J/A+A/642/A145 OH 6035MHz line in high-mass SFRs (Szymczak+, 2020)
A search for the OH 6035 MHz line in high-mass star-forming regions.
Szymczak M., Wolak P., Bartkiewicz A., Aramowicz M., Durjasz M.
<Astron. Astrophys., 642, A145 (2020)>
=2020A&A...642A.145S 2020A&A...642A.145S (SIMBAD/NED BibCode)
ADC_Keywords: Masers ; Radio lines
Keywords: masers - stars: massive - stars: formation - ISM: molecules -
radio lines: ISM
Abstract:
The excited states of OH masers detected in the environment of
high-mass young stellar objects (HMYSOs) are important for improving
our understanding of the physical conditions of these objects and also
provide information about their magnetic fields.
We aim to search for excited-state OH 6035MHz maser emission in HMYSOs
which might have escaped detection in previous surveys or were never
searched for. Methods. A sample of HMYSOs derived from untargeted
surveys of the 6668MHz methanol maser line was observed at 6035MHz OH
transition with the Torun 32m radio telescope. The 6035MHz detections
were observed in the OH 6031MHz line. Two-thirds of the detections
were observed at least three times over a two-year period.
Out of 445 targets, 37 were detected at 6035MHz, including seven new
discoveries. The 6031MHz line was detected towards ten 6035MHz
sources, one of which was not previously reported. All the newly
detected sources are faint with the peak flux density lower than 4Jy
and show significant or high variability on timescales of 4 to 20
months. Zeeman pair candidates identified in three new sources imply a
magnetic field intensity of 2-11mG. Comparison of our spectra with
those obtained ∼10yr ago indicates different degrees of variability
but there is a general increase in the variability index on an ∼25yr
timescale, usually accompanied by significant changes in the profile
shape.
Description:
Observations of the 2{PI}3/2, J=5-2, F=3-3 OH transition at
6035.092MHz were carried out from June to September 2018 with the
Torun 32m radio telescope. Detections were reobserved in two sessions:
November-December 2018 and March-April 2019, and since then several
sources have been monitored. Furthermore, all of them were also
searched for the 2{PI}3/2, J=5/2, F=2-2 line at 6030.747MHz.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 34 28 Variability indices of 6035MHz emission for the
main feature on timescales of 2 (vi2),
10 (vi10), and 25 (vi25) years
tablea1.dat 145 30 Properties of 6035 and 6031MHz OH maser emission
for previously known sources
tablea2.dat 48 404 Non-detections
tablea3.dat 85 43 6035 and 6031MHz OH Zeeman pair candidates
identified in the present sample
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See also:
J/A+A/325/255 : 5cm OH masers survey (Baudry+ 1997)
J/MNRAS/451/74 : Excited-state hydroxyl maser polarimetry (Green+, 2015)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Source Source name (GLLL.lll+BB.bbb)
17- 19 A3 --- n_Source Note on Source (1)
21- 24 F4.2 --- vi2 Variability indices of 6035MHz emission for
the main feature on timescales of 2 years
26- 29 F4.2 --- vi10 ? Variability indices of 6035MHz emission for
the main feature on timescales of 10 years
31- 34 F4.2 --- vi25 ? Variability indices of 6035MHz emission for
the main feature on timescales of 25 years
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Note (1): For sources with complex spectra, the velocity and polarisation of
the feature used are noted as follows:
1 = 21.5km/s LHC
2 = large changes in the spectrum shape
3 = 58.4km/s RHC
4 = 66.38km/s LHC
5 = 55.0km/s RHC
6 = 7.87km/s RHC
7 = -43.3km/s LHC
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Source Source name (GLLL.lll+BB.bbb)
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 27 F5.2 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 40 F5.2 arcsec DEs Declination (J2000)
42- 47 F6.2 km/s DV1a 6035MHz lower value of velocity range of
I Stokes emission
49- 53 F5.1 km/s DV1b 6035MHz upper value of velocity range of
I Stokes emission
55- 60 F6.2 km/s VpLHC1 ?=- 6035MHz LHC peak velocity
62- 67 F6.2 Jy SpLHC1 ?=- 6035MHz LHC peak flux density
69- 74 F6.2 Jy.km/s SiLHC1 6035MHz LHC integrated flux density
76- 81 F6.2 km/s VpRHC1 6035MHz RHC peak velocity
83- 88 F6.2 Jy SpRHC1 6035MHz RHC peak flux density
90- 95 F6.2 Jy.km/s SiRHC1 6035MHz RHC integrated flux density
97-101 F5.1 km/s DV2a ? 6031MHz lower value of velocity range of
I Stokes emission
103-107 F5.1 km/s DV2b ? 6031MHz upper value of velocity range of
I Stokes emission
109-114 F6.2 km/s VpLHC2 ?=- 6031MHz LHC peak velocity
116-120 F5.2 Jy SpLHC2 ?=- 6031MHz LHC peak flux density
122-126 F5.2 Jy.km/s SiLHC2 ? 6031MHz LHC integrated flux density
128-133 F6.2 km/s VpRHC2 ? 6031MHz RHC peak velocity
135-139 F5.2 Jy SpRHC2 ? 6031MHz RHC peak flux density
141-145 F5.2 Jy.km/s SiRHC2 ? 6031MHz RHC integrated flux density
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Source Source name (GLLL.lll+BB.bbb)
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 27 F5.2 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 40 F5.2 arcsec DEs Declination (J2000)
42- 46 F5.1 km/s Vc(6668) Central velocity of observation
48 I1 --- Ref ? Reference of detection for previously known
sources (1)
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Note (1): References as follows:
1 = Caswell & Vaile (1995MNRAS.273..328C 1995MNRAS.273..328C)
2 = Avison et al. (2016MNRAS.461..136A 2016MNRAS.461..136A)
3 = Baudry et al. (1997, Cat. J/A+A/325/255)
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Source Source name (GLLL.lll+BB.bbb)
17- 22 F6.2 km/s VfLHC LHC peak velocity (1)
24- 29 F6.2 Jy SfLHC LHC peak flux density (1)
32- 37 F6.2 km/s VfRHC RHC peak velocity (1)
39- 44 F6.2 Jy SfRHC RHC peak flux density (1)
46- 51 F6.2 km/s Vd Demagnetized velocity
53 A1 --- n_Vd [a] a: 6031MHz transition,
else 6035MHz transition
55- 59 F5.1 gauss B Magnetic field strength
61 A1 --- Rel [A/B] Reliability parameter (2)
63 A1 --- l_B1 Limit flag on B1
64- 67 F4.1 gauss B1 ? Estimate of the magnetic field strength
from the literature
69 I1 --- r_B1 ? Reference for B1 (3)
72- 75 F4.1 gauss B2 ? Estimate of the magnetic field strength
from the literature
77 I1 --- r_B2 ? Reference for B2 (3)
80- 83 F4.1 gauss B3 ? Estimate of the magnetic field strength
from the literature
85 I1 --- r_B3 ? Reference for B3 (3)
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Note (1): The peak velocities (Vf) and peak flux densities (Sf) are obtained by
fitting Gaussian components to the spectra of LHC and RHC features.
Note (2): The reliability parameter describes two cases of Zeeman splitting
estimation: both polarised spectral features showed single Gaussian
components (A) or were blended (B).
Note (3): References as follows:
1 = Caswell & Vaile (1995MNRAS.273..328C 1995MNRAS.273..328C)
2 = Caswell (2003MNRAS.341..551C 2003MNRAS.341..551C)
3 = Baudry et al. (1997, cat. J/A+A/325/255)
4 = Green et al. (2015, Cat. J/MNRAS/451/74)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Jan-2021