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J/ApJ/715/671           X-ray and IR emission from YSOs            (Wolk+, 2010)

X-ray and infrared emission from young stellar objects near LkHα 101. Wolk S.J., Winston E., Bourke T.L., Gutermuth R., Megeath S.T., Spitzbart B.D., Osten R. <Astrophys. J., 715, 671-695 (2010)> =2010ApJ...715..671W
ADC_Keywords: X-ray sources ; Stars, pre-main sequence ; YSOs ; Photometry, infrared ; Spectral types ; Equivalent widths Keywords: infrared: stars - stars: distances - stars: protostars - X-rays: stars stars: individual (LkHα101) - stars: pre-main sequence Abstract: We report on a multiwavelength study of a partially embedded region of star formation centered on the Herbig Be star LkHα 101. Using two 40ks Chandra observations, we detect 213 X-ray sources in the ∼17'x17' ACIS-I field. We combine the X-ray data with Two Micron All Sky Survey near-IR observations and Spitzer IRAC and MIPS 24um observations to obtain a complete picture of the cluster. A total of 158 of the X-ray sources have infrared counterparts. Of these, we find nine protostars, 48 Class II objects, five transition objects, and 72 Class III objects. From the Spitzer data we identify an additional 10 protostars, 53 Class II objects, and four transition disk candidates which are not detected by Chandra. We obtained optical spectra of a sample of both X-ray-detected and non-X-ray-detected objects. Combining the X-ray, Spitzer, and spectral data, we obtain independent estimates of cluster distance and the total cluster size -excluding protostars. We obtain consistent distance estimates of 510+100-40pc and a total cluster size of 255+50-25 stars. We find the Class II:III ratio is about 5:7 with some evidence that the Class III sources are spatially more dispersed. The cluster appears very young with three sites of active star formation and a median age of about 1Myr. Description: The original goal of this program was the simultaneous Chandra and VLA observation of active stars (Osten & Wolk 2009ApJ...691.1128O). The field was observed by Chandra on 2005 March 6 starting at 17:16 UT for 40.2ks of total time and 39.6ks of the so-called good time (ObsID 5429). It was observed again on 2005 March 8 starting at 17:43 UT for essentially the same duration (ObsID 5428). The region near LkHα 101 was observed with the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer for Spitzer (MIPS) on board the Spitzer Space Telescope as a part of a GTO program (PID 6 - Structure and Incidence of Young Embedded Clusters; Gutermuth et al. 2009, Cat. J/ApJS/184/18). IRAC observations were made on 2005 May 13. MIPS data were obtained from 24um observations on 2005 October 9. Spectroscopy in the far-red was carried out using the Hectospec multi-object moderate dispersion spectrograph on the converted 6.5m MMT on Mt. Hopkins, Arizona, in 2005 October, 2006 March, and 2006 November. The spectral range covered was 3000-9000Å, with a resolution of ∼6Å. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 41 213 X-ray sources detected in the LkHα 101 field table2.dat 51 140 2MASS photometry of X-ray sources table3.dat 89 158 Spitzer photometry of X-ray sources table4.dat 57 87 LkHα 101 cluster spectral classification table7.dat 64 88 Spectral fits to X-ray sources table8.dat 64 30 Spectral fits to X-ray sources (lower quality) table10.dat 55 69 PMS stars detected by Spitzer but not detected in X-rays (2MASS colors) table11.dat 81 69 PMS stars not detected in X-rays (Spitzer)
See also: B/chandra : The Chandra Archive Log (CXC, 1999-2012) B/mk : Catalogue of Stellar Spectral Classifications (Skiff, 2012) II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009) J/AJ/128/1233 : LkHa 101 and the young cluster in NGC 1579 (Herbig+, 2004) J/AJ/126/1916 : JHK photometry of young clusters near the Sun (Porras+, 2003) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq [2/231] Running source number (skips indicate the spurious detections) 5- 22 A18 --- ID Source identification; (HHMMSS.ss+DDMMSS.s; <LkHa101CXO JHHMMSS.ss+DDMMSS.s> in Simbad) 24- 29 F6.1 arcsec Off Offset from axis 31- 34 I4 ct RCts Raw counts 36- 41 F6.1 ct NCts Net counts
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq [2/231] Source index number 5- 8 F4.2 arcsec X/2M X-ray/2MASS positional offset 10- 14 F5.1 arcsec Off2M Offset from axis 16- 20 F5.2 mag Jmag 2MASS J band magnitude 22- 25 F4.2 mag e_Jmag ? Uncertainty in Jmag 27- 31 F5.2 mag Hmag 2MASS H band magnitude 33- 36 F4.2 mag e_Hmag ? Uncertainty in Hmag 38- 42 F5.2 mag Kmag 2MASS K band magnitude 44- 47 F4.2 mag e_Kmag ? Uncertainty in Kmag 49- 51 A3 --- Qual 2MASS photometry quality codes
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq [2/231] Source index number (1) 5- 8 F4.2 arcsec X/Sptz X-ray/Spitzer positional offset 10- 14 F5.1 arcsec Off Offset from axis 16- 20 F5.2 mag [3.6] ? Spitzer/IRAC 3.6 micron band magnitude 22- 26 F5.2 mag [4.5] ? Spitzer/IRAC 4.5 micron band magnitude 28- 32 F5.2 mag [5.8] ? Spitzer/IRAC 5.8 micron band magnitude 34- 38 F5.2 mag [8.0] ? Spitzer/IRAC 8.0 micron band magnitude 40- 43 F4.2 mag [24] ? Spitzer/MIPS 24 micron band magnitude 45- 48 F4.2 mag e_[3.6] ? Uncertainty in [3.6] 50- 53 F4.2 mag e_[4.5] ? Uncertainty in [4.5] 55- 58 F4.2 mag e_[5.8] ? Uncertainty in [5.8] 60- 63 F4.2 mag e_[8.0] ? Uncertainty in [8.0] 65- 68 F4.2 mag e_[24] ? Uncertainty in [24] 70- 73 F4.2 mag AK The K band extinction 75- 88 A14 --- Class Source classification (1, 2, III, T(transition), gal (background galaxy), or LkHα 101) 89 A1 --- f_Class [b] b: star within 90" of LkHalpha 101 (2)
Note (1): In addition to their IAU approved Names: <LkHa101CXO JHHMMSS.ss+DDMMSS.s> given in Table 1, these sources are equally identified as: <LkHa101SST JHHMMSS.ss+DDMMSS.s>. Note (2): Stars with a notation "b" are within 90 arcsec of LkHα 101. Their proximity, led to the conclusion that they were cluster members, despite missing some IRAC data. For these stars 2MASS data played an enhanced role in determining Class identification.
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq [2/231]? Chandra identification number 5- 22 A18 --- ID LkHaSST identification (HHMMSS.ss+DDMMSS.s; <LkHa101SST JHHMMSS.ss+DDMMSS.s> in Simbad) 24- 27 A4 --- SpT MK spectral type 29- 31 F3.1 --- e_SpT SpT uncertainty 33- 37 I5 K Teff Effective temperature 39- 44 F6.3 [-] logL Overall luminosity log(Lbol/L0) 46- 53 F8.2 0.1nm EWHa Hα (6563Å) equivalent width 55- 57 F3.1 0.1nm EWLi ? LiI (6707Å) equivalent width
Byte-by-byte Description of file: table7.dat table8.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq [2/231] Source index number 5- 10 F6.1 ct NCts Net counts 12- 16 F5.2 10+22/cm2 NH Hydrogen column density 18- 21 F4.2 10+22/cm2 e_NH ? The 1σ uncertainty in NH 23 A1 --- l_kT Limit flag on kT 25- 30 F6.2 keV kT Effective temperature 32- 35 F4.2 keV e_kT ? The 1σ uncertainty in kT 37- 42 F6.2 [mW/m2] logF.A Log of Absorbed flux; erg/s/cm2 44- 49 F6.2 [mW/m2] logF.U Log of Unabsorbed flux; erg/s/cm2 51- 54 F4.2 --- chi2 The reduced chi^2^ of the fit (1) 56- 64 A9 --- Model Model used in fit (2)
Note (1): Included for "cstat" models for completeness. One model was calculated with C statistics, it is unclear how this relates to goodness of fit. The formal errors are unbiased however. Note (2): The model used for the fit is coded in two parts. The left hand side indicates the type of model used. The right hand side indicates the data set. The overall model is written: LHS_RHS. LHS as follows: cstat = C-statistics used for the fit with an initial guess of kT=1keV and NH=1021cm-2. crs = c-stat used for initial guess with those input parameters and then refit using Raymond-Smith plasma for final fit. Mekal = again c-stat used for initial guess and then Mekal for final fit, APEC = cstat used for initial guess and then APEC for final fit. RHS as follows: 29 = only data from first observation (Obsid = 5429) used in fit, 28 = only data from second observation (Obsid = 5428) used in fit, all = data from both observations used in fit.
Byte-by-byte Description of file: table10.dat
Bytes Format Units Label Explanations
1- 18 A18 --- ID Source identification; (HHMMSS.ss+DDMMSS.s; <LkHa101SST JHHMMSS.ss+DDMMSS.s> in Simbad) (1) 20- 24 F5.2 mag Jmag ? 2MASS J band magnitude 26- 29 F4.2 mag e_Jmag ? Uncertainty in Jmag 31- 35 F5.2 mag Hmag ? 2MASS H band magnitude 37- 40 F4.2 mag e_Hmag ? Uncertainty in Hmag 42- 46 F5.2 mag Ksmag ? 2MASS Ks band magnitude 48- 51 F4.2 mag e_Ksmag ? Uncertainty in Kmag 53- 55 A3 --- Qual 2MASS photometry quality codes
Note (1): Source 042955.68+352021.2 has been modified at CDS into 042955.68+352021.0 as in table 11 and 2MASS catalog.
Byte-by-byte Description of file: table11.dat
Bytes Format Units Label Explanations
1- 18 A18 --- ID Source identification; (HHMMSS.ss+DDMMSS.s; <LkHa101SST JHHMMSS.ss+DDMMSS.s> in Simbad) 20 A1 --- f_ID [*] outside Chandra field of view (1) 22- 26 F5.2 mag [3.6] Spitzer/IRAC 3.6 micron band magnitude 28- 31 F4.2 mag e_[3.6] Uncertainty in [3.6] 33- 37 F5.2 mag [4.5] ? Spitzer/IRAC 4.5 micron band magnitude 39- 42 F4.2 mag e_[4.5] ? Uncertainty in [4.5] 44- 48 F5.2 mag [5.6] ? Spitzer/IRAC 5.6 micron band magnitude 50- 53 F4.2 mag e_[5.6] ? Uncertainty in [5.6] 55- 59 F5.2 mag [8.0] ? Spitzer/IRAC 8.0 micron band magnitude 61- 64 F4.2 mag e_[8.0] ? Uncertainty in [8.0] 66- 69 F4.2 mag [24] ? Spitzer/MIPS 24 micron band magnitude 71- 74 F4.2 mag e_[24] ? Uncertainty in [24] 76- 79 F4.2 mag AK The K band extinction 81 A1 --- Cl [012T] Classification (Class 0, I, II or T=possible transition objects)
Note (1): * = These Spitzer identified PMS stars are off the Chandra field of view.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 21-May-2012
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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