Astron. Astrophys. 330, 612-618 (1998)

Rapid expansion in the VLBI structure of LSI+61°303

M. Peracaula ^{1, 2}, D.C. Gabuzda ³ and A.R. Taylor <sup>1

1</sup> Department of Physics and Astronomy, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4 Canada
² Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Av. Diagonal 647, E-08028 Barcelona, Spain
³ Astro Space Center, Lebedev Physical Institute, 53 Leninsky Pr., 117924 Moscow, Russia

Received 28 January 1997 / Accepted 18 September 1997

Abstract

We present the results of global VLBI observations at 6 cm wavelength of the X-ray binary LSI+61°303 made at epoch 1992.4. During the course of our 24 hour VLBI observing session, the integrated flux measured simultaneously with the VLA indicated that the source was experiencing a minor flare, with the total flux rising and falling by mJy. Our VLBI observations indicate that this brightening occurred on milli-arcsecond scales, and was accompanied by an increase of the compact radio structure size with velocity , which appeared to decelerate rapidly upon reaching a dimension of about 4 AU.

Key words: stars: individual: LSI+61O 303 stars: variables stars: emission-line, Be radio continuum: stars X-rays: stars

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Contents

• 1. Introduction
• 2. Observations
• 3. Results
• 4. Discussion
  • 4.1. Evolution of the VLBI structure
  • 4.2. Was the expanding source actually a double source?
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: January 16, 1998
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