- ID:
- ivo://nasa.heasarc/rassdwarf
- Title:
- ROSAT All-Sky Survey: A-K Dwarfs/Subgiants
- Short Name:
- RASS/Dwarf
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This catalog presents X-ray data for all the main-sequence and subgiant stars of spectral types A, F, G, and K and luminosity classes IV and V listed in the Bright Star Catalogue (also known as the HR Catalogue) that have been detected as X-ray sources in the ROSAT All-Sky Survey (RASS). A number of stars in the appropriate spectral type range that do not have assigned luminosity classes have also been included. The catalogue contains 980 such HR stars detected as X-ray sources out of a total of 3054 stars in the HR Catalogue that satisfy the selection criteris, implying an average detection rate of 32%. In addition to the measured ROSAT PSPC count rates, source detection parameters, hardness ratios, and X-ray fluxes, X-ray luminosities derived from Hipparcos parallaxes are also listed. This database was created at the HEASARC in February 1999 based on the ADC/<a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+AS/132/155">CDS Catalog J/A+AS/132/155</a>. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/chasfrxray
- Title:
- ROSAT All-Sky Survey: Chamaeleon Star Forming Region Study
- Short Name:
- RASS/Cham
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This catalog contains a source list derived from observations of the ROSAT all-sky survey (RASS) in the direction of the Chamaeleon star-forming region cloud complex, as well as spectroscopic identifications for the detected X-ray sources. The main purpose of this identification program was the search for low-mass pre-main sequence stars. Sixteen previously known PMS stars were detected with high confidence by ROSAT: eight are classical T Tauri stars and eight are weak-line T Tauri stars. Seventy-seven new weak-line T Tauri stars were identified on the basis of the presence of strong Li 6707 Angstrom absorption, a spectral type later than F0, and chromospheric emission. In addition, 6 new dKe-dMe candidates were found among the RASS sources. Coordinates and count rates are given for all of the X-ray sources. This online catalog was created by the HEASARC in September 1999 based on a machine-readable table obtained from the ADC/CDS data centers (J/A+AS/114/109). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/rassgiant
- Title:
- ROSATAll-SkySurvey:Giants&Supergiants
- Short Name:
- RASS/Giant
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The ROSAT All-Sky Survey Catalogue of Optically Bright Late-Type Giant and Supergiant Stars contains X-ray data for all late-type (spectral types of A through M, inclusive) giants and supergiants (luminosity classes of I through III-IV, inclusive) listed in the Bright Star Catalogue (BSC) that have been detected in the ROSAT All-Sky Survey. The RASS giants and supergiants catalog contains 450 entries of X-ray emitting, evolved late-type stars, which corresponds to an average detection rate of 11.7 percent. For each star, the ROSAT PSPC count rate, the hardness ratio, the apparent X-ray flux (calculated using an individual energy-conversion-factor based on the hardness ratio), and the ratio of X-ray to bolometric flux are given. The full details of the data selection, the source detection criteria, etc., are given in the paper by Huensch, Schmitt and Voges (1998, A&AS, 127, 251) describing this catalog; essentially for a star to be identified as an X-ray source, the X-ray source had to have at least a 99.9 percent existence probability, corresponding to a likelihood of greater than or equal to 7, and lie within 90 arcseconds of the optical position. Given the number of sky locations examined and the total number of RASS sources, it is expected that of order 27.4 of the 450 claimed associations in this catalog will be chance coincidences. This database was created at the HEASARC in July 1998 based on the ADC/<a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+AS/127/251">CDS Catalog J/A+AS/127/251</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/hyadesxray
- Title:
- ROSAT All-Sky Survey: Hyades Cluster Region
- Short Name:
- RASS/Hyades
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This catalog contains the results of a complete X-ray survey of the Hyades cluster region using X-ray data from the ROSAT All-Sky Survey (RASS) that was published by Stern, Schmitt and Kahabka in 1995. The Hyades survey covered over 900 square degrees of the sky. Over 185 optically identified Hyades were detected down to a limiting X-ray luminosity of about 1-2x10<sup>28</sup> ergs/s in the 0.1-1.8keV energy band. Among solar-like stars, i.e., main-sequence stars of spectral type G, the RASS detection rate was about 90%. Stern et al. argue that the presence of many binary systems in the cluster is a key factor influencing the Hyades X-ray luminosity function. Short-period (a few days or less) binaries are anomalously X-ray bright, as might have been expected; however, the X-ray luminosity functions of K and possibly M binary stars of all types are significantly different from their single counterparts, confirming the results of Pye et al. (1994, MNRAS, 266, 798) based on a smaller K star sample drawn from deep ROSAT pointings. Comparison with Einstein Observatory studies of a subset of Hyades stars demonstrates a general lack of significant (> a factor of 2) long-term X-ray variability. Stern et al. suggest that this may be the result of the dominance of a small-scale, turbulent dynamo in the younger Hyades stars compared to the large-scale, cyclic dynamo observed in the Sun. The HYADESXRAY database consists of X-ray data for 440 probable and possible Hyades members that were included in the Stern et al. survey and were listed in Table 1 of their published paper. The database contains both stars which were detected as X-ray sources and those which were not: for the latter, upper limits to their X-ray emission are provided. For all listed stars, their X-ray luminosities based on a Hyades distance of 45 pc are provided; for some stars, for which individually determined distances from either the Schwan (1991, A&A, 243, 386) or the Hanson (1975, AJ, 80, 379) proper motion surveys are available, their X-ray luminosities based on these alternate distances are also provided. There were 4 stars detected as RASS sources out of over 180 new Hyades candidates listed in the Reid (1992, MNRAS, 257, 257) proper motion survey which were included in Table 2 (but not Table 1) of the Stern et al. paper. These stars are not included in the current database, but are listed in the help section entitled Reid_Stars (q.v.). Similarly, there were 20 stars detected as RASS sources but which were considered by Stern et al. to be non-members of the Hyades which were included in their Table 3 (but not Table 1). These stars are not included in the current database, but are listed in the help section entitled Rejected_Hyades (q.v.). This HEASARC catalog was created in July 1997, derived from <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/448/683">CDS Catalog J/ApJ/448/683</a> obtained from <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/448/683/">https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/448/683/</a>. Additional information provided in the HEASARC documentation was taken from the original published version of the paper containing this catalog. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/rasscns3
- Title:
- ROSAT All-Sky Survey: Nearby Stars
- Short Name:
- RASS/CNS3
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This catalog presents X-ray data for all entries in the Third Catalogue of Nearby Stars (CNS3: Gliese and Jahreiss, 1991, ADC/CDS Cat. <V/70>) that have been detected as X-ray sources in the ROSAT All-Sky Survey (RASS). The catalog contains 1252 entries, yielding an average detection rate of 32.9 percent of the 3802 CNS3 stars. In addition to count rates, source detection parameters, X-ray hardness ratios, and X-ray fluxes, X-ray luminosities derived from Hipparcos parallaxes are also listed. For a star to have been considered by the authors to have been detected as an X-ray source in the RASS, an X-ray source with an existence likelihood of 7 or more (equivalent to a source existence probablity of 99.9 percent or more) had to lie within 90 arcseconds of its 1990 epoch CNS3 position. The choice of this cut-off radius was based on a Monte Carlo simulation of about the same number of random positions that were used as input positions. At an offset of 90 arcseconds between the optical and X-ray positions the probability that the X-ray source is attributable to the star and not to a unrelated background object is 50 percent; this probability increases very rapidly for smaller values of the offset, notice. This database was created in June 1999 based on tables provided by the ADC/CDS data centers supplemented by additional tabular material provided to the HEASARC by the author Dr. M. Huensch. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/rassob
- Title:
- ROSAT All-Sky Survey: OB Stars
- Short Name:
- RASS/OB
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- For detailed statistical analysis of the X-ray emission of hot stars, stars of spectral type O and B listed in the Yale Bright Star Catalogue were selected and searched for in the ROSAT All-Sky Survey. This database table displays a compilation of the derived X-ray data for a complete sample of bright OB stars. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/rasswd
- Title:
- ROSAT All-Sky Survey: White Dwarfs
- Short Name:
- RASS/WDw
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table lists all white dwarf stars, both previously-cataloged and newly discovered, which have been detected in the ROSAT All-Sky Survey. The positions and count rates of the X-ray sources associated with each star are given, as well as spectral types and other star names for those stars which have been previously cataloged. This database table also lists distances estimated via Balmer line profile fitting, corrected (for IS absorption) X-ray luminosities, and each star's contribution to the X-ray luminosity function for all DA white dwarfs which were detected in the ROSAT All-Sky Survey. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/orionxstar
- Title:
- ROSAT HRI Orion Group 1 Stars
- Short Name:
- ORIONXST
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This catalog presents some of the results from 3 deep ROSAT High Resolution Imager (HRI) observations of the Orion Nebula star-forming region. The fields covered by the X-ray images contain over 1500 catalogued stars in a roughly 0.8 square degree region centered on the Trapezium. In all, 389 distinct X-ray sources were detected, at least two-thirds of which were associated with a single proper-motion cluster member. X-ray emission was detected from stars of all spectral types, from the massive O- and B-type components of the Trapezium to the coolest, low-mass pre-main-sequence (PMS) stars. In the research paper in which these data were presented (Gagne et al. 1995), the authors focussed primarily on X-ray emission from the late-type PMS stars. Of the ~100 late-type cluster members with measured spectral types, approximately three-fourths were detected; the authors derived X-ray luminosity upper limits for the remaining stars. They found that coronal X-ray emission appeared to turn on at around a spectral type of F6, with the upper envelope of activity increasing with decreasing effective temperature. The current database is a representation of Table 6 from Gagne et al. (1995) (notice that the data given in Tables 2 and 3 of this reference is included in the HEASARC database ORIONXRAY, q.v.) which lists X-ray and other data for 175 Orion stars for which spectral types, spectroscopic rotational velocities, and/or spot-modulated photometric rotational periods are available. The X-ray data (either detections or upper limits) are given in the form of X-ray luminosities log Lx and X-ray to bolometric luminosity ratios (log Lx/Lbol). The conversion factor from HRI counts to log Lx was derived for each star based on (i) an assumed 1 keV Raymond and Smith thermal spectrum, (ii) a distance of 440 pc, and (iii) a column density of 2 x 10<sup>21</sup> cm<sup>-2</sup> per magnitude of visual extinction A(V), where accurate A(V) values are used when available, or otherwise a moderate absorption of 0.25 magnitudes is assumed. Notice that, for stars not identified as candidate optical counterparts in Tables 2 and 3 of Gagne et al. (the HEASARC database ORIONXRAY), the derived upper limit to the X-ray luminosity usually corresponds to the 3 sigma upper limit to the observed count rate. For a handful of stars in the Trapezium region where a star was eliminated as a candidate optical counterpart, despite being within the source search circle, because a more likely counterpart had a smaller position offset, the upper limit corresponds to either half the observed X-ray source count rate or to 3 sigma, whichever is the highest. Such cases are indicated in this database by the presence of the string "NN" in the parameter 'Note'. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/pleiadxray
- Title:
- ROSAT PSPC Catalog of the Pleiades (Micela et al. 1996)
- Short Name:
- PSPC/Pleiades
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This catalog contains the results of a deep X-ray survey of the core region of the Pleiades open cluster carried out with ROSAT. In a single PSPC field (~1 degree in radius), 99 of 214 Pleiades stars are detected in X-rays, and upper limits are computed for the remainder. This catalog lists the characteristics of these stars taken from the literature, including their rotational data, as well as their X-ray characteristics. The nucleus of the composite catalog used in this study is the catalog compiled from the published literature for the Einstein investigations of the Pleiades (Micela et al. 1990, ApJ, 348, 557). This list has been extended by the results of recent surveys to a completeness limit of visual magnitude of about 18. This database was created at the HEASARC in April 2002 based on the ADC/<a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/102/75">CDS Catalog J/ApJS/102/75</a> and is derived from Tables 1 and 5 of the published paper. This is a service provided by NASA HEASARC .
