- ID:
- ivo://nasa.heasarc/rassdsstar
- Title:
- ROSAT All-Sky Survey and SDSS Sample of X-Ray Emitting Stars
- Short Name:
- RASSDSSTAR
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The ROSAT All-Sky Survey (RASS) was the first imaging X-ray survey of the entire sky. Combining the RASS Bright and Faint Source Catalogs yields an average of about three X-ray sources per square degree. However, while X-ray source counterparts are known to range from distant quasars to nearby M dwarfs, the RASS data alone are often insufficient to determine the nature of an X-ray source. As a result, large-scale follow-up programs are required to construct samples of known X-ray emitters. The authors use optical data produced by the Sloan Digital Sky Survey (SDSS) to identify 709 stellar X-ray emitters cataloged in the RASS and falling within the SDSS Data Release 1 footprint. Most of these are bright stars with coronal X-ray emission unsuitable for SDSS spectroscopy, which is designed for fainter objects (g > 15<sup>mag</sup>). Instead, the authors use SDSS photometry, correlations with the Two Micron All Sky Survey (2MASS) and other catalogs, and spectroscopy from the Apache Point Observatory 3.5 m telescope to identify these stellar X-ray counterparts. Their sample of 707 X-ray-emitting F, G, K, and M stars is one of the largest X-ray-selected samples of such stars. The authors derive distances to these stars using photometric parallax relations appropriate for dwarfs on the main sequence, and use these distances to calculate their X-ray luminosities L<sub>X</sub>. They also identify a previously unknown cataclysmic variable (CV) as a RASS counterpart. Much more information on the SDSS is available at the project's web site at <a href="http://www.sdss.org/">http://www.sdss.org/</a>. This table was created by the HEASARC in April 2009 based on the the machine-readable version of Table 4 from the reference paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .
Number of results to display per page
Search Results
- ID:
- ivo://nasa.heasarc/rassgiant
- Title:
- ROSATAll-SkySurvey:Giants&Supergiants
- Short Name:
- RASS/Giant
- Date:
- 10 May 2024
- 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:
- 10 May 2024
- 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="ftp://cdsarc.u-strasbg.fr/cats/J/ApJ/448/683/">ftp://cdsarc.u-strasbg.fr/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/rassob
- Title:
- ROSAT All-Sky Survey: OB Stars
- Short Name:
- RASS/OB
- Date:
- 10 May 2024
- 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:
- 10 May 2024
- 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/pleiadxray
- Title:
- ROSAT PSPC Catalog of the Pleiades (Micela et al. 1996)
- Short Name:
- PSPC/Pleiades
- Date:
- 10 May 2024
- 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 .
- ID:
- ivo://nasa.heasarc/orionxray
- Title:
- ROSAT Survey of the Orion Nebula
- Short Name:
- HRI/Orion
- Date:
- 10 May 2024
- 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 concatenation of Tables 2 and 3 from Gagne et al. (1995) which list the 389 distinct X-ray sources and their candidate optical counterparts. A detection criterion of 3 sigma was used, i.e., a sigal-to-noise ratio criterion of 3. 324 of the X-ray sources have a single candidate optical counterpart, 50 of the X-ray sources (listed in Table 3 of the original paper) have multiple candidates for the optical counterparts, and the remainder have no optical counterparts. Notice that Table 6 of Gagne et al. (1995) which presents a compilation of optical and X-ray data for a sub-group of the Orion stars for which data on the spectral types and the spectroscopic rotational velocities or the photometric rotational periods are available is not part of this database. This database was created at the HEASARC in December 1997 based on a computer-readable version of Tables 2 and 3 of Gagne et al. (1995) that was obtained from the CDS (their catalog J/ApJ/445/280). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/sacy
- Title:
- SACY (Search for Associations Containing Young Stars) Catalog
- Short Name:
- SACY
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The SACY (Search for Associations Containing Young Stars) Catalog contains the results from a high-resolution optical spectroscopic survey aimed to search for nearby young associations and young stars among optical counterparts of ROSAT All-Sky Survey X-ray sources in the Southern Hemisphere. 1953 late-type (B-V>=0.6), potentially young, optical counterparts were selected out of a total of 9574 1RXS sources for follow-up observations. At least one high-resolution spectrum was obtained for each of 1511 targets. This paper is the first in a series presenting the results of the SACY survey in which the sample of X-ray selected stars and the supporting optical observations are described. The SACY sample is defined by Hipparcos (<a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/239">CDS Cat. <I/239></a>) and Tycho-2 (<a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/259">CDS Cat. <I/259></a>) stars within an error radius of 2.6 times the positional error of the ROSAT All-Sky Bright Source Catalogue (1RXS, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/IX/10">CDS Cat. <IX/10></a>). The used cut-off (B-V=0.6), corresponding approximately to a G0 dwarf, is near the hottest stars where the strength of the LiI line can be used as an youth indicator. All Hipparcos stars having M_v < 2.0 have been excluded. The northern boundary limits of the survey are given in Table 1 of the reference paper. In addition to the 1511 stars observed at least once, 115 stars with data taken from the literature have been added in order to complement the sample. In addition to these 1626 stars in the SACY sample (sources with source number prefixes of 'S'), entries for 165 other observed stars (sources with source number prefixes of 'O') are also included in this table. Most of the spectroscopic observations (~70%) were performed with the FEROS spectrograph at the 1.5m/ESO telescope at La Silla between January 1999 and September 2002 (ON-ESO agreement and ESO program identification 67.C-0123). Two more runs (ESO program identifications 072.C-0393 and 077.C-0138) were carried out at the 2.2m/ESO telescope. Another set of data (~30%) was collected at the coude spectrograph attached to 1.60m telescope at the Observatorio rio do Pico dos Dias (OPD), LNA, Brazil. Some spectra are a re-analysis of the ones taken for the PDS program. A few observations were collected using the CORALIE attached to the Swiss Euler Telescope at La Silla. UBV(RI)c photometry for part of the sample was obtained using FOTRAP at the 0.60m Zeiss telescope of the OPD. When a star was not observed photometrically by the authors, they tried to obtain some useful photometric data from the Hipparcos and Tycho Catalogues or in the available literature in the SIMBAD. For multiple stars, magnitudes and colors were corrected in order to take into account the presence of the companion(s). This table was created by the HEASARC in March 2007 based on the CDS table J/A+A/460/695, files table3.dat and table4.dat This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/sdssdr10wd
- Title:
- Sloan Digital Sky Survey DR10 New White Dwarf Catalog
- Short Name:
- SDSSDR10WD
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors report the discovery of 9,088 new spectroscopically confirmed white dwarfs and subdwarfs in the Sloan Digital Sky Survey (SDSS) Data Release 10 (DR10). They obtain T<sub>eff</sub>, log g and masses for hydrogen-atmosphere white dwarf stars (DAs) and helium-atmosphere white dwarf stars (DBs), and estimate the calcium/helium abundances for the white dwarf stars with metallic lines (DZs) and carbon/helium for carbon-dominated spectra (DQs). They found 1 central star of a planetary nebula, 2 new oxygen spectra on helium-atmosphere white dwarfs, 71 DQs, 42 hot DO/PG1159s, 171 white dwarf+main-sequence star binaries, 206 magnetic DAHs, 327 continuum-dominated DCs, 397 metal-polluted white dwarfs, 450 helium-dominated white dwarfs, 647 subdwarfs and 6887 new hydrogen-dominated white dwarf stars. The targeted white dwarfs were required to be point sources with clean photometry, and to have USNO-B Catalog counterparts (Monet et al.. 2003, AJ, 125, 984, CDS Cat. I/284). They were also restricted to regions inside the DR7 imaging footprint and required to have colors within the ranges g < 19.2, (u-r) < 0.4, -1 < (u-g) < 0.3, -1 < (g-r) < 0.5 and to have low Galactic extinction A<sub>r</sub> < 0.5 mag. Additionally, targets that did not have (u-r) < -0.1 and (g-r) < -0.1 were required to have USNO proper motions larger than 2 arcseconds per century (20 milliarcseconds per year). Objects satisfying the selection criteria that had not been observed previously by the SDSS were denoted by the WHITEDWARF_NEW target flag, while those with prior SDSS spectra are assigned the WHITEDWARF_SDSS flag. Some of the latter were re-observed with BOSS in order to obtain the extended wavelength coverage that the BOSS spectrograph offers. The color selection used includes DA stars with temperatures above ~14,000 K, helium-atmosphere white dwarfs above ~8000 K, as well as many rarer classes of white dwarfs. Hot subdwarfs (sdB and sdO) were targeted as well. Note that this catalog does not include stars from the earlier SDSS white dwarf catalogs, e.g., Eisenstein et al. (2006, ApJS, 167, 40, available in the HEASARC database as the SDSSDWDSD table), Kleinman et al. (2013, ApJS, 205, 5, available in the HEASARC database as the SDSSDR7WD table).. This table was created by the HEASARC in October 2017 based on an electronic version of Table 6 from the reference paper which was obtained from the CDS as their catalog J/MNRAS/446/4078 file table6.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/sdssdr7wd
- Title:
- Sloan Digital Sky Survey DR7 White Dwarf Catalog
- Short Name:
- SDSSDR7WD
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a new catalog of spectroscopically confirmed white dwarf stars from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) spectroscopic catalog. The authors find 20,407 white dwarf spectra, representing 19,712 stars, and provide atmospheric model fits to 14,120 DA and 1011 DB white dwarf spectra from 12,843 and 923 stars, respectively. These numbers represent more than a factor of two increase in the total number of white dwarf stars from the previous SDSS white dwarf catalogs based on DR4 data. The distribution of subtypes varies from previous catalogs due to the authors' more conservative, manual classifications of each star in our catalog, supplementing their automatic fits. In particular, they find a large number of magnetic white dwarf stars whose small Zeeman splittings mimic increased Stark broadening that would otherwise result in an overestimated log g if fit as a non-magnetic white dwarf. The authors calculate mean DA and DB masses for their clean, non-magnetic sample and find the DB mean mass is statistically larger than that for the DAs. This table lists the 20,407 white dwarf spectra corresponding to 19,712 distinct stars. This table was created by the HEASARC in January 2013 based on the electronic version of Table 2 from the reference paper which was obtained from the ApJS web site. One duplicate entry was removed from the table in June 2019. This is a service provided by NASA HEASARC .