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COUP - Chandra Orion Ultradeep Point Source Catalog |
HEASARC Archive |
Overview
The Chandra Orion Ultradeep Project (COUP) was a deep observation of the Orion Nebula Cluster (ONC) that was obtained with the Chandra X-Ray Observatory's Advanced CCD Imaging Spectrometer (ACIS). This Browse table contains the COUP catalog of more than 1600 X-ray point sources that were detected in the exceptionally deep 2003 January observation, which was an 838 ks exposure made over a continuous period of 13.2 days. The COUP observation provides the most uniform and comprehensive data set on the X-ray emission of normal stars ever obtained in the history of X-ray astronomy.Catalog Bibcode
2005ApJS..160..319GReferences
Chandra Orion Ultradeep Project: observations and sources lists.
Getman K.V., Flaccomio E., Broos P.S., Grosso N., Tsujimoto M.,
Townsley L., Garmire G.P., Kastner J., Li J., Harnden F.R.JR, Wolk S.,
Murray S.S., Lada C.J., Muench A.A., McCaughrean M.J., Meeus G.,
Damiani F., Micela G., Sciortino S., Bally J., Hillenbrand L.A., Herbst W.,
Preibisch T., Feigelson E.D.
<Astrophys. J. Suppl. Ser., 160, 319-352 (2005)>
=2005ApJS..160..319G
Provenance
This table was created by the HEASARC in September 2006 based on the CDS catalog J/ApJS/160/319, tables 2, 4, 6, 7, 8, 9, and 10.Parameters
Coup_Number
This parameter is the running COUP source number, which
was used in the reference paper and in other COUP papers. Sources are listed
in order of increasing J2000 right ascension.
Name
The X-ray source name in the standard IAU position-based format
(JHHMMSS.s-DDMMSS) with the prefix 'COUP J' for Chandra Orion Ultradeep
Project, J2000.
RA
The Right Ascension of the X-ray source in the selected equinox.
This was given in J2000 decimal degrees to a precision of 1 microdegree
(0.0036 arcseconds) in the original table. For sources with off-axis
angles theta < 5 arcminutes, the positions are obtained from a simple
centroiding algorithm within the acis_extract procedure. For sources
located farther off-axis, the wavelet positions were improved by
correlating the event distribution with PSF images using a matched-filter
technique implemented by acis_extract.
Dec
The Declination of the X-ray source in the selected equinox.
This was given in J2000 decimal degrees to a precision of 1 microdegree
(0.0036 arcseconds) in the original table. For sources with off-axis
angles theta < 5 arcminutes, the positions are obtained from a simple
centroiding algorithm within the acis_extract procedure. For sources
located farther off-axis, the wavelet positions were improved by
correlating the event distribution with PSF images using a matched-filter
technique implemented by acis_extract.
LII
The Galactic Longitude of the X-ray source.
BII
The Galactic Latitude of the X-ray source.
Error_Radius
The X-ray source's positional uncertainty in arcseconds.
These errors are calculated within acis_extract as 68% (1 sigma)
confidence intervals using the Student's T-distribution.
Off_Axis
The off-axis angle (theta) for the X-ray source in arcminutes.
Problem_Flags
This parameter comprises 6 bytes which contain flags
indicating a variety of warnings and difficulties. A "u" in byte 1 denotes
uncertain objects; these are very weak sources without stellar counterparts
that satisfy the detection criteria but are subjectively not completely
convincing: seventy-four sources have "u" designations. A "d" in byte 2
refers to a double source, defined as two sources with overlapping 90%
point spread function (PSF) contours. A "p" in byte 3 defines a possible
piled-up source, when the surface brightness of the source exceeds a level
of 0.003 counts s-1 pixel-1. A "t" in byte 4 indicates that a source
region crosses a bright source readout trail. A "w" in byte 5 indicates
that the source is located in the wings of any bright source with > 20,000
counts. An "x" in byte 6 indicates a region of inhomogeneous or low exposure
map, where the source is located near or on chip gaps, bad pixel columns,
or field edges. Sources designated "x" will have disturbed light curves.
Wavdetect_Flag
This parameter is a flag indicating the source detection
map for the CIAO wavdetect program, defined as follows:
0 = no detection map for wavdetect
1 = total band (0.5 - 8 keV) image
2 = soft band (0.5 - 2 keV) image only
3 = hard band (2 - 8 keV) image only
4 = total band image with background filtered in Very Faint mode only
The great majority of sources (1522 of 1616) were found in the total band
image; still, 45 sources were found only in the soft band, and 36 only in
the hard band.
Pwdetect_Flag
This parameter is a flag indicating the source detection
map (the type of event list on which a source was detected) using the
Palermo wavelet transform detection code, PWDetect, defined as follows:
0 = no detection map for Palermo wavelet detection
1 = Very Faint mode 0.3 - 7 keV band image
2 = sub-pixel enhanced resolution (SER) 0.3 - 7 keV band image
Detect_Flag_1
This parameter and the two other similar parameters
contains information on the detection procedure. This specific flag
refers to the CIAO wavdetect program and is coded as follows:
0 = no detection using wavdetect
1 = wavdetect probability threshold of 1 x 10-6
2 = wavdetect probability threshold of 1 x 10-5
Detect_Flag_2
This parameter and the two other similar parameters
contains information on the detection procedure. This specific flag
refers to the Palermo Wavelet Detection method PWDetect and is coded
as follows:
0 = no detection using Palermo wavelet detection
1 = detection using Palermo wavelet detection
Detect_Flag_3
This parameter and the two other similar parameters
contains information on the detection procedure. This specific flag
(if non-zero) refers to sources which were found only by visual inspection,
(A total of 123 of the 1616 sources were found only by visual inspection),
and is coded as follows:
0 = not needed
1 = source found by both Penn State and Palermo groups
2 = source found only by Penn State group
3 = source found only by Palermo group
AE_Significance
The source significance as calculated by acis_extract,
SigAE, which indicates how many times the source's net (background-subtracted)
counts exceed the uncertainty in that quantity: SigAE = NetCts/sigma(NetCts).
Pwdetect_Significance
The probability of source existence, expressed in
Gaussian sigmas, as calculated by the Palermo Wavelet Detection program,
PWDetect.
ACIS_Source_Number
The X-ray source counterparts from the previous
Chandra study with the ACIS (Feigelson et al. 2002, ApJ, 574, 258)
detector. The Einstein, ROSAT, and ASCA counterpart sources are
given by Feigelson et al. (2002).
HRC_Source_Number
The X-ray source counterparts from the previous
Chandra study with the HRI (Flaccomio et al. 2003, ApJ, 582, 382)
detector. The Einstein, ROSAT, and ASCA counterpart sources are
given by Feigelson et al. (2002).
Total_Counts
The source counts contained in this parameter are the number
of counts in the total (0.5 - 8 keV) energy band extracted for each source,
and including the background counts.
Bck_Counts
The number of background counts in the total band scaled to
the extracted area corrected for small differences that may be present in
the exposure maps of the source and background regions.
Counts
The net or background-corrected counts: this is the difference
between the total extracted source counts (total_counts) and the scaled
local background counts bck_counts).
Extraction_Area
The area of the source extraction polygon in 0.5" x 0.5"
pixels.
PSF_Fraction
The fraction of the PSF at the fiducial energy of 1.497 keV
enclosed within the extracted area.
Exposure
The "effective" exposure time, Exp, at the source location, in
seconds (the HEASARC converted this from the ks units used in the published
version of this table so as to confirm with its standards). This quantity is
derived by normalizing the ratio of an average exposure map ("Ct_Fl") to the
one obtained for the region with the maximum value of the exposure map.
Specifically, Exp = (Ct_Fl/Ct_Flmax) x 838,000 s, where 838,000 s is the COUP
"observed" exposure time (the sum of all 6 of the individual exposures
listed in Table 1 of the published paper). This quantity summarizes the
variation in the "depth" to which the sources were observed.
Flux_Conv_Factor
The value of the exposure map averaged over the source
region (Ct_Fl) in units of 109 counts s cm2 photon-1 and represents a
conversion factor between the photon incident flux and detected counts.
Photon_Flux
The 0.5 - 8.0 keV incident photon flux, IncFl, in
photons/cm2/s. This is a rough estimate of the incident photon flux at
the telescope aperture, where IncFl = NetCts/<ARF>/Exp. Note that this flux
estimate becomes inaccurate when the spectrum is not flat over the total
0.5 - 8 keV band covered by the ARF. Summing the fluxes computed over narrow
energy bands will produce a more accurate result, and parametric spectral
fitting should produce the most accurate flux estimates.
Median_Photon_Energy
The background-corrected median photon energy
MedE in the 0.5 - 8.0 keV range. This parameter and IncFl (photon_flux) can
be used together for estimating the luminosities of weak sources (say,
NetCts <~ 20) for which nonlinear spectral fitting packages are ineffective.
HR_1
The hardness ratio HR1 defined by HR = (Ctsh - Ctss)/(Ctsh + Ctss),
where Ctsx are the counts in a band "x", and subscripts "h" and "s" refer
to a harder and softer band, respectively. For COUP, the authors define HR1
to reproduce the commonly used hardness ratio between the s = 0.5 - 2.0 keV
and h = 2.0 - 8.0 keV bands. For each energy band, acis_extract computes the
net counts corrected for the local background in the appropriate band.
HR_1_Neg_Err
The lower 1-sigma statistical uncertainty in the HR1 hardness
ratio. Confidence intervals encompassing 68% of the expected error, equivalent
to +/- 1 sigma in a Gaussian distribution, are estimated first by calculating
upper and lower errors in total and background counts using Gehrels (1986,
ApJ, 303, 336: eqs. [7] and [12]) and then propagating those errors to net
counts using Lyons (1993, Am. J Phys, 61, 189: eq. [1.31]). The authors then
propagate errors from net counts to upper and lower uncertainties on hardness
ratios using the method in Lyons (1993). When net counts are negative in an
energy band, the authors clip them at zero (to ensure that hardness ratios
are bounded by [-1, 1]) and choose to set their lower errors to zero. In
cases where the 68% confidence interval of soft band net counts contains zero
(very hard sources), the authors consider the upper uncertainties in hardness
ratios to be unreliable and do not report them; similarly, they do not report
the lower uncertainties in hardness ratios of very soft sources. When the 68%
confidence interval of both bands contains zero counts, they do not report
hardness ratios, because their errors would be large.
HR_1_Pos_Err
The upper 1-sigma statistical uncertainty in the HR1 hardness
ratio. Confidence intervals encompassing 68% of the expected error, equivalent
to +/- 1 sigma in a Gaussian distribution, are estimated first by calculating
upper and lower errors in total and background counts using Gehrels (1986,
ApJ, 303, 336: eqs. [7] and [12]) and then propagating those errors to net
counts using Lyons (1993, Am. J Phys, 61, 189: eq. [1.31]). The authors then
propagate errors from net counts to upper and lower uncertainties on hardness
ratios using the method in Lyons (1993). When net counts are negative in an
energy band, the authors clip them at zero (to ensure that hardness ratios
are bounded by [-1, 1]) and choose to set their lower errors to zero. In
cases where the 68% confidence interval of soft band net counts contains zero
(very hard sources), the authors consider the upper uncertainties in hardness
ratios to be unreliable and do not report them; similarly, they do not report
the lower uncertainties in hardness ratios of very soft sources. When the 68%
confidence interval of both bands contains zero counts, they do not report
hardness ratios, because their errors would be large.
HR_2
The hardness ratio HR2 defined by HR = (Ctsh - Ctss)/(Ctsh + Ctss),
where Ctsx are the counts in a band "x", and subscripts "h" and "s" refer
to a harder and softer band, respectively. For COUP, the authors define HR2
to highlight the softer part of the spectrum between s = 0.5 - 1.7 keV and h
= 1.7 - 2.8 keV. For each energy band, acis_extract computes the net counts
corrected for the local background in the appropriate band.
HR_2_Neg_Err
The lower 1-sigma statistical uncertainty in the HR2 hardness
ratio. Confidence intervals encompassing 68% of the expected error, equivalent
to +/- 1 sigma in a Gaussian distribution, are estimated first by calculating
upper and lower errors in total and background counts using Gehrels (1986,
ApJ, 303, 336: eqs. [7] and [12]) and then propagating those errors to net
counts using Lyons (1993, Am. J Phys, 61, 189: eq. [1.31]). The authors then
propagate errors from net counts to upper and lower uncertainties on hardness
ratios using the method in Lyons (1993). When net counts are negative in an
energy band, the authors clip them at zero (to ensure that hardness ratios
are bounded by [-1, 1]) and choose to set their lower errors to zero. In
cases where the 68% confidence interval of soft band net counts contains zero
(very hard sources), the authors consider the upper uncertainties in hardness
ratios to be unreliable and do not report them; similarly, they do not report
the lower uncertainties in hardness ratios of very soft sources. When the 68%
confidence interval of both bands contains zero counts, they do not report
hardness ratios, because their errors would be large.
HR_2_Pos_Err
The upper 1-sigma statistical uncertainty in the HR2 hardness
ratio. Confidence intervals encompassing 68% of the expected error, equivalent
to +/- 1 sigma in a Gaussian distribution, are estimated first by calculating
upper and lower errors in total and background counts using Gehrels (1986,
ApJ, 303, 336: eqs. [7] and [12]) and then propagating those errors to net
counts using Lyons (1993, Am. J Phys, 61, 189: eq. [1.31]). The authors then
propagate errors from net counts to upper and lower uncertainties on hardness
ratios using the method in Lyons (1993). When net counts are negative in an
energy band, the authors clip them at zero (to ensure that hardness ratios
are bounded by [-1, 1]) and choose to set their lower errors to zero. In
cases where the 68% confidence interval of soft band net counts contains zero
(very hard sources), the authors consider the upper uncertainties in hardness
ratios to be unreliable and do not report them; similarly, they do not report
the lower uncertainties in hardness ratios of very soft sources. When the 68%
confidence interval of both bands contains zero counts, they do not report
hardness ratios, because their errors would be large.
HR_3
The hardness ratio HR3 defined by HR = (Ctsh - Ctss)/(Ctsh + Ctss),
where Ctsx are the counts in a band "x", and subscripts "h" and "s" refer to
a harder and softer band, respectively. For COUP, the authors define HR3 to
measure the harder part of the spectrum between s = 1.7 - 2.8 keV and h = 2.8
- 8.0 keV. For each energy band, acis_extract computes the net counts
corrected for the local background in the appropriate band.
HR_3_Neg_Err
The lower 1-sigma statistical uncertainty in the HR3 hardness
ratio. Confidence intervals encompassing 68% of the expected error, equivalent
to +/- 1 sigma in a Gaussian distribution, are estimated first by calculating
upper and lower errors in total and background counts using Gehrels (1986,
ApJ, 303, 336: eqs. [7] and [12]) and then propagating those errors to net
counts using Lyons (1993, Am. J Phys, 61, 189: eq. [1.31]). The authors then
propagate errors from net counts to upper and lower uncertainties on hardness
ratios using the method in Lyons (1993). When net counts are negative in an
energy band, the authors clip them at zero (to ensure that hardness ratios
are bounded by [-1, 1]) and choose to set their lower errors to zero. In
cases where the 68% confidence interval of soft band net counts contains zero
(very hard sources), the authors consider the upper uncertainties in hardness
ratios to be unreliable and do not report them; similarly, they do not report
the lower uncertainties in hardness ratios of very soft sources. When the 68%
confidence interval of both bands contains zero counts, they do not report
hardness ratios, because their errors would be large.
HR_3_Pos_Err
The upper 1-sigma statistical uncertainty in the HR3 hardness
ratio. Confidence intervals encompassing 68% of the expected error, equivalent
to +/- 1 sigma in a Gaussian distribution, are estimated first by calculating
upper and lower errors in total and background counts using Gehrels (1986,
ApJ, 303, 336: eqs. [7] and [12]) and then propagating those errors to net
counts using Lyons (1993, Am. J Phys, 61, 189: eq. [1.31]). The authors then
propagate errors from net counts to upper and lower uncertainties on hardness
ratios using the method in Lyons (1993). When net counts are negative in an
energy band, the authors clip them at zero (to ensure that hardness ratios
are bounded by [-1, 1]) and choose to set their lower errors to zero. In
cases where the 68% confidence interval of soft band net counts contains zero
(very hard sources), the authors consider the upper uncertainties in hardness
ratios to be unreliable and do not report them; similarly, they do not report
the lower uncertainties in hardness ratios of very soft sources. When the 68%
confidence interval of both bands contains zero counts, they do not report
hardness ratios, because their errors would be large.
Log_NH
The logarithm of the hydrogen column density, in atoms cm-2, obtained from
the spectral fit. Fitted values with log NH < 20.0 atoms cm-2 are
truncated at 20.0 because ACIS-I spectra are insensitive to differences in
very low column densities.
Log_NH_Error
The 1-sigma error in the logarithm of the hydrogen column
density, in atoms cm-2, obtained from the spectral fit.
Temperature_1
The temperature T1 of the first plasma component found in
the spectral fit, in keV. One-temperature spectral fit results were recorded
for 980 COUP sources and two-temperature results for 563 sources. Spectral
models for 73 sources with very poor statistics (net counts < 20) are left
blank. In cases of two-temperature fits, T1 is the energy of the soft
component. Fitted values with kT > 15 keV are truncated at 15 keV because
the data cannot discriminate between very high-temperature values.
Temperature_1_Error
The 1-sigma statistical error in the temperature T1
of the first plasma component found in the spectral fit, in keV.
Temperature_2
The temperature T2 of the second harder plasma component
found in the spectral fit, if needed, in keV. One-temperature spectral fit
results were recorded for 980 COUP sources and two-temperature results for
563 sources. Spectral models for 73 sources with very poor statistics (net
counts < 20) are left blank. Fitted values with kT > 15 keV are truncated
at 15 keV because the data cannot discriminate between very high-temperature
values.
Temperature_2_Error
The 1-sigma statistical error in the temperature T2
of the second plasma component found in the spectral fit, in keV.
Log_EM_1
The logarithm of the emission measure of the first plasma
component, in cm-3, found in the spectral fit.
Log_EM_1_Error
The 1-sigma error in the logarithm of the emission measure
of the first plasma component, in cm-3.
Log_EM_2
The logarithm of the emission measure of the second plasma
component, in cm-3, found in the spectral fit.
Log_EM_2_Error
The 1-sigma error in the logarithm of the emission measure
of the second plasma component, in cm-3.
Reduced_Chi_Squared
The reduced chi-squared (chi2 per the number of degrees of freedom) for the
overall spectral fit.
Chi_Squared_DoF
The degrees of freedom for the overall spectral fit.
Fit_Quality_Flag
Details regarding the spectral fitting process for individual sources are
provided by this parameter and the spect_model_flags parameter. This
parameter marks sources where the model was formally inadequate, based on the
null hypothesis probability Pchi of chi-squared for the relevant degrees of
freedom: "m" indicates a marginal fit with 0.005 < Pchi < 0.05, and "p"
indicates a poor fit with Pchi < 0.005.
Spect_Model_Flags
Details regarding the spectral fitting process for individual sources are
provided by this parameter and the fit_quality_flag parameter. This parameter
presents a three-part flag giving details of the spectral modeling for each
source. The first part gives the minimum number of events in each spectral
group. The second part indicates whether two absorption components are
needed. The third part gives the number of plasma components used in the
accepted fit, 1 or 2. A "g" indicates that the spectral result has been
chosen from a grid of initial parameter values.
Fit_Comment_Flags
This parameter is a conjunction of eight flags having default values of 0
which give important information on source-specific spectral features and
problems, some obtained from visual inspection of the spectral fit and the
location of the source in the ACIS image. The first flag (byte 1) is set to l
to indicate the presence of narrow spectral features in the data that are not
present in the model, probably due to elemental abundances inconsistent with
the authors' assumption of 0.3 times the solar values. A total of 186 COUP
sources are flagged with spectral features. The second and third bytes
contain flags which indicate that soft (s) or hard (h) excesses,
respectively, were present in the data that were not in the model. In most
cases, this can be attributed to poor subtraction of nonuniform local
background around weak sources. The fourth byte contains a flag (c) which
signals that the spectrum may be corrupted by a close star component. The
fifth byte contains a flag (p) which indicates that the spectral fit is
unreliable due to poor statistics and/or a poor fit based on visual
examination rather than chi-squared values. The sixth byte contains a flag
(m) which marks cases where the authors defined the background extraction
region with a manual (rather than automatic) procedure (see Section 5 of the
paper). The seventh byte contains a flag (a) which marks the 24 heavily
piled-up sources requiring annular extraction, as discussed in Section 6 of
the paper. The eighth byte contains a flag (w) which notes 26 additional
sources that appeared weakly piled up for which the usual whole polygonal
extraction region was used.
Gap_Flag
This parameter contains a flag which is set to "x" in 33 cases where the
sources were located on an ACIS CCD chip gap. In these cases, variability
tests were performed on data extracted from the primary CCD only. These
sources may exhibit spurious short-term variability.
Log_Prob_Var
The acis_extract package applies the nonparametric one-sample
Kolmogorov-Smirnov (K-S) test to establish whether variations are present
above those expected from Poisson noise associated with a constant source.
This parameter reports the logarithm of test significance, log P_KS_:
probability values log PKS <= -3.0 can be considered almost definitely
variable, while variability has not been reliably detected when log PKS >
-2.0. Log PKS has been truncated at -4.0 for strong sources with
high-amplitude variability because the tail of the statistic distribution is
not well defined.
Num_BB_Segments
The number of segments BBNum used in the Bayesian block (BB) parametric model
of source variability. In this model, developed by Scargle (1998, ApJ, 504,
405), the light curve is segmented into a contiguous sequence of constant
count rates. The change points between constant count rates are determined by
an iterative maximum-likelihood procedure for a Poissonian process. This
parameter and the min_count_rate and max_count_rate parameters contains the
results derived from the BB variability analysis.
Min_Count_Rate
The count rate of the lowest Bayesian block segment, in ct/ks. The minimum
count rate might sometimes be viewed as the quiescent level between flaring
events. The ratio of maximum to minimum count rates may, within errors, be
viewed as a measure of variability amplitude. The authors caution, however,
that visual examination and individual analysis of light curves is needed for
a full understanding of COUP source variability.
Min_Count_Rate_Error
The 1-sigma uncertainty in the minimum Bayesian block count rate, in ct/ks
(from Gehrels 1986, ApJ, 303, 336), assuming Poisson statistics within the
segment.
Max_Count_Rate
The count rate of the highest Bayesian block segment, in ct/ks. The minimum
count rate might sometimes be viewed as the quiescent level between flaring
events. The ratio of maximum to minimum count rates may, within errors, be
viewed as a measure of variability amplitude. The authors caution, however,
that visual examination and individual analysis of light curves is needed for
a full understanding of COUP source variability.
Max_Count_Rate_Error
The 1-sigma uncertainty in the maximum Bayesian block count rate, in ct/ks
(from Gehrels 1986, ApJ, 303, 336), assuming Poisson statistics within the
segment.
Log_Lx_Soft_Limit
This parameter is set to "<" to indicate that the soft-band X-ray luminosity
is an upper limit.
Log_Lx_Soft
X-ray luminosities are provided in three broad bands: this parameter Ls is
the log of the source luminosity in the soft 0.5 - 2.0 keV band. Luminosities
are calculated from fluxes F in these bands according to L = 4 x pi x D2 x
F, assuming a distance D = 450 pc to the Orion Nebula region. For 1543 of the
1616 COUP sources, fluxes were obtained from the thermal plasma spectral fits
(Section 7 of the paper) using XSPEC's flux tool, which integrates the model
spectrum over the desired band. Since the ARFs used with XSPEC incorporate
instrumental effects, such as the unextracted PSF fraction and absorption by
hydrocarbon contamination on the detector, no additional correction factors
are needed at this stage.
Log_Lx_Hard_Limit
This parameter is set to "<" to indicate that the hard-band X-ray luminosity
is an upper limit.
Log_Lx_Hard
X-ray luminosities are provided in three broad bands: this parameter Lh is
the log of the source luminosity in the hard 2.0 - 8.0 keV band. Luminosities
are calculated from fluxes F in these bands according to L = 4 x pi x D2 x
F, assuming a distance D = 450 pc to the Orion Nebula region. For 1543 of the
1616 COUP sources, fluxes were obtained from the thermal plasma spectral fits
(Section 7 of the paper) using XSPEC's flux tool, which integrates the model
spectrum over the desired band. Since the ARFs used with XSPEC incorporate
instrumental effects, such as the unextracted PSF fraction and absorption by
hydrocarbon contamination on the detector, no additional correction factors
are needed at this stage.
Log_Lx_Hard_Corr
The log of the estimated luminosity in the hard band, corrected for
interstellar absorption. This is calculated by running XSPEC's flux tool with
the fitted plasma energies and emission measures but with zero absorption,
which gives an estimate of the intrinsic source emission prior to
interstellar absorption.
Log_Lx_Tot
X-ray luminosities are provided in three broad bands: this parameter Lt is
the log of the source luminosity in the total 0.5 - 8.0 keV band.
Luminosities are calculated from fluxes F in these bands according to L = 4 x
pi x D2 x F, assuming a distance D = 450 pc to the Orion Nebula region. For
1543 of the 1616 COUP sources, fluxes were obtained from the thermal plasma
spectral fits (Section 7 of the paper) using XSPEC's flux tool, which
integrates the model spectrum over the desired band. Since the ARFs used with
XSPEC incorporate instrumental effects, such as the unextracted PSF fraction
and absorption by hydrocarbon contamination on the detector, no additional
correction factors are needed at this stage.
Log_Lx_Tot_Corr
The log of the estimated luminosity in the total band, corrected for
interstellar absorption. This is calculated by running XSPEC's flux tool with
the fitted plasma energies and emission measures but with zero absorption,
which gives an estimate of the intrinsic source emission prior to
interstellar absorption.
Optical_Id_Number
The identifier for the probable optical stellar counterpart to the X-ray
source, using an integral code where designations between 0 and 9999 are from
Hillenbrand (1997, AJ, 113, 1733) and those between 10,000 and 11,000 are
from Herbst et al. (2002, A&A, 396, 513).
Xray_Opt_Offset
The offset between the optical and COUP positions, in arcseconds.
Vmag
The V magnitude of the optical counterpart, from Hillenbrand (1997, AJ, 113,
1733).
Imag
The I magnitude of the optical counterpart, from Hillenbrand (1997, AJ, 113,
1733).
Spect_Type
The spectral type of the optical counterpart, from Hillenbrand (1997, AJ,
113, 1733), updated with the work of Luhman et al. (2000, ApJ, 540, 1016) and
Lucas et al. (2001, MNRAS, 326, 695).
A_Vmag
The visual absorption of the optical counterpart, derived as in Hillenbrand
(1997, AJ, 113, 1733).
Log_T_Eff
The log of the stellar effective temperature, in K, based on the
counterpart's spectral type, following Hillenbrand & White (2004, ApJ, 604,
741). Users should be cautious when using the intrinsic stellar properties
listed in this table as they are less accurate than the precision given in
the tables. Errors arise from intrinsic photometric variability,
uncertainties in spectral types and conversions to effective temperatures and
bolometric luminosities, and, for the mass and age estimates, uncertainties
in theoretical evolutionary tracks (see Hillenbrand & White 2004, ApJ, 604,
741).
Log_L_Bol
The log of the stellar bolometric luminosity, in units of solar luminosities,
derived as in Hillenbrand (1997, AJ, 113, 1733). Users should be cautious
when using the intrinsic stellar properties listed in this table as they are
less accurate than the precision given in the tables. Errors arise from
intrinsic photometric variability, uncertainties in spectral types and
conversions to effective temperatures and bolometric luminosities, and, for
the mass and age estimates, uncertainties in theoretical evolutionary tracks
(see Hillenbrand & White 2004, ApJ, 604, 741).
Stellar_Radius
The stellar radius, in units of solar radii, derived as in Hillenbrand (1997,
AJ, 113, 1733). Users should be cautious when using the intrinsic stellar
properties listed in this table as they are less accurate than the precision
given in the tables. Errors arise from intrinsic photometric variability,
uncertainties in spectral types and conversions to effective temperatures and
bolometric luminosities, and, for the mass and age estimates, uncertainties
in theoretical evolutionary tracks (see Hillenbrand & White 2004, ApJ, 604,
741).
Stellar_Mass
The stellar mass, in units of solar masses, as recalculated
by the authors using the PMS evolutionary tracks of Siess et al. (2000,
A&A, 358, 593). Users should be cautious when using the intrinsic stellar
properties listed in this table as they are less accurate than the precision
given in the tables. Errors arise from intrinsic photometric variability,
uncertainties in spectral types and conversions to effective temperatures and
bolometric luminosities, and, for the mass and age estimates, uncertainties
in theoretical evolutionary tracks (see Hillenbrand & White 2004, ApJ, 604,
741).
Log_Stellar_Age
The log of the stellar age, in years, as recalculated
by the authors using the PMS evolutionary tracks of Siess et al. (2000,
A&A, 358, 593). Users should be cautious when using the intrinsic stellar
properties listed in this table as they are less accurate than the precision
given in the tables. Errors arise from intrinsic photometric variability,
uncertainties in spectral types and conversions to effective temperatures and
bolometric luminosities, and, for the mass and age estimates, uncertainties
in theoretical evolutionary tracks (see Hillenbrand & White 2004, ApJ, 604,
741).
Ik_Excess
This parameter, the K-band near-IR excess attributable to a hot
circumstellar disk, Delta(I - K), and the eq_width_ca_ii parameter describe
properties associated with circumstellar material and accretion which
were measured by Hillenbrand et al. (1998, AJ, 116, 1816).
Eq_Width_Ca_II
This parameter is the equivalent width of the Ca II
infrared triplet lines with lambda = 8542 Angstroms, EW(Ca). A negative value
here represents an emission line. EW(Ca) values were measured by Hillenbrand
et al. (1998, AJ, 116, 1816).
Vmag_Average
The average V magnitude <V> of the stellar counterpart
derived from ~ 90 epochs of photometric monitoring by Herbst et al.
(2002, A&A, 396, 513).
Vmag_Average_Error
The standard deviation in the average V magnitude
Delta V derived from ~ 90 epochs of photometric monitoring by Herbst et al.
(2002, A&A, 396, 513).
Vmag_Range
The range in the V magnitude about the mean derived from ~ 90
epochs of photometric monitoring by Herbst et al. (2002, A&A, 396, 513).
Rotation_Period
The photometric rotational period, in days, derived from
periodicity attributed to rotationally modulated starspots during ~ 90 epochs
of photometric monitoring by Herbst et al. (2002, A&A, 396, 513).
IR_Name
The infrared (JHK) counterpart source identifier obtained from the
merged catalog of McCaughrean et al. (2005, in preparation)= McC05 for the
inner region of the COUP field, and the 2MASS designation for the outer region.
Xray_IR_Offset
The (COUP-JHK) source positional offset, in arcseconds.
Jmag
The J magnitude from the appropriate JHK catalog.
Hmag
The H magnitude from the appropriate JHK catalog.
Ks_Mag
The Ks magnitude from the appropriate JHK catalog.
Ref_IR_Photometry
This parameter contains a reference code for
sources from McC05 indicating the source of the photometry: 1 from the
VLT; 2 and 3 from the New Technology Telescope and Fred Lawrence Whipple
Observatory surveys, respectively, presented by Muench et al. (2002, ApJ,
573, 366)); 4 from the compilation of Hillenbrand (1997, AJ, 113, 1733);
and 5 from 2MASS or other sources.
Quality_Flag_2MASS
The photometry quality flag for 2MASS sources has
values as follows: A, signal-to-noise ratio (SNR) >= 10; B, SNR >=
7; C, SNR >= 5; D, low-significance detection; E, PSF fitting poor; F,
reliable photometric errors not available; and X, source detected but
no valid photometry is available.
Contcon_Flag_2MASS
The 2MASS contamination and confusion flag has
values as follows: 0, no problem; b, possible multiple source; c,
photometric confusion from nearby star; d, diffraction spike confusion
from nearby star; p, persistence contamination from nearby star; and s,
electronic stripe from nearby star.
Lmag_Flag
A reference code for the L-band data which indicates whether
the photometry is obtained from the surveys of Muench et al. (2002, ApJ, 573,
366), designated with an "M," or Lada et al. (2004, AJ, 128, 1254),
designated with an "L".
Lmag_Id_Number
The running source number for the L-band counterpart from
the L-band catalog.
Lmag
The L magnitude for the IR source from the L-band catalog.
Class
The HEASARC Browse object classification of the optical counterpart,
based on its spectral type.
Contact Person
Questions regarding the COUP database table can be addressed to the HEASARC Help Desk.Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:26:20 EDT
- HEASARC Director: Dr. Andy Ptak
- NASA Official: Dr. Andy Ptak
- Web Curator: J.D. Myers
- Last Modified: 16-Sep-2024