J/ApJ/846/160 6.7GHz Class II methanol maser survey (Yang+, 2017)
A 6.7GHz methanol maser survey at high galactic latitudes.
Yang K., Chen Xi, Shen Z.-Q., Li X.-Q., Wang J.-Z., Jiang D.-R., Li J.,
Dong J., Wu Y.-J., Qiao H.-H., Ren Z.
<Astrophys. J., 846, 160 (2017)>
=2017ApJ...846..160Y 2017ApJ...846..160Y
ADC_Keywords: Masers ; Radio lines ; Photometry, infrared ; Spectra, radio
Keywords: ISM: molecules ; masers ; radio lines: ISM ; stars: formation
Abstract:
We performed a systematic 6.7GHz Class II methanol maser survey using
the Shanghai Tianma Radio Telescope toward targets selected from the
all-sky Wide-Field Infrared Survey Explorer (WISE) point catalog. In
this paper, we report the results from the survey of those at high
Galactic latitudes, i.e., |b|>2°. Of 1473 selected WISE point
sources at high latitude, 17 point positions that were actually
associated with 12 sources were detected with maser emission,
reflecting the rarity (1%-2%) of methanol masers in the region away
from the Galactic plane. Out of the 12 sources, 3 are detected for the
first time. The spectral energy distribution at infrared bands shows
that these new detected masers occur in the massive star-forming
regions. Compared to previous detections, the methanol maser changes
significantly in both spectral profiles and flux densities. The
infrared WISE images show that almost all of these masers are located
in the positions of the bright WISE point sources. Compared to the
methanol masers at the Galactic plane, these high-latitude methanol
masers provide good tracers for investigating the physics and
kinematics around massive young stellar objects, because they are
believed to be less affected by the surrounding cluster environment.
Description:
The observations were performed between 2015 September and 2016 July
with the Shanghai TianMa radio telescope (TMRT) in China. The rest
frequency of the methanol 51 to 60 A+ transition line
(6.6685192GHz) was covered with a spectral window of a bandwidth of
23.4MHz. The spectral resolution is 1.431kHz, corresponding to a
velocity resolution of ∼0.09km/s.
For the detected methanol maser sources (12 in total), we used the
on-the-fly (OTF) mode to map a large region (usually 5') to obtain a
position of the methanol maser.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 78 1473 Source catalog
table3.dat 135 16 The OTF observations
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See also:
II/328 : AllWISE Data Release (Cutri+ 2013)
VIII/96 : 6-GHz methanol multibeam maser catalogue (Caswell+, 2010-12)
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
J/A+AS/110/81 : Methanol masers towards IRAS sources (van der Walt+ 1995)
J/MNRAS/291/261 : Methanol maser of IRAS-selected sources (Walsh+ 1997)
J/MNRAS/301/640 : Ultracompact H II regions studies. II. (Walsh+, 1998)
J/A+AS/134/115 : Medicina 6.7GHz methanol masers survey (Slysh+ 1999)
J/A+AS/143/269 : 6.7GHz methanol maser emission survey (Szymczak+, 2000)
J/A+A/403/1095 : 6.7GHz methanol masers survey of YSOs (Minier+, 2003)
J/A+A/432/737 : General Cat. of 6.7GHz Methanol Masers (Pestalozzi+, 2005)
J/MNRAS/377/571 : GLIMPSE methanol masers non-detections (Ellingsen+, 2007)
J/other/PASA/26.454 : Precise positions of methanol masers (Caswell, 2009)
J/ApJ/699/1153 : Kinematic dist. to GRS molecular clouds (Roman-Duval+, 2009)
J/MNRAS/439/2584 : Southern methanol masers at 36 and 44GHz (Voronkov+, 2014)
J/ApJ/833/18 : Ultra-compact HII regions & methanol masers. I. (Hu+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/1473] Index number
6- 12 F7.3 deg GLON Galactic longitude
14- 20 F7.3 deg GLAT Galactic latitude
22- 23 I2 h RAh [0/23] Hour of Right Ascension (J2000)
25- 26 I2 min RAm Minute of Right Ascension (J2000)
28- 31 F4.1 s RAs Second of Right Ascension (J2000)
33 A1 --- DE- Sign of the Declination (J2000)
34- 35 I2 deg DEd [0/79] Degree of Declination (J2000)
37- 38 I2 arcmin DEm Arcminute of Declination (J2000)
40- 43 F4.1 arcsec DEs Arcsecond of Declination (J2000)
45- 49 F5.2 mag w1mag [1.4/16] WISE 3.4 micron band magnitude
51- 55 F5.2 mag w2mag [-1.2/12] WISE 4.6 micron band magnitude
57- 61 F5.2 mag w3mag [-2.2/12] WISE 12 micron band magnitude
63- 67 F5.2 mag w4mag [-5/6] WISE 22 micron band magnitude
69- 73 F5.2 mag w1-w2 [2/10.2] WISE (w1-w2) color index
75- 78 F4.2 mag w3-w4 [2/7.4] WISE (w3-w4) color index
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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- 2 I2 --- Fig [1/12] Figure number within figure 6 (1)
4- 18 A15 --- Name Source name (GLL.lll+BB.bbb)
20- 21 I2 h RACh Pointing center hour of Right Ascension (J2000)
23- 24 I2 min RACm Minute of Right Ascension (J2000)
26- 29 F4.1 s RACs Second of Right Ascension (J2000)
31 A1 --- DEC- Pointing center sign of the Declination (J2000)
32- 33 I2 deg DECd Pointing center degree of Declination (J2000)
35- 36 I2 arcmin DECm Arcminute of Declination (J2000)
38- 41 F4.1 arcsec DECs Arcsecond of Declination (J2000)
43 I1 arcmin lth [5/7] Side length of each region for the TMRT
OTF observations
45- 55 A11 "Y/M/D" Epoch Epoch of observation
57- 58 I2 h RAh Fitting center hour of Right Ascension (J2000)
60- 61 I2 min RAm Minute of Right Ascension (J2000)
63- 67 F5.2 s RAs Second of Right Ascension (J2000)
69 A1 --- DE- Fitting center sign of the Declination (J2000)
70- 71 I2 deg DEd Fitting center degree of Declination (J2000)
73- 74 I2 arcmin DEm Arcminute of Declination (J2000)
76- 79 F4.1 arcsec DEs Arcsecond of Declination (J2000)
81- 85 F5.1 km/s Vp [-73/21] Velocity peak of emission
87- 91 F5.1 Jy Sp [0.8/839] Peak flux density at 6.7GHz
93- 97 F5.1 Jy.km/s Si [0.3/328] Integrated flux density
99-100 I2 h RAIh ? Hour of Right Ascension (J2000) (2)
102-103 I2 min RAIm ? Minute of Right Ascension (J2000) (2)
105-110 F6.3 s RAIs ? Second of Right Ascension (J2000) (2)
112 A1 --- DEI- ? Sign of the Declination (J2000) (2)
113-114 I2 deg DEId ? Degree of Declination (J2000) (2)
116-117 I2 arcmin DEIm ? Arcminute of Declination (J2000) (2)
119-123 F5.2 arcsec DEIs ? Arcsecond of Declination (J2000) (2)
125-130 A6 --- Ref Reference(s) for interferometric positions (3)
132-135 F4.1 arcsec Sep [3/19.4]? Separation between the fitting centers
and interferometric positions
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Note (1): Figure 6 shows on the left, the velocity-integrated intensity map of
the source with maser emission. The "o" represents the position of
the WISE source in the single-point survey, and the "+" represents the
fitted peak position of the methanol emission from the TMRT OTF
observation. On the right: spectra in the fitting center.
Note (2): The positions determined by interferometric observation
(Hu et al. 2016, J/ApJ/833/18)
Note (3): References as follows:
H = Hu et al. 2016, J/ApJ/833/18
M = Minier et al. 2000A&A...362.1093M 2000A&A...362.1093M
M1 = Minier et al. 2001A&A...369..278M 2001A&A...369..278M
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-May-2018