2019A&A...626A..36D


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.03CEST21:41:08

2019A&A...626A..36D - Astronomy and Astrophysics, volume 626A, 36-36 (2019/6-1)

ALMA reveals the magnetic field evolution in the high-mass star forming complex G9.62+0.19.

DALL'OLIO D., VLEMMINGS W.H.T., PERSSON M.V., ALVES F.O., BEUTHER H., GIRART J.M., SURCIS G., TORRELLES J.M. and VAN LANGEVELDE H.J.

Abstract (from CDS):


Context. The role of magnetic fields during the formation of high-mass stars is not yet fully understood, and the processes related to the early fragmentation and collapse are as yet largely unexplored. The high-mass star forming region G9.62+0.19 is a well known source, presenting several cores at different evolutionary stages.
Aims. We seek to investigate the magnetic field properties at the initial stages of massive star formation. We aim to determine the magnetic field morphology and strength in the high-mass star forming region G9.62+0.19 to investigate its relation to the evolutionary sequence of the cores.
Methods. We made use of Atacama Large Millimeter Array (ALMA) observations in full polarisation mode at 1 mm wavelength (Band 7) and we analysed the polarised dust emission. We estimated the magnetic field strength via the Davis-Chandrasekhar-Fermi and structure function methods.
Results. We resolve several protostellar cores embedded in a bright and dusty filamentary structure. The polarised emission is clearly detected in six regions: two in the northern field and four in the southern field. Moreover the magnetic field is orientated along the filament and appears perpendicular to the direction of the outflows. The polarisation vectors present ordered patterns and the cores showing polarised emission are less fragmented. We suggest an evolutionary sequence of the magnetic field, and the less evolved hot core exhibits a stronger magnetic field than the more evolved hot core. An average magnetic field strength of the order of 11 mG was derived, from which we obtain a low turbulent-to-magnetic energy ratio, indicating that turbulence does not significantly contribute to the stability of the clump. We report a detection of linear polarisation from thermal line emission, probably from methanol or carbon dioxide, and we tentatively compared linear polarisation vectors from our observations with previous linearly polarised OH masers observations. We also compute the spectral index, column density, and mass for some of the cores.
Conclusions. The high magnetic field strength and smooth polarised emission indicate that the magnetic field could play an important role in the fragmentation and the collapse process in the star forming region G9.62+019 and that the evolution of the cores can be magnetically regulated. One core shows a very peculiar pattern in the polarisation vectors, which can indicate a compressed magnetic field. On average, the magnetic field derived by the linear polarised emission from dust, thermal lines, and masers is pointing in the same direction and has consistent strength.

Abstract Copyright: © ESO 2019

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

VizieR on-line data: <Available at CDS (J/A+A/626/A36): list.dat fits/*>

Simbad objects: 28

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Number of rows : 28

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 QSO B1730-130 QSO 17 33 02.70578476 -13 04 49.5481484   18 18.5 18.78 17.39 ~ 982 1
2 4C 09.57 BLL 17 51 32.81857318 +09 39 00.7284829   17.46 16.78 15.57   ~ 811 1
3 [GRM93] G09.61+0.20 A Rad 18 06 11.9 -20 31 41           ~ 14 0
4 GAL 009.62+00.19 HII 18 06 13.9 -20 31 44           ~ 186 0
5 [GRM93] G09.61+0.20 B Rad 18 06 14.1 -20 31 43           ~ 17 0
6 [GRM93] G09.61+0.20 C HII 18 06 14.4 -20 31 25           ~ 17 0
7 [LLL2017] MM1 cor 18 06 14.49 -20 31 27.9           ~ 2 0
8 [LLL2017] MM2 cor 18 06 14.508 -20 31 30.50           ~ 2 0
9 [LLL2017] MM4 cor 18 06 14.656 -20 31 31.77           ~ 2 0
10 [GRM93] G09.61+0.20 E HII 18 06 14.7 -20 31 32           ~ 41 0
11 [LLL2017] MM5 cor 18 06 14.705 -20 31 12.63           ~ 2 0
12 [LLL2017] MM3 cor 18 06 14.758 -20 31 30.13           ~ 2 0
13 [LLL2017] MM6 cor 18 06 14.781 -20 31 34.85           ~ 3 0
14 [LLL2017] MM7 cor 18 06 14.798 -20 31 37.21           ~ 2 0
15 [GRM93] G09.61+0.20 G Rad 18 06 14.805 -20 31 37.17           ~ 9 0
16 [LLL2017] MM8 cor 18 06 14.852 -20 31 39.54           ~ 2 0
17 [GRM93] G09.61+0.20 F Rad 18 06 14.89 -20 31 38.9           ~ 26 1
18 [GRM93] G09.61+0.20 D HII 18 06 14.9 -20 31 43           ~ 18 0
19 [LLL2017] MM10 cor 18 06 14.924 -20 31 41.40           ~ 2 0
20 [LLL2017] MM11 cor 18 06 14.925 -20 31 36.49           ~ 2 0
21 [LLL2017] MM9 cor 18 06 15.013 -20 31 41.27           ~ 2 0
22 [LLL2017] MM12 cor 18 06 15.024 -20 31 46.28           ~ 2 0
23 [GRM93] G09.61+0.20 H Rad 18 06 15.047 -20 31 36.72           ~ 8 0
24 [GRM93] G09.61+0.20 I Rad 18 06 15.172 -20 31 37.97           ~ 7 0
25 GRS G012.89 +00.49 HII 18 11 51.3 -17 31 29           ~ 144 0
26 QSO J1832-2039 BLL 18 32 11.0447839878 -20 39 48.202176867   18.56 20.2     ~ 37 1
27 QSO B1921-293 BLL 19 24 51.05595514 -29 14 30.1210524   18.71 18.21 15.07   ~ 689 0
28 [MBS2007c] CygX-N44 Rad 20 39 01.01 +42 22 50.2           ~ 362 0

    Equat.    Gal    SGal    Ecl

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2020.07.03-21:41:08

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