MYSTIXIRES - Massive Young Star-Forming Complex Study in IR & X-Rays: IR-Excess Sources

Overview

The Massive Young Star-Forming Complex Study in Infrared and X-rays (MYStIX) project provides a comparative study of 20 Galactic massive star-forming complexes with distances between 0.4 and 3.6 kpc. Probable stellar members in each target complex are identified using X-ray and/or infrared data via two pathways: (1) X-ray detections of young/massive stars with coronal activity/strong winds or (2) infrared excess (IRE) selection of young stellar objects (YSOs) with circumstellar disks and/or protostellar envelopes. In this particular study, the authors present the methodology for the second pathway using Spitzer/IRAC, 2MASS, and UKIRT imaging and photometry. Although IRE selection of YSOs is well-trodden territory, MYStIX presents unique challenges. The target complexes range from relatively nearby clouds in uncrowded fields located toward the outer Galaxy (e.g., NGC 2264, the Flame Nebula) to more distant, massive complexes situated along complicated, inner Galaxy sightlines (e.g., NGC 6357, M 17). The authors combine IR spectral energy distribution (SED) fitting with IR color cuts and spatial clustering analysis to identify IRE sources and to isolate probable YSO members in each MYStIX target field from the myriad types of contaminating sources that can resemble YSOs: extragalactic sources, evolved stars, nebular knots, and even unassociated foreground/background YSOs. Applying their methodology consistently across 18 of the target complexes, they produce the MYStIX IRE Source (MIRES) Catalog comprising 20,719 sources, including 8,686 probable stellar members of the MYStIX target complexes. They also classify the SEDs of 9,365 IR counterparts to MYStIX X-ray sources to assist the first pathway, the identification of X-ray-detected stellar members.

The MYStIX project, described by Feigelson et al. (2013, ApJS, 209, 26), provides a comprehensive, parallel study of 20 Galactic massive star-forming regions. The basic input data for the MIRES Catalog were near-IR (NIR) and mid-IR (MIR) photometric catalogs. The authors also used NIR and MIR images and mosaics for visualizing the point-source populations with respect to various nebular structures. They provide high-level descriptions of each input catalog in section 2 of the reference paper.

This table contains the MYStIX IRE Source (MIRES) Catalog comprising IR data on 20,719 sources, including 8,686 probable stellar members of the MYStIX target complexes, viz., massive star-forming regions (MSFRs), which was given in Table 2 of the reference paper. It does not include the IR data of the above-mentioned 9,365 IR counterparts to MYStIX X-ray sources (the SED Classification of IR Counterparts to MYStIX X-ray sources (SCIM-X Catalog) that were listed in Table 7 of the reference paper.

Catalog Bibcode

2013ApJS..209...31P

References

The MYStIX infrared-excess source catalog.
    Povich M.S., Kuhn M.A., Getman K.V., Busk H.A., Feigelson E.D., Broos P.S.,
    Townsley L.K., King R.R., Naylor T.
   <Astrophys. J. Suppl. Ser., 209, 31 (2013)>
   =2013ApJS..209...31P    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in February 2014 based on CDS Catalog J/ApJS/209/31 file table2.dat.

Parameters

SFR_Name
The designation of the MYStIX star-forming region (SFR). See Table 2 of Kuhn et al. (2013, ApJS, 209, 27) for more information on the SFRs.

Name
The infrared source designation, e.g., 'MIRES Glll.llll+bb.bbbb'. The main part of the name is based on the Galactic coordinates of the source given to a precision of 10^-4 degrees in both Galactic latitude and longitude, while the 'MIRES' prefix stands for 'MYStIX IR-Excess Source'.

RA
The Right Ascension of the infrared source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of 10^-7 degrees in the original tables.

Dec
The Declination of the infrared source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of 10^-7 degrees in the original tables.

LII
The Galactic Longitude of the infrared source.

BII
The Galactic Latitude of the infrared source.

Jmag
The J-band magnitude of the infrared source that was used for the SED fitting.

Jmag_Error
The uncertainty in the J-band magnitude of the infrared source that was used in the SED Fitting. The uncertainties in the seven IR magnitudes used for SED fitting have been reset to their 'floor' or minimum values. As described in Section 3.1 of the reference paper,this was done to mitigate the effects of unreported systematic uncertainties and intrinsic source variability. The authors set the minimum uncertainty used in SED fitting to 5% in the JHK_S) bands. These floor values were used only where the reported uncertainties in the catalogs were smaller, otherwise the original uncertainties were used. It is important to note that these reset uncertainties are the ones published in MIRES, because they are used in all of the authors' analysis; for the original uncertainties, the reader is referred to the source catalogs referenced in Section 2 of the reference paper, King et al. (2013, ApJS, 209, 28), or the GLIMPSE Catalog (CDS Cat. II/293).

Jmag_Flag
This flag parameter indicates the provenance of the J-band source which was matched to the IRAC Source: 0 = 2MASS, 1 = UKIRT, -1 = None.

Hmag
The H-band magnitude of the infrared source that was used for the SED fitting.

Hmag_Error
The uncertainty in the H-band magnitude of the infrared source that was used in the SED Fitting. The uncertainties in the seven IR magnitudes used for SED fitting have been reset to their 'floor' or minimum values. As described in Section 3.1 of the reference paper,this was done to mitigate the effects of unreported systematic uncertainties and intrinsic source variability. The authors set the minimum uncertainty used in SED fitting to 5% in the JHK_S) bands. These floor values were used only where the reported uncertainties in the catalogs were smaller, otherwise the original uncertainties were used. It is important to note that these reset uncertainties are the ones published in MIRES, because they are used in all of the authors' analysis; for the original uncertainties, the reader is referred to the source catalogs referenced in Section 2 of the reference paper, King et al. (2013, ApJS, 209, 28), or the GLIMPSE Catalog (CDS Cat. II/293).

Hmag_Flag
This flag parameter indicates the provenance of the H-band source which was matched to the IRAC Source: 0 = 2MASS, 1 = UKIRT, -1 = None.

Ks_Mag
The K_S-band magnitude of the infrared source that was used for the SED fitting.

Ks_Mag_Error
The uncertainty in the K_S-band magnitude of the infrared source that was used in the SED Fitting. The uncertainties in the seven IR magnitudes used for SED fitting have been reset to their 'floor' or minimum values. As described in Section 3.1 of the reference paper,this was done to mitigate the effects of unreported systematic uncertainties and intrinsic source variability. The authors set the minimum uncertainty used in SED fitting to 5% in the JHK_S) bands. These floor values were used only where the reported uncertainties in the catalogs were smaller, otherwise the original uncertainties were used. It is important to note that these reset uncertainties are the ones published in MIRES, because they are used in all of the authors' analysis; for the original uncertainties, the reader is referred to the source catalogs referenced in Section 2 of the reference paper, King et al. (2013, ApJS, 209, 28), or the GLIMPSE Catalog (CDS Cat. II/293).

Ks_Mag_Flag
This flag parameter indicates the provenance of the K_S-band source which was matched to the IRAC Source: 0 = 2MASS, 1 = UKIRT, -1 = None.

IRAC_3p6_um_Mag
The Spitzer/IRAC 3.6-um magnitude of the infrared source that was used for the SED fitting.

IRAC_3p6_um_Mag_Error
The uncertainty in the IRAC 3.6um-band magnitude of the infrared source that was used in the SED Fitting. The uncertainties in the seven IR magnitudes used for SED fitting have been reset to their 'floor' or minimum values. As described in Section 3.1 of the reference paper,this was done to mitigate the effects of unreported systematic uncertainties and intrinsic source variability. The authors set the minimum uncertainty used in the SED fitting to 5% for the IRAC 3.6-um, and 4.5-um bands and to 10% for the IRAC 5.8-um and 8.0-um bands. These floor values were used only where the reported uncertainties in the catalogs were smaller, otherwise the original uncertainties were used. It is important to note that these reset uncertainties are the ones published in MIRES, because they are used in all of the authors' analysis; for the original uncertainties, the reader is referred to the source catalogs referenced in Section 2 of the reference paper, King et al. (2013, ApJS, 209, 28), or the GLIMPSE Catalog (CDS Cat. II/293).

IRAC_4p5_um_Mag
The Spitzer/IRAC 4.5-um magnitude of the infrared source that was used for the SED fitting, or the upper limit in brightness thereof, if irac_4p5_um_mag_flag = 'E'. The 4.5-um band can be brightened significantly by shocked molecular line emission produced by protostellar outflows. In Section 3.3 of the reference paper, the authors discuss the criteria that they used to identify such cases which they labeled as candidate 4.5-um excess or [4.5]E objects. Rather than discard these sources, they treated their observed emission-contaminated fluxes as upper limits when fitting their SEDs.

IRAC_4p5_um_Mag_Error
The uncertainty in the IRAC 4.5um-band magnitude of the infrared source that was used in the SED Fitting. This is not given for cases in which the 4.5-um band is contaminated (i.e., when the parameter irac_4p5_um_mag_flag = 'E'). The uncertainties in the seven IR magnitudes used for SED fitting have been reset to their 'floor' or minimum values. As described in Section 3.1 of the reference paper,this was done to mitigate the effects of unreported systematic uncertainties and intrinsic source variability. The authors set the minimum uncertainty used in the SED fitting to 5% for the IRAC 3.6-um, and 4.5-um bands and to 10% for the IRAC 5.8-um and 8.0-um bands. These floor values were used only where the reported uncertainties in the catalogs were smaller, otherwise the original uncertainties were used. It is important to note that these reset uncertainties are the ones published in MIRES, because they are used in all of the authors' analysis; for the original uncertainties, the reader is referred to the source catalogs referenced in Section 2 of the reference paper, King et al. (2013, ApJS, 209, 28), or the GLIMPSE Catalog (CDS Cat. II/293).

IRAC_4p5_um_Mag_Flag
This flag parameter for the Spitzer/IRAC 4.5-um magnitude value is set to 'E' for [4.5]E objects (see next parameter).

IRAC_5p8_um_Mag
The Spitzer/IRAC 5.8-um magnitude of the infrared source that was used for the SED fitting.

IRAC_5p8_um_Mag_Error
The uncertainty in the IRAC 5.8um-band magnitude of the infrared source that was used in the SED Fitting. The uncertainties in the seven IR magnitudes used for SED fitting have been reset to their 'floor' or minimum values. As described in Section 3.1 of the reference paper,this was done to mitigate the effects of unreported systematic uncertainties and intrinsic source variability. The authors set the minimum uncertainty used in the SED fitting to 5% for the IRAC 3.6-um, and 4.5-um bands and to 10% for the IRAC 5.8-um and 8.0-um bands. These floor values were used only where the reported uncertainties in the catalogs were smaller, otherwise the original uncertainties were used. It is important to note that these reset uncertainties are the ones published in MIRES, because they are used in all of the authors' analysis; for the original uncertainties, the reader is referred to the source catalogs referenced in Section 2 of the reference paper, King et al. (2013, ApJS, 209, 28), or the GLIMPSE Catalog (CDS Cat. II/293).

IRAC_8p0_um_Mag
The Spitzer/IRAC 8.0-um magnitude of the infrared source that was used for the SED fitting.

IRAC_8p0_um_Mag_Error
The uncertainty in the IRAC 8.0um-band magnitude of the infrared source that was used in the SED Fitting. The uncertainties in the seven IR magnitudes used for SED fitting have been reset to their 'floor' or minimum values. As described in Section 3.1 of the reference paper,this was done to mitigate the effects of unreported systematic uncertainties and intrinsic source variability. The authors set the minimum uncertainty used in the SED fitting to 5% for the IRAC 3.6-um, and 4.5-um bands and to 10% for the IRAC 5.8-um and 8.0-um bands. These floor values were used only where the reported uncertainties in the catalogs were smaller, otherwise the original uncertainties were used. It is important to note that these reset uncertainties are the ones published in MIRES, because they are used in all of the authors' analysis; for the original uncertainties, the reader is referred to the source catalogs referenced in Section 2 of the reference paper, King et al. (2013, ApJS, 209, 28), or the GLIMPSE Catalog (CDS Cat. II/293).

Ukirt_Catalog_Label
The name of the matched infrared source in the UKIRT Catalog (King et al., 2013, ApJS, 209, 28).

Num_Ukirt_Alt_Matches
The number of other UKIRT sources providing possible alternative matches to the IRAC source.

SED_Class
The SED classification flag of the infrared source:

  0 = Likely YSO,
  1 = Starburst galaxy with strong PAH emission,
  2 = Obscured AGN with intrinsic dust emission,
  3 = Unresolved nebular knot of PAH emission in H II region.

SED_Chi_Squared
The reduced Chi-Squared Chi²₀/N_data of the best-fit SED model for the infrared source, where N_data is the number of relevant bands. For [4.5]E SEDs (sources with the parameter value of 'E' for irac_4p5_um_flag) where the 4.5-um flux was used as an upper limit, 3 <= N_data <= 6, while for all other SEDs, 4 <= N_data <= 7.

Vmag_Extinction
The visual extinction of the infrared source, in magnitudes, determined from the chi²-weighted mean of all acceptable SED fits. See Section 4.1 of the reference paper for more details and some caveats.

YSO_Stage
The evolutionary stage classification of the infrared source derived from fitting its SED with the YSO models of Robitaille et al. (2006, ApJS, 167, 256, hereafter RW06), using the following schema:

      1 = Stage 0/I YSO dominated by infalling, dusty envelope,
      2 = Stage II/III YSO dominated by optically thick (II) or thin (III)
          circumstellar disk,
     -1 = ambiguous case.

All sources in MIRES, regardless of their SED class, were fit with RW06 models and hence can be classified according to their YSO evolutionary stage.

Membership_Prob_Density
The probability that a source at a given coordinate is a complex member, based on spatial clustering analysis, calculated as 1-f_con, where the "contamination fraction", f_con, is the fraction of MIRES sources that are expected to belong to the distributed (unclustered) component (presumably foreground/background contaminants), No probability values are assigned to MIRES Catalog sources falling within designated "control" fields for the clustering analysis.

Membership_Flag
This binary flag is set to 1 if an MIRES source is a probable member of the 'parent' MYStIX MSFR, or otherwise is set to 0. There are 8,686 MIRES sources which are considered probable members of their 'parent' MYStIX MSFRs.

Chandra_FOV_Flag
This binary flag is set to 1 if an MIRES source is within the FOV of one or more of the Chandra/ACIS observations which were used for MYStIX, or otherwise is set to 0. The area covered by these Chandra FOVs is a subset of the MIRES extended membership field. MIRES sources with both the membership_flag and chandra_fov_flag bits set are adopted as "MYStIX Probable Complex Members" or MPCMs (Broos et al. 2013, ApJS, 209, 32).

Contact Person

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

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:31:22 EDT