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IC1396NCXO - IC 1396N Chandra X-Ray Point Source Catalog

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Overview

The IC 1396N cometary globule (CG) within the large nearby HII region IC 1396 has been observed with the Advanced CCD Imaging Spectrometer (ACIS) detector on board the Chandra X-Ray Observatory on 2004 October 16.93 to 17.30. 117 X-ray sources are detected, of which ~ 50-60 are likely members of the young open cluster Trumpler 37 dispersed throughout the HII region, and 25 are associated with young stars formed within the globule. Infrared photometry (2MASS and Spitzer) shows that the X-ray population is very young: 3 older Class III stars, 16 classical T Tauri stars, and 6 protostars including a Class 0/I system. The authors infer a total T Tauri population of ~ 30 stars in the globule, including the undetected population, with a star formation efficiency of 1%-4%. An elongated source spatial distribution with an age gradient oriented toward the exciting star is discovered in the X-ray population of IC 1396N, supporting similar findings in other cometary globules. The geometric and age distribution is consistent with the radiation-driven implosion (RDI) model for triggered star formation in CGs by H II region shocks.

The authors include only results arising from the imaging array (ACIS-I) of four abutted 1024 x 1024 pixel front-side illuminated CCDs covering about 17' x 17' on the sky. The aim point of the array was R.A. = 21h40m42.4s, Dec. = +58d1609.7" (J2000.0) or (l,b) = (100.0, + 4.2), and the satellite roll angle (i.e., orientation of the CCD array relative to the north-south direction) was 245.9 degrees. The total net exposure time of the observation is 30 ks with no background flaring due to solar activity or data losses.


Catalog Bibcode

2007ApJ...654..316G

References

X-ray study of triggered star formation and protostars in IC 1396N.
    Getman K.V., Feigelson E.D., Garmire G., Broos P., Wang J.
   <Astrophys. J., 654, 316-337 (2007)>
   =2007ApJ...654..316G    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in February 2009 based on the electronic version of Tables 1 and 2 from the paper which were obtained from the CDS (their catalog J/ApJ/654/316 files table1.dat and table2.dat).

Parameters

Source_Number
A unique identification number in order of increasing J2000.0 Right Ascension for each Chandra X-ray source in this catalog.

Alt_Name
An alternative name for the Chandra X-ray source, using the '[GFG2007]' prefix (for Getman, Feigelson, Garmire 2007) and the source number value, e.g., '[GFG2007] 117'.

Name
The IAU-style position-based source designation, using the 'CXOU' prefix recommended for Chandra X-ray sources, and the J2000.0 equatorial coordinates of the source, e.g., 'CXOU J214114.5+581915'. Notice that in the tables in the reference paper the names were given with one more place of precision than used here, e.g., 'CXOU J214114.52+581915.6', but that the HEASARC has truncated these in accordance with the recommended format for such sources in the CDS Dictionary of Nomenclature of Celestial Object.

RA
The Right Ascension of the Chandra X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to an accuracy of 10-6 degrees (0.0036 arcseconds) in the original table.

Dec
The Declination of the Chandra X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to an accuracy of 10-6 degrees (0.0036 arcseconds) in the original table.

LII
The Galactic Longitude of the Chandra X-ray source.

BII
The Galactic Latitude of the Chandra X-ray source.

Off_Axis
The off-axis angle of the X-ray source from the aim point, in arcminutes.

FB_Counts
The estimated net counts from the extracted area for the X-ray source in the total energy band (0.5 - 8.0 keV).

FB_Counts_Error
The RMS 1-sigma uncertainty in the estimated net total-band counts in the X-ray source.

Bck_Counts
The estimated background counts within the extracted area for the X-ray source in the total energy band.

HB_Counts
The estimated net counts from the extracted area for the X-ray source in the hard energy band (2 - 8 keV).

PSF_Fraction
The fraction of the PSF at the fiducial energy of 1.497 keV whivh is enclosed within the extracted area for the X-ray source. Note that a reduced PSF fraction (significantly below 90%) may indicate that the source is in a crowded region or on the edge of the field.

Significance
The source significance, calculated by ACIS Extract, being the ratio of the source's net (background-subtracted) full-band counts NF to the uncertainty on that quantity, sigma(NF). The authors followed a procedure similar to that of Getman et al. (2006, ApJS, 163, 306): the list of candidate sources was trimmed to omit sources with fewer than ~4 estimated source background-subtracted counts, i.e., NF/PSF_fraction <~ 4. In this case, the above criterion is equivalent to accepting sources with a source significance of >~ 1.

Source_Anomaly_Flag
This parameter can contain a flag [g] which indicates that the fractional time that the Chandra X-ray source was on a detector (FRACEXPO from mkarf) was < 0.9.

Var_Flag
This parameter can contain a flag which has a variability characterization of the Chandra X-ray source based on the one-sided Kolmogorov-Smirnov (K-S) statistics, as follows:

     a = no evidence for variability
     b = possibly variable
     c = definitely variable
  
No test was performed for sources with fewer than four total full-band counts. No value is reported for sources in chip gaps or on field edges.

Exposure
The effective exposure time, in seconds (s), for the Chandra X-ray source.

Median_Energy
The background-corrected median photon energy of the Chandra X-ray source in the total (0.5 - 8 keV) energy band, in keV.

TwoMASS_Name
The name of the 2MASS counterpart of the Chandra X-ray source in the standard format (2MASS JHHMMSSss+DDMMSSs). Of the 117 X-ray sources, 66 are identified with 2MASS NIR counterparts.

CXO_2MASS_Offset
The Chandra-2MASS positional offset, in arcseconds. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

Jmag_Limit
This parameter is set to '>' if the quoted J-band magnitude is a lower limit to the actual magnitude.

Jmag
The J-band magnitude of the 2MASS counterpart of the Chandra X-ray source. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

Hmag_Limit
This parameter is set to '>' if the quoted H-band magnitude is a lower limit to the actual magnitude.

Hmag
The H-band magnitude of the 2MASS counterpart of the Chandra X-ray source. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

Ks_Mag
The K_s-band magnitude of the 2MASS counterpart of the Chandra X-ray source. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

TwoMASS_Photo_Flags
The photometry quality flags for the 2MASS counterpart of the Chandra X-ray source. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

TwoMASS_Conf_Flags
The confusion-contamination flags for the 2MASS counterpart of the Chandra X-ray source. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

Nisini_Number
The NIR identifier NN of the counterpart to the Chandra X-ray source as given by Nisini et al. (2001, A&A, 376, 553). The full names of such sources should be '[NMV2001] YSO NN'. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

Nisini_Kmag
The K-band magnitude of the counterpart to the Chandra X-ray source as given by Nisini et al. (2001, A&A, 376, 553). This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

CXO_Spitzer_Offset
The Chandra-Spitzer positional offset, in arcseconds. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

IRAC_3p6_um_Mag
The Spitzer IRAC 3.6um magnitude of the mid-infrared (MIR) counterpart to the Chandra X-ray source. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

IRAC_3p6_um_Mag_Error
The RMS uncertainty in the Spitzer 3.6um magnitude of the mid-infrared (MIR) counterpart to the Chandra X-ray source.

IRAC_4p5_um_Mag
The Spitzer IRAC 4.5um magnitude of the mid-infrared (MIR) counterpart to the Chandra X-ray source. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

IRAC_4p5_um_Mag_Error
The RMS uncertainty in the Spitzer 4.5um magnitude of the mid-infrared (MIR) counterpart to the Chandra X-ray source.

IRAC_5p8_um_Mag_Limit
This parameter is set to '>' if the quoted 5.8um band magnitude is a lower limit to the actual magnitude.

IRAC_5p8_um_Mag
The Spitzer 5.8um magnitude of the mid-infrared (MIR) counterpart to the Chandra X-ray source. This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

IRAC_5p8_um_Mag_Error
The RMS uncertainty in the Spitzer 5.8um magnitude of the mid-infrared (MIR) counterpart to the Chandra X-ray source.

Pre_Ms_Type
The suggested pre-main sequence class of the object based on the presence of a NIR counterpart and its position in the color-color NIR-MIR diagrams (see Fig. 4 of the reference paper). This information is given only for 25 of the X-ray sources which the authors consider as likely stellar members of the IC 1396N globule.

Source_Flag
This parameter can contain a flag [abc] which indicates that there is a note concerning the source as follows:

       a:  X-ray source 60 is offset by 3.2" to the north of the radio continuum
           source VLA 1 and by 5.0" to the northwest of the millimeter source
           BIMA 1 of Beltran et al. (2002, ApJ, 573, 246).
       b:  X-ray source 66 is within 0.5" of the radio continuum source VLA 2
           and millimeter source BIMA 2 of Beltran et al. (2002). This is also
           millimeter source A of Codella et al. (2001, A&A, 376, 271).
       c:  X-ray source 68 is within 1.0" of the radio continuum source VLA 3
           and millimeter source BIMA 3 of Beltran et al. (2002). This is also
           millimeter source B of Codella et al. (2001).
  

Class
The HEASARC Browse object Cclassification, based on the pre_ms_type parameter value, where available.


Contact Person

Questions regarding the IC1396NCXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 6-Feb-2009