1999A&A...344..668G


Query : 1999A&A...344..668G

1999A&A...344..668G - Astronomy and Astrophysics, volume 344, 668-674 (1999/4-2)

Submillimetre polarization and constraints on dust grain alignment.

GREAVES J.S., HOLLAND W.S., MINCHIN N.R., MURRAY A.G. and STEVENS J.A.

Abstract (from CDS):

Polarization at 800 and 1100µm has been observed in the star-forming regions Mon R2, DR21 and W3-IRS4. These data have been used to test proposed mechanisms for producing polarized dust emission in the submillimetre. It was found that illumination effects are not sufficient to explain the observed polarization, and that some degree of grain alignment is required. In general, mechanical alignment (via collisions with molecules) and radiative alignment of asymmetrical grains are the most probable mechanisms. The degrees and directions of polarization observed in DR21 are found to be wavelength dependent at 800 to 1100µm. A search of previous JCMT polarimetry results shows that for about half the sources observed, p(1100) is greater than p(800), while in most of the other sources the two values of p are in agreement. A possible explanation for this result is that there are two (or more) non-cospatial grain populations along the line of sight, with different degrees of polarizability and different opacity indices. This can produce bias effects in the polarization percentage and position angle. Thus the choice of wavelength is not immaterial in dust emission polarimetry, as is commonly believed.

Abstract Copyright:

Journal keyword(s): ISM: magnetic fields - polarization

Simbad objects: 14

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Number of rows : 14
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 MPCM J022530.99+620620.9 HII 02 25 31.18 +62 06 24.5           O8V-B0.5V 100 1
2 NAME W3 IRS 5 Y*O 02 25 40.54 +62 05 51.4           B1 339 0
3 W 3 MoC 02 27 04.10 +61 52 27.1           ~ 995 3
4 NAME Mon R2 IRS 2 * 06 07 45.83 -06 22 53.5           B0 106 0
5 NAME Mon R2 IRS 1 cor 06 07 46.20 -06 23 09.5           B0 62 0
6 NAME Mon R2 HII 06 07 47.58 -06 22 42.6           ~ 692 2
7 NAME Mon R2 IRS 3 Y*O 06 07 47.8 -06 22 55           ~ 139 0
8 NAME rho Oph A Cloud MoC 16 26 26.4 -24 22 33           ~ 277 1
9 NAME VLA 1623-243 Y*O 16 26 26.42 -24 24 30.0           ~ 395 0
10 [SSG2006] MMS002 smm 16 26 26.50 -24 24 30.9           ~ 241 0
11 NAME rho Oph A SM 1N cor 16 26 27.12 -24 23 34.8           ~ 45 0
12 NAME rho Oph A SM 1 cor 16 26 27.60 -24 23 55.0           ~ 59 0
13 VSSG 27 Y*O 16 26 30.46896 -24 22 57.1440           M 61 1
14 GRS G081.70 +00.50 SFR 20 39 01.6 +42 19 38           O4.5 1001 0

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2022.05.20-18:38:45

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