J/ApJS/262/42 VLBA obs. of masers in the Scutum Spiral Arm (Li+, 2022)
Accurate distances of massive young stars in the Scutum Spiral Arm.
Li J.J., Immer K., Reid M.J., Sanna A., Rygl K.L.J., Xu Y., Zhang B.,
Brunthaler A., Menten K.M.
<Astrophys. J. Suppl. Ser., 262, 42 (2022)>
=2022ApJS..262...42L 2022ApJS..262...42L
ADC_Keywords: Star Forming Region; Masers; Milky Way; Parallaxes, trigonometric;
Proper motions; Radio sources
Keywords: Trigonometric parallax
Abstract:
As part of the Bar and Spiral Structure Legacy (BeSSeL) Survey, we
have used the Very Long Baseline Array (VLBA) to measure
16 trigonometric parallaxes and proper motions of molecular masers
associated with 14 high-mass star-forming regions in the Scutum arm in
the first quadrant of the Milky Way. This increases the number of
maser sources with accurate distances in this arm to 42. The Scutum
arm can now be traced over a length of ∼8kpc and spanning ∼100° of
Galactic azimuth. We find that the large inward peculiar motions noted
by Immer+ (2019A&A...632A.123I 2019A&A...632A.123I) are concentrated near the end of the
Galactic bar, while away from the bar modest peculiar motions more
typical of spiral arms are seen, strengthening the suggestion that the
large motions are induced by the bar.
Description:
Our observations used the VLBA operated by the National Radio
Astronomy Observatory (NRAO) and were performed under the programs of
BR149 and BR198. Fifteen 6.7GHz CH3OH masers were observed with four
7hr shared tracks spanning at least one year (between 2012-Sep-14 and
2015-Apr-2). One 22GHz H2O maser (G028.39+00.08) was also observed
at six epochs (between 2013-Nov-4 and 2015-Apr17).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 79 14 Parallaxes and proper motions of sources in
the Scutum Arm
table3.dat 74 58 Positions and brightnesses of the maser spots;
see Appendix A
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See also:
J/AJ/126/2562 : Second VLBA calibrator survey: VCS2 (Fomalont+, 2003)
J/AJ/129/1163 : Third VLBA calibrator survey: VCS3 (Petrov+, 2005)
J/ApJS/166/526 : Compact extragalactic radio sources (Xu+, 2006)
J/ApJS/194/25 : VLBA calibrator search for the BeSSeL survey (Immer+, 2011)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/ApJ/885/131 : ∼200 high-mass SFR plx & proper motion with VLBI (Reid+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Identifier of the source (GLLL.ll+BB.bb)
15 A1 --- f_Name Flag on Name (1)
17- 21 F5.2 deg GLON [0.31/33.39] Galactic longitude
23- 27 F5.2 deg GLAT [-0.38/0.22] Galactic latitude
29- 33 F5.3 mas plx [0.113/0.352] Parallax
35- 39 F5.3 mas e_plx [0.01/0.096] Parallax uncertainty
41- 43 F3.1 kpc Dist [2.8/8.8] Distance
45- 47 F3.1 kpc e_Dist [0.2/1.8] Lower uncertainty on Dist
49- 51 F3.1 kpc E_Dist [0.2/3.1] Upper uncertainty on Dist
53- 57 F5.2 mas/yr muX [-2.48/0.21] Proper motion in eastward direction
(µx=µαcosδ)
59- 62 F4.2 mas/yr e_muX [0.13/0.45] muX uncertainty
64- 68 F5.2 mas/yr muY [-5.4/-1.57] Proper motion in northward direction
(µy=µδ)
70- 73 F4.2 mas/yr e_muY [0.13/0.64] muY uncertainty
75- 77 I3 km/s Vlsr [10/110] Local Standard of Rest velocity
79 I1 km/s e_Vlsr [3/5] Vlsr uncertainty
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Note (1): Flag as follows:
a = for G010.32-00.15 we give variance-weighted averages of G010.32-00.15
and G010.34-00.14
b = for G028.39+00.08 we give variance-weighted averages of its water and
methanol maser parallaxes and its methanol maser proper motion
c = for G031.28+00.06 we give variance-weighted averages from this paper and
Zhang+ (2014ApJ...781...89Z 2014ApJ...781...89Z)
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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- 13 A13 --- Name Identifier of the source
15 A1 --- f_Name Flag on Name (a=methanol maser; b=water maser)
17- 18 I2 h RAh [17/18] Hour of right ascension (J2000) (1)
20- 21 I2 min RAm Minute of right ascension (J2000)
23- 30 F8.5 s RAs Second of right ascension (J2000)
32 A1 --- DE- Sign of declination (J2000) (1)
33- 34 I2 deg DEd Degree of declination (J2000) (1)
36- 37 I2 arcmin DEm Arcminute of declination (J2000)
39- 45 F7.4 arcsec DEs Arcsecond of declination (J2000)
47- 49 F3.1 deg phi [0.5/4.5]? Angular separation between the
maser and the calibrator
51- 56 F6.3 Jy/beam bright [0.009/68.9] Peak brightness (1)
58- 62 F5.1 km/s Vlsr [11.6/110.7]? Local Standard of Rest velocity
64- 66 F3.1 mas Beam1 [1.7/9.6] the naturally weighted (NW) beam (1)
67 A1 --- --- [x]
68- 70 F3.1 mas Beam2 [1.2/4.2] the naturally weighted (NW) beam (1)
72- 74 I3 deg PA [-19/40] Position angle, east of north,
of the naturally weighted (NW) beam (1)
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Note (1): The maser absolute position, the peak brightness, the size, and the
P.A. of the naturally weighted (NW) beam are listed for the first
epoch for each source; see Table 2 (Epochs 5-7, if any, are not
included below):
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Code Source Epoch 1 Epoch 2 Epoch 3 Epoch 4
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BR149B G000.31-00.20 2012 Sep 14 2013 Mar 05 2013 Apr 02 2013 Sep 12
BR149C G010.32-00.15 2012 Sep 22 2013 Mar 10 2013 Apr 07 2013 Sep 16
G011.10-00.11 2012 Sep 22 2013 Mar 10 2013 Apr 07 2013 Sep 16
BR149F G018.87+00.05 2012 Oct 09 2013 Mar 07 2013 Apr 14 2013 Oct 01
G019.36-00.03 2012 Oct 09 2013 Mar 07 2013 Apr 14 2013 Oct 01
BR149H G028.30-00.38 2012 Oct 14 2013 Mar 18 2013 Apr 16 2013 Oct 19
G028.39+00.08 2012 Oct 14 2013 Mar 18 2013 Apr 16 2013 Oct 19
BR149I G028.83-00.25 2012 Oct 15 2013 Mar 19 2013 Apr 19 2013 Oct 20
BR149J G030.19-00.16 2012 Oct 21 2013 Mar 23 2013 Apr 18 2013 Oct 21
BR149K G031.28-00.06 2012 Oct 22 2013 Mar 25 2013 Apr 22 2013 Oct 23
BR149M G033.39+00.00 2012 Nov 05 2013 Mar 28 2013 Apr 25 2013 Oct 26
BR198E G009.21-00.20 [2013 Sep 13] 2014 Apr 04 2014 Sep 06 2014 Oct 17
G010.34-00.14 [2013 Sep 13] 2014 Apr 04 2014 Sep 06 2014 Oct 17
BR198H G022.03+00.22 [2013 Oct 02] 2014 Mar 27 2014 Sep 08 2014 Oct 27
G024.63-00.32 [2013 Oct 02] 2014 Mar 27 2014 Sep 08 2014 Oct 27
BR198L G028.39+00.08 [2013 Nov 04] 2014 Apr 07 2014 Jul 20 2014 Sep 14
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Note: Epochs in square brackets were not used owing to electronic failures.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 21-Nov-2022