2011A&A...526A..38T


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.14CEST17:14:22

2011A&A...526A..38T - Astronomy and Astrophysics, volume 526A, 38-38 (2011/2-1)

Dynamics of the 6.7 and 12.2 GHz methanol masers around Cepheus A HW2.

TORSTENSSON K.J.E., VAN LANGEVELDE H.J., VLEMMINGS W.H.T. and BOURKE S.

Abstract (from CDS):

The 6.7GHz methanol maser is exclusively associated with high-mass star formation. However, it remains unclear what structures harbour the methanol masers. Cepheus A is one of the closest regions of massive star formation, making it an excellent candidate for detailed studies. We determine the dynamics of maser spots in the high-mass star-forming region Cepheus A in order to infer where and when the maser emission occurs. Very long baseline interferometry (VLBI) observations of the 6.7 and 12.2GHz methanol masers allows for mapping their spatial and velocity distribution. Phase-referencing is used to determine the astrometric positions of the maser emission, and multi-epoch observations can reveal 3D motions. The 6.7GHz methanol masers are found in a filamentary structure over ∼1350AU, straddling the waist of the radio jet HW2. The positions agree well with previous observations of both the 6.7 and 12.2GHz methanol masers. The velocity field of the maser spots does not show any sign of rotation, but is instead consistent with an infall signature. The 12.2GHz methanol masers are closely associated with the 6.7GHz methanol masers, and the parallax that we derive confirms previous measurements. We show that the methanol maser emission very likely arises in a shock interface in the equatorial region of Cepheus A HW2 and presents a model in which the maser emission occurs between the infalling gas and the accretion disk/process.

Abstract Copyright:

Journal keyword(s): stars: formation - masers - ISM: individual objects: Cepheus A - ISM: general

Simbad objects: 9

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Number of rows : 9

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 GAL 174.20-00.08 Cld 05 30 45.9 +33 47 56           ~ 184 2
2 7C 055201.39+394824.00 QSO 05 55 30.80561150 +39 48 49.1649664     18.0 17.5   ~ 466 2
3 3C 345 QSO 16 42 58.8100340220 +39 48 36.999540578   16.81 16.59 16.84   ~ 1554 2
4 NAME BL Lac BLL 22 02 43.2913773726 +42 16 39.978417860   15.66 14.72     ~ 2006 1
5 JVAS B2230+625 Rad 22 32 22.86554 +62 49 36.4362           ~ 4 0
6 NAME Cepheus A East SFR 22 54.3 +61 46           ~ 64 0
7 NAME Cep A HW 2 Y*O 22 56 17.9 +62 01 49           B0.5 195 0
8 NAME Cepheus A SFR 22 56 17.9 +62 01 49           ~ 697 2
9 ICRF J230241.3+640552 Bz? 23 02 41.31499697 +64 05 52.8488544           ~ 31 1

    Equat.    Gal    SGal    Ecl

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2020.07.14-17:14:23

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