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J/ApJ/614/267     Chandra sources in Cha I North              (Feigelson+, 2004)

An X-ray census of young stars in the Chamaeleon I North cloud. Feigelson E.D., Lawson W.A. <Astrophys. J., 614, 267-283 (2004)> =2004ApJ...614..267F
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; X-ray sources ; Photometry, infrared Keywords: open clusters and associations: individual (Chamaeleon I) - stars: low-mass, brown dwarfs - stars: luminosity function, mass function - stars: pre-main-sequence - X-rays: stars Abstract: Sensitive X-ray imaging surveys provide a new and effective tool to establish the census of pre-main-sequence (PMS) stars in nearby young stellar clusters. We report here a deep Chandra X-Ray Observatory observation of PMS stars in the Chamaeleon I North cloud, achieving a limiting luminosity of log Lt∼27ergs/s (0.5-8keV band) in a 0.8x0.8pc2 region. Of the 107 X-ray sources, 37 are associated with Galactic stars of which 27 are previously recognized cloud members. Description: A 16'x16' region of the Cha I North cloud was observed with the imaging array of the Advanced CCD Imaging Spectrometer (ACIS-I) detector on board the Chandra X-Ray Observatory. The observation took place on 2001 July 2.25-3.04UT. We also obtained VI-band CCD images of most of the ACIS field with the 1m telescope and CCD detector at the South African Astronomical Observatory (SAAO) during 2002 February. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 51 107 Chandra sources and counterparts in Cha I North table2.dat 57 37 X-ray properties of Chandra Cha I North stellar sources table3.dat 92 37 Optical-infrared properties of Chandra Cha I North stellar sources
See also: I/284 : The USNO-B1.0 Catalog (Monet+ 2003) II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) B/denis : The DENIS database (DENIS Consortium, 2005) J/AJ/124/1001 : JHKs photometry of Cha I variables (Carpenter, 2002) J/AJ/121/2673 : 3µm survey of the Chamaeleon I dark cloud (Kenyon+, 2001) J/AJ/121/974 : JHK photometry in Cha I (Gomez+, 2001) J/A+AS/114/109 : Cha X-ray sources + optical identifications (Alcala+ 1995) J/A+A/423/1029 : XMM-Newton obs, in Cha I South (Stelzer+, 2004) J/A+A/416/555 : Brown Dwarfs in ChaI Dark Cloud (Lopez-Marti+ 2004) J/A+A/357/219 : ISOCAM observations in Cha I. (Persi+, 2000) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [FL2004] Source designation 4 A1 --- f_[FL2004] [a] Flag on [FL2004] (G1) 5- 6 I2 h RAh Hour of Right Ascension (J2000.0) (1) 8- 9 I2 min RAm Minute of Right Ascension (J2000.0) (1) 11- 14 F4.1 s RAs Second of Right Ascension (J2000.0) (1) 16 A1 --- DE- Sign of the Declination (J2000.0) (1) 17- 18 I2 deg DEd Degree of Declination (J2000.0) (1) 20- 21 I2 arcmin DEm Arcminute of Declination (J2000.0) (1) 23- 26 F4.1 arcsec DEs Arcsecond of Declination (J2000.0) (1) 28- 31 F4.1 arcmin theta Off-axis angle 33- 36 I4 ct counts Background-subtracted extracted counts (2) 38- 39 I2 --- CHRX ? Cross-reference to earlier ROSAT sources (Feigelson et al., 1993ApJ...416..623F) 41- 47 A7 --- Star Stellar counterpart (3) 49- 51 F3.1 arcsec X-IR ? Offset between Chandra and 2MASS positions
Note (1): Position (J2000.0) from the ACIS image aligned to 2MASS sources. Generally, positions are accurate to less than 0.3" for off-axis angle θ<5'and more than 100 counts. Positional accuracy degrades to ∼1" for fainter on-axis sources and to 2"-3" for sources far off-axis (θ>10'). Note (2): The 0.5-8keV events in the 95% enclosed-energy polygon after subtracting background and rounding to the nearest integer obtained from acis_extract. Note (3): Name from the cloud membership list by Carpenter et al. (2002, Cat. J/AJ/124/1001). "Field" indicates previously unremarked stellar counterparts. The remainder of the X-ray sources are probably extragalactic.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [FL2004] Source identification 4 A1 --- f_[FL2004] [a] Flag on [FL2004] (G1) 5- 11 A7 --- OName Other name 13- 16 I4 ct CX CX events (1) 18- 19 I2 ct BX BX values, background counts scaled to the extraction region (1) 21 A1 --- Var [a-c] Variability indicator (1) (2) 23- 26 F4.1 [cm-2] logNH Hydrogen column density 27 A1 --- u_logNH Uncertainty flag on logNH 29- 32 F4.1 keV kT1 Plasma energy 33 A1 --- u_kT1 Uncertainty flag on kT1 35- 37 F3.1 keV e_kT1 ? Error in kT1 39- 41 F3.1 keV kT2 ? Plasma energy 43- 46 F4.1 [10-7W] logLs Log of X-ray luminosity Ls in the soft 0.5-2keV band (3) 48- 51 F4.1 [10-7W] logLt Log of X-ray luminosity Lt in the total 0.5-8keV band (3) 53- 56 F4.1 [10-7W] logLc ? Absorption-corrected luminosity Lc
Note (1): The analysis used acis_extract, version 1.1, for extraction and variability analysis, see Note (2): The variability indicator based on the arrival times of the extracted events. It is coded to the probability of the Kolmogorov-Smirnov test PKS that the source has no significant variation during the exposure, as follows: a = PKS>0.05 (no evidence for variability), b = 0.005>PKS>0.05 (possibly variable), c = PKS<0.005 (definitely variable). Note (3): The X-ray luminosities assume the star lies at a distance of 160pc.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [FL2004] Source designation 5- 11 A7 --- OName Star name 13- 18 A6 --- Prop Property flag (1) 20- 25 A6 --- Class Classification type (2) 27- 30 F4.1 mag Rmag ? USNO-B1.0 (Cat. I/284) R magnitude 32- 36 F5.2 mag Imag ? i or I magnitude (3) 38- 42 F5.2 mag Jmag 2MASS J magnitude 43 A1 --- u_Jmag Uncertainty flag on Jmag 45- 49 F5.2 mag Hmag 2MASS H magnitude 50 A1 --- u_Hmag Uncertainty flag on Hmag 52 A1 --- l_Kmag Limit flag on Kmag 53- 57 F5.2 mag Kmag 2MASS K magnitude 58 A1 --- u_Kmag Uncertainty flag on Kmag 60- 64 F5.2 mag m6.7 ? 6.7µm band magnitude (4) 66- 69 F4.2 mag m14.3 ? 14.3µm band magnitude (4) 71- 75 A5 --- SpType Spectral type 77- 82 F6.3 solLum Lbol ? Bolometric luminosity 83 A1 --- u_Lbol [?] Uncertainty flag on Lbol 84- 87 F4.2 solMass Mass ? Mass 88 A1 --- u_Mass Uncertainty flag on Mass 90 A1 --- l_Age Limit flag on Age 91- 92 I2 Myr Age ? Age
Note (1): Six-character flag indicating the properties of that star from Carpenter et al. (2002, Cat. J/AJ/124/1001): variable in optical or K, Hα emission, Li absorption, X-ray source (prior to the present study), infrared excess, and far-infrared source. Note (2): The classification type, defined as follows: WTT = weak-lined T Tauri star CTT = classical T Tauri star I = imbedded BD = brown dwarf AB = Herbig AeBe star Note (3): i or I magnitudes from the second DENIS data release (Cat. B/denis) or our SAAO I survey (this paper). Note (4): 6.7 and 14.3µm magnitudes from the Infrared Space Observatory survey.
Global Notes: Note (G1): "a" indicates that source 105 lies at the edge of the ACIS detector where, because of the broad telescope point-spread function and satellite dithering, many of the source photons may be lost. This can result in an underestimate of the source luminosity and an apparent positional offset of the centroid.
History: From electronic version of the journal
(End) Marianne Brouty [CDS] 19-Oct-2005
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