J/A+A/490/1055 Chandra survey of Tr 16 low-mass stars (Albacete-Colombo+, 2008)
An X-ray survey of low-mass stars in Trumpler 16 with Chandra.
Albacete-Colombo J.F., Damiani F., Micela G., Sciortino S., Harnden F.R.Jr
<Astron. Astrophys., 490, 1055-1070 (2008)>
=2008A&A...490.1055A 2008A&A...490.1055A
ADC_Keywords: Clusters, open ; Stars, early-type ; X-ray sources
Keywords: stars: formation - stars: early-type - stars: pre-main sequence -
X-rays: stars
Abstract:
We identify and characterize low-mass stars in the ∼3Myr old Trumpler
16 region by means of a deep Chandra X-ray observation, and study
their optical and near-IR properties. We compare the X-ray activity of
Trumpler 16 stars with the known characteristics of Orion and Cygnus
OB2 stars.
We analyzed a 88.4ks Chandra ACIS-I observation pointed at the center
of Trumpler 16. Because of diffuse X-ray emission, source detection
was performed using the PWDetect code for two different energy ranges:
0.5-8.0keV and 0.9-8.0keV. Results were merged into a single final
list. We positionally correlated X-ray sources with optical and 2MASS
catalogs. Source events were extracted with the IDL-based routine
ACIS-Extract. X-ray variability was characterized using the
Kolmogorov-Smirnov test and spectra were fitted by using XSPEC. The
X-ray spectra of early-type, massive stars were analyzed individually.
Our list of X-ray sources consists of 1035 entries, 660 of which have
near-IR counterparts and are probably associated with Trumpler 16
members.
Description:
Trumpler 16 was observed with the ACIS detector on board the Chandra
X-ray Observatory (CXO) on 2006 August 31 (obsId 6402), as part of the
Guaranteed Time Observation (GTO) Chandra program. The total effective
exposure time was 88.4ks.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 135 1035 Trumpler 16 source catalog
table2.dat 98 1035 Near-IR counterparts of Trumpler 16 X-ray sources
table3.dat 57 1035 X-ray spectral fits of Trumpler 16 sources
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/AJ/105/980 : Stellar content of Tr 14 and Tr 16 (Massey+ 1993)
J/ApJ/549/578 : BV photometry of Trumpler 14 and 16 (Degioia-Eastwood+, 2001)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [ADM2008] Sequential number
6- 23 A18 --- CXOTr16 Source designation (HHMMSS.ss+DDMMSS.s),
CXOTr16 JHHMMSS.ss+DDMMSS.s in Simbad
25- 26 I2 h RAh Right ascension (J2000)
28- 29 I2 min RAm Right ascension (J2000)
31- 35 F5.2 s RAs Right ascension (J2000)
37 A1 --- DE- Declination sign (J2000)
38- 39 I2 deg DEd Declination (J2000)
41- 42 I2 arcmin DEm Declination (J2000)
44- 48 F5.2 arcsec DEs Declination (J2000)
50- 53 F4.2 arcsec e_Pos Error in position
55- 59 F5.2 arcmin theta Off-axis angle from the aim point of the
observation
61- 66 F6.2 --- signi Significance of the source in number of
sigma over background
68- 71 I4 pix Area Source extraction area
73- 76 F4.2 % PSF PSF fraction within the extraction area,
assuming E=1.49keV
78- 82 I5 ct Ct Background-corrected extracted source counts
in the 0.5-8.0keV band (NetCounts)
84- 90 F7.3 ct/ks CRT Total count rate in the 0.5-8.0keV band
92- 98 F7.3 ct/ks CRS Soft count rate in the 0.5-2.0keV band
100-106 F7.3 ct/ks CRH Hard count rate in the 2.0-8.0keV band
108-111 F4.2 --- Q25 ?=- Source photon quantile at 25%
113-116 F4.2 --- Q50 Source photon quantile at 50%
118-121 F4.2 --- Q75 ?=- Source photon quantile at 75%
123-126 F4.2 keV Ex Median photon energy
128-132 F5.2 [-] logPks ?=- Kolmogorov-Smirnov probability of
non-variability
134-135 I2 --- Flag Flag from PWDetect detection code (1)
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Note (1): Flag as follows:
-1 = sources detected only in the 0.9-8.0 keV band
-2 = sources detected in both bands, Sig(0.9-8.0)>Sig(0.5-8.0)
-3 = sources detected in both bands, Sig(0.9-8.0)<Sig(0.5-8.0)
-4 = sources detected only in the 0.5-8.0 keV band
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [ADM2008] Sequential number
6- 21 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs),
2MASS JHHMMSSss+DDMMSSs in Simbad
23- 26 F4.2 arcsec Offset ? Offset X-ray to 2MASS source
28 A1 --- l_Jmag Limit lfag on Jmag
29- 33 F5.2 mag Jmag ? 2MASS J magnitude
35- 38 F4.2 mag e_Jmag ? rms uncertainty on Jmag
40 A1 --- l_Hmag Limit flag on Hmag
41- 45 F5.2 mag Hmag ? 2MASS H magnitude
47- 50 F4.2 mag e_Hmag ? rms uncertainty on Hmag
52 A1 --- l_Ksmag Limit flag on Ksmag
53- 57 F5.2 mag Ksmag ? 2MASS Ks magnitude
59- 62 F4.2 mag e_Ksmag ? rms uncertainty on Ksmag
64- 66 A3 --- Qual ?=- 2MASS JHKs quality flag (1)
68- 70 A3 --- Cflg Artifact contamination, confusion (2)
72- 76 F5.2 mag AV ? Absorption in V band
78- 82 F5.2 solMass Mass ?=- Estimated source Mass
84- 98 A15 --- n_Mass Notes (3)
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Note (1): Three character flag, one character per band [JHK], that provides a
summary of the net quality of the default photometry in each band.
A = Detections in any brightness regime where valid measurements were
made (Rflg="1","2" or "3") with [jhk]snr>10 AND [jhk]cmsig<0.10857.
B = Detections in any brightness regime where valid measurements were
made (Rflg="1","2" or "3") with [jhk]snr>7 AND [jhk]cmsig<0.15510.
C = Detections in any brightness regime where valid measurements were
made (Rflg="1","2" or "3") with [jhk]snr>5 AND [jhk]cmsig<0.21714.
D = Detections in any brightness regime where valid measurements were
made (Rflg="1","2" or "3") with no [jhk]snr OR [jhk]cmsig requirement
E = This category includes detections where the goodness-of-fit
quality of the profile-fit photometry was very poor (Rflg=2 and
[jhk]psfchi>10.0), or detections where psf fit photometry did not
converge and an aperture magnitude is reported (Rflg=4), or
detections where the number of frames was too small in relation to
the number of frames in which a detection was geometrically
possible (Rflg="1" or Rflg="2").
U = Upper limit on magnitude.
Note (2): Contamination and confusion flag. Three character flag, one character
per band [JHKs], that indicates that the photometry and/or position
measurements of a source may be contaminated or biased due to
proximity to an image artifact or nearby source of equal or greater
brightness.
0 = Source is unaffected by known artifacts, or is not detected
in the band
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
p = Persistence. Source may be contaminated by a latent image left
by a nearby bright star
s = Electronic stripe. Source measurement may be contaminated by a
stripe from a nearby bright star
Note (3): The "Mass-deg." flag indicates mass degeneracy according to a
Siess-based Jmag-Mass calibration
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [ADM2008] Sequential number
6- 10 I5 --- Ct3 Net counts
12- 16 F5.2 --- chi2 ?=- Best-fit χ2 value
18- 22 F5.2 [cm-2] logNH ?=- Best-fit hydrogen column density
24- 27 F4.2 [cm-2] e_logNH ?=- rms uncertainty on logNH
29- 33 F5.2 keV kT ?=- Best-fit plasma temperature
35- 38 F4.2 keV e_kT ?=- rms uncertainty on kT
39 A1 --- n_kT [*] * for upper limit
41- 45 F5.2 [10-7W] logLX Best-fit X-ray luminosity
47- 57 A11 --- Notes Other name or comments
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Jan-2009