J/A+A/555/A83 X-ray properties of HM1 and IC2944/2948 (Naze+, 2013)
X-ray properties of the young open clusters HM1 and IC 2944/2948.
Naze Y., Rauw G., Sana H., Corcoran M.F.
<Astron. Astrophys. 555, A83 (2013)>
=2013A&A...555A..83N 2013A&A...555A..83N
ADC_Keywords: Clusters, open ; X-ray sources
Keywords: X-rays: stars - stars: early-type -
open clusters and associations: individual: HM1 -
open clusters and associations: individual: IC2944 -
open clusters and associations: individual: IC2948
Abstract:
Using XMM-Newton data, we study for the first time the X-ray emission
of HM1 and IC2944/2948. Low-mass, pre-main sequence objects with an
age of a few Myr are detected, as well as a few background or
foreground objects. Most massive stars in both clusters display the
usual high-energy properties of that kind of objects, though with
log(Lx/Lbol) apparently lower in HM1 than in IC2944/2948. Comparing
with studies of other clusters, it seems that low S/N at soft
energies, due to the high extinction, may the main cause of this
difference. In HM1, the two Wolf-Rayet stars show contrasting
behaviours: WR89 is extremely bright, but much softer than WR87. It
remains to be seen whether wind-wind collisions or magnetically
confined winds can explain such emissions. In IC2944/2948, the X-ray
sources concentrate around HD101205; a group of massive stars to the
north of this object appears rather isolated, suggesting that there
exist two subclusters in the field-of-view.
Description:
The tables provide the list of detected sources in both clusters, with
their basic properties (position, count rates, hardness ratios) and
with their probable counterparts (distance, name).
XMM-Newton has observed HM1 for 25ks on Rev. 1877 (with MEDIUM filter)
and IC 2944/2948 for 40ks on Rev. 2209 (with THICK filter). Our
XMM-Newton observation reveals only 58 sources for HM1, of which 7 may
be spurious as they are not even clearly detected by eye (Fig. 1 and
Table 1).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 157 58 Parameters of the detected X-ray sources in HM1
table3.dat 126 368 Parameters of detected X-ray sources in IC2944/2948
table4.dat 96 261 Counterparts of the X-ray sources of IC2944/2948
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See also:
B/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2013)
B/xmm : XMM-Newton Observation Log (XMM-Newton Science Operation Center, 2012)
VII/239 : History and Accurate Positions for the NGC/IC Objects (Corwin, 2004)
VII/101 : Star Clusters/Associations. III. Open Clusters (Ruprecht+ 1983)
J/A+AS/146/251 : Open clusters absolute proper motions. I. (Baumgardt+, 2000)
J/A+A/371/908 : Havlen-Moffat No. 1 UBVRI photometry (Vazquez+, 2001)
J/A+A/388/168 : Absolute proper motions of 93 open clusters (Dias+, 2002)
J/AJ/125/1397 : Kinematics, age and abundances of open clusters (Chen+, 2003)
J/ApJS/161/118 : byHα photometry in open clusters (McSwain+, 2005)
J/ApJ/648/591 : Stellar rotation in young clusters. II. (Huang+, 2006)
J/ApJ/648/580 : Rotational velocities in 19 open clusters (Huang+, 2006)
J/AJ/131/1559 : Diameters of Galactic open clusters (van den Bergh+, 2006)
J/AN/328/889 : Mean Radial Velocities of open clusters (Kharchenko+, 2007)
J/MNRAS/416/817 : RV catalog of O-type stars in IC 2944 & Cen OB2 (Sana+, 2011)
J/A+A/548/A97 : Catalogue of variable stars in open clusters (Zejda+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- XID [1/58] Identifier
4 A1 --- u_XID [?] Uncertainty flag on XID (1)
6- 7 I2 h RAh X-ray Right ascension (J2000)
9- 10 I2 min RAm X-ray Right ascension (J2000)
12- 17 F6.3 s RAs X-ray Right ascension (J2000)
19 A1 --- DE- X-ray Declination sign (J2000)
20- 21 I2 deg DEd X-ray Declination (J2000)
23- 24 I2 arcmin DEm X-ray Declination (J2000)
26- 30 F5.2 arcsec DEs X-ray Declination (J2000)
32- 37 F6.2 ct/ks Cm1 ? Count rate for MOS1 (0.3-10keV) (G1)
39- 42 F4.2 ct/ks e_Cm1 ? Error on MOS1 count rate
44 A1 --- u_Cm1 Uncertainty flag on Cm1 (G1)
46- 51 F6.2 ct/ks Cm2 ? Count rate for MOS2 (0.3-10keV) (G1)
53- 56 F4.2 ct/ks e_Cm2 ? Error on MOS2 count rate
58 A1 --- u_Cm2 Uncertainty flag on Cm2 (G1)
60- 65 F6.2 ct/ks Cpn ? Count rate for pn (0.3-10keV) (G1)
67- 70 F4.2 ct/ks e_Cpn ? Error on pn count rate
72 A1 --- u_Cpn Uncertainty flag on Cpn (G1)
74- 78 F5.2 --- HR1 [-1/1]? Hardness Ratio M/S for pn (G2)
80- 84 F5.2 --- e_HR1 ? Error on HR1
86- 90 F5.2 --- HR2 [-1/1]? Hardness Ratio H/M for pn (G2)
92- 95 F4.2 --- e_HR2 ? Error on HR2
97- 99 F3.1 arcsec Dist1 ? Distance from VB counterpart (2)
102-104 I3 --- VB [1/440]? Number in VB catalog (2)
108-110 F3.1 arcsec Dist2 ? Distance from 2MASS counterpart
112-127 A16 --- 2MASS Name of 2MASS counterpart
131-157 A27 --- Com Additional informations (other name,
spectral type)
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Note (1): A "?" after the XID indicates a potentially spurious source.
Sources 34 and 21 actually refer to the same object, whereas sources 14, 15,
36 and 43 are in the wings of source 1 and source 16 appears also as a wing
of source 3.
Note (2): The VB catalog comes from Vazquez & Baume (2001, Cat. J/A+A/371/908;
<Cl* HM 1 VB NNN> in Simbad).
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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 --- XID [1/368] Identifier
4- 6 A3 --- u_XID [? ext] Uncertainty flag on XID (1)
8- 9 I2 h RAh X-ray Right ascension (J2000)
11- 12 I2 min RAm X-ray Right ascension (J2000)
14- 19 F6.3 s RAs X-ray Right ascension (J2000)
21 A1 --- DE- X-ray Declination sign (J2000)
22- 23 I2 deg DEd X-ray Declination (J2000)
25- 26 I2 arcmin DEm X-ray Declination (J2000)
28- 32 F5.2 arcsec DEs X-ray Declination (J2000)
34- 35 I2 h RACh Corrected right ascension (J2000) (2)
37- 38 I2 min RACm Corrected right ascension (J2000) (2)
40- 45 F6.3 s RACs Corrected right ascension (J2000) (2)
47 A1 --- DEC- Corrected declination sign (J2000) (2)
48- 49 I2 deg DECd Corrected declination (J2000) (2)
51- 52 I2 arcmin DECm Corrected declination (J2000) (2)
54- 58 F5.2 arcsec DECs Corrected declination (J2000) (2)
60- 66 F7.3 ct/ks Cm1 ? Count rate for MOS1 (G1)
68- 72 F5.3 ct/ks e_Cm1 ? Error on MOS1 count rate
74- 80 F7.3 ct/ks Cm2 ? Count rate for MOS2 (G1)
82- 86 F5.3 ct/ks e_Cm2 ? Error on MOS2 count rate
88- 94 F7.3 ct/ks Cpn ? Count rate for pn (G1)
96-100 F5.3 ct/ks e_Cpn ? Error on pn count rate
102-107 F6.3 --- HR1 ? Hardness Ratio M/S for pn (G2)
109-113 F5.3 --- e_HR1 ? Error on HR1
115-120 F6.3 --- HR2 ? Hardness Ratio H/M for pn (G2)
122-126 F5.3 --- e_HR2 ? Error on HR2
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Note (1): A '?' indicates probably spurious sources, whereas 'ext' refers to
an extended source.
Note (2): When the position of the massive O-stars of the field is superposed to
the X-ray image, a shift is clearly seen. Comparing the Hipparcos positions of
the massive O-stars with their associated X-ray sources (excluding HD101413
and HD101436, which are heavily distorted because of their off-axis position),
we found an average shift of RAHip-RAXMM=0.45s and DEHip-DEXMM=0.41"
in declination. We thus corrected the coordinates of the X-ray sources by
adding these values to the ones found by the detection algorithm (these values
appear in the "corrected" RA and DE columns), and only then correlated with
other existing catalogs.
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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- 3 I3 --- XID [1/367] Identifier
4 A1 --- f_XID [+] More than one 2MASS counterpart (1)
6- 10 F5.3 arcsec Dist1 Distance from 2MASS counterpart
12- 27 A16 --- 2MASS Name of 2MASS counterpart
29- 32 F4.2 arcsec Dist2 ? Distance from MG counterpart (2)
34- 36 I3 --- MG [8/110]? Number in MG catalog (2)
38- 42 F5.1 0.1nm EWHa ? Equivalent width of Hα in MG catalog (2)
44- 47 F4.2 arcsec Dist3 ? Distance from Simbad counterpart
49- 70 A22 --- SName Name of Simbad counterpart
72- 96 A25 --- Com Additional informations (sp. type, period...) (3)
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Note (1): A '+' indicates the presence of a second 2MASS counterpart within 3",
at a larger distance than the first one listed here.
Note (2): The MG catalog is from McSwain & Gies (2005, Cat. J/ApJS/161/118;
<Cl* IC 2944 MG NNN> for Simbad). Their data were converted into Hα
equivalent widths using formula (4) of McSwain & Gies (2005ApJ...622.1052M 2005ApJ...622.1052M).
Equivalent widths are positive for Hα absorption. In six cases, Hα
can be considered in emission as the absolute equivalent widths exceed 10Å.
Note that for XID=100, there is a second counterpart in the MG catalog: MG 23,
at 2.38", which has an equivalent width of -13.0Å.
Note (3): Spectral types come from Sana et al. (2011, Cat. J/MNRAS/416/817)
for O-stars, from Simbad otherwise. The last 21 rows correspond to
potentially spurious sources ('?' in Table 3).
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Global Notes:
Note (G1): The count rates are given in counts per kiloseconds for the total
band (0.3-10keV energy band), and uncertain values are indicated by a ":"
(source partially in a gap); missing values could not be calculated (e.g.
the source is in a gap, over a bad column, or out of the field-of-view for
that instrument).
Note (G2): Three energy bands (soft=S=0.3-1.0keV, medium=M=1.0-2.0keV,
hard=H=2.0-10.0keV) were defined and used to compute 2 hardness ratios:
HR1=(M-S)/(M+S) and HR2=(H-M)/(H+M).
Acknowledgements:
Yael Naze, ynaze(at)uliege.be
(End) Yael Naze [Univ. of Liege], Patricia Vannier [CDS] 21-May-2013