J/A+A/423/1029 XMM-Newton obs, in Cha I South (Stelzer+, 2004)
XMM-Newton probes the stellar population in Chamaeleon I South.
Stelzer B., Micela G., Neuhaeuser R.
<Astron. Astrophys., 423, 1029-1044 (2004)>
=2004A&A...423.1029S 2004A&A...423.1029S
ADC_Keywords: X-ray sources ; Stars, pre-main sequence ; Equivalent widths
Keywords: X-rays: stars - stars: pre-main-sequence -
stars: low-mass, brown dwarfs - stars: coronae - stars: activity
Abstract:
We report on a 30ks XMM-Newton observation of the central region of
the Cha I star forming cloud. The field includes a substantial
fraction of the known pre-main-sequence population of Cha I South,
including all thirteen known very-low mass Hα emitters. We
detect two bona-fide brown dwarfs (spectral types M 7.5 and M 8) and
seven Hα emitting objects near the hydrogen burning mass limit,
including six of seven earlier detections by ROSAT.
Description:
A 30ks XMM-Newton observation centered on the candidate brown dwarf
ChaHα 3 was carried out on April 9, 2002 with the European
Photon Imaging Camera (EPIC) as prime instrument.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 118 58 X-ray sources detected in the EPIC observation
of Cha I at ML>20.
table35.dat 112 52 Optical and IR properties for all Cha I members
and candidate members in the XMM-Newton FOV,
and X-ray luminosities in the 0.4-2.5keV band
for d=160pc (tables 3 and 5 of the paper)
refs.dat 61 13 References
table4.dat 71 25 Spectral parameters of bright X-ray sources in
the Cha I XMM-Newton field.
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See also:
J/A+A/357/219 : ISOCAM observations in Cha I. (Persi+, 2000)
J/A+AS/114/109 : Cha X-ray sources + optical identifications (Alcala+ 1995)
J/AJ/121/974 : JHK photometry in Cha I (Gomez+, 2001)
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/A+A/416/555 : Brown Dwarfs in ChaI Dark Cloud (Lopez-Marti+ 2004)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- XName Designation, XMM-Cha I-NN
14- 16 A3 --- Instr Instrument (1)
18- 19 I2 h RAh X-ray right ascension (J2000)
21- 22 I2 min RAm X-ray right ascension (J2000)
24- 27 F4.1 s RAs X-ray right ascension (J2000)
29 A1 --- DE- X-ray declination sign (J2000)
30- 31 I2 deg DEd X-ray declination (J2000)
33- 34 I2 arcmin DEm X-ray declination (J2000)
36- 39 F4.1 arcsec DEs X-ray declination (J2000)
41- 47 F7.1 --- ML Maximum likelihood of source existence
49- 54 F6.1 ct Cts Number of broad band source counts
56- 59 F4.1 ct e_Cts rms uncertainty on Cts
61- 67 F7.1 s ExpTime Exposition time
69 A1 --- l_HR1 Limit flag on HR1
70- 74 F5.2 --- HR1 ? Hardness ratio, HR1 (2)
76- 79 F4.2 --- e_HR1 ? rms uncertainty on HR1
81 A1 --- l_HR2 Limit flag on HR2
82- 86 F5.2 --- HR2 ? Hardness ratio, HR2 (2)
88- 91 F4.2 --- e_HR2 ? rms uncertainty on HR2
93-108 A16 --- Name Optical/IR counterpart (3)
111-114 F4.1 arcsec OffOX ? Distance between the X-ray source and
the counterpart
115 A1 --- --- [/]
116-118 F3.1 arcsec OffOX2 ? Second offset between optical and X-ray
positions
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Note (1): Instruments as follows:
M 1 = EPIC-MOS 1 detector
M 2 = EPIC-MOS 2 detector
PN = EPIC-PN detector
ALL = EPIC-PN + EPIC-MOS 1 + EPIC-MOS 2 detectors
Note (2): For sources detected in the merged image we list the hardness
ratios computed from the corresponding source found in PN, and no
hardness ratio is computed if the source is detected only in the
merged image.
Note (3): Identification nomenclature:
BYB NN: Baud et al., 1984ApJ...278L..53B 1984ApJ...278L..53B
2M HHMMSS-DDMMSS: 2 MASS catalogue, Cat. II/246
CHXR-NN: Feigelson et al., 1993ApJ...416..623F 1993ApJ...416..623F, CHXR NN
CCE 98-NN: Cambresy et al., 1998A&A...338..977C 1998A&A...338..977C, [CCE98] 2-NN
ChaHαNN: Comeron et al., 2000A&A...359..269C 2000A&A...359..269C, [NC98] Cha HA N
KG 2001-NNN: Kenyon & Gomez, 2001, Cat. J/AJ/121/2673, [KG2001] NNN
HM NN: Henize & Mendoza, 1973ApJ...180..115H 1973ApJ...180..115H, Ass CHA T 1-NN
CHXR-NN: Feigelson & Kriss, 1989ApJ...338..262F 1989ApJ...338..262F, CHX NNa
Sz NN: Schwartz, 1977ApJS...35..161S 1977ApJS...35..161S
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Byte-by-byte Description of file: table35.dat
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Bytes Format Units Label Explanations
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1 A1 --- Memb [mc] Spectroscopically confirmed (m) Cha I
member or Photometric Cha I candidates (c)
3- 18 A16 --- Name Optical/IR designation
20- 23 A4 --- SpType MK spectral type
25 I1 --- r_SpType ? Reference for spectral type
27 A1 --- l_EWHa Limit flag on EWHa
28- 33 F6.1 0.1nm EWHa ? Hα equivalent width (1)
36- 40 F5.1 0.1nm EWHa2 ? Second value of Hα equivalent
width (1)
43- 44 I2 --- r_EWHa ? Reference for EWHa
45 A1 --- --- [/]
46 I1 --- r_EWHa2 ? Reference for EWHa2
48 A1 --- Vtype [WC-] TTS type (2)
50- 53 F4.2 mag A(IJ) Extinction, in I or J band, used to
derive Lbol
54 A1 --- u_A(IJ) Uncertainty flag on A(IJ)
55 A1 --- n_A(IJ) [*] Note on A(IJ) (3)
57- 61 F5.2 mag IJmag I or J magnitude used to derive Lbol
63 A1 --- Band [IJ] Band in which is the extinction and
the magnitude
65- 69 A5 --- r_IJmag Reference for magnitude
71- 75 F5.2 [solLum] logLbol Bolometric luminosity (4)
77- 80 F4.2 [K] logTeff Effective temperature (4)
82- 83 A2 --- l_Age [≤ ] Limit flag on Age
84- 87 F4.1 Myr Age ? Age (4)
89- 92 F4.2 solMass Mass ? Mass (4)
94 A1 --- l_logLX Limit flag on logLX
95- 99 F5.2 [10-7W] logLX ? X-ray luminosity in the 0.4-2.5keV band
for d=160pc
101 A1 --- f_logLX [LSN] Method used to derive LX (5)
103 A1 --- l_log(LX/Lbol) Limit flag on log(LX/Lbol)
104-108 F5.2 --- log(LX/Lbol) ? X-ray to bolometry flux ratio
110-112 I3 % KSProb ? Probability for variability of the
source according to the KS-test
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Note (1): The Hα equivalent width is negative for emission.
If more than one Hα measurement is available for a given star
we list the maximum and the minimum value observed.
Note (2): The T Tauri type is assigned on the basis of EWHα using
the criteria put forth by Martin (1998AJ....115..351M 1998AJ....115..351M).
Note (3): * indicates AJ calculated from the literature values for AV
using the Rieke & Lebofsky (1985ApJ...288..618R 1985ApJ...288..618R) extinction law.
Note (4): The bolometric luminosity, effective temperature, age and mass
have been computed as described in Sect. 3.3. Lbol has been calculated
for d=160pc. We assign an age of 5x105yr to objects on the
birthline.
Note (5): Method used to derive X-ray luminosity as follows:
S = spectral fit with 2-T model and column density fixed to the value
expected for the galactic NH-AV relation
L = absorption from the literature and logT[K]=6.95
N = absorption newly derived in this paper from JHK colors and
logT[K]=6.95
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 40 A17 --- Aut Author's name
42- 61 A20 --- Com Comments
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- XName Designation, XMM-Cha I-NN
16- 31 A16 --- Name Optical/IR designation
32- 35 I4 ct Counts Number of counts in the background-subtracted
spectrum
37- 40 F4.2 --- chi2 Reduced χ2 of best fit
42- 43 I2 --- DOF Degree Of Freedom
45- 48 F4.2 10+22cm-2 NH Absorbing hydrogen column density (1)
50- 53 F4.2 keV kT1 First X-ray temperature of 2-component
thermal MEKAL model
55- 59 F5.2 keV kT2 Second X-ray temperature of 2-component
thermal MEKAL model
61- 65 F5.2 [mW/m2] logEM1 Emission measure of first temperature
component (2)
67- 71 F5.2 [mW/m2] logEM2 Emission measure of second temperature
component (2)
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Note (1): Absorbing hydrogen column density derived from AJ using the
relation by Paresce (1984AJ.....89.1022P 1984AJ.....89.1022P) and held fixed during the
fitting process.
Note (2): Emission measures assuming a distance of 160 pc.
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Nomenclature Notes: KG 2001-101 = BYB 43; CHXR-76 = BYB 34
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Sep-2005