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 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:
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FileName Lrecl Records Explanations
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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
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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
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Bytes Format Units Label Explanations
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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 1993ApJ...416..623F)
41- 47 A7 --- Star Stellar counterpart (3)
49- 51 F3.1 arcsec X-IR ? Offset between Chandra and 2MASS positions
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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.
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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- 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
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Note (1): The analysis used acis_extract, version 1.1, for extraction and
variability analysis, see
http://www.astro.psu.edu/xray/docs/TARA/ae_users_guide.html
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.
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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- 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
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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.
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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.
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History:
From electronic version of the journal
(End) Marianne Brouty [CDS] 19-Oct-2005