CMAOB1XMM - CMa OB1 XMM-Newton X-Ray Point Source Catalog

Overview

The Canis Major OB1 association has an intriguing scenario of star formation, especially in the region called Canis Major R1 (CMa R1) traditionally assigned to a reflection nebula, but in reality an ionized region. The authors focused on the young stellar population associated with CMa R1, for which previous results from ROSAT, optical, and near-infrared data had revealed two stellar groups with different ages, suggesting a possible mixing of populations originated from distinct star formation episodes (see the table CMAR1XRAY).

The authors used X-ray data to characterize the detected sources according to hardness ratios, light curves, and spectra. They also provided estimates of mass and age, using the information from likely counterparts based on the 2MASS catalogue. The 2MASS-derived data on the counterparts, where matched, are provided in the associated table (CMAOB1NIR).

This table contains a catalog of 387 XMM-Newton sources, of which 78% are confirmed as members or probable members of the CMa R1 association. Flares (or similar events) were observed for 13 sources and the spectra of 21 bright sources could be fitted by a thermal plasma model. Mean values of fits parameters were used to estimate X-ray luminosities.

The authors found a minimum value of log(L_X [erg/s]) = 29.43, indicating that the sample of low-mass stars (M_* <= 0.5 M_sun), which are faint X-ray emitters, is incomplete. Among the 250 objects selected as the complete subsample (defining a "best sample"), 171 are found to the east of the cloud, near Z CMa and dense molecular gas, of which 50% of them are young (<5Myr) and 30% are older (>10Myr). The opposite happens to the west, near GU CMa, in areas lacking molecular gas: among 79 objects, 30% are young and 50% are older. These findings confirm that a first episode of distributed star formation occurred in the whole studied region ~10Myr ago and dispersed the molecular gas, while a second, localized episode (<5Myr) took place in the regions where molecular gas is still present.

For this work, four fields (each about 30-arcmin diameter with some overlap) were observed with the XMM-Newton satellite. These fields are located inside the arc-shaped ionized nebula, next to Z CMa - Field E (east); around GU CMa - Field W (west); and between both - Field C (center) and Field S (south), as shown in Figure 1 of the reference paper.

These observations were performed with the EPIC cameras (MOS1, MOS2, and PN) in full frame mode with a medium filter. The C, W, and S fields had an exposure time without background corrections of about 30 ks while field E had 40 ks.

  RA(J2000)  | Dec(J2000)  | Designation(s)

  07 04 18.3 | -11 27 24.0 | CMa cluster east (Field E)
  07 02 58.4 | -11 34 44.7 | CMa cluster center (Field C)
  07 02 29.5 | -11 47 12.4 | CMa cluster south (Field S)
  07 01 23.0 | -11 19 56.6 | CMa cluster west (Field W)

Catalog Bibcode

2018A&A...609A.127S

References

Star formation history of Canis Major OB1.
II. A bimodal X-ray population revealed by XMM-Newton.
    Santos-Silva T., Gregorio-Hetem J., Montmerle T., Fernandes B., Stelzer B.
   <Astron. Astrophys., 609, A127 (2018)>
   =2018A&A...609A.127S    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in October 2018 based upon the CDS Catalog J/A+A/609/A127 file tableb1.dat.

Parameters

Name
This is the X-ray source designation, using the prefix "[S2018] CMaX" to designate the reference paper origin for the naming scheme and Canis Major (CMa) X-ray source. The E, C, S, W in the name refers to the field where the source is located.

Alt_Name
The standard source designation recommended by the CDS Dictionary of Nomenclature of Celestial Objects, using the prefix of 'CMaOB1 J' to designate the Canis Major OB1 association and J2000.0 equatorial coordinates truncated to 0.1 seconds of time in RA and to 1 arcsecond in Dec.

RA
The Right Ascension of the XMM-Newton source in the selected equinox.

Dec
The Declination of the XMM-Newton source in the selected equinox.

LII
The Galactic longitude of the XMM-Newton source.

BII
The Galactic latitude of the XMM-Newton source.

Detect_Likelihood
The maximum likelihood for the source detection, based on two possible source detection algorithms. The first uses the XMM-Newton Scientific Analysis System (SAS) EMOSAICPROC metatask, which takes into account the merged data from various observations and instruments. The second method searches for detections using the SAS EDETECT_CHAIN tool on individual detector images, since the former method uses combined images and thus may miss valid sources due to placement problems, such as falling outside the field of view, or inside a bad column or near a gap of one or more of the instruments. In both detection methods, a source is considered a detection if the maximum likelihood is greater than or equal to 15.

PN_Rate
The XMM-Newton EPIC camera PN count rate, in counts per second (converted by the HEASARC from the original units of ct/ks).

PN_Rate_Error
The RMS uncertainty in the XMM-Newton EPIC camera PN count rate, in counts per second (converted by the HEASARC from the original units of ct/ks).

M1_Rate
The XMM-Newton EPIC camera MOS1 count rate, in counts per second (converted by the HEASARC from the original units of ct/ks).

M1_Rate_Error
The RMS uncertainty in the XMM-Newton EPIC camera MOS1 count rate, in counts per second (converted by the HEASARC from the original units of ct/ks).

M2_Rate
The XMM-Newton EPIC camera MOS2 count rate, in counts per second (converted by the HEASARC from the original units of ct/ks).

M2_Rate_Error
The RMS uncertainty in the XMM-Newton EPIC camera MOS2 count rate, in counts per second (converted by the HEASARC from the original units of ct/ks).

Hardness_Ratio11
The XMM-Newton EPIC camera PN hardness ratio, calculated as HR11=(M-S)/(M+S), where M gives the net counts in the 1.0-2.0keV band and S gives the net counts in the 0.5-1.0 keV band.

Hardness_Ratio11_Error
The RMS uncertainty in the hardness_ratio11, HR11, as defined above.

Hardness_Ratio21
The XMM-Newton EPIC camera PN hardness ratio, calculated as HR21=(H-M)/(H+M) where H gives the net counts in the 2.0-7.3 keV band and M gives the net counts in the 1.0-2.0keV band.

Hardness_Ratio21_Error
The RMS uncertainty in the hardness_ratio21, HR21, as defined above.

Hardness_Ratio12
The XMM-Newton EPIC camera PN hardness ratio, calculated as HR12=(M-S)/(M+S) where M gives the net counts in the 0.5-2.0 keV band and S gives the net counts in the 0.2-0.5 keV band.

Hardness_Ratio12_Error
The RMS uncertainty in the hardness_ratio12, HR12, as defined above.

Hardness_Ratio22
The XMM-Newton EPIC camera PN hardness ratio, calculated as HR22=(H-M)/(H+M) where H gives the net counts in the 2.0-4.5 keV band and M gives the net counts in the 0.5-2.0 keV band.

Hardness_Ratio22_Error
The RMS uncertainty in the hardness_ratio22, HR22, as defined above.

Contact Person

Questions regarding the CMAOB1XMM database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Wednesday, 23-Nov-2022 19:34:03 EST