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CMAOB1NIR - CMa OB1 XMM-Newton Point Source Near-Infrared Counterpart Properties Catalog

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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 observations performed with XMM-Newton resulted in a sample of 387 X-ray sources (187, 84, 37, and 79 in Fields E, C, S , and W, respectively), 340 of which have one or more NIR (2MASS) counterparts. This table contains the 2MASS photometry, estimates of age and mass, and infrared classification of members of the CMa R1 region and counterparts to X-ray sources, based on 2MASS and WISE data. The authors also used X-ray data to characterize the detected sources (387 sources) according to hardness ratios, light curves, and spectra (see the associated table CMAOB1XMM).

For this work, four fields (each about 30-arcmin diameter with some overlap) were defined. 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.

  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)

The authors have selected NIR counterparts by searching the 2MASS catalog for candidates located less that 10'' away from the nominal X-ray source positions. No counterpart was found for 45 sources. Candidates for which the distance seems to be incompatible with the CMaR1 molecular cloud were disregarded. This table includes the complete list of NIR counterparts, however the authors only consider as reliable those flagged as 'AAA' in the 2MASS catalog (i.e., with S/N > 10, magnitude errors <0.1 mag, and above the JHK completeness limits), given by the twomass_flags field in this table. There are 340 such reliable NIR counterparts for 290 X-ray sources, including 46 X-ray sources with multiple counterpart candidates.

X-ray and NIR data have revealed that most (79%) of the XMM-Newton sources are probable members of CMa R1. The combination of the results from both analyses can confirm their young nature. On the other hand, 21% of the XMM-Newton sample are probably field objects. Among these, 6% (23/387) have infrared counterparts that probably are foreground stars and 4% (17/387) have counterparts that are too faint (bad quality data) without reliable classification. The other 11% of undefined sources (44/387) do not have 2MASS data because they are classified as possible background objects. The authors have seen that the XMM-Newton error boxes may include multiple NIR counterparts. In such cases, they restricted the comparative analysis to the 158 X-ray sources of their "best sample" that are associated with a single NIR counterpart, as described in Section 4.3 of the reference paper.

A distance of 1 kpc to CMa OB1 is assumed for this table.


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 tableb2.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.

Multiplicity_Index
This flag indicates multiplicity index for CMaX source. The possible values are 'a', 'b', 'c', 'd', and 'e'. These indices are ranked by distance from the X-ray source.

Source_ID
The unique source identification for the near-infrared counterpart to the CMaX source. It is a compound of name and multiplicity_index.

Source_Flag
This flag (value 'Y') indicates that the counterpart candidate is not considered because the distance is incompatible with the cloud. Given their locations on the color-magnitude diagram, these sources appear below the main sequence, and are likely field stars (see Section 4.1 in reference paper).

Offset
The distance from the X-ray source center, in arcseconds.

TwoMASS_Name
2MASS identification using the standard source designation recommended by the CDS Dictionary of Nomenclature of Celestial Objects, using the prefix of '2MASS J' and J2000.0 equatorial coordinates truncated to 0.2 seconds of time in RA and to 0.1 arcsecond in Dec.

RA
The Right Ascension of the 2MASS source in the selected equinox.

Dec
The Declination of the 2MASS source in the selected equinox.

LII
The Galactic longitude of the 2MASS source.

BII
The Galactic latitude of the 2MASS source.

Jmag
The 2MASS J magnitude of the near-infrared 2MASS counterpart. The typical 3-sigma limit for the 2MASS survey is 17.1 in the J band.

Jmag_Error
The rms uncertainty in the 2MASS J magnitude.

Hmag
The 2MASS H magnitude of the near-infrared 2MASS counterpart. The typical 3-sigma limit for the 2MASS survey is 16.4 in the H band.

Hmag_Error
The rms uncertainty in the 2MASS H magnitude.

Ks_Mag
The 2MASS Ks magnitude of the near-infrared 2MASS counterpart. The typical 3-sigma limit for the 2MASS survey is 15.3 in the Ks band.

Ks_Mag_Error
The rms uncertainty in the 2MASS Ks magnitude.

TwoMASS_Flags
The 2MASS photometric quality flag. This three character flag contains one character per band [JHKs], that provides a summary of the net quality of the default photometry in each band. For more detail about the 2MASS flags, see the 2MASS documentation about quality flags.

Mass
This contains the estimated mass, based on 2MASS photometry, in units of solar masses. As described in section 4.1 of the reference paper, the authors use the color-magnitude diagram with theoretical isochrones for 0.2 to 20 Myr, zero-age main sequence, early main sequence, and 0.1 to 7 solar mass evolutionary tracks. The masses are estimated from comparing the data with the theoretical curves and interpolating the models. However, this technique was not applied for the cases that the candidates had redder colors than the range of models, many of which have been classified as disk-bearing stars.

Age
This field contains the estimated stellar age, based on 2MASS photometry, in units of Myr. As described in section 4.1 of the reference paper, the authors use the color-magnitude diagram with theoretical isochrones for 0.2 to 20 Myr, zero-age main sequence, early main sequence, and 0.1 to 7 solar mass evolutionary tracks. The ages are estimated from comparing the data with the theoretical curves and interpolating the models. However, this technique was not applied for the cases that the candidates had redder colors than the range of models, many of which have been classified as disk-bearing stars.

Source_Notes
This field contains the infrared classification of the NIR counterpart as young stellar objects (YSOs) based on WISE colors, as described in section 4.2 of the reference paper. Based on Koenig & Leisawitz (2014), the WISE color-selection separate stars into the following classes: 'Class I' are candidate protostars, 'Class II' are candidate T Tauri stars and Herbig AeBe stars. Both of these classes contain disk-bearing stars with NIR-excess. The 'Class III' designated objects are not YSOs. Those classified by "??" could not be classified due to bad quality WISE data.


Contact Person

Questions regarding the CMAOB1NIR database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Monday, 29-Oct-2018 16:50:50 EDT