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ORIONXRAY: Help

ORIONXRAY - ROSAT Survey of the Orion Nebula


Overview

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.


Catalog Bibcode

1995ApJ...445..280G

References

     Gagne M., Caillault J.-P., Stauffer J.R.
     Astrophys. J. 445, 280 (1995)
     =1995ApJ...445..280G      (SIMBAD/NED BibCode)

Provenance

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).

Parameters

Name
A designation for the X-ray source that we have constructed in the standard IAU way from the J2000 coordinates and the prefix "RX" that indicates the object is a ROSAT X-ray source.

RA
The Right Ascension of the X-ray source.

Dec
The Declination of the X-ray source.

LII
The galactic longitude of the X-ray source.

BII
The galactic latitude of the X-ray source.

Xray_Number
A running number used in Table 2 of the original reference that is ordered by increasing RA in J2000 co-ordinates.

Count_Rate
The corrected ROSAT HRI count rate in counts/s.

Count_Rate_Error
The 1-sigma RMS uncertainty in the HRI count rate in counts/s.

Flag_Mult_ID
A 'Y' indicates that there are multiple candidate optical counterparts.

Variable_Name_1
The variable star name for the first optical counterpart candidate (minus the constellation name of Orion); thus "V479" means that the counterpart is the variable star V479 Ori(onis).

Parenago_Name_1
The Parenago (1954, Trans. Sternberg Astr. Inst., Vol. 25) designation of the first optical counterpart candidate.

Jones_Name_1
The Jones & Walker (1988, AJ, 95, 1755) designation of the first optical counterpart candidate.

Mem_Prob_1
Membership Probability

RA_Offset_1
The offset in the direction of right ascension of the first optical counterpart candidate in arcsec.

Dec_Offset_1
The offset in the direction of declination of the first optical counterpart candidate in arcsec.

Parenago_Name_2
The Parenago (1954, Trans. Sternberg Astr. Inst., Vol. 25) designation of the second optical counterpart candidate.

Jones_Name_2
The Jones & Walker (1988, AJ, 95, 1755) designation of the second optical counterpart candidate.

Mem_Prob_2
Membership Probability First Candidate

RA_Offset_2
The offset in the direction of right ascension of the second optical counterpart candidate in arcsec.

Dec_Offset_2
The offset in the direction of declination of the second optical counterpart candidate in arcsec.

Parenago_Name_3
The Parenago (1954, Trans. Sternberg Astr. Inst., Vol. 25) designation of the third optical counterpart candidate.

Jones_Name_3
The Jones & Walker (1988, AJ, 95, 1755) designation of the third optical counterpart candidate.

Mem_Prob_3
Membership Probability Second Candidate

RA_Offset_3
The offset in the direction of right ascension of the third optical counterpart candidate in arcsec.

Dec_Offset_3
The offset in the direction of declination of the third optical counterpart candidate in arcsec.


Contact Person

Questions regarding the ORIONXRAY database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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