J/ApJS/248/18 44 and 95GHz observations of class I methanol masers (Yang+, 2020)
44GHz methanol masers: observations toward 95GHz methanol masers.
Yang W., Xu Ye, Choi Y.K., Ellingsen S.P., Sobolev A.M., Chen Xi, Li J.,
Lu D.
<Astrophys. J. Suppl. Ser., 248, 18 (2020)>
=2020ApJS..248...18Y 2020ApJS..248...18Y
ADC_Keywords: Masers; Radio sources; Infrared sources; Interferometry;
H II regions; Millimetric/submm sources
Keywords: Star formation ; Interstellar masers ; Radio sources ;
Interstellar molecules
Abstract:
We report a simultaneous 44 and 95GHz class I methanol maser survey
toward 144 sources from the 95GHz class I methanol maser catalog. The
observations were made with the three telescopes of the Korean very
long baseline interferometry network operating in single-dish mode.
The detection rates are 89% at 44GHz and 77% at 95GHz. There are 106
new discoveries at 44GHz. Comparing the previous 95GHz detections with
new observations of the same transitions made using the Purple
Mountain Observatory 13.7m radio telescope shows no clear evidence of
variability on a timescale of six years. Emission from the 44 and
95GHz transitions shows strong correlations in peak velocity, peak
flux density, and integrated flux density, indicating that they are
likely cospatial. We found that the peak flux density ratio
Spk,95/Spk,44 decreases as the 44GHz peak flux density increases.
We found that some class I methanol masers in our sample might be
associated with infrared dark clouds, while others are associated with
HII regions, indicating that some sources occur at an early stage of
high-mass star formation, while others are located toward more evolved
sources.
Description:
The 95GHz methanol maser sources in which we searched for emission
from the 44GHz methanol transition were selected using the criteria
detailed in Section 2.1. A total of 144 95GHz methanol maser sources
were identified (see Table 1).
The observations of the 44.06943GHz (70-61A+) and 95.16946GHz
(80-71A+) class I methanol maser transitions took place in the
period 2016 October to December using the Korean very long baseline
interferometry network (KVN) 21m radio antennas in single-dish
telescope mode. There are three KVN stations: KVN Yonsei telescope
(Seoul), KVN Ulsan telescope (Ulsan), and KVN Tamna telescope (Jeju
island). Each of the KVN antennas are equipped with multifrequency
receiving systems able to simultaneously operate in the 43 and 86GHz
bands, which enables observing 44 and 95GHz methanol transitions at
the same time.
Telescope pointing observations were performed at least once an hour,
resulting in a pointing accuracy better than ∼6".
We reobserved 13 sources using the Purple Mountain Observatory (PMO)
13.7m radio telescope in Delingha, China on 2018 December 4 and 6.
See Section 2.3 for further explanations.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 58 144 Target sources
table4.dat 65 261 Parameters of Gaussian fits to 44GHz methanol maser
detections
table5.dat 65 238 Parameters of Gaussian fits to 95GHz methanol maser
detections
table6.dat 84 59 The IRAS counterparts for 44-GHz class I methanol
masers
table8.dat 56 25 Masers that may be associated with HII regions
--------------------------------------------------------------------------------
See also:
II/125 : IRAS catalogue of Point Sources, Version 2.0 (IPAC 1986)
VIII/96 : 6-GHz methanol multibeam maser catalogue (Caswell+, 2010-12)
II/328 : AllWISE Data Release (Cutri+ 2013)
J/ApJS/91/659 : Ultracompact HII regions radio images (Kurtz+ 1994)
J/AZh/72/22 : A 95 GHz Survey of Methanol Masers (Valtts+, 1995)
J/A+A/314/615 : Maps of the 36 GHz methanol emission (Liechti+, 1996)
J/A+A/308/573 : Ammonia on YSOs IRAS sources (Molinari+ 1996)
J/A+A/336/339 : VLA obs. of ultracompact HII regions (Molinari+ 1998)
J/MNRAS/301/640 : Ultracompact H II regions studies. II. (Walsh+, 1998)
J/other/ChJAA/3.49 : Velocity & distance of methanol maser sources (Xu+, 2003)
J/ApJS/155/149 : CH3OH 70-61 A+ maser sources (Kurtz+, 2004)
J/MNRAS/359/1498 : Class I and class II methanol masers (Ellingsen+, 2005)
J/A+A/432/737 : General Cat. of 6.7GHz Methanol Masers (Pestalozzi+, 2005)
J/ApJ/641/389 : Millimetric observations of IRDC cores (Rathborne+, 2006)
J/ApJ/639/227 : MSX IRDC candidate catalog (Simon+, 2006)
J/AJ/133/1528 : IR nebulae around young stellar objects (Connelley+, 2007)
J/ApJ/656/255 : Arecibo methanol maser Gal. plane survey (Pandian+, 2007)
J/AJ/136/2391 : GLIMPSE Extended Green Objects catalog (Cyganowski+, 2008)
J/A+A/482/585 : JHK photometry of stars in Sh 2-212 (Deharveng+, 2008)
J/A+A/505/405 : A catalogue of Spitzer dark clouds (Peretto+, 2009)
J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010)
J/ApJS/196/9 : 95GHz methanol masers toward GLIMPSE EGOs (Chen+, 2011)
J/ApJS/200/5 : 95GHz class I methanol maser survey (Chen+, 2012)
J/ApJS/206/9 : New EGOs from Spitzer GLIMPSE II survey. I. (Chen+, 2013)
J/ApJ/763/2 : 95GHz methanol masers in molecular outflows (Gan+, 2013)
J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/MNRAS/439/2584 : Southern methanol masers at 36 and 44GHz (Voronkov+, 2014)
J/ApJ/810/42 : Hydrogen RRL parameters of H II regions (Anderson+, 2015)
J/MNRAS/448/2344 : MALT-45, a 7mm survey of the southern Galaxy (Jordan+, 2015)
J/A+A/590/A72 : Herschel counterparts of SDC (Peretto+, 2016)
J/ApJS/231/20 : A new 95GHz methanol maser catalog. I. (Yang+, 2017)
J/ApJS/234/33 : A GBT survey of large Galactic HII regions (Anderson+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source identifier
17- 20 A4 --- f_Name Flag(s) on Source (1)
22- 23 I2 h RAh Hour of Right Ascension (J2000)
25- 26 I2 min RAm Minute of Right Ascension (J2000)
28- 32 F5.2 s RAs Second of Right Ascension (J2000)
34 A1 --- DE- Sign of the Declination (J2000)
35- 36 I2 deg DEd Degree of Declination (J2000)
38- 39 I2 arcmin DEm Arcminute of Declination (J2000)
41- 44 F4.1 arcsec DEs Arcsecond of Declination (J2000)
46 A1 --- 44Det Detection at 44 GHz?
48 A1 --- 95Det Detection at 95 GHz?
50 A1 --- New A new 44GHz detection? (2)
52- 54 F3.1 Jy sigma44 [0.2/2.6] The 1σ noise level
in 44GHz observation
56- 58 F3.1 Jy sigma95 [0.4/6.3] The 1σ noise level
in 44GHz observation
--------------------------------------------------------------------------------
Note (1): Flag as follows:
d = unreliable flux densities due to poor weather (24 occurrences).
* = Previous interferometric observations (9 occurrences).
dd = Maser candidates (Yang+ 2017, J/ApJS/231/20 -- 10 occurrences).
i = Maser candidates that may be associated with an infrared dark cloud
(see Table 7 -- 5 occurrences).
Note (2): Reference for cross-matching new 44GHz detections:
Ladeyschikov+ (2019AJ....158..233L 2019AJ....158..233L).
References for interferometric observations:
1. Kurtz+ (2004, J/ApJS/155/149);
2. Gomez-Ruiz+ (2016ApJS..222...18G 2016ApJS..222...18G);
3. Rodriguez-Garza+ (2017ApJS..233....4R 2017ApJS..233....4R).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source identifier
17 A1 --- m_Name The 44GHz component identifier
19- 24 F6.2 km/s Vpk44 [-57.7/114.4] The 44GHz peak velocity
26- 29 F4.2 km/s e_Vpk44 [0/0.4] Uncertainty in Vpk44 (1)
31- 34 F4.2 km/s DelV44 [0.2/5.5] The 44GHz line width
36- 39 F4.2 km/s e_DelV44 [0/1.5] Uncertainty in DelV44 (1)
41- 45 F5.1 Jy Spk44 [0.5/335] Peak 44GHz flux density
47- 49 F3.1 Jy e_Spk44 [0.2/2.6] Uncertainty in Spk44 (1)
51- 55 F5.1 J/km/s S44 [0.3/185] Integrated 44GHz flux density
57- 59 F3.1 J/km/s e_S44 [0.1/6.8] Uncertainty in S44 (1)
61- 65 F5.1 J/km/s intS44 [0.4/221.1]? Total integrated 44GHz
flux density (2)
--------------------------------------------------------------------------------
Note (1): The corresponding fitting error for each of the maser features that
have been estimated from Gaussian fits.
Note (2): Obtained by adding the integrated flux density of all maser
features in the source.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source identifier
17 A1 --- m_Name The 95GHz component identifier
19- 24 F6.2 km/s Vpk95 [-57.8/114.2] The 95GHz peak velocity
26- 29 F4.2 km/s e_Vpk95 [0/0.9] Uncertainty in Vpk95 (1)
31- 34 F4.2 km/s DelV95 [0.2/9.4] The 95GHz line width
36- 39 F4.2 km/s e_DelV95 [0/1.6] Uncertainty in DelV95 (1)
41- 45 F5.1 Jy Spk95 [0.6/165.4] Peak 95GHz flux density
47- 49 F3.1 Jy e_Spk95 [0.4/6.3] Uncertainty in Spk95 (1)
51- 55 F5.1 J/km/s S95 [0.4/131.4] Integrated 95GHz flux density
57- 59 F3.1 J/km/s e_S95 [0.1/6.1] Uncertainty in S95 (1)
61- 65 F5.1 J/km/s intS95 [0.6/147.1]? Total integrated 95GHz
flux density (2)
--------------------------------------------------------------------------------
Note (1): The corresponding fitting error for each of the maser features that
have been estimated from Gaussian fits.
Note (2): Obtained by adding the integrated flux density of all maser
features in the source.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source identifier
17- 18 I2 arcsec ASep [0/59] Angular separation between Source
and IRAS positions
20- 30 A11 --- IRAS IRAS identifier (HHMm+DDMM; B1950)
32- 38 F7.4 Jy F12 [0.2/78.5] IRAS 12um band flux density
40- 46 F7.3 Jy F25 [1.6/478.2] IRAS 25um band flux density
48- 55 F8.2 Jy F60 [13.5/12790] IRAS 60um band flux density
57- 64 F8.2 Jy F100 [43.8/26780] IRAS 100um band flux density
66 I1 --- q_F12 [1/3] Flux quality in F12
68 I1 --- q_F25 [1/3] Flux quality in F25
70 I1 --- q_F60 [1/3] Flux quality in F60
72 I1 --- q_F100 [1/3] Flux quality in F100
74- 78 F5.2 kpc Dist [0.3/11.7] Distance (1)
80- 84 F5.1 10+3Lsun LBol [0.1/665.6] Bolometric luminosity of
IRAS source (2)
--------------------------------------------------------------------------------
Note (1): From Yang+ 2017, J/ApJS/231/20, primarily using
kinematic distances calculated from Reid+ (2014, J/ApJ/783/130).
Note (2): Bolometric luminosities were calculated based on
Connelley+ (2007, J/AJ/133/1528).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Maser identifier
17- 18 I2 arcsec ASep [2/48] Angular separation of KVN targeted
center and WISE HII regions
20- 34 A15 --- WISE WISE HII region identifier
36- 38 I3 arcsec Rad [19/608] WISE radius of HII region
40- 42 I3 km/s Vel0 Lower velocity range of class I methanol maser
43 A1 --- --- [-]
44- 46 I3 km/s Vel1 Upper velocity range of class I methanol maser
48- 52 F5.1 km/s Vrrl [-28.2/108.1] RRL velocity of HII regions
54- 56 F3.1 --- Spkr [0.4/0.9]? Peak flux density ratio between
95 and 44GHz methanol masers
(Spk,95/Spk,44)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Jul-2020