Browse
this table...

NGC2244CXO - NGC 2244/Rosette Nebula Chandra X-Ray Point Source Catalog

HEASARC
Archive

Overview

This table contains the point source catalog based on the first high spatial resolution X-ray study of NGC 2244, the 2 Myr old stellar cluster in the Rosette Nebula, using Chandra. Over 900 X-ray sources are detected within 20 arcminutes of the cluster central position (J2000.0 RA and Dec of 6 31 59.9, +4 55 36); 77% of these X-ray sources have optical or FLAMINGOS NIR stellar counterparts and are mostly previously uncataloged young cluster members. The X-ray-selected population is estimated to be nearly complete between 0.5 and 3 Msolar. A number of further results emerge from the analysis: (1) The X-ray luminosity function (XLF) and the associated K-band LF indicate a normal Salpeter IMF for NGC 2244. This is inconsistent with the top-heavy IMF reported from earlier optical studies that lacked a good census of <4 Msolar stars. By comparing the NGC 2244 and Orion Nebula Cluster XLFs, the authors estimate a total population of ~2000 stars in NGC 2244. (2) The spatial distribution of X-ray stars is strongly concentrated around the central O5 star, HD 46150. The other early O star, HD 46223, has few companions. The cluster's stellar radial density profile shows two distinctive structures: a power-law cusp around HD 46150 that extends to ~0.7 pc, surrounded by an isothermal sphere extending out to 4 pc with core radius 1.2 pc. This double structure, combined with the absence of mass segregation, indicates that this 2 Myr old cluster is not in dynamical equilibrium. (3) The fraction of X-ray-selected cluster members with K-band excesses caused by inner protoplanetary disks is 6%, slightly lower than the 10% disk fraction estimated from the FLAMINGOS study based on the NIR-selected sample. (4) X-ray luminosities for 24 stars earlier than B4 confirm the long-standing log (L_X/L_bol) ~ -7 relation. The Rosette OB X-ray spectra are soft and consistent with the standard model of small-scale shocks in the inner wind of a single massive star.

Catalog Bibcode

2008ApJ...675..464W

References

A Chandra Study of the Rosette Star-forming Complex. I. The Stellar Population
and Structure of the Young Open Cluster NGC 2244
    Wang J., Townsley L.K., Feigelson E.D., Broos P.S., Getman K.V., ,
    Roman-Zuniga C.G., Lada E.
    <Astrophys. J. 675, 464 (2008)>
    =2008ApJ...675..464W      (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in July 2008 based on electronic versions of Tables 2, 3, 4, 5 and 6 of the reference paper which were obtained from the electronic ApJ web site.

Parameters

Source_Number
A running source number in order of increasing J2000.0 Right Ascension, which uniquely identifies the X-ray source.

Alt_Name
An alternative name for the X-ray source using the '[WTF2008] Main' prefix followed by the source number for the 805 sources from Table 2 of the reference paper (the Main Catalog), or the '[WTF2008] Secondary' prefix followed by the source number for the 114 sources from Table 3 of the reference paper (the Secdondary Catalog), as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

Name
The name of the X-ray source using the 'CXOU' prefix (for Chandra X-ray Observatory, Unregistered source) and the J2000 coordinates of the source in the (higher precision than standard) HHMMSS.ss+DDMMSS.s format.

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000 decimal degree coordinates and to a precision of 10-6 degrees in the original table.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000 decimal degree coordinates and to a precision of 10-6 degrees in the original table.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Error_Radius
The statistical positional error of the X-ray source, i.e., the estimated 1-sigma standard deviation of the random component of the position error, in arcseconds. This is computed as (standard deviation of PSF inside extraction region)/(number of counts extracted)0.5.

Off_Axis
The off-axis angle of the X-ray source from the nominal pointing direction, in arcminutes.

Counts
The estimated net counts extracted in the total energy band (0.5 - 8 keV) for the X-ray source.

Counts_Error
The average of the upper and lower 1-sigma errors in the total-band counts for the X-ray source.

Bck_Counts
The background counts in the total-band (0.5 - 8 keV) in the X-ray source extraction region.

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

PSF_Fraction
The fraction of the PSF (at 1.497 keV) enclosed within the extraction region for the X-ray source. Note that a reduced PSF fraction (significantly below 90%) may indicate that the source is in a crowded region.

Significance
The photometric significance of the X-ray source, computed as net counts divided by upper error in the net counts.

Log_Bck_Prob_Limit
This flag parameter is set to '<' if the corresponding value of log P_B (log_bck_prob) is an upper limit.

Log_Bck_Prob
The log of the probability (log P_B) that the extracted counts (total band) are solely from the background. Some sources have P_B values above the 1% threshold that defines the catalog because local background estimates can rise during the final extraction iteration after sources are removed from the catalog. Sources with P_B < 0.001 (0.1%) are considered primary sources (source_flag = 'M' for 'Main'), while those with P_B >= 0.001 (0.1%) are considered tentative (source_flag = 'S' for 'Secondary').

Source_Anomaly_Flag
This flag parameter indicates the presence of the following source anomalies, using the following codes:

  g: fractional time that the source was on a detector (FRACEXPO from mkarf) is <0.9
  e: source on field edge
  p: source piled up
  s: source on readout streak
  

Source_Variable_Flag
This flag parameter contains codes which characterize the X-ray source variability in the total band based on the K-S statistic, as follows (no value is reported for sources with fewer than four counts or for sources in chip gaps or on field edges):

  a: no evidence for variability (P_KS > 0.05)
  b: possibly variable (0.005 < P_KS < 0.05)
  c: definitely variable (P_KS < 0.005)
  

Exposure
The effective exposure time for the X-ray source, in seconds. This is the approximate time the source would have to be observed on-axis (i.e., no telescope vignetting) on a nominal region of the detector (with no dithering over insensitive regions of the detector) in order to obtain the reported number of source counts.

Median_Energy
The background-corrected total-band median photon energy of the X-ray source photons, in keV.

Log_NH_Neg_Err
The lower 90% confidence level error in the best-fit value of log n_H, in H atoms/cm2. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

Log_NH
The logarithm of the best-fit column density, log n_H, in H atoms/cm2.

Log_NH_Flag
If this flag parameter is marked with a value of 'i', this indicates that the corresponding parameter value was frozen in the fit.

Log_NH_Pos_Err
The upper 90% confidence level error in the best-fit value of log n_H, in H atoms/cm2. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

APEC_kT_Neg_Err
The lower 90% confidence level error in the best-fit value of the plasma temperature from the APEC model, kT, in keV. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

APEC_kT
The best-fit value of the plasma temperature from the APEC model, kT, in keV. All such fits used the ``wabs(apec)'' model in XSPEC and assumed 0.3 solar abundances (Imanishi et al. (2001, ApJ, 557, 747), Feigelson et al. (2002, ApJ, 574, 258).

APEC_kT_Flag
If this flag parameter is marked with a value of 'i', this indicates that the corresponding parameter value was frozen in the fit.

APEC_kT_Pos_Err
The upper 90% confidence level error in the best-fit value of the plasma temperature from the APEC model, kT, in keV. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

Log_EM_Neg_Err
The lower 90% confidence level error in the best-fit value of the logarithm of the model emission measure, log EM, in cm-3. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

Log_EM
The logarithm of the model emission measure log EM derived from the best-fit APEC model, assuming a distance of 1.4 kpc to NGC 2244, in cm-3.

Log_EM_Pos_Err
The upper 90% confidence level error in the best-fit value of the logarithm of the model emission measure, log EM, in cm-3. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

Log_SB_Lx_Obs
The logarithm of the observed soft-band (0.5 - 2 keV) luminosity of the X-ray source, assuming a distance of 1.4 kpc, in erg/s (omitted when log n_H > 22.5 cm-2, since the soft-band emission is essentially unmeasurable in such cases).

Log_HB_Lx_Obs
The logarithm of the observed hard-band (2 - 8 keV) luminosity of the X-ray source, assuming a distance of 1.4 kpc, in erg/s.

Log_HB_Lx
The logarithm of the absorption-corrected hard-band (2 - 8 keV) Luminosity of the X-ray source assuming a distance of 1.4 kpc, in erg/s. This is omitted when log n_H > 22.5 cm-2, since the soft-band emission is essentially unmeasurable in such cases.

Log_Lx_Obs
The logarithm of the observed total-band (0.5 - 8 keV) luminosity of the X-ray source assuming a distance of 1.4 kpc, in erg/s.

Log_Lx
The logarithm of the absorption-corrected total-band (0.5 - 8 keV) luminosity of the X-ray source assuming a distance of 1.4 kpc, in erg/s. This is omitted when log n_H > 22.5 cm-2, since the soft-band emission is essentially unmeasurable in such cases.

Spect_Notes
This parameter contains notes on the details of the APEC spectral fit, coded as follows:

      2T = two-temperature model was used;
       H = fit was performed by hand, usually because the automated fit
           yielded non-physical results.
  

Opt_Name
The name of the well-known OB counterpart to the X-ray source, if there is one.

Spectral_Index_Neg_Err
The lower 90% confidence level error in the best-fit value of the power-law photon index, Gamma. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

Spectral_Index
The best-fit value of the power-law photon index, Gamma, for the power-law fit to the spectrum.

Spectral_Index_Pos_Err
The upper 90% confidence level error in the best-fit value of the power-law photon index, Gamma. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

Log_PL_Norm_Neg_Err
The lower 90% confidence level error in the best-fit value of the logarithm of the power-law normalization, log PL_Norm, for a power-law fit to the spectrum of the X-ray source. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

Log_PL_Norm
The logarithm of the power-law normalization of the best-fit model, log PL_Norm, for a power-law fit to the spectrum of the X-ray source.

Log_PL_Norm_Pos_Err
The upper 90% confidence level error in the best-fit value of the logarithm of the power-law normalization, log PL_Norm, for a power-law fit to the spectrum of the X-ray source. More significant digits are used for uncertainties <0.1 in order to avoid large rounding errors; for consistency, the same number of significant digits is used for both lower and upper uncertainties. Uncertainties are missing when XSPEC was unable to compute them or when their values were so large that the parameter is effectively unconstrained. Fits lacking uncertainties, fits with large uncertainties, and fits with frozen parameters should be viewed merely as splines to the data to obtain rough estimates of luminosities; the listed parameter values are unreliable.

USNO_Name
The USNO B1.0 source designation of the stellar counterpart to the X-ray source.

MJD95_Number
The Massey, Johnson, & Degioia-Eastwood (1995, ApJ, 454, 151: MJD95) source identifier of the stellar counterpart to the X-ray source.

PS02_Number
The Park & Sung (2002, AJ, 123, 892: PS02) source identifier of the stellar counterpart to the X-ray source.

BC02_Number
The Berghofer & Christian (2002, A&A, 384, 890: BC02) source identifier of the stellar counterpart to the X-ray source.

Umag
The U Band magnitude of the stellar counterpart to the X-ray source.

Bmag
The B Band magnitude of the stellar counterpart to the X-ray source.

Vmag
The V Band magnitude of the stellar counterpart to the X-ray source.

Rmag
The R Band magnitude of the stellar counterpart to the X-ray source.

Imag
The I Band magnitude of the stellar counterpart to the X-ray source.

Halpha_Mag
The H-alpha band magnitude of the stellar counterpart to the X-ray source.

TwoMASS_Name
The designation of the 2MASS counterpart to the X-ray source.

Flamingos_ID
The FLAMINGOS source identifier of the near-IR counterpart to the X-ray source (see Section 3.1 of the reference paper for more details).

Jmag
The FLAMINGOS, else 2MASS, J-band magnitude of the near-IR counterpart to the X-ray source

Hmag
The FLAMINGOS, else 2MASS, H-band magnitude of the near-IR counterpart to the X-ray source

Kmag
The FLAMINGOS, else 2MASS, K-band magnitude of the near-IR counterpart to the X-ray source

TwoMASS_Flags
The 2MASS source Photmetric Quality (Contamination and Confusion) flag values for the likely 2MASS counterpart to the X-ray source, as defined in the Explanatory Supplement to the 2MASS All Sky Data Release at http://www.ipac.caltech.edu/2mass/releases/allsky/doc/sec2_2a.html.

Notes
This parameter contains some additional notes about the stellar counterpart to the X-ray source, which may contain the following abbreviations:

   [OI81]=Ogura & Ishida (1981),
   [MJD95]=Massey, Johnson, & Degioia-Eastwood (1995),
   [BC02]=Berghofer & Christian (2002),
   [PS02]=Park & Sung (2002),
   [LR04]=Li & Rector (2004),
   ProbMem=Probability of being a cluster member from proper motion data,
   [M82]=Marschall et al. (1982),
   [D06]=Dias et al. (2006).
  

Source_Flag
This flag parameter (created by the HEASARC) is set to 'M' to indicate the specified source is one of the 805 sources from the Main Chandra Catalog listed in Table 2 of the reference paper, or to 'S' to indicate the specified source is one of the 114 sources from the Secondary Chandra Catalog listed in Table 3 of the reference paper. The authors chose two thresholds on the probability P_B that the X-ray source was a background fluctuation rather than a 'real' source when defining their final source list: P_B < 0.001 for the primary sources and P_B >= 0.001 for the secondary sources.


Contact Person

Questions regarding the NGC2244CXO database table can be addressed to the HEASARC User Hotline.

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