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ChaMP Extended Stellar Survey (ChESS) X-Ray Catalog

Metadata Updated: February 6, 2026

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 .

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

Downloads & Resources

Dates

Metadata Created Date April 11, 2025
Metadata Updated Date February 6, 2026

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date April 11, 2025
Metadata Updated Date February 6, 2026
Publisher High Energy Astrophysics Science Archive Research Center
Maintainer
Identifier ivo://nasa.heasarc/chesscat
Data Last Modified 2026-02-03
Category Astrophysics
Public Access Level public
Bureau Code 026:00
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id db539279-c91a-4743-9abe-e06081ac6317
Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
Harvest Source Title NASA Data.json
Homepage URL https://heasarc.gsfc.nasa.gov/W3Browse/all/chesscat.html
Program Code 026:000
Source Datajson Identifier True
Source Hash e7db0e96bdad89ab66c35c434a5bd435f81e3f73f63c6ac7d8b3727d9f5ce31b
Source Schema Version 1.1

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