J/AJ/169/12 Observations & fitted parameters of OH maser emission (Qiao+, 2025)
5cm OH masers in northern star formation regions.
Qiao H.-H., Ouyang X.-J., Shen Z.-Q., Breen S.L., Yang K., Chen Xi, Li J.
<Astron. J., 169, 12 (2025)>
=2025AJ....169...12Q 2025AJ....169...12Q
ADC_Keywords: Masers; Star Forming Region; Polarization; Interstellar medium;
Radio sources
Keywords: Interstellar masers ; Catalogs ; Star formation ;
Interstellar molecules
Abstract:
We present a 6.0GHz excited-state OH maser survey toward 155 northern
star formation regions utilizing the Shanghai Tianma Radio Telescope.
In total, we detect 44 6.0GHz OH masers, 8 of which are new detections
(one at 6016MHz, two at 6030MHz, and five at 6035MHz). Of these
44 detected 6.0GHz OH masers, 13 sites exhibit 6030MHz OH masers, all
44 sites show the 6035MHz transition, one site (G009.620+0.194) has
the only 6016MHz OH maser, and one site (W3(OH)) shows the only
6049MHz OH maser. The 6016MHz OH maser is the first OH maser of this
transition detected in star formation regions. Investigations of the
association between 6030/6035MHz OH masers with 1665MHz ground-state OH,
6.7GHz methanol, and 22GHz water masers show that 1665MHz OH masers
are good indicators of 6.0GHz OH masers (29% detection rate), which is
consistent with previous results. The majority (more than 77%) of
6030 and 6035MHz OH masers are associated with 6.7GHz methanol and/or
22GHz water masers. Comparison between our spectra with previous
spectra, we find that only two sources remain fairly stable since
their discoveries. We identify 80 Zeeman pairs in 32 6.0GHz OH maser
sites with typical magnetic field strengths of less than 10mG. The
magnetic field directions derived from these 32 maser sites with
Zeeman pairs are consistent with previous work, which indicates that
the 6.0GHz OH masers may be potential tracers of the large-scale
Galactic magnetic field.
Description:
The observations were conducted with the 65m fully steerable Shanghai
Tianma Radio Telescope (TMRT) on 2018 July 7-15, 2018 September 3-4
and 6-8, and 2019 April 3, 5, 9-10, and 16.
The C-band receiver of the TMRT has a frequency range of 4-8GHz. Four
spectral windows, each having a bandwidth of 23.4 MHz, were arranged
to cover the excited-state OH transitions at 6.0 GHz, i.e., 6016.746,
6030.747, 6035.092, and 6049.084 MHz. Each spectral window had a
spectral resolution of 1.431kHz, equivalent to a velocity resolution
of about 0.07km/s at 6.0GHz. The aperture efficiency is about 55% with
a sensitivity of about 1.5Jy/K. The beam size at 6.0GHz is about 2.7'.
We adopted the position-switching mode to conduct the observations.
Each source was observed in eight ON-OFF cycles with one cycle of 3
minutes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 112 59 Star formation regions showing 6.0GHz OH emission
table2.dat 65 176 Fitted line parameters of the 6.0GHz OH emission
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See also:
VIII/96 : 6-GHz methanol multibeam maser catalogue (Caswell+, 2010-12)
J/A+AS/101/153 : Galactic H2O masers (Palagi+ 1993)
J/A+AS/120/283 : H2O maser features in ultracompact HII regions (Hofner+, 1996)
J/A+A/325/255 : 5cm OH masers survey (Baudry+ 1997)
J/A+AS/143/269 : 6.7GHz methanol maser emission survey (Szymczak+, 2000)
J/A+A/414/235 : OH maser emission from star forming regions (Szymczak+, 2004)
J/A+A/434/613 : Water maser survey of methanol maser sources (Szymczak+, 2005)
J/ApJ/668/331 : OH masers in W3(OH) (Fish+, 2007)
J/other/PASA/26.454 : Precise positions of methanol masers (Caswell, 2009)
J/MNRAS/416/1764 : H2O Southern Galactic Plane Survey (HOPS) (Walsh+, 2011)
J/MNRAS/442/2240 : Accurate water maser positions from HOPS (Walsh+, 2014)
J/MNRAS/451/74 : Excited-state hydroxyl maser polarimetry (Green+, 2015)
J/MNRAS/461/136 : MMB Survey ex-OH catalogue (Avison+, 2016)
J/A+A/642/A145 : OH 6035MHz line in high-mass SFRs (Szymczak+, 2020)
J/ApJ/928/129 : 4.7GHz OH masers in north. star formation regions (Qiao+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Name of source in galactic coordinates
(GLLL.lll+BB.bbb)
17- 20 I4 --- Freq [6016/6049] Frequency of the OH transition
22- 31 A10 "Y/M/D" Epoch Observation date
33- 37 F5.1 km/s Vmin [-63/112] Lower limit of the velocity range
of the OH emission
39- 43 F5.1 km/s Vmax [-62/114] Upper limit of the velocity range
of the OH emission
45- 49 F5.1 km/s Vp [-62/114] Peak velocity of the maser
emission at the brightest channel
51- 55 F5.1 Jy Sp [0.2/146] Peak flux density
(flux density of the brightest channel)
57- 61 F5.1 Jy SpLHC [0/149] Peak flux densities at peak of the
LHC polarization spectrum
63- 66 F4.1 Jy.km/s SiLHC [0/76] Integrated flux density at peak of
the LHC polarization spectrum
68- 72 F5.1 km/s VpLHC [-62/102] Velocity at peak of the LHC
polarization spectrum
74- 78 F5.1 Jy SpRHC [0.1/139] Peak flux densities at peak of
the LHC polarization spectrum
80- 83 F4.1 Jy.km/s SiRHC [0.1/81] Integrated flux density at peak of
the LHC polarization spectrum
85- 89 F5.1 km/s VpRHC [-62/113] Velocity at peak of the LHC
polarization spectrum
91- 98 A8 --- Alias Alias of the maser
100- 104 A5 --- RefOH Reference of the OH maser emission (1)
106- 108 A3 --- RefCH3OH Reference for methanol (CH3OH) maser
detection toward this source (2)
110- 112 A3 --- RefH2O Reference for water (H2O) maser detection
toward this source (2)
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Note (1): References as follows:
New = New OH maser emission; 8 occurrences
C2003 = J. L. Caswell (2003MNRAS.341..551C 2003MNRAS.341..551C); 8 occurrences
CV95 = Caswell & Vaile (1995MNRAS.273..328C 1995MNRAS.273..328C); 6 occurrences
C2001 = J. L. Caswell (2001MNRAS.326..805C 2001MNRAS.326..805C); 16 occurrences
A2016 = Avison+ (J/MNRAS/461/136); 3 occurrences
O2022 = Ouyang+ (2022ApJS..260...51O 2022ApJS..260...51O); 1 occurrence
S2020 = Szymczak+ (J/A+A/642/A145); 3 occurrences
BD97 = Baudry+ (J/A+A/325/255); 13 occurrences
GU84 = Guilloteau+ (1984A&A...131...45G 1984A&A...131...45G); 1 occurrence
Note (2): References as follows:
N = No detection or listing of the reference; CH3OH: 7 occurrences;
H2O: 6 occurrences
Cas = Caswell+2010 (VIII/96); CH3OH: 3 occurrences
Wal = Walsh+2014 (J/MNRAS/442/2240); H2O: 4 occurrences
Gre = Green+ (2010MNRAS.409..913G 2010MNRAS.409..913G); CH3OH: 8 occurrences
For = Forster & Caswell (1989A&A...213..339F 1989A&A...213..339F); H2O: 16 occurrences
Pal = Palagi+1993 (J/A+AS/101/153); H2O: 10 occurrences
Bre = Breen+ (2015MNRAS.450.4109B 2015MNRAS.450.4109B); CH3OH: 17 occurrences
HC = Hofner & Churchwell, 1996 (J/A+AS/120/283); H2O: 1 occurrence
Szy = Szymczak+2005 (J/A+A/434/613); H2O: 4 occurrences
SHK = Szymczak+2000 (J/A+AS/143/269); CH3OH: 5 occurrences
KH = Kurtz & Hofner (2005AJ....130..711K 2005AJ....130..711K); H2O: 1 occurrence
HS = Harvey-Smith+ (2008MNRAS.384..719H 2008MNRAS.384..719H); CH3OH: 2 occurrences
Goe = Goedhart+ (2004MNRAS.355..553G 2004MNRAS.355..553G); CH3OH: 1 occurrence
SRM = Scalise+ (1989A&A...221..105S 1989A&A...221..105S); H2O: 1 occurrence
Grb = Green+ (2012MNRAS.420.3108G 2012MNRAS.420.3108G); CH3OH: 1 occurrence
CHO = Choi+ (2014ApJ...790...99C 2014ApJ...790...99C); H2O: 1 occurrence
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Name of source in galactic coordinates
(GLLL.lll+BB.bbb)
17- 20 I4 MHz Freq [6016/6049] Frequency of the OH transition
22- 27 F6.2 km/s VelLSR [-63/114] Peak velocity of the fitted
spectral component
29- 32 F4.2 km/s e_VelLSR [0/0.14] Uncertainty in LSRVel
34- 37 F4.2 km/s FWHM [0.1/7] Full width at half maximum (FWHM)
line width
39- 42 F4.2 km/s e_FWHM [0/0.5] Uncertainty in DeltaV
44- 48 F5.2 Jy.km/s Sint [0.03/60.2] Integrated flux density of the
fitted spectral feature
50- 53 F4.2 Jy.km/s e_Sint [0.01/2.3] Uncertainty in Sint
55- 60 F6.2 Jy Sp [0.1/117] Peak flux density of the fitted
spectral feature
62- 65 F4.2 Jy sigma [0.03/0.2]? 1σ noise level of each
spectrum obtained from the Gaussian fitting
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 20-Oct-2025