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

Resolving the radio nebula around Lyrae

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

1</sup> 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 Lyrae obtained with MERLIN at 5 GHz. We find a nebula surrounding the binary with a brightness temperature of 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 ), ionized by the radiation field of the hotter companion. This nebula, surrounding the binary, is the proof that 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 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)

© European Southern Observatory (ESO) 2000

Online publication: June 26, 2000

helpdesk.link@springer.de