Polarisation observations of H_2O J_(K-1) K_1 = 5_(32) – 4_(41) 620.701 GHz maser emission with Herschel/HIFI in Orion KL
| Autor: | Volker Tolls, Patrick W. Morris, S. C. Jones, Martin Harwit, Alexander Kraus, Karl M. Menten, Martin Houde, David Teyssier, M. R. Kidger, Gary J. Melnick, A. Marston, C. MCoey |
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| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: |
Heterodyne
FOS: Physical sciences Context (language use) Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 7. Clean energy 01 natural sciences law.invention Radio telescope Atmosphere law 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Maser 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics Line (formation) Physics Spectrometer 010308 nuclear & particles physics Molecular cloud Astronomy and Astrophysics Astrophysics - Astrophysics of Galaxies 13. Climate action Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) |
| Popis: | Context. The high intensities and narrow bandwidths exhibited by some astronomical masers make them ideal tools for studying star-forming giant molecular clouds. The water maser transition $J_{K_{-1}K_{1}}=5_{32}-4_{41}$ at 620.701 GHz can only be observed from above Earth's strongly absorbing atmosphere; its emission has recently been detected from space. Aims. We sought to further characterize the star-forming environment of Orion KL by investigating the linear polarisation of a source emitting a narrow 620.701 GHz maser feature with the heterodyne spectrometer HIFI on board the Herschel Space Observatory. Methods. High-resolution spectral datasets were collected over a thirteen month period beginning in 2011 March, to establish not only the linear polarisation but also the temporal variability of the source. Results. Within a $3\sigma$ uncertainty, no polarisation was detected to an upper limit of approximately 2%. These results are compared with coeval linear polarisation measurements of the 22.235 GHz $J_{K_{-1}K_{1}}=6_{16}-5_{23}$ maser line from the Effelsberg 100-m radio telescope, typically a much stronger maser transition. Although strongly polarised emission is observed for one component of the 22.235 GHz maser at 7.2 km s$^{-1}$, a weaker component at the same velocity as the 620.701 GHz maser at 11.7 km s$^{-1}$ is much less polarised. Comment: Accepted for publication in A&A |
| Databáze: | OpenAIRE |
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