J/ApJ/930/114 44GHz VLA obs. of methanol masers in DR21(OH) (Wenner+, 2022)
Long-term variability of Class I methanol masers in the high-mass star-forming
region DR21(OH).
Wenner N., Sarma A.P., Momjian E.
<Astrophys. J., 930, 114 (2022)>
=2022ApJ...930..114W 2022ApJ...930..114W
ADC_Keywords: Masers; Star Forming Region; Radio sources; Cross identifications
Keywords: Star formation ; Star forming regions ; Massive stars ;
Interferometers ; Interstellar masers ; Astrophysical masers
Abstract:
High-mass stars play an important role in the interstellar medium, but
much remains to be known about their formation. Class I methanol
masers may be unique tracers of an early stage of high-mass star
formation, and a better understanding of such masers will allow them
to be used as more effective probes of the high-mass star-forming
process. We present an investigation of the long-term variability of
Class I methanol masers at 44GHz toward the high-mass star-forming
region DR21(OH). We compare observations taken in 2017 to observations
from 2012, and also to 2001 data from the literature. A total of
57 maser spots were found in the 2017 data, with center velocities
ranging between -8.65 to +2.56km/s. The masers are arranged in a
western and an eastern lobe with two arcs in each lobe that look like
bow shocks, consistent with previous observations. The general trend
is an increase in intensity from 2001 to 2012, and a decrease from
2012 to 2017. Variability appears to be more prevalent in the inner
arc of the western lobe than in the outer arc. We speculate that this
may be a consequence of episodic accretion, in which a later accretion
event has resulted in ejection of material whose shock reached the
inner arc at some point in time after 2001. We conclude that class I
methanol masers are variable on long timescales (of the order of 5-10yr).
Description:
We observed the 70-61 A+ Class I CH3OH maser emission line at
44GHz toward the high-mass star-forming region DR21(OH) with the Karl
G. Jansky Very Large Array (VLA) of the NRAO on 2017 May 24. The VLA
was in the C-configuration with a maximum baseline length of 3.4km.
Objects:
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RA (ICRS) DE Designation(s)
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20 39 01.01 +42 22 50.1 DR 21 (OH) = W 75S(OH)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 64 82 Fitted parameters of the observed 44GHz ClassI
CH3OH masers in DR21(OH)
table5.dat 35 49 Observed masers in DR21(OH) from
Araya+ (2009ApJ...698.1321A 2009ApJ...698.1321A)
table6.dat 73 29 Observed masers in DR21(OH)
from Momjian & Sarma (2017ApJ...834..168M 2017ApJ...834..168M ; M-S)
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See also:
J/ApJS/155/149 : CH3OH 70-61 A+ maser sources (Kurtz+, 2004)
J/MNRAS/439/2584 : Southern methanol masers at 36 and 44GHz (Voronkov+, 2014)
J/ApJ/854/170 : Methanol (CH3OH) and OH masers in NGC 6334I (Hunter+, 2018)
J/ApJS/245/12 : 6.7GHz methanol masers & RRLs in MSX regions (Ouyang+, 2019)
J/ApJS/248/18 : 44 and 95GHz obs. of class I methanol masers (Yang+, 2020)
J/ApJS/256/7 : 18cm OH masers VLA obs. toward 80 SFRs (Bayandina+, 2021)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID [1/57] Maser identifier
3 A1 --- m_ID [a-d] Component identifier on the maser ID
5- 6 I2 h RAh [20] Hour of right ascension (J2000)
8- 9 I2 min RAm [38/39] Minute of right ascension (J2000)
11- 15 F5.2 s RAs Second of right ascension (J2000)
17 A1 --- DE- [+] Sign of declination (J2000)
18- 19 I2 deg DEd [42] Degree of declination (J2000)
21- 22 I2 arcmin DEm [22/23] Arcminute of declination (J2000)
24- 27 F4.1 arcsec DEs Arcsecond of declination (J2000)
29- 34 F6.2 Jy/beam Int [0.09/278] Intensity
36- 39 F4.2 Jy/beam e_Int [0.01/9] Int uncertainty
41- 46 F6.3 km/s Vel [-8.7/2.6] Center velocity
48- 52 F5.3 km/s e_Vel [0.001/0.2] Vel uncertainty
54- 58 F5.3 km/s Width [0.19/1.8] Velocity linewidth
60- 64 F5.3 km/s e_Width [0.001/0.3] Width uncertainty
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Byte-by-byte Description of file: table[56].dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Maser identifier
8 A1 --- m_Name [ab] Component identifier on the maser name
10- 11 I2 h RAh [20] Hour of right ascension (J2000)
13- 14 I2 min RAm [38/39] Minute of right ascension (J2000)
16- 20 F5.2 s RAs Second of right ascension (J2000)
22 A1 --- DE- [+] Sign of declination (J2000)
23- 24 I2 deg DEd [42] Degree of declination (J2000)
26- 27 I2 arcmin DEm [22/23] Arcminute of declination (J2000)
29- 32 F4.1 arcsec DEs Arcsecond of declination (J2000)
34- 35 I2 --- ID [2/56]? Corresponding 2017 maser
36 A1 --- m_ID [a-d] Component identifier on the 2017 maser ID
38- 43 F6.2 Jy/beam Int [0.3/324]? Intensity (only for Table 6)
45- 48 F4.2 Jy/beam e_Int [0.01/4]? Int uncertainty
50- 55 F6.3 km/s Vel [-2.4/2.6]? Center velocity (only for Table 6)
57- 61 F5.3 km/s e_Vel [0.001/0.2]? Vel uncertainty
63- 67 F5.3 km/s Width [0.2/0.8]? Velocity linewidth (only for Table 6)
69- 73 F5.3 km/s e_Width [0.001/0.2]? Width uncertainty
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDs] 19-Mar-2024