J/ApJ/702/1615 CH3OH maser survey of EGOs (Cyganowski+, 2009)
A class I and class II CH3 OH maser survey of EGOs from the GLIMPSE survey. Cyganowski C.J., Brogan C.L., Hunter T.R., Churchwell E. <Astrophys. J., 702, 1615-1647 (2009)> =2009ApJ...702.1615C
ADC_Keywords: Masers ; Radio lines ; Interferometry Keywords: infrared: stars - ISM: jets and outflows - masers - stars: formation - techniques: interferometric Abstract: We present the results of a high angular resolution Very Large Array (VLA) Class I 44GHz and Class II 6.7GHz CH3OH maser survey of a sample of ∼20 massive young stellar object (MYSO) outflow candidates selected on the basis of extended 4.5um emission in Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire images. These 4.5um selected candidates are referred to as extended green objects (EGOs), for the common coding of this band as green in three-color Infrared Array Camera images. The detection rate of 6.7GHz Class II CH3OH masers, which are associated exclusively with massive YSOs, toward EGOs is ≳64% - nearly double the detection rate of surveys using other MYSO selection criteria. The detection rate of Class I 44GHz CH3OH masers, which trace molecular outflows, is ∼89% toward EGOs associated with 6.7GHz CH3OH masers. Description: The fixed-frequency 6.7GHz EVLA (Expanded Very Large Array) observations at the NRAO were obtained on 2008 February 1 in the B configuration and 2008 February 9, 17, and 19 in the CnB configuration: 13 EVLA antennas were available for these observations. Our 44GHz VLA observations, of the 18 EGOs observed with fixed frequency at 6.7GHz plus G11.92-0.61, were obtained on 2008 February 16 and 18 in the CnB configuration, in fixed frequency mode: 26 antennas were available for these observations. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file sample.dat 97 22 Extended Green Objects (EGO) sample (table 5 and positions from table 4) table7.dat 69 1206 Fitted properties: 6.7GHz masers table8.dat 69 1524 Fitted properties: 44GHz masers
See also: J/AJ/136/2391 : GLIMPSE Extended Green Objects catalog (Cyganowski+, 2008) J/ApJS/155/149 : CH3OH 70-61 A+ maser sources (Kurtz+, 2004) Byte-by-byte Description of file: sample.dat
Bytes Format Units Label Explanations
1- 11 A11 --- EGO Extended Green Object name (GLL.ll+B.bb) 13- 14 I2 h RAh VLA Hour of right ascension (J2000) (1) 16- 17 I2 min RAm VLA Minute of right ascension (J2000) (1) 19- 22 F4.1 s RAs VLA Second of right ascension (J2000) (1) 24 A1 --- DE- VLA Sign of declination (J2000) (1) 25- 26 I2 deg DEd VLA Degree of declination (J2000) (1) 28- 29 I2 arcmin DEm VLA Arcminute of declination (J2000) (1) 31- 34 F4.1 arcsec DEs VLA Arcsecond of declination (J2000) (1) 35 A1 --- n_EGO [g] Source not targeted (2) 37- 38 I2 h RAIh ? 24um Hour of right ascension (J2000) (3) 40- 41 I2 min RAIm ? 24um Minute of right ascension (J2000) (3) 43- 46 F4.1 s RAIs ? 24um Second of right ascension (J2000) (3) 48 A1 --- DEI- 24um Sign of declination (J2000) (3) 49- 50 I2 deg DEId ? 24um Degree of declination (J2000) (3) 52- 53 I2 arcmin DEIm ? 24um Arcminute of declination (J2000) (3) 55- 56 I2 arcsec DEIs ? 24um Arcsecond of declination (J2000) (3) 57 A1 --- n_24 [cfh ] Flag on 24um source (4) 59- 62 F4.1 Jy Flux ? Integrated MIPS 24um flux density from Cyganowski et al. (2008, Cat. J/AJ/136/2391) unless otherwise noted 64 A1 --- leFlux Limit flag on e_Flux 65- 67 F3.1 Jy e_Flux ? Flux density uncertainty 68 A1 --- f_Flux [cde ] Flag on Flux (4) 70- 97 A28 MJy/sr Contour Contour levels (in figure 1)
Note (1): Coordinates from phase tracking centers of the VLA observations (Section 2.1). In some cases, these differ slightly from the positions in Cyganowski et al. (2008, Cat. J/AJ/136/2391). Note (2): g = EGO not targeted in our survey but within VLA primary beam (6.7' FHWP) at 6.7GHz. The positions given are the EGO positions from Cyganowski et al. (2008, Cat. J/AJ/136/2391), not the VLA pointing center. Note (3): MIPS 24um counterpart position estimated, using ds9 regions, as the center of a circle around the most prominent Airy ring for each 24um source. We employ this method because it can be applied consistently for all sources. Estimated uncertainties are ∼1" for isolated, unsaturated sources, up to ∼2"-4" for blended and saturated sources (based on comparison with centroids generated by the modified "iracworks" program, see note (e)). Note (4): Flag as follows: c = No discrete 24um counterpart. d = Probable EGO counterpart is blended with other 24um source(s) and/or diffuse emission that may or may not be associated with the EGO, precluding a reliable flux estimate. e = Source is saturated. Flux was estimated using a modified version of the "iracworks" saturated source software contributed by Tom Jarrett and available at http://spider.ipac.caltech.edu/staff/jarrett/irac/tools/. The software fits the PSF wings of a source whose core is saturated, and was modified by Katherine Johnston and Remy Indebetouw to operate on MIPS 24um data. Uncertainty in the reported flux is estimated to be 20%. f = Position of the northern of two blended 24um sources (see Figure 1(j)), the probable EGO counterpart. h = Nearest 24um source, see Figure 1(s). It is unclear whether or not this MIPS source is associated with the EGO to its west.
Byte-by-byte Description of file: table.dat
Bytes Format Units Label Explanations
1- 11 A11 --- EGO Field Name (GLL.ll+B.bb); Target EGO 13- 14 I2 h RAh Hour of Right Ascension (J2000) 16- 17 I2 min RAm Minute of Right Ascension (J2000) 19- 24 F6.3 s RAs Second of Right Ascension (J2000) 26- 30 F5.3 arcsec e_RAs Uncertainty in RAs 32 A1 --- DE- Sign of the Declination (J2000) 33- 34 I2 deg DEd Degree of Declination (J2000) 36- 37 I2 arcmin DEm Arcminute of Declination (J2000) 39- 44 F6.3 arcsec DEs Arcsecond of Declination (J2000) 46- 50 F5.3 arcsec e_DEs Uncertainty in DEs 52- 57 F6.2 Jy Int Intensity at 6.7GHz or 44GHz in units of Jy/beam (1) 59- 62 F4.2 Jy e_Int Uncertainty in Int 64- 69 F6.2 km/s Vel LSR Velocity
Note (1): * For table 7 (6.7GHz masers): TB(K)=7794*I(Jy/beam)*(3.5313)/(θmaj*θmin) where θmaj and θmin are the dimensions of the synthesized beam in arcseconds from Table 1 (3.5313 square arcseconds is the median value of θmaj*θmin for the 6.7GHz observations). * For table 8 (44GHz masers): TB(K)=2198*I(Jy/beam)*(0.2867)/(θmaj*θmin) where θmaj and θmin are the dimensions of the synthesized beam in arcseconds from Table 2 (0.2867 square arcseconds is the median value of θmaj*θmin for the 44GHz observations).
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Oct-2011
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