J/ApJ/589/509 Chandra observations of Trumpler 14 and 16 (Evans+, 2003)
Chandra observations of associates of η Carinae. I. Luminosities.
Evans N.R., Seward F.D., Krauss M.I., Isobe T., Nichols J., Schlegel E.M.,
Wolk S.J.
<Astrophys. J. 589, 509 (2003)>
=2003ApJ...589..509E 2003ApJ...589..509E
ADC_Keywords: Clusters, open ; X-ray sources ; Photometry
Keywords: open clusters and associations: individual: Trumpler 14, Trumpler 16 -
X-rays: stars
Abstract:
The region around the η Carinae Nebula has three OB associations,
which contain a Wolf-Rayet star and several massive O3 stars. An early
Chandra ACIS-I image was centered on η Car and includes Trumpler
16 and part of Trumpler 14. The Chandra image confirms the well-known
result that O and very early B stars are X-ray sources with
LX~=10-7Lbol over an X-ray luminosity range of about 100. Two new,
anomalously strong X-ray sources have been found among the hot star
population: Tr 16-244, a heavily reddened O3 I star, and Tr 16-22, a
heavily reddened O8.5 V star. Two stars have an unusually large
LX/Lbol: HD 93162, a Wolf-Rayet star (and possible binary), and
Tr 16-22, a possible colliding-wind binary. In addition, a population
of sources associated with cool stars is detected. In the
color-magnitude diagram, these X-ray sources sit above the sequence of
field stars in the Carina arm. The OB stars are on average more X-ray
luminous than the cool star X-ray sources. X-ray sources among A stars
have X-ray luminosities similar to those of cooler stars and may be
due to cooler companions. Upper limits are presented for B stars that
are not detected in X-rays. These upper limits are also the upper
limits for any cool companions that the hot stars may have. Hardness
ratios are presented for the most luminous sources in bands 0.5-0.9,
0.9-1.5, and 1.5-2.04keV. The available information on the binary
nature of the hot stars is discussed, but binarity does not correlate
with X-ray strength in a simple way.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tab12.dat 83 154 X-Ray Sources: OB stars and Not OB Stars
(tables 1 and 2 of the paper)
tab34.dat 55 154 X-Ray Sources: Hardness Ratios:
OB Stars and Not OB stars
(tables 3 and 4 of the paper)
table5.dat 53 132 Photometry of Low Mass X-ray sources
tab68.dat 68 23 X-Ray Sources: Hot Star Identifications and
Binaries Velocities (tables 6 and 8 of the paper)
table7.dat 74 32 Non-detections: OB Stars
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See also:
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)
J/A+AS/116/75 : Region of the open cluster Tr 14 (Vazquez+, 1996)
J/AJ/105/1822 : Open clusters near eta Car (Cudworth+ 1993)
Byte-by-byte Description of file: tab12.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Sample [N OB] OB: OB stars, NOB: Not OB stars
5- 7 I3 --- [ESK2003] Source number
9- 10 I2 h RAh Hour of Right Ascension (J2000)
12- 13 I2 min RAm Minute of Right Ascension (J2000)
15- 19 F5.2 s RAs Second of Right Ascension (J2000)
21 A1 --- DE- Sign of the Declination (J2000)
22- 23 I2 deg DEd Degree of Declination (J2000)
25- 26 I2 arcmin DEm Arcminute of Declination (J2000)
28- 31 F4.1 arcsec DEs Arcsecond of Declination (J2000)
33- 36 F4.1 arcmin Rad The radial distance from the aim point
38- 43 F6.1 ct TCts Total counts from 0.5 to 2.04keV
45- 48 F4.1 ct e_TCts Error in TCts (1)
50- 54 F5.1 ct SCts Soft counts from 0.5 to 0.9keV
56- 59 F4.1 ct e_SCts Error in SCts (1)
61- 66 F6.1 ct MCts Medium counts from 0.9 to 1.5keV
68- 71 F4.1 ct e_MCts Error in MCts (1)
73- 78 F6.1 ct HCts Hard counts from 1.5 to 2.04keV
80- 83 F4.1 ct e_HCts Error in HCts (1)
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Note (1): Computed by DMEXTRACT using Poisson statistics.
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Byte-by-byte Description of file: tab34.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Sample [N OB] OB: OB stars, NOB: Not OB stars
5- 7 I3 --- [ESK2003] Source number
9- 13 F5.2 --- HRMS The (Medium-Soft)/(Medium+Soft) ratio
15- 18 F4.2 --- e_HRMS Error on HRMS (1)
20- 24 F5.2 --- HRHM ? The (Hard-Medium)/(Hard+Medium) ratio
26- 29 F4.2 --- e_HRHM ? Error on HRHM (1)
31- 36 F6.2 [mW/m2] logFX Log of the X-ray Flux in erg/cm2/s (2)
39- 43 F5.2 [mW/m2] e_logFX Error on logFX
45- 49 F5.2 [10-7W] logLX Log of the X-ray luminosity in erg/s (2)
51- 55 F5.2 [10-7W] e_logLX Error in logLX
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Note (1): Errors have been propagated from the errors on the energy bands.
Note (2): Fluxes and luminosities have been calculated from total count rates.
PIMMS (Portable Interactive Multi-Mission Simulator) was used to
calculate a conversion from counts to energy. The count rates were
calculated on the basis of 9.630ks of good time. A Raymond-Smith
plasma model spectrum with logT=6.65 was used, a spectrum typical of a
stellar source found in young associations. The extinction is fairly
uniform over the field. A column of NH=3x1021cm-2 was adopted,
corresponding to E(B-V)=0.52mag, which is typical of the field (Massey
& Johnson, 1993, Cat. J/AJ/105/980). With these parameters, a
conversion factor of 1.4x10-11ergs/cm2/s (counts/s) was derived.
Conversion factors differed by less than a factor of 2 for a range of
logT from 6.4 to 7.1. Luminosities were derived from fluxes using a
distance of 2.5kpc
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [ESK2003] X-Ray identification
5- 6 I2 h RAh Hour of Right Ascension (J2000)
8- 9 I2 min RAm Minute of Right Ascension (J2000)
11- 15 F5.2 s RAs Second of Right Ascension (J2000)
17 A1 --- DE- Sign of the Declination (J2000)
18- 19 I2 deg DEd Degree of Declination (J2000)
21- 22 I2 arcmin DEm Arcminute of Declination (J2000)
24- 27 F4.1 arcsec DEs Arcsecond of Declination (J2000)
29- 33 F5.3 mag B-V ? The (B-V) color index
35- 40 F6.3 mag Vmag ? The V band magnitude
42- 46 F5.3 mag V-Ic ? The (V-Ic) color index
48- 52 A5 --- n_[ESK2003] Individual notes (1)
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Note (1): Notes are numbered as follows:
1 = Two stars;
1a = Not resolved; not plotted;
1b = Not resolved; estimated combined magnitude;
1c = Resolved; position match poor; not plotted;
1d = Resolved; likely source used;
2 = High background;
3 = Contamination from nearby bright star;
4 = Uncertain identification;
5 = Faint star;
6 = The star is overexposed. V<12.5;
7 = Outside the observed fields.
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Byte-by-byte Description of file: tab68.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Optical identification (1)
16- 18 I3 --- [ESK2003] ? Sequential number
20- 24 F5.2 mag Vmag V magnitude (1)
26- 32 A7 --- SpType MK spectral type
34- 37 F4.2 mag E(B-V) Extinction in B-V (1)
39- 43 F5.1 mag Mbol Bolometric magnitude (2)
45- 49 F5.2 [---] log(LX/Lbol) X-ray luminosity to bolometric luminosity
ratio
52 A1 --- Bin [YN] Binary status
53 A1 --- u_Bin Uncertainty flag on Bin
55- 57 F3.1 d Porb ? Orbital period
58 A1 --- --- [,]
60- 62 F3.1 d Porb2 ? Second orbital period
65- 68 A4 --- r_Porb Reference for Porb, separated by comma (3)
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Note (1): From Massey & Johnson, 1993, Cat. J/AJ/105/980
Note (2): From Massey et al., 2001AJ....121.1050M 2001AJ....121.1050M
Note (3): References for orbital period are numbered as follows:
1 = Penny et al., 1993PASP..105..588P 1993PASP..105..588P
2 = Levato et al., 1991ApJS...75..869L 1991ApJS...75..869L
3 = Morrell et al., 2001MNRAS.326...85M 2001MNRAS.326...85M
4 = Albacete Colombo et al., 2001MNRAS.326...78A 2001MNRAS.326...78A
5 = Albacete Colombo et al., 2002MNRAS.336.1099A 2002MNRAS.336.1099A
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq Source number,
[ESK2003] NotDetected NN in Simbad
4- 5 I2 h RAh Right ascension (J2000.0)
7- 8 I2 min RAm Right ascension (J2000.0)
10- 14 F5.2 s RAs Right ascension (J2000.0)
16 A1 --- DE- Declination sign (J2000.0)
17- 18 I2 deg DEd Declination (J2000.0)
20- 21 I2 arcmin DEm Declination (J2000.0)
23- 26 F4.1 arcsec DEs Declination (J2000.0)
28- 31 F4.1 ct CountsSA Source area counts
33- 35 F3.1 ct e_CountsSA rms uncertainty on e_CountsSA
37- 41 F5.1 ct CountsBA Background area counts
43- 46 F4.1 ct e_CountsBA rms uncertainty on e_CountsBA
49- 53 F5.1 ct Counts Net counts
55- 57 F3.1 ct e_Counts rms uncertainty on Counts
59- 62 F4.1 arcmin Rad Radius
64- 67 A4 --- SpType MK Spectral type
69- 74 F6.3 [10-7W] logLX Upper limit of X-ray luminosity
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 24-Jun-2003