J/ApJS/196/9 95GHz methanol maser survey toward GLIMPSE EGOs (Chen+, 2011)
A 95 GHz class I methanol maser survey toward GLIMPSE Extended Green Objects (EGOs). Chen X., Ellingsen S.P., Shen Z.-Q., Titmarsh A., Gan C.-G. <Astrophys. J. Suppl. Ser., 196, 9 (2011)> =2011ApJS..196....9C
ADC_Keywords: Infrared sources ; Millimetric/submm sources ; Stars, masers ; Interstellar medium ; Radio lines Keywords: ISM: molecules - masers - radio lines: ISM - stars: formation Abstract: We report the results of a systematic survey for 95GHz class I methanol masers toward a new sample of 192 massive young stellar object candidates associated with ongoing outflows (known as extended green objects or EGOs) identified from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) survey. The observations were made with the Australia Telescope National Facility (ATNF) Mopra 22m radio telescope and resulted in the detection of 105 new 95GHz class I methanol masers. For 92 of the sources our observations provide the first identification of a class I maser transition associated with these objects (i.e., they are new class I methanol maser sources). Our survey proves that there is indeed a high detection rate (55%) of class I methanol masers toward EGOs. Comparison of the GLIMPSE point sources associated with EGOs with and without class I methanol maser detections shows that they have similar mid-IR colors, with the majority meeting the color selection criteria -0.6<[5.8]-[8.0]<1.4 and 0.5<[3.6]-[4.5]<4.0. Investigations of the Infrared Array Camera and Multiband Imaging Photometer for Spitzer 24um colors and the associated millimeter dust clump properties (mass and density) of the EGOs for the sub-samples based on the class of methanol masers they are associated with suggest that the stellar mass range associated with class I methanol masers extends to lower masses than for class II methanol masers, or alternatively class I methanol masers may be associated with more than one evolutionary phase during the formation of a high-mass star. Description: The observations were made using the Mopra 22m telescope (Australia) during 2009 August 9-20. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 56 192 Sample parameters table3.dat 76 336 Observed properties of 95GHz class I methanol maser sources detected table7.dat 65 37 Properties of mm dust clumps associated with methanol masers
See also: J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010) J/ApJ/702/1615 : Class I and II CH3OH maser survey of EGOs (Cyganowski+, 2009) J/AJ/136/2391 : GLIMPSE Extended Green Objects catalog (Cyganowski+, 2008) J/MNRAS/301/640 : Ultracompact H II regions studies. II. (Walsh+, 1998) J/ApJS/91/347 : A 5-GHz VLA Survey of the Galactic Plane (Becker+ 1994) J/ApJS/91/659 : Ultracompact HII regions radio images (Kurtz+ 1994) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 12 A12 --- EGO Source designation (GLLL.ll+B.bb) 14- 21 A8 --- n_EGO Note(s) on individual sources (1) 23- 24 I2 h RAh Hour of right ascension (J2000) (2) 26- 27 I2 min RAm Minute of right ascension (J2000) 29- 32 F4.1 s RAs Second of right ascension (J2000) 34 A1 --- DE- Sign of declination (J2000) (2) 35- 36 I2 deg DEd Degree of declination (J2000) 38- 39 I2 arcmin DEm Arcminute of declination (J2000) 41- 42 I2 arcsec DEs Arcsecond of declination (J2000) 44 A1 --- DC [Y/N] EGO associated with an IR dark cloud?, from Cyganowski et al. (2008, Cat. J/AJ/136/2391) 46 A1 --- II [YN-] EGO associated with a 6.7GHz Class II methanol maser? (3) 48 A1 --- OH [YN-] EGO associated with a 1665 or 1667MHz OH maser? (4) 50 A1 --- UC [YN-] EGO associated with an ultra-compact HII region? (4) 52 A1 --- mm [YN-] EGO associated with a 1.1mm continuum source? (4) 54 I1 --- Rk [1,5]? Table selection for the source (5) 56 A1 --- I [YN-] Detection with 95GHz class I methanol masers in our observations?
Note (1): Flag as follows: g = The sources have been included in the Chen et al. (2009MNRAS.396.1603C) sample (10 members in total). h = source with 95GHz class I methanol maser detections in our survey, which are shown in the [3.6]-[4.5] vs. [5.8]-[8.0] color-color diagram (Figure 4) obtained with integrated fluxes from Tables 1 and 3 of Cyganowski et al. (2008, Cat. J/AJ/136/2391). i = source without 95GHz class I methanol maser detections in our survey, which are shown in the [3.6]-[4.5] vs. [5.8]-[8.0] color-color diagram (Figure 4) obtained with integrated fluxes from Tables 1 and 3 of Cyganowski et al. (2008, Cat. J/AJ/136/2391). h*,i* = source which locates in the left-upper of the color region and outside Stage I evolutionary zone derived by Robitaille et al. (2006ApJS..167..256R; see Section 4.1 and Figure 4). j = Source with 95GHz class I methanol maser detections in our survey, which is plotted in the [3.6]-[4.5] vs. [5.8]-[8.0] color-color diagram obtained with GLIMPSE point-source fluxes in Figure 5. j* = Source which lies in the region outside Stage I (see Section 4.1 and Figure 5). k = Source without 95GHz class I methanol maser detections in our survey, which is plotted in the [3.6]-[4.5] vs. [5.8]-[8.0] color-color diagram obtained with GLIMPSE point-source fluxes in Figure 5. k* = Source which lies in the region outside Stage I (see Section 4.1 and Figure 5). l,m,n represent the three different subsamples for the IRAC and MIPS 24um color analysis with integrated fluxes of EGOs as follows: l = source associated with both a class I methanol maser and a class II methanol maser with an accurate position, m = source associated with only a class II maser (with an accurate position), n = source associated with only class I maser emission. + = the source is plotted in [3.6]-[5.8] vs. [8.0]- color diagram (Figure 6; see Section 4.2). Note (2): The targeted positions for the observations are the EGO positions given in the EGO catalog of Cyganowski et al. (2008, Cat. J/AJ/136/2391), with the exception of IRDC18223-3, the position for which is from Beuther & Steinacker (2007ApJ...656L..85B). Note (3): Associations with 6.7GHz class II methanol masers within 30" identified from the 6.7GHz maser catalogs (Cyganowski et al. 2009, Cat. J/ApJ/702/1615; Caswell 2009PASA...26..454C; Xu et al. 2009A&A...507.1117X; Caswell et al. 2010MNRAS.404.1029C; Green et al. 2010MNRAS.409..913G) and our recent class II methanol maser surveys with the University of Tasmania Mt. Pleasant 26m (A. Titmarsh et al. 2011, in preparation). Code as follows: - = sources for which 6.7GHz maser emission is detected in the Mt. Pleasant survey, but for which accurate positional information is not available, Y = sources with 6.7GHz masers with accurate positions from high-resolution observations, N = sources without 6.7GHz maser detections in the Mt. Pleasant survey. Note (4): Associations with OH masers, UC HII regions, and 1.1mm continuum sources within 30", identified from 1665 and 1667MHz OH maser catalog (Caswell, 1998MNRAS.297..215C), UC HII catalogs (Wood & Churchwell 1989ApJS...69..831W; Becker et al. 1994, Cat. J/ApJS/91/347; Kurtz et al. 1994, Cat. J/ApJS/91/659; Walsh et al. 1998, Cat. J/MNRAS/301/640; Cyganowski et al. 2009, Cat. J/ApJ/702/1615), and 1.1mm continuum BOLOCAM GPS (BGPS) archive (Rosolowsky et al. 2010, Cat. J/ApJS/188/123). Note (5): 1-5 represent that the sources are selected from Tables 1-5 of Cyganowski et al. (2008, Cat. J/AJ/136/2391; <EGO GLLL.ll+B.bb(a)> in Simbad), respectively. The source IRDC18223-3 is selected from Beuther & Steinacker (2007ApJ...656L..85B). Sources from Tables 1, 2, and 5 and IRDC18223-3 are classified as "likely" outflow candidates, while those from Tables 3 and 4 are classified as "possible" outflow candidates in our analysis.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 12 A12 --- EGO Source name (GLLL.ll+B.bb) 14- 19 F6.2 Jy.km/s S Integrated flux density at 95GHz (1) 21- 24 F4.2 Jy.km/s e_S Formal uncertainty in S 26- 31 F6.2 km/s VLSR Velocity at peak maser emission (1) 33- 36 F4.2 km/s e_VLSR Formal uncertainty in VLSR 38- 41 F4.2 km/s DelV Line width; FWMH (1) 43- 46 F4.2 km/s e_DelV Formal uncertainty in DelV 48- 53 F6.2 Jy Pk Peak flux density at 95GHz (1) 55- 58 F4.2 Jy rms ? 1σ noise in observed maser spectrum 60- 65 F6.2 Jy.km/s SInt ? Total integrated flux density at 95GHz (2) 67- 70 F4.1 kpc Dist ? Kinematic distance (3) 72- 76 F5.1 10-6Lsun Lm ? Integrated luminosity (4)
Note (1): Of maser feature estimated from Gaussian fits to 95GHz class I methanol maser lines. The corresponding values in main beam temperature TM B (K) can be obtained by dividing the flux density by a factor of 9.3 (see Section 2.2). Note (2): Of the maser spectrum obtained from summing the integrated flux density of all maser features in each source in the "S" column. Note (3): Estimated from galactic rotation curve of Reid et al. (2009ApJ...700..137R). The distances to G49.07-0.33, G309.91+0.32, G310.15+0.76 which cannot be derived from the galactic rotation curve are assumed to be 5kpc. Note (4): Estimated with assuming maser isotropic emission, i.e. Lm=4πDist2SInt.
Byte-by-byte Description of file: table7.dat
Bytes Format Units Label Explanations
1- 11 A11 --- EGO EGO name (GLL.ll+B.bb except for IRDC18223-3) 13- 17 A5 --- n_EGO [d-j, ] Notes on individual sources (1) 19- 33 A15 --- BGPS BGPS name (GLLL.lll+BB.bbb) (2) 35 A1 --- l_Robj Limit flag on Robj 36- 38 I3 arcsec Robj Associated 1.1mm BGPS source radius (3) 40- 44 F5.2 Jy Sint Associated 1.1mm BGPS source flux density (3) 46- 50 I5 Msun Mass Gas mass of clump (4) 52 A1 --- l_nH2 Limit flag on nH2 53- 56 F4.1 10+3cm-3 nH2 Beam-averaged volume density of clump (4) 58- 61 F4.1 10+22cm-2 NH2 Beam-averaged column density N(H2) of clump (5) 63- 65 I3 --- Av Reddening vector A_ν_ of clump (5)
Note (1): Flag as follows: e,f = The sources associated with GLIMPSE point sources whose colors locate outside and in the color region occupied by Stage I derived by Robitaille et al. (2006ApJS..167..256R) in Figure 5, respectively. See more details in Section 4.1. g = The sources are selected from the Chen et al. (2009MNRAS.396.1603C) sample. h = a source associated with both a class I methanol maser and a high-precision position class II methanol maser (including 21 members), i = a source associated with class I masers but without high-precision position class II maser information (including nine members), h = a source associated with only class I maser emission and without class II maser detection by Mt. Pleasant (including seven members). d = Sources with integrated flux measurements from Cyganowski et al. (2008, Cat. J/AJ/136/2391) are also overlapped in the [3.6]-[5.8] vs. [8.0]- color analysis of Figure 6. Note (2): The associated 1.1mm BGPS continuum source identified from BGPS catalog (Rosolowsky et al. 2010, Cat. J/ApJS/188/123). Note (3): The associated 1.1mm BGPS source radius and flux density used in the calculation. Note that a flux calibration correction factor of 1.5 was needed to apply to the flux density listed here when calculating the gas mass (see Dunham et al. 2010ApJ...717.1157D). All sources are resolved with the BGPS beam expect G34.28+0.18. We assumed the beam size as an upper limit on the object radius of this source. Note (4): The gas mass and beam-averaged volume density of clump derived from the corresponding 1.1mm continuum source. The beam size of BGPS is 33". Note (5): We adopt Av=10-21xN(H2) from Bohlin et al. (1978ApJ...224..132B).
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 16-Nov-2011
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