2011A&A...529A..95V


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.14CET21:12:58

2011A&A...529A..95V - Astronomy and Astrophysics, volume 529A, 95-95 (2011/5-1)

Zeeman splitting of 6.7 GHz methanol masers. On the uncertainty of magnetic field strength determinations.

VLEMMINGS W.H.T., TORRES R.M. and DODSON R.

Abstract (from CDS):

To properly determine the role of magnetic fields during massive star formation, a statistically significant sample of field measurements probing different densities and regions around massive protostars needs to be established. However, relating Zeeman splitting measurements to magnetic field strengths needs a carefully determined splitting coefficient. Polarization observations of, in particular, the very abundant 6.7GHz methanol maser, indicate that these masers appear to be good probes of the large scale magnetic field around massive protostars at number densities up to nH2≃109cm–3. We thus investigate the Zeeman splitting of the 6.7GHz methanol maser transition. We have observed of a sample of 46 bright northern hemisphere maser sources with the Effelsberg 100-m telescope and an additional 34 bright southern masers with the Parkes 64-m telescope in an attempt to measure their Zeeman splitting. We also revisit the previous calculation of the methanol Zeeman splitting coefficients and show that these were severely overestimated making the determination of magnetic field strengths highly uncertain.In total 44 of the northern masers were detected and significant splitting between the right- and left-circular polarization spectra is determined in >75% of the sources with a flux density >20Jy/beam. Assuming the splitting is due to a magnetic field according to the regular Zeeman effect, the average detected Zeeman splitting corrected for field geometry is ∼0.6m/s. Using an estimate of the 6.7GHz A-type methanol maser Zeeman splitting coefficient based on old laboratory measurements of 25GHz E-type methanol transitions this corresponds to a magnetic field of ∼120mG in the methanol maser region. This is significantly higher than expected using the typically assumed relation between magnetic field and density (B∝nH20.47) and potentially indicates the extrapolation of the available laboratory measurements is invalid. The stability of the right- and left-circular calibration of the Parkes observations was insufficient to determine the Zeeman splitting of the Southern sample. Spectra are presented for all sources in both samples.There is no strong indication that the measured splitting between right- and left-circular polarization is due to non-Zeeman effects, although this cannot be ruled out until the Zeeman coefficient is properly determined. However, although the 6.7GHz methanol masers are still excellent magnetic field morphology probes through linear polarization observations, previous derivations of magnetic fields strength turn out to be highly uncertain. A solution to this problem will require new laboratory measurements of the methanol Lande-factors.

Abstract Copyright:

Journal keyword(s): masers - polarization - stars: formation - magnetic fields

Simbad objects: 100

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Number of rows : 100

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME W 3 OH HII 02 27 04.1 +61 52 22           ~ 929 2
2 GAL 174.20-00.08 Cld 05 30 45.9 +33 47 56           ~ 180 2
3 SH 2-231 HII 05 39 12.9 +35 45 54           ~ 115 0
4 NAME Mon R2 HII 06 07 46.6 -06 22 59           ~ 635 2
5 [PMB2005] CH3OH 213.70-12.6 Mas 06 07 47.870 -06 22 57.00           ~ 2 0
6 RAFGL 5180 SFR 06 08 54.1 +21 38 25           ~ 110 0
7 NAME SH 2-255 IRS 1 Y*O 06 12 54.0060 +17 59 22.958           ~ 310 0
8 IC 2162 HII 06 13 04.1 +17 58 44           ~ 334 2
9 LBN 196.49-01.60 HII 06 14 38.40 +13 49 44.7           ~ 160 1
10 DG 121 HII 07 32 09.9 -16 58 14           ~ 50 0
11 PN K 2-15 HII 08 48 39.0560793425 -42 53 54.008936868   12.86 12.01 11.72 10.79 B0V 64 2
12 NAME NGC 3576 IRS 1 HII 11 11 54.8 -61 18 26           ~ 30 1
13 OHIO N 001 Rad 12 03 08.09 +07 15 30.1           ~ 15 1
14 GAL 305.20+00.21 HII 13 11 11.7 -62 34 44           ~ 25 0
15 3C 286 Sy1 13 31 08.2885060664 +30 30 32.960825108   17.51 17.25     ~ 3618 1
16 IRAS 13471-6120 Y*O 13 50 41.832 -61 35 09.96           ~ 33 0
17 GAL 309.92+00.48 HII 13 50 42.0 -61 35 09           ~ 30 0
18 IRAS 13484-6100 HII 13 51 57.8 -61 15 46           ~ 13 0
19 GAL 316.64-00.09 HII 14 44 20.5 -59 55 21           ~ 7 0
20 OH 318.95 -0.20 cor 15 00 55.40 -58 58 52.1           ~ 52 0
21 OH 322.16 +0.63 Mas 15 18 34.64 -56 38 25.3           ~ 30 0
22 IRAS 15278-5620 HII 15 31 43.2 -56 30 25           ~ 34 1
23 IRAS 15394-5358 HII 15 43 20.69 -54 07 35.7           ~ 23 0
24 IRAS 15541-5349 HII 15 57 59.75 -53 58 00.4           ~ 45 0
25 IRAS 15566-5304 mul 16 00 30.8 -53 12 35           ~ 10 0
26 GAL 331.28-00.19 HII 16 11 26.6 -51 41 57           ~ 31 0
27 IRAS 16313-4840 HII 16 35 08.0 -48 46 16           ~ 25 0
28 GAL 337.70-00.05 HII 16 38 32 -47 00.5           ~ 13 0
29 IRAS 16411-4604 FIR 16 44 48.71664 -46 10 23.4876           ~ 2 0
30 IRAS 16465-4437 FIR 16 50 10.0 -44 42 16           ~ 3 0
31 GAL 339.88-01.26 HII 16 52 04.7 -46 08 34           ~ 29 0
32 [JD2012] G341.211-00.233 HII 16 52 22 -44 28.0           ~ 11 0
33 IRAS 16533-4009 HII 16 56 45.58 -40 14 32.4           ~ 46 0
34 IRAS 17008-4040 HII 17 04 20.5 -40 44 26           ~ 20 0
35 IRAS 17016-4124 SFR 17 05 11.160 -41 29 06.00           ~ 47 0
36 NAME NGC 6334F (C) HII 17 20 53.45 -35 47 02.6           ~ 201 1
37 IRAS 17233-3606 HII 17 26 42.8 -36 09 17           ~ 67 0
38 IRAS 17269-3312 Y*O 17 30 14.072 -33 14 13.42           ~ 12 0
39 IRAS 17589-2312 HII 18 01 57.1 -23 12 37           ~ 20 0
40 GAL 009.62+00.19 HII 18 06 13.9 -20 31 44           ~ 184 0
41 [PNE98] 009.621+0.120 Mas 18 06 14.659 -20 31 31.57           ~ 28 0
42 GAL 008.67-00.30 HII 18 06 19.027 -21 37 32.32           ~ 64 0
43 GAL 010.46+00.03 HII 18 08 35.5 -19 52 09           ~ 46 0
44 [HBM2005] G10.47+0.02 cor 18 08 37.9 -19 51 41           ~ 7 0
45 MMB G010.299-00.146 Mas 18 08 56.0595 -20 05 59.787           ~ 47 0
46 GAL 010.30-00.15 HII 18 08 58.315 -20 05 15.27           ~ 78 0
47 GRS G012.89 +00.49 HII 18 11 51.3 -17 31 29           ~ 143 0
48 [UFM2015] G012.887+00.492 cor 18 11 51.3327 -17 31 26.394           ~ 18 1
49 GAL 012.02-00.03 HII 18 12 01.9 -18 31 56           ~ 27 0
50 AGAL G012.024-00.031 cor 18 12 01.9652 -18 31 57.165           ~ 27 0
51 W 33b SFR 18 13 54.68 -18 01 48.1           ~ 73 0
52 [HBM2005] G12.68-0.18 cor 18 13 54.7674 -18 01 44.258           ~ 24 0
53 IRAS 18128-1640 FIR 18 15 45.5 -16 38 58           ~ 13 0
54 GAL 014.11+00.09 Mas 18 15 46.34 -16 38 56.4           ~ 7 0
55 IRAS 18134-1942 HII 18 16 22.506 -19 41 23.36           ~ 46 0
56 IRAS 18151-1208 Y*O 18 17 58.114 -12 07 24.84           ~ 99 0
57 [M91] B182455.8-111624 Mas 18 27 44.1 -11 14 54           ~ 12 0
58 IRAS 18249-1116 cor 18 27 44.98032 -11 14 47.5044           ~ 28 0
59 RAFGL 7009S Y*O 18 34 20.911 -05 59 42.23           ~ 185 0
60 [THW2006] G025.650+01.049SMM smm 18 34 21.1 -05 59 43           ~ 6 0
61 [M91] B183155.8-083417 Mas 18 34 39.0 -08 31 36           ~ 11 0
62 Caswell CH3OH 023.01-00.41 Mas 18 34 39.9 -09 00 44           ~ 17 0
63 GAL 023.44-00.18 HII 18 34 43.6 -08 32 25           ~ 46 0
64 RRF 159 cor 18 36 12.9048 -07 12 06.646           ~ 32 0
65 [SKH2002] 25.71+0.04 Mas 18 38 03.150 -06 24 15.00           ~ 9 0
66 IRAS 18353-0628 HII 18 38 04.9 -06 25 28           ~ 20 0
67 GRS G024.80 +00.10 SFR 18 38 14.8 -06 47 39           ~ 100 0
68 [SVG93] 183626.4-062714 Mas 18 39 04.7 -06 24 17           ~ 10 0
69 Caswell CH3OH 028.15+00.00 Mas 18 42 40.9 -04 15 26           ~ 11 0
70 [HBM2005] G29.86-0.04 mm 18 46 00.2 -02 45 09           ~ 8 0
71 [M91] B184327.1-024236 Mas 18 46 03.6 -02 39 24           ~ 14 1
72 SNR G030.8-00.0 SNR 18 47 32 -01 56.5           ~ 425 0
73 W 43s Rad 18 47 41.68 -02 00 24.3           ~ 22 0
74 IRAS 18456-0129 HII 18 48 12.7 -01 26 34           ~ 23 0
75 IRAS 18470-0050 * 18 49 37.049 -00 46 49.86           ~ 7 0
76 [BK2004] J185328.7+003158 Mas 18 53 28.7 +00 31 58           ~ 14 0
77 IRAS 18512+0029 * 18 53 45.9757287672 +00 33 33.046055933           ~ 6 0
78 [WWS2012] G035.03+00.35 cor 18 54 00.7975 +02 01 24.083           ~ 21 0
79 GAL 035.03+00.35 HII 18 54 01.0 +02 01 32           ~ 35 0
80 IRAS 18517+0437 SFR 18 54 13.8 +04 41 32           ~ 55 0
81 GAL 035.2-00.74 MoC 18 58 13 +01 40.6           ~ 151 0
82 IRAS 18556+0136 mul 18 58 13.1 +01 40 35           ~ 132 0
83 SNR G035.2-01.8 SNR 19 01.6 +01 14           ~ 142 0
84 GAL 035.20-01.74 Y*O 19 01 47.0 +01 13 08           ~ 70 1
85 IRAS 19049+0720 FIR 19 07 20.9 +07 25 12           ~ 3 0
86 W 49n HII 19 10 13.2 +09 06 12           ~ 403 3
87 [OMN2000] Region 3 PoC 19 23 29.3 +14 31 38           ~ 148 0
88 NAME W 51 North Rad 19 23 40.0 +14 30 51           ~ 140 0
89 W 51 SNR 19 23 50 +14 06.0           ~ 1119 1
90 [KJB2003] G49.586-0.385 HII 19 23 54.7 +14 35 44           ~ 11 0
91 [KCW94] 069.540-00.975 HII 20 10 09.0 +31 31 35           ~ 166 1
92 IRAS 20081+3122 Y*O 20 10 09.036 +31 31 34.14           ~ 170 0
93 Onsala 1 Mas 20 10 09.2036 +31 31 36.090           ~ 178 0
94 IRAS 20126+4104 Y*O 20 14 25.8816186803 +41 13 36.869078243           B2.5-B0.5 388 0
95 NAME Cyg X FIR 33 Y*O 20 38 35.9 +42 37 22           B1.5 357 1
96 NAME LDN 1206 IR Cluster Cl* 22 28 52 +64 13.7           ~ 3 0
97 IRAS 22272+6358A Cld 22 28 52.2 +64 13 43           ~ 47 0
98 NAME Cepheus A SFR 22 56 17.9 +62 01 49           ~ 692 2
99 NGC 7538 OpC 23 13 37 +61 30.0           ~ 815 0
100 [SW2010] IRS 11 S Mas 23 13 43.93 +61 26 50.3           ~ 9 0

    Equat.    Gal    SGal    Ecl

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2019.11.14-21:12:58

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