Browse
this table...

NGC1333CXO - NGC 1333 Chandra X-Ray Point Source Catalog

HEASARC
Archive

Overview

NGC 1333, a highly active star formation region within the Perseus molecular cloud complex, has been observed on 2000 July 12.96 - 13.48 with the ACIS-I detector on board the Chandra X-Ray Observatory. The aim point of the array was 3 29 06.1, +31 19 38 (J2000,0 RA and Dec), the satellite roll angle was 95.7 degrees, and the effective exposure time after removing time intervals contaminated by background flaring was 37.8 ks.

In this image with a sensitivity limit in luminosity of ~1028 erg/s for X-ray sources at the 318 pc distance of NGC 1333, 127 X-ray sources were detected, most with subarcsecond positional accuracy. While 32 of these sources appear to be foreground stars and extragalactic background objects, 95 X-ray sources are identified with known cluster members. The X-ray luminosity function of the discovered young stellar object (YSO) population spans a range of log L_X ~= 28.0 - 31.5 erg s-1 in the 0.5 - 8 keV band, and the absorption column densities range from log N_H ~=20 to 23 cm-2 . Most of the sources have plasma temperatures between 0.6 and 3 keV, but a few sources show higher temperatures up to ~7 keV. Comparison with K-band source counts indicates that all of the known cluster members with K < 12 and about half of the members with K > 12 were detected. (K ~= 11, the peak of the K-band luminosity function, corresponds to 0.2 - 0.4 M_solar stars for a cluster age of ~1 Myr). Seven of the 20 known YSOs in NGC 1333 which are producing jets or molecular outflows were detected, as well as one deeply embedded object without outflows. No evident difference in X-ray emission of young stars with and without outflows is found.

This present table contains X-ray, optical and near-infrared information on the 109 X-ray sources that were detected above a source significance threshold of 1 x 10-6 in any of 3 energy bands: soft: 0.5 - 2.0 keV, hard: 2.0 - 8.0 keV, or full: 0.5 - 8.0 keV, excluding 8 sources that were deemed to be spurious on visual examination of the images. The faintest on-axis source emerging from the wavelet detection procedure has 5 extracted counts, corresponding to a source of log L_X ~ 28.0 in the total (0.5 - 8.0 keV) band for a source with negligible interstellar absorption (A_V ~ 1) and a typical source spectrum of a kT ~ 1 keV thermal plasma. This limit increases to 28.6 (29.3) if the absorption is increased to A_V ~ 5 (10). The sensitivity decreases by a factor of 4 at the edge of the field compared to the central regions. 80 of the significant 109 sources (73%) have counterparts in a non-X-ray band. This table does not include 18 tentative X-ray sources listed in Table 3 of the reference paper that were found by the authors by searching for concentrations of photons spatially coincident with known sources from near-IR, mm/sub-mm, and radio catalogs of this region which did not reach the detection signifance given above. Most of these tentative sources are believed to be real sources.


Catalog Bibcode

2002ApJ...575..354G

References

Chandra study of young stellar objects in the NGC 1333 star-forming cloud.
    Getman K.V., Feigelson E.D., Townsley L., Bally J., Lada C.J., Reipurth B.
   <Astrophys. J. 575, 354 (2002)>
   =2002ApJ...575..354G

Provenance

This table was created by the HEASARC in March 2007 based on CDS catalog J/ApJ/575/354 files table1.dat and table2.dat.

Parameters

Source_Number
A running X-ray source number in order of increasing J2000.0 Right Ascension.

Name
The name for the X-ray source using the 'CXONGC1333' prefix and the truncated J2000.0 coordinates (JHHMMSS.s+DDMMSS), as registered with the CDS Dictionary of Nomenclature of Celestial Objects.

Alt_Name
An alternative name for the X-ray source using the '[GFT2002]' prefix (for Getman, Feigelson and Townsley, 2002) and the source number, as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.01 seconds of time in the original table. The X-ray positions given here include a correction for systematic errors in the Chandra aspect system of -0.26" in RA which was derived by comparing the original ACIS-I positions of 12 X-ray sources with those of their optical counterparts in the Tycho-2 and/or USNO-A2.0 Catalogs.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.1 arcseconds in the original table. The X-ray positions given here include a correction for systematic errors in the Chandra aspect system of -0.65" in Declination which was derived by comparing the original ACIS-I positions of 12 X-ray sources with those of their optical counterparts in the Tycho-2 and/or USNO-A2.0 Catalogs.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Off_Axis
The off-axis distance of the X-ray source from the aimpoint of the ACIS observation, in arcminutes.

P97_Number
The Preibisch (1997A&A...324..690P) ROSAT HRI source number of the X-ray source.

Hj83_Number
The number NNN of the optical counterpart star from Table 3 of Herbig & Jones (1983AJ.....88.1040H), referred to in Simbad as '[HJ83] NNN'.

Br2001_Flag
This flag parameter is set to 'Y' to indicates that the counterpart to the X-ray source is visible in Bally & Reipurth's (2001ApJ...546..299B) H-alpha/[S II] image of the region.

Offset_Usnoa2_CXO
The angular offset between the Chandra X-ray position and the USNO-A2.0 (CDS Cat. <I/252>) counterpart position, in arcseconds, if the latter exists.

Imag
The (SDSS) I-band magnitude of the near-IR counterpart to the X-ray source, as measured from a MOSAIC CCD image of the region taken by the authors on the KPNO 4-m Telescope which had a limiting magnitude of ~23.

Imag_Flag
A caution flag on the I magnitude with the following possible values:

        y = star is saturated;
        C = confused region where X-ray position lost in the glare of a
            nearby source or reflection nebula.
  

Asr_Number
The NIR counterpart number in the Aspin et al. (1994, CDS Cat. <J/A+AS/106/165>) reference.

Lal96_Number
The NIR counterpart number in the Lada et al. (1996AJ....111.1964L) reference.

Lal96_Flag
This parameter flag is set to 'B' to denote blended cases where ACIS resolved a close double that is unresolved in the Lada et al. infrared data.

Kmag
The K-band magnitude of the near-IR counterpart to the X-ray source given in Lada et al. (1996AJ....111.1964L), except for sources with the source number values of 9, 35 and 51, for which the photometry of Aspin (1994, CDS Cat. <J/A+AS/106/165>) is used.

JH_Color
The (J-H) color index of the near-IR counterpart to the X-ray source given in Lada et al. (1996AJ....111.1964L).

HK_Color
The (H-K) color index of the near-IR counterpart to the X-ray source given in Lada et al. (1996AJ....111.1964L).

Notes_Flag
This flag parameter flag contains a (non-blank) numerical code from 1 to 23 indicating that there is a note concerning other counterparts to the X-ray source in the file ftp://cdsarc.u-strasbg.fr/cats/J/ApJ/575/354/notes.dat (look for the line(s) beginning with the value of this parameter).

Counts
The extracted full-band (0.5 - 8 keV) counts C_xtr of the X-ray source from within the event extraction radius R_xtr, the radius encircling about 90% of the energy (99% for very strong sources with >1000 counts), which increases with off-axis distance because of the deterioration of the Chandra PSF.

Bck_Counts
The extracted full-band (0.5 - 8 keV) background counts B_xtr from 4 circular regions with radii R_xtr/2 surrounding the source position. Backgroun extraction circles are manually adjusted for crowded regions of the field. The mean background level is ~0.018 counts arcsec-2.

Extraction_Radius
The event extraction radius R_xtr, in arcseconds, used to extract the X-ray counts. R_xtr is the radius encircling about 90% of the energy (99% for very strong sources with > 1000 counts), and increases with off-axis distance because of the deterioration of the Chandra PSF.

PSF_Fraction
The fraction f_PSF of the source events within the chosen event extraction radius.

Count_Rate
The average X-ray source count rate CR, in ct/s, as given by CR = (C_xtr - B_xtr)/(f_PSF * E_net), where C_xtr are the source counts, B_xtr the background counts, f_PSF the fraction of the total counts extracted from the source extraction region (typically ~0.9) and E_net = 37800 s is the effective exposure time.

Variability_Class
The variability class of the X-ray source as found by comparing the observed arrival times of photons to those expected from a constant source using the Kolmogorov-Smirnov (K-S) one-sample test, coded as follows:

       Flare = flare
      Pos fl = possible flare
       Const = constant
  
where sources were classified as 'constant' if the probability of accepting the null hypothesis was P_KS > 0.05, as 'possible flare' if 0.005 < P_KS < 0.05, and as 'flare' if P_KS < 0.005.

Log_NH_Limit
This parameter is a limit flag which is set to '<' if the logarithm of the spectral model hydrogen column density is an upper limit.

Log_NH
The logarithm of the best-fit spectral model hydrogen column density, in atoms cm-2.

Log_NH_Lower
The logarithm of the (best-fit - 1-sigma) spectral model hydrogen column density, in atoms cm-2.

Log_NH_Upper
The logarithm of the (best-fit + 1-sigma) spectral model hydrogen column density, in atoms cm-2.

Te_Plasma_Limit
This parameter is a limit flag which is set to '>' if the best-fit spectral model plasma temperature is a lower limit.

Te_Plasma
THe best-fit plasma temperature, in keV, from a one-temperature optically thin thermal plasma MEKAL model, assuming a uniform density plasma with 0.3 times solar elemental abundances.

Te_Plasma_Lower
The (best-fit - 1-sigma) spectral model plasma temperature, in keV.

Te_Plasma_Upper
The (best-fit + 1-sigma) spectral model plasma temperature.

Log_Lx_Soft_Limit
This parameter is a limit flag which is set to '<' if the logarithm of the soft-band (0.5 - 2.0 keV) luminosity is an upper limit.

Log_Lx_Soft
The logarithm of the soft-band (0.5 - 2 keV) luminosity of the X-ray source, in erg/s, assuming a distance to NGC 1333 of 318 pc.

Log_Lx_Hard_Limit
This parameter is a limit flag which is set to '<' if the logarithm of the hard-band (2.0 - 8.0 keV) luminosity is an upper limit.

Log_Lx_Hard
The logarithm of the hard-band (2 - 8 keV) luminosity of the X-ray source, in erg/s, assuming a distance to NGC 1333 of 318 pc.

Log_Lx_Tot_Limit
This parameter is a limit flag which is set to '<' if the logarithm of the total-band (0.5 - 8.0 keV) luminosity is an upper limit.

Log_Lx_Tot
The logarithm of the total-band (0.5 - 8 keV) luminosity of the X-ray source, in erg/s, assuming a distance to NGC 1333 of 318 pc.

Log_Lx_Tot_Corr_Limit
This parameter is a limit flag which is set to '<' if the logarithm of the corrected total-band (0.5 - 8.0 keV) luminosity is an upper limit.

Log_Lx_Tot_Corr
The logarithm of the total-band (0.5 - 8 keV) luminosity of the X-ray source, in erg/s, corrected for the estimated interstellar absorption and assuming a distance to NGC 1333 of 318 pc.

Source_Flag
This parameter contains flags giving either details of the spectral fit for an X-ray source, if non-standard, or on the location of the source, as follows:

        a = kT and logNH may be unreliable but are reported here to allow
            the reproduction of the spline-like fits to the event distribution
            for the calculation of broad-band luminosities logLt.
        b = Fitted plasma energies above ~ 10 keV and column densities below
            ~20.0cm-2 are not well-determined.
        c = Foreground stars:
            source number 5 (distance is less than 318 pc)
            source number 33 (distance is 192pc, Preibisch (1997A&A...324..690P)).
        d = No spectral fit is done as a result of a small number of counts.
            Most of these sources have an approximate total-band X-ray luminosity
            of ~1028 erg/s.
  

Contact Person

Questions regarding the NGC1333CXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 28-Aug-2012