2004A&A...428..479W


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.21CET21:12:38

2004A&A...428..479W - Astronomy and Astrophysics, volume 428, 479-495 (2004/12-3)

The polarization of mm methanol masers.

WIESEMEYER H., THUM C. and WALMSLEY C.M.

Abstract (from CDS):

We present a survey of the polarization properties of mm-wavelength methanol masers, comprising both classes, and transitions from 84.5 to 157.0GHz. Linear polarization is found in more than half of the observed objects, and circular polarization is tentatively detected in two sources. Class I and class II CH3OH masers show similar polarization properties. The largest linear polarization is found in the 133GHz class I maser towards L379 (39.5%), and in the 157GHz class II maser towards G9.62+0.19 (36.7%). The spectral profiles of the polarization angle of class I masers are mostly flat, except for two sources showing a linear slope. Since the mm-line methanol masers are expected to be weakly (or not) saturated, we suggest that the stronger fractional polarizations found by us are enhanced by anisotropic pumping and radiative losses. In NGC 7538, we find, for both maser classes, a good agreement between our polarization angles, and those measured for the submillimeter dust continuum. This can be taken as evidence for magnetic alignment of dust grains. It is also possible that an unsaturated maser with equally populated magnetic substates simply amplifies polarized continuum seed radiation. For class II masers, the polarization properties of the various velocity components towards a given source with detectable polarization are quite homogeneous. A possible explanation is discussed. Since methanol is non-paramagnetic, the circular polarization of the unsaturated maser emission can only be due to variations of the angle between the magnetic field and the line of sight along the maser propagation path.

Abstract Copyright:

Journal keyword(s): masers - polarization - techniques: polarimetric - surveys - stars: formation - ISM: magnetic fields

Simbad objects: 21

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Number of rows : 21

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 OMC 2 MoC 05 35 27 -05 10.1           ~ 375 1
2 SH 2-231 HII 05 39 12.9 +35 45 54           ~ 116 0
3 NGC 2264 OpC 06 40 58 +09 53.7     3.9     ~ 1559 1
4 NAME M 8E Y*O 18 04 53.26 -24 26 42.3           ~ 56 0
5 GAL 009.62+00.19 HII 18 06 13.9 -20 31 44           ~ 184 0
6 [VES2000] 181115.70-175653.0 Mas 18 11 15.70 -17 56 53.0           ~ 8 0
7 NAME W 33-Met HII 18 14 12.5 -17 55 44           ~ 27 0
8 W 33a Y*O 18 14 39.0 -17 52 03           ~ 573 0
9 IRAS 18277-1517 FIR 18 30 33.717 -15 15 07.50           ~ 10 0
10 LDN 379 DNe 18 30 34.0 -15 15 10           ~ 33 0
11 [OMN2000] Region 3 PoC 19 23 29.3 +14 31 38           ~ 149 0
12 [VES2000] 192128.90+142348.0 Mas 19 23 46.5 +14 29 41           ~ 12 0
13 W 51f PoC 19 23 47.8 +14 33 13           ~ 11 0
14 NAME DR 21W PoC 20 38 55.0 +42 19 24           ~ 22 0
15 NAME DR 21(OH) M Rad 20 39 01 +42 29.8           ~ 83 0
16 GRS G081.70 +00.50 SFR 20 39 01.6 +42 19 38           O4.5 935 0
17 NAME Cepheus A East SFR 22 54.3 +61 46           ~ 63 0
18 NAME Cepheus A SFR 22 56 17.9 +62 01 49           ~ 692 2
19 NGC 7538 OpC 23 13 37 +61 30.0           ~ 821 0
20 [WBN74] NGC 7538 IRS 1 Y*O 23 13 45.318 +61 28 11.69           ~ 361 3
21 NAME NGC 7538-44GHz Mas 23 13 46.4 +61 27 33           ~ 4 0

    Equat.    Gal    SGal    Ecl

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2020.01.21-21:12:38

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