2010A&A...521L..51H


Query : 2010A&A...521L..51H

2010A&A...521L..51H - Astronomy and Astrophysics, volume 521, L51-51 (2010/10-1)

Polarisation observations of VY Canis Majoris H2O 532-441 620.701 GHz maser emission with HIFI.

HARWIT M., HOUDE M., SONNENTRUCKER P., BOOGERT A.C.A., CERNICHARO J., DE BECK E., DECIN L., HENKEL C., HIGGINS R.D., JELLEMA W., KRAUS A., McCOEY C., MELNICK G.J., MENTEN K.M., RISACHER C., TEYSSIER D., VAILLANCOURT J.E., ALCOLEA J., BUJARRABAL V., DOMINIK C., JUSTTANONT K., DE KOTER A., MARSTON A.P., OLOFSSON H., PLANESAS P., SCHMIDT M., SCHOEIER F.L., SZCZERBA R. and WATERS L.B.F.M.

Abstract (from CDS):

Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight. We have aimed to elucidate the nature and structure of the VY CMa water vapour masers in part by observationally testing a theoretical prediction of the relative strengths of the 620.701GHz and the 22.235GHz maser components of ortho H2O.In its high-resolution mode (HRS) the Herschel Heterodyne Instrument for the Far Infrared (HIFI) offers a frequency resolution of 0.125MHz, corresponding to a line-of-sight velocity of 0.06km/s, which we employed to obtain the strength and linear polarisation of maser spikes in the spectrum of VY CMa at 620.701GHz. Simultaneous ground based observations of the 22.235GHz maser with the Max-Planck-Institut fuer Radioastronomie 100-m telescope at Effelsberg, provided a ratio of 620.701GHz to 22.235GHz emission.We report the first astronomical detection to date of H2O maser emission at 620.701GHz. In VY CMa both the 620.701 and the 22.235GHz polarisation are weak. At 620.701GHz the maser peaks are superposed on what appears to be a broad emission component, jointly ejected from the star. We observed the 620.701GHz emission at two epochs 21 days apart, both to measure the potential direction of linearly polarised maser components and to obtain a measure of the longevity of these components. Although we do not detect significant polarisation levels in the core of the line, they rise up to approximately 6% in its wings.

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - stars: winds, outflows - supergiants - circumstellar matter - masers - reference systems

Simbad objects: 2

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Number of rows : 2
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 V* VY CMa s*r 07 22 58.32877 -25 46 03.2355 12.01 10.19 7.95     M5Iae 1059 0
2 [DE95] LDN 1157 B1 out 20 39 11 +68 01.3           ~ 228 0

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2022.10.02-02:18:10

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