Query : 2015A&A...575A..49C

2015A&A...575A..49C - Astronomy and Astrophysics, volume 575A, 49-49 (2015/3-1)

OH and H2O maser variations in W33B.


Abstract (from CDS):

The active star-forming region W33B is a source of OH and H2O maser emission located in distinct zones around the central object. The aim was to obtain the complete Stokes pattern of polarised OH maser emission and to trace its variability and to investigate flares and long-term variability of the H2O maser and evolution of individual emission features. Observations in the OH lines at a wavelength of 18cm were carried out on the Nancay radio telescope (France) at a number of epochs in 2008-2014; H2O line observations (long-term monitoring) at λ=1.35cm were performed on the 22 m radio telescope of the Pushchino Radio Astronomy Observatory (Russia) between 1981 and 2014. We have observed strong variability of the emission features in the main 1665- and 1667MHz OH lines as well as in the 1612MHz satellite line. Zeeman splitting has been detected in the 1665MHz OH line at 62km/s and in the 1667MHz line at 62 and 64km/s. The magnetic field intensity was estimated to be from 2 to 3mG. The H2O emission features form filaments, chains with radial-velocity gradients, or more complicated structures including large-scale ones. Long-term observations of the hydroxyl maser in the W33B region have revealed narrowband polarised emission in the 1612MHz line with a double-peak profile characteristic of type IIb circumstellar masers. The 30 year monitoring of the water-vapour maser in W33B showed several strong flares of the H2O line. The observed radial-velocity drift of the H2O emission features suggests propagation of an excitation wave in the masering medium with a gradient of radial velocities. In OH and H2O masers some turbulent motions of material are inferred.

Abstract Copyright:

Journal keyword(s): masers - ISM: magnetic fields - ISM: molecules - ISM: lines and bands - ISM: individual objects: W33B

VizieR on-line data: <Available at CDS (J/A+A/575/A49): list.dat fig7/*>

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 W 33b SFR 18 13 54.68 -18 01 48.1           ~ 80 0
2 W 33c Rad 18 13 59.0 -17 57 38           ~ 14 0
3 SNR G012.8-00.2 SFR 18 14 14.0 -17 55 50           ~ 251 0
4 W 33a Y*O 18 14 39.56547 -17 52 02.2260           ~ 683 0
5 JCMTLSP J181444.3-175227 Rad 18 14 44.1 -17 52 17           ~ 7 0
6 NAME Scutum Spiral Arm PoG ~ ~           ~ 341 0

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