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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
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:
FileName Lrecl Records Explanations
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
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
Bytes Format Units Label Explanations
1- 4 I4 --- [ADM2008] Sequential number 6- 23 A18 --- CXOTr16 Source designation (, CXOTr16 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)
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
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
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)
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
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
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
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Jan-2009
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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