, and X-ray data-quality tests to create our catalog, the ChaMP Extended Stellar Survey (ChESS), from a sample of 2121 matched ChaMP/SDSS sources. Our cuts retain 92% of the spectroscopically confirmed stars in the original sample while excluding 99.6% of the 684 spectroscopically confirmed extragalactic sources. Fewer than 3% of the sources in our final catalog are previously identified stellar X-ray emitters. For 42 catalog members, spectroscopic classifications are available in the literature. We present new spectral classifications and H{alpha} measurements for an additional 79 stars. The catalog is dominated by main-sequence stars; we estimate the fraction of giants in ChESS is ~10%. We identify seven giant stars (including a possible Cepheid and an RR Lyrae star) as ChaMP sources, as well as three cataclysmic variables. Future papers will present analyses of source variability and comparisons of this catalog to models of stellar activity in the Galactic disk.
- ID:
- ivo://nasa.heasarc/chesscat
- Title:
- ChaMP Extended Stellar Survey (ChESS) X-Ray Catalog
- Short Name:
- CHESSCAT
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The ChaMP Extended Stellar Survey (ChESS) X-ray catalog contains 348 X-ray-emitting stars identified from correlating the Extended Chandra Multiwavelength Project (ChaMP), a wide-area serendipitous survey based on archival X-ray images, with the Sloan Digital Sky Survey (SDSS). The authors used morphological star/galaxy separation, matching to an SDSS quasar catalog, an optical color-magnitude cut, and X-ray data-quality tests to create this catalog, from a sample of 2121 matched ChaMP/SDSS sources. Their cuts retain 92% of the spectroscopically confirmed stars in the original sample while excluding 99.6% of the 684 spectroscopically confirmed extragalactic sources. Fewer than 3% of the sources in their final catalog are previously identified stellar X-ray emitters. For 42 catalog members, spectroscopic classifications are available in the literature. New spectral classifications and H-alpha measurements are presented for an additional 79 stars. The catalog is dominated by main-sequence stars; the authors estimate the fraction of giants in ChESS to be ~10%. They identify seven giant stars (including a possible Cepheid and an RR Lyrae star) as ChaMP sources, as well as three cataclysmic variables. They derive distances from ~10 to 2000 pc for the stars in the catalog using photometric parallax relations appropriate for dwarfs on the main sequence and calculate their X-ray and bolometric luminosities. These stars lie in a unique space in the L<sub>X</sub>-distance plane, filling the gap between the nearby stars identified as counterparts to sources in the ROSAT All Sky Survey and the more distant stars detected in deep Chandra and XMM-Newton surveys. For 36 newly identified X-ray-emitting M stars, the authors calculated L<sub>H-alpha</sub>/L<sub>bol</sub>. The quantities L<sub>H-alpha</sub>/L<sub>bol</sub> and L<sub>X</sub>/L<sub>bol</sub> are linearly related below L<sub>X</sub>/L<sub>bol</sub> ~ 3 x 10<sup>-4</sup>, while L<sub>H-alpha</sub>/L<sub>bol</sub> appears to turn over at larger L<sub>X</sub>/L<sub>bol</sub> values. Stars with reliable SDSS photometry have an ~0.1 mag blue excess in u-g, likely due to increased chromospheric continuum emission. Photometric metallicity estimates suggest that the sample is evenly split between the young and old disk populations of the Galaxy; the lowest activity sources belong to the old disk population, a clear signature of the decay of magnetic activity with age. This table was created by the HEASARC in January 2009 based on the electronic version of Tables 2 and 3 from the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
