A&A 494, L1-L4 (2009)
DOI: 10.1051/0004-6361:200811186

Letter

Water masers in the Saturnian system

S. V. Pogrebenko¹, L. I. Gurvits¹, M. Elitzur², C. B. Cosmovici³, I. M. Avruch^{1, 4}, S. Montebugnoli⁵, E. Salerno⁵, S. Pluchino^{3, 5}, G. Maccaferri⁵, A. Mujunen⁶, J. Ritakari⁶, J. Wagner⁶, G. Molera⁶, and M. Uunila<sup>6

1</sup>  Joint Institute for VLBI in Europe, PO Box 2, 7990 AA Dwingeloo, The Netherlands
    e-mail: [pogrebenko;lgurvits]@jive.nl
²  Department of Physics and Astronomy, University of Kentucky, 600 Rose Street, Lexington, KY 40506-0055, USA
    e-mail: moshe@pa.uky.edu
³  Istituto Nazionale di Astrofisica (INAF) – Istituto di Fisica dello Spazio Interplanetario (IFSI), via del Fosso del Cavaliere, 00133 Rome, Italy
    e-mail: cosmo@ifsi-roma.inaf.it
⁴  Science & Technology BV, PO 608 2600 AP Delft, The Netherlands
    e-mail: avruch@stcorp.nl
⁵  Istituto Nazionale di Astrofisica (INAF) – Istituto di Radioastronomia (IRA) – Stazione Radioastronomica di Medicina, via Fiorentina 3508/B, 40059 Medicina (BO), Italy
    e-mail: [s.montebugnoli;e.salerno;g.maccaferri]@ira.inaf.it; s.pluchino@med.ira.inaf.it
⁶  Helsinki University of Technology TKK, Metsähovi Radio Observatory, 02540 Kylmälä, Finland
    e-mail: [amn;jr;jwagner;gofrito;minttu]@kurp.hut.fi

Received 18 October 2008 / Accepted 4 December 2008

Abstract
Context. The presence of water has long been seen as a key condition for life in planetary environments. The Cassini spacecraft discovered water vapour in the Saturnian system by detecting absorption of UV emission from a background star. Investigating other possible manifestations of water is essential, one of which, provided physical conditions are suitable, is maser emission.
Aims. We report detection of water maser emission at 22 GHz associated with several Kronian satellites using Earth-based radio telescopes.
Methods. We searched for water maser emission in the Saturnian system in an observing campaign using the Metsähovi and Medicina radio telescopes. Spectral data were Doppler-corrected over orbital phase for the Saturnian satellites, yielding detections of water maser emission associated with the moons Hyperion, Titan, Enceladus, and Atlas.
Results. The detection of Saturnian water molecules by remote astronomical observation can be combined with in situ spacecraft measurements to harmonise the physical model of the Saturnian system.

Key words: masers -- radio lines: solar system -- planets and satellites: general

© ESO 2009

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