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Astron. Astrophys. 358, 229-232 (2000)

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Resolving the radio nebula around [FORMULA] Lyrae

G. Umana 1, P.F.L. Maxted 2, C. Trigilio 1, R.P. Fender 3,4, F. Leone 5 and S.K. Yerli 3

1 Istituto di Radioastronomia del C.N.R., Stazione VLBI di Noto, C.P. 141, Noto (SR), Italy
2 University of Southampton, Department of Physics and Astronomy, Highfield, Southampton, SO17 1BJ, UK
3 Astronomy Centre, Department of Physical Sciences, University of Sussex, Falmer, Brighton BN1 9QH, UK
4 Astronomical Institute `Anton Pannekoek', Center for High-Energy Astrophysics, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
5 Osservatorio Astrofisico di Catania, Viale A. Doria 6, 95125 Catania, Italy

Received 15 March 2000 / Accepted 11 April 2000

Abstract

In this paper we present high spatial resolution radio images of the puzzling binary system [FORMULA] Lyrae obtained with MERLIN at 5 GHz. We find a nebula surrounding the binary with a brightness temperature of [FORMULA] K approximately 40 AU across. This definitively confirms the thermal origin of the radio emission, which is consistent with emission from the wind of the B6-8 II component (mass loss of order of [FORMULA]), ionized by the radiation field of the hotter companion. This nebula, surrounding the binary, is the proof that [FORMULA] Lyrae evolved in a non-conservative way, i. e. not all the mass lost by the primary is accretted by the secondary, and present measurements indicate that almost 0.015 [FORMULA] had been lost from the system since the onset of the Roche lobe overflow phase.

Moreover, the nebula is aligned with the jet-like structures inferred from recent optical measurements, indicating a possible connection among them.

Key words: stars: binaries: spectroscopic – stars: chemically peculiar – stars: individual: fi Lyr

Send offprint requests to: G. Umana (umana@ira.noto.cnr.it)

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© European Southern Observatory (ESO) 2000

Online publication: June 26, 2000
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