J/ApJS/169/353 Chandra sources in M17 (Broos+, 2007)
The young stellar population in M17 revealed by Chandra.
Broos P.S., Feigelson E.D., Townsley L.K., Getman K.V., Wang J.,
Garmire G.P., Jiang Z., Tsuboi Y.
<Astrophys. J. Suppl. Ser., 169, 353-385 (2007)>
=2007ApJS..169..353B 2007ApJS..169..353B
ADC_Keywords: Clusters, open ; Stars, early-type ; Stars, pre-main sequence ;
X-ray sources
Keywords: open clusters and associations: individual (M17) - stars: early-type -
stars: pre-main-sequence - X-rays: individual (M17) - X-rays: stars
Abstract:
We report here results from a Chandra ACIS observation of the stellar
populations in and around the M17 HII region. The field reveals 886
sources with observed X-ray luminosities (uncorrected for absorption)
between ∼29.3ergs/s<logLX<32.8ergs/s, 771 of which have stellar
counterparts in infrared images.
Description:
M17 was observed with the Imaging Array of the Chandra ACIS camera
(ACIS-I, 17'x17' field of view) for roughly 40ks in 2002 March.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 107 845 Primary Chandra catalog: basic source properties
table2.dat 107 41 Tentative Chandra catalog: basic source properties
table3.dat 127 546 X-ray spectroscopy for photometrically selected
sources: thermal plasma fits
table4.dat 99 52 X-ray spectroscopy for photometrically selected
sources: power law fits
table5.dat 144 886 Stellar counterparts
notes.dat 80 221 Individual notes
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See also:
Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [BFT2007] Source sequence number, sorted by RA
5- 22 A18 --- CXOUJ IAUC source name (HHMMSS.ss+DDMMSS.s)
(CXOU JHHMMSS.ss+DDMMSS.s in Simbad)
24- 33 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
35- 44 F10.6 deg DEdeg Declination in decimal degrees (J2000)
46- 48 F3.1 arcsec errPos Position error (1)
50- 53 F4.1 arcmin OffAng Off-axis angle
55- 60 F6.1 ct Tcts Net extracted total (0.5-8keV) band counts
62- 65 F4.1 ct e_Tcts Averaged upper and lower 1σ error
in Tcts
67- 70 F4.1 ct Bcts Background extracted total (0.5-8keV) band
counts
72- 77 F6.1 ct Hcts Net extracted hard (2-8keV) band counts
79- 82 F4.2 --- Frac PSF fraction enclosed within the extraction
region (G1) (2)
84- 87 F4.1 --- Sig Photometric significance (3)
89 A1 --- l_logP Limit flag on logP
90- 94 F5.1 [-] logP Log probability that total (0.5-8keV) band
extracted counts are solely from background
(4)
96 A1 --- Anom [g] Source anomalies (5)
98 A1 --- Var [abc] Total (2-8keV) band variability
characterization (6)
100-103 F4.1 ks Exp Effective exposure (7)
105-107 F3.1 keV Emed Background-corrected total (0.5-8keV) band
median photon energy
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Note (1): Estimated standard deviation of the random component of the
position error, (σx2+σy2)-0.5. The single-axis
position errors, σxand σy, are estimated from the
single-axis standard deviations of the PSF inside the extraction
region and the number of counts extracted.
Note (2): Enclosed within the extraction region. Note that a reduced PSF
fraction (significantly below 90%) may indicate that the source is in
a crowded region.
Note (3): Computed as (net counts)/(upper error on net counts).
Note (4): Some sources have PB 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.
Note (5): Source anomalies: g indicates that the fractional time that
source was on a detector (FRACEXPO from mkarf) is <0.9.
Note (6): Based on K-S statistic, total band variability characterization
defined as follows:
a = no evidence for variability (0.05<PKS);
b = possibly variable (0.005<PKS<0.05);
c = definitely variable (PKS<0.005).
blank = source with fewer than 4 counts or a source in chip gaps
or on field edges.
Note (7): Approximate time the source would have to be observed on-axis
(no telescope vignetting) on a nominal region of the detector (no
dithering over insensitive regions of the detector) to obtain the
reported number of counts.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- [BFT2007] Source sequence number, sorted by RA
5- 22 A18 --- CXOUJ IAUC source name (HHMMSS.ss+DDMMSS.s)
(CXOU JHHMMSS.ss+DDMMSS.s in Simbad)
24- 29 F6.1 ct Tcts Net extracted total (0.5-8keV) band counts
31- 34 F4.1 --- Sig Photometric significance (1)
36- 39 F4.2 [cm-2] e_logNH ? Lower 90% confidence level in logNH (2)
41- 44 F4.1 [cm-2] logNH Log of best fit H I column density (G2)
46- 49 F4.2 [cm-2] E_logNH ? Upper 90% confidence level in logNH (2)
51 A1 --- f_logNH [e] Flag on logNH (G3)
53- 56 F4.2 keV e_kT ? Lower 90% confidence level in kT (2)
58- 61 F4.1 keV kT Best fit plasma temperature (G2)
63- 67 F5.2 keV E_kT ? Upper 90% confidence level in kT (2)
69 A1 --- f_kT [e] Indicates the model parameter was
frozen in the fit
71- 74 F4.2 [cm-3] e_logEM ? Lower 90% confidence level in logEM (2)
76- 79 F4.1 [cm-3] logEM Log of model emission measure (G2)
81- 84 F4.2 [cm-3] E_logEM ? Upper 90% confidence level in logEM (2)
86- 90 F5.2 [10-7W] logLs ? Log of soft band (0.5-2keV) luminosity
in erg/s
92- 96 F5.2 [10-7W] logLh Log of hard band (2-8keV) luminosity
in erg/s
98-102 F5.2 [10-7W] logLhc Log of absorption-corrected hard
band (2-8keV) luminosity in erg/s (G3)
104-108 F5.2 [10-7W] logLt Log of total band (0.5-8keV) luminosity
in erg/s
110-114 F5.2 [10-7W] logLtc ? Log of absorption-corrected total
band (0.5-8keV) luminosity in erg/s (G3)
116-127 A12 --- n_[BFT2007] Note on [BFT2007] (3)
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Note (1): Computed as (net counts)/(upper error on net counts).
Note (2): 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.
Note (3): "2T" means a two-temperature model was used; the second
temperature is shown in parentheses. See spectra in Figure 12.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- [BFT2007] Source sequence number, sorted by RA
5- 22 A18 --- CXOUJ IAUC source name (HHMMSS.ss+DDMMSS.s)
(CXOU JHHMMSS.ss+DDMMSS.s in Simbad)
24- 27 F4.1 ct Tcts Net extracted total (0.5-8keV) band counts
29- 31 F3.1 --- Sig Photometric significance (1)
33- 35 F3.1 [cm-2] e_logNH ? Lower 90% confidence level in logNH (G1)
37- 40 F4.1 [cm-2] logNH Log of best fit H I column density (G2)
42- 44 F3.1 [cm-2] E_logNH ? Upper 90% confidence level in logNH (G1)
46- 48 F3.1 --- e_Gamma ? Lower 90% confidence level in Gamma (G1)
50- 52 F3.1 --- Gamma ? Best fit power law photon index (G2)
54- 56 F3.1 --- E_Gamma ? Upper 90% confidence level in Gamma (G1)
58- 60 F3.1 [-] e_logNo ? Lower 90% confidence level in logNo (G1)
62- 65 F4.1 [-] logNo Log of model spectrum power law
normalization (G2)
67- 69 F3.1 [-] E_logNo ? Upper 90% confidence level in logNo (G1)
71- 75 F5.2 [10-7W] logLs ? Log of soft band (0.5-2keV) luminosity
in erg/s
77- 81 F5.2 [10-7W] logLh Log of hard band (2-8keV) luminosity
in erg/s
83- 87 F5.2 [10-7W] logLhc Log of absorption-corrected hard band
(2-8keV) luminosity in erg/s (G3)
89- 93 F5.2 [10-7W] logLt Log of total band (0.5-8keV) luminosity
in erg/s
95- 99 F5.2 [10-7W] logLtc ? Log of absorption-corrected total band
(0.5-8keV) luminosity in erg/s (G3)
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Note (1): Computed as (net counts)/(upper error on net counts).
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- [BFT2007] Source sequence number, sorted by RA
5- 22 A18 --- CXOUJ IAUC source name (HHMMSS.ss+DDMMSS.s)
(CXOU JHHMMSS.ss+DDMMSS.s in Simbad)
24- 26 I3 --- CEN ? Chini, Elsaesser & Neckel ID
(1980A&A....91..186C 1980A&A....91..186C)
(Cl* NGC 6618 CEN NNN in Simbad)
28- 36 A9 --- SpType MK Spectral type (1)
38- 40 I3 --- B ? Hanson, Howarth & Conti (1997ApJ...489..698H 1997ApJ...489..698H)
ID (Cl* NGC 6618 B NNN in Simbad) (2)
42- 57 A16 --- 2MASS The 2MASS designation
59- 61 A3 --- f_2MASS Flag on 2MASS (3)
63- 67 A5 --- SIRIUS SIRIUS catalog running sequence number (4)
69 A1 --- f_SIRIUS [a] Indicates a source outside the SIRIUS
field of view
71- 87 A17 --- GLIMPSE GLIMPSE designation (5)
89- 91 A3 --- Match The 2MASS/SIRIUS/GLIMPSE match flag (6)
93 A1 --- n_[BFT2007] [*] Indicates additional notes
(detailed in notes.dat)
95 A1 --- l_Jmag [>] Limit flag on Jmag
97-101 F5.2 mag Jmag ? The J band magnitude (7)
102 A1 --- u_Jmag Photometry error exceeds 0.1mag in Jmag
104 A1 --- l_Hmag [>] Limit flag on Hmag
106-110 F5.2 mag Hmag ? The H band magnitude (7)
111 A1 --- u_Hmag Photometry error exceeds 0.1mag in Hmag
113 A1 --- l_Kmag [>] Limit flag on Kmag
115-119 F5.2 mag Kmag ? The K band magnitude (7)
120 A1 --- u_Kmag Photometry error exceeds 0.1mag in Kmag
122-126 F5.2 mag 3.6mag ? GLIMPSE 3.6µm band magnitude (8)
128-132 F5.2 mag 4.5mag ? GLIMPSE 4.5µm band magnitude (8)
134-138 F5.2 mag 5.8mag ? GLIMPSE 5.8µm band magnitude (8)
140-144 F5.2 mag 8.0mag ? GLIMPSE 8.0µm band magnitude (8)
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Note (1): Spectral type follows the ID (CEN). Spectral types preceded by
"H:" come from Hanson, Howarth, & Conti (1997ApJ...489..698H 1997ApJ...489..698H); others
come from SIMBAD, then Chini, Elsaesser, & Neckel (1980A&A....91..186C 1980A&A....91..186C).
Note (2): Derived from Bumgardner (1992, M.S. thesis, Ohio State Univ.).
Note (3): These three characters report the 2MASS Contamination and
Confusion Flag (see Cat. II/246, or Explanatory Supplement at
http://www.ipac.caltech.edu/2mass/releases/allsky/doc/sec2_2a.html).
They are defined as follows:
p = persistence. Source may be contaminated by a latent image left
by a nearby bright star;
c = photometric confusion. Source photometry is biased by a nearby
star that has contaminated the background estimation. This is
very common in high source density regions;
d = diffraction spike confusion. Source may be contaminated by a
diffraction spike from a nearby star ;
s = electronic stripe. Source measurement may be contaminated by a
stripe from a nearby bright star;
b = bandmerge confusion. In the process of merging detections in
the different bands for this source, there was more than one
possible match between the different band components. This
occurs in regions of very high source density, or when
multiple sources were split in one band but not another;
0 = source is unaffected by known artifacts, or is not detected in band.
Note (4): From Jiang et al. (2002ApJ...577..245J 2002ApJ...577..245J).
Note (5): GLIMPSE (a Spitzer legacy science program) designation.
Sources are taken from the Highly Reliable Catalog, Version 1
at http://www.astro.wisc.edu/sirtf/glimpsedata.html.
Note (6): Match ambiguity flags. An "s" in the first/second/third position
indicates there are "secondary" (i.e. multiple) matches with the
2MASS/SIRIUS/GLIMPSE catalog respectively.
Note (7): Values are generally taken from SIRIUS when a match is
identified, or from 2MASS otherwise. However the bright sources #366,
701, 720, and 854 suffer saturation in the SIRIUS photometry so the
2MASS values are reported instead. Magnitudes have been corrected to
the CIT photometry system Elias et al. (1982AJ.....87.1029E 1982AJ.....87.1029E). 2MASS
values are annotated by > when the 2MASS Photometric Quality Flag
indicates a flux upper limit (flag=U), and are omitted when the flag
indicates poor photometry (flag=E).
Note (8): Median photometric errors for the reported counterparts are 0.13,
0.12, 0.16, 0.16mag in the four bands. Maximum errors are 0.34, 0.32,
0.34, 0.35mag.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [BFT2007] Source sequence number, sorted by RA
5- 80 A76 --- Note Text of note
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Global Notes:
Note (G1): 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.
Note (G2): All fits used the "wabs(apec)" (in table3) or the
"wabs(powerlaw)" (in table4) model in XSPEC and assumed 0.3Z☉
abundances. The emission measure for the model spectrum assumes a
distance of 1.6kpc.
Note (G3): Absorption-corrected luminosities are omitted when
logNH>22.5cm-2 since the soft band emission is essentially
unmeasurable.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 22-Dec-2008