J/ApJ/675/464 Chandra observations of NGC 2244 (Wang+, 2008)
A Chandra study of the Rosette star-forming complex.
I. The stellar population and structure of the young open cluster NGC 2244.
Wang J., Townsley L.K., Feigelson E.D., Broos P.S., Getman K.V.,
Roman-Zuniga C.G., Lada E.
<Astrophys. J., 675, 464-490 (2008)>
=2008ApJ...675..464W 2008ApJ...675..464W
ADC_Keywords: Clusters, open ; X-ray sources ; Cross identifications
Keywords: ISM: individual (Rosette Nebula) -
open clusters and associations: individual (NGC 2244) -
stars: formation - stars: luminosity function, mass function -
stars: pre-main sequence - X-rays: stars -
ISM: individual objects (Rosette Nebula)
Abstract:
We present the first high spatial resolution X-ray study of NGC 2244,
the 2Myr old stellar cluster in the Rosette Nebula, using Chandra.
Over 900 X-ray sources are detected; 77% have optical or FLAMINGOS NIR
stellar counterparts and are mostly previously uncataloged young
cluster members.
Description:
The Rosette complex was observed with the Imaging Array of the Chandra
Advanced CCD Imaging Spectrometer (ACIS-I).
The entire observation consisted of four ∼20ks ACIS-I snapshots in
2001 January (T03, Fig. 2), a deep 75ks ACIS-I image in 2004 January
centered on the O5 star HD 46150 in NGC 2244 (Fig. 2a), and one 20ks
ACIS-I pointing at the twin cluster to NGC 2244 (Li,
2005ApJ...625..242L 2005ApJ...625..242L) in 2007.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 103 805 Chandra Main Catalog: basic source properties
table3.dat 103 114 Chandra Secondary Catalog: tentative source
properties
table4.dat 123 588 X-ray spectroscopy for photometrically selected
sources: thermal plasma fits
table5.dat 100 42 X-ray spectroscopy for photometrically selected
sources: power law fits
table6.dat 310 919 Stellar counterparts
--------------------------------------------------------------------------------
See also:
I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJ/454/151 : OB Associations of the Northern Milky Way (Massey+ 1995)
J/A+A/384/890 : BVRIHalpha photometry of NGC2244 X-ray stars (Berghoefer+ 2002)
J/A+A/446/949 : Open clusters proper motions based on UCAC2 (Dias+, 2006)
Byte-by-byte Description of file: table[23].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Source Sequence number; sorted by RA (1)
5- 22 A18 --- CXOU Source IAUC designation; HHMMSS.ss+DDMMSS.s
24- 32 F9.6 deg RAdeg Right Ascension in decimal degrees (J2000)
34- 41 F8.6 deg DEdeg Declination in decimal degrees (J2000)
43- 45 F3.1 arcsec epos Estimated random component of position
error (2)
47- 50 F4.1 arcmin OffAng Off-axis angle
52- 57 F6.1 ct Ncts Estimated net 0.5-8keV band extracted counts
59- 62 F4.1 ct e_Ncts Average 1σ error in Ncts
64- 67 F4.1 ct Bcts Background 0.5-8keV band extracted counts
69- 73 F5.1 ct Hcts Estimated net 2-8keV band extracted counts
75- 78 F4.2 --- PSF Fraction of PSF (at 1.497keV) within
extraction region (3)
80- 83 F4.1 --- Signi Photometric significance (4)
85 A1 --- l_logPB Limit flag on logPB
86- 90 F5.1 [-] logPB Log probability that all 0.5-8keV counts from
background (5)
92 A1 --- Anom Source anomalies (6)
94 A1 --- Var Variability characterization (7)
96- 99 F4.1 ks Exp Effective exposure time (8)
101-103 F3.1 keV Emed Background-corrected median 0.5-8keV photon
energy
--------------------------------------------------------------------------------
Note (1): Source named in Simbad:
<[WTF2008] Main NNN> for table 2, and
<[WTF2008] Secondary NNN> for table 3
Note (2): 1σ, computed as
(standard deviation of PSF in extraction region)/(# of counts extracted)0.5
Note (3): Note that a reduced PSF fraction (significantly below 90%) may
indicate that the source is in a crowded region.
Note (4): Computed as (net counts)/(upper error on net counts).
Note (5): Some sources have PB values above the 1% threshold that defines
the catalog because local background estimates can rise during the
final extraction iteration after sources are removed from the catalog.
Note (6): Source anomalies code as follows:
g = fractional time that source was on a detector (FRACEXPO from
mkarf) is <0.9
e = source on field edge
p = source piled up
s = source on readout streak
Note (7): Variability characterization, based on K-S statistic, as follows:
a = no evidence for variability (0.05<PKS);
b = possibly variable (0.005<PKS<0.05);
c = definitely variable (PKS<0.005). No value is reported for
sources with fewer than 4 counts or for sources in chip gaps or
on field edges.
Note (8): Approximate time the source would have to be observed on axis to
obtain the reported number of counts.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Source Sequence number; sorted by RA
5- 22 A18 --- CXOU Source IAUC designation; HHMMSS.ss+DDMMSS.S
24- 29 F6.1 ct Ncts Estimated net 0.5-8keV band extracted counts
31- 34 F4.1 --- Signi Photometric significance (G1)
36- 39 F4.2 [cm-2] e_logNH ? Lower 90% confidence interval in logNH (G2)
41- 44 F4.1 [cm-2] logNH Log of best fit column density (3)
45 A1 --- f_logNH [i] Indicates logNH frozen in the fits
47- 50 F4.2 [cm-2] E_logNH ? Upper 90% confidence interval in logNH (G2)
52- 55 F4.2 keV e_kT ? Lower 90% confidence interval in kT (G2)
56- 59 F4.1 keV kT Best fit plasma temperature (3)
60 A1 --- f_kT [i] Indicates kT frozen in the fits
62- 66 F5.2 keV E_kT ? Upper 90% confidence interval in kT (G2)
68- 71 F4.2 [cm-3] e_logEM ? Lower 90% confidence interval in logEM (G2)
73- 76 F4.1 [cm-3] logEM Log of emission measure of model spectrum (3)
78- 81 F4.2 [cm-3] E_logEM ? Upper 90% confidence interval in logEM (G2)
83- 87 F5.2 [10-7W] logS ? Log of 0.5-2keV band luminosity
89- 93 F5.2 [10-7W] logH Log of 2-8keV band luminosity
95- 99 F5.2 [10-7W] logHc Log of absorption-corrected 2-8keV band
luminosity (G4)
101-105 F5.2 [10-7W] logT Log of 0.5-8keV band luminosity
107-111 F5.2 [10-7W] logTc ? Log of absorption-corrected 2-8keV band
luminosity (G4)
113-129 A17 --- Notes Additional notes (5)
--------------------------------------------------------------------------------
Note (3): All fits used the "wabs(apec)" model in XSPEC and assumed 0.3Z☉
abundances (Imanishi et al., 2001ApJ...557..747I 2001ApJ...557..747I, Feigelson et al.,
2002, Cat. J/ApJ/574/258). Emission measure assumes a distance of 1.4kpc.
Note (5): Additional notes:
2T = two-temperature model was used;
H = fit was performed by hand, usually because the automated fit
yielded non-physical results. Names of well-known OB
counterparts are listed here for the convenience of the reader.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Source Sequence number; sorted by RA
5- 22 A18 --- CXOU Source IAUC designation; HHMMSS.ss+DDMMSS.s
24- 28 F5.1 ct Ncts Estimated net 0.5-8keV band extracted counts
30- 32 F3.1 --- Signi Photometric significance (G1)
34- 36 F3.1 [cm-2] e_logNH ? Lower 90% confidence interval in logNH (G2)
38- 41 F4.1 [cm-2] logNH Log of best fit column density (3)
43- 45 F3.1 [cm-2] E_logNH ? Upper 90% confidence interval in logNH (G2)
47- 49 F3.1 keV e_gamma ? Lower 90% confidence interval in gamma (G2)
51- 53 F3.1 keV gamma Best fit power law photon index (3)
55- 57 F3.1 keV E_gamma ? Upper 90% confidence interval in gamma (G2)
59- 61 F3.1 [cm-3] e_logNor ? Lower 90% confidence interval in logNor (G2)
63- 66 F4.1 [cm-3] logNor Log of model power law normalization (3)
68- 70 F3.1 [cm-3] E_logNor ? Upper 90% confidence interval in logNor (G2)
72- 76 F5.2 [10-7W] logS ? Log of 0.5-2keV band luminosity
78- 82 F5.2 [10-7W] logH Log of 2-8keV band luminosity
84- 88 F5.2 [10-7W] logHc Log of absorption-corrected 2-8keV band
luminosity (G4)
90- 94 F5.2 [10-7W] logT Log of 0.5-8keV band luminosity
96-100 F5.2 [10-7W] logTc ? Log of absorption-corrected 2-8keV band
luminosity (G4)
--------------------------------------------------------------------------------
Note (3): All fits used the "wabs(powerlaw)" model in XSPEC.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Source Sequence number; sorted by RA
5- 22 A18 --- CXOU Source IAUC designation; HHMMSS.ss+DDMMSS.s
24- 35 A12 --- USNO Source USNO B1.0 (I/284) designation;
NNNN-NNNNNNN
37- 39 I3 --- MJD95 ? Massey et al. (1995, Cat. J/ApJ/454/151) ID
41- 43 I3 --- PS02 ? Park & Sung (2002AJ....123..892P 2002AJ....123..892P) ID,
<Cl* NGC 2244 PS NNN in Simbad
45- 47 I3 --- BC02 ? Berghofer & Christian (2002,
Cat. J/A+A/384/890) ID, [BC2002] NNN
49- 53 F5.2 mag Umag ? The U band magnitude
55- 59 F5.2 mag Bmag ? The B band magnitude
61- 65 F5.2 mag Vmag ? The V band magnitude
67- 71 F5.2 mag Rmag ? The R band magnitude
73- 77 F5.2 mag Imag ? The I band magnitude
79- 83 F5.2 mag Hamag ? The Hα band magnitude
85-100 A16 --- 2MASS Source 2MASS (II/246) designation;
HHMMSSss+DDMMSSs
102-114 A13 --- FLAM The FLAMINGOS (Section 3.1) ID,
HHMMSS+DDMMSS
116-120 F5.2 mag Jmag ? 2MASS J band magnitude
122-126 F5.2 mag Hmag ? 2MASS H band magnitude
128-132 F5.2 mag Ksmag ? 2MASS KS band magnitude
134-139 A6 --- Q2Flag The 2MASS photometric quality flags (1)
141-310 A170 --- Notes Additional notes (2)
--------------------------------------------------------------------------------
Note (1): See Cutri et al. (2003, Cat. II/246) for details.
Note (2): For convenience:
[OI81] = Ogura & Ishida (1981PASJ...33..149O 1981PASJ...33..149O)
[MJD95] = Massey, Johnson & Degioia-Eastwood (1995, Cat. J/ApJ/454/151),
[BC02] = Berghofer & Christian (2002, Cat. J/A+A/384/890)
[PS02] = Park & Sung (2002AJ....123..892P 2002AJ....123..892P)
[LR04] = Li & Rector (2004ApJ...600L..67L 2004ApJ...600L..67L)
[M82] = Marschall et al. (1982AJ.....87.1497M 1982AJ.....87.1497M)
[D06] = Dias et al. (2006, Cat. J/A+A/446/949)
ProbMem = Probability of being a cluster member from proper motion data
--------------------------------------------------------------------------------
Global notes:
Note (G1): Computed as (net counts)/(upper error on net counts).
Note (G2): More significant digits are used for uncertainties <0.1 in order
to avoid large rounding errors; for consistency, the same number of
significant digits is used for both lower and upper uncertainties.
Uncertainties are missing when XSPEC was unable to compute them or
when their values were so large that the parameter is effectively
unconstrained. Fits lacking uncertainties should be considered to
merely be a spline to the data to obtain rough estimates of
luminosities; actual parameter values are unreliable.
Note (G4): Absorption-corrected luminosities are are omitted when
logNH>22.5 since the soft band emission is essentially unmeasurable.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Wang et al. Paper II. 2009ApJ...696...47W 2009ApJ...696...47W Cat. J/ApJ/696/47
Wang et al. Paper III. 2010ApJ...716..474W 2010ApJ...716..474W Cat. J/ApJ/716/474
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 03-Jul-2010