Astronomy & Astrophysics

Issue		A&A Volume 500, Number 2, June III 2009
Page(s)		827 - 831
Section		Interstellar and circumstellar matter
DOI		10.1051/0004-6361/200911785
Published online		29 April 2009

A&A 500, 827-831 (2009)
DOI: 10.1051/0004-6361/200911785

A high-speed bipolar outflow from the archetypical pulsating star Mira A

J. Meaburn¹, J. A. López², P. Boumis³, M. Lloyd¹, and M. P. Redman⁴

¹ Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester, M13 9PL, UK
    e-mail: jmeaburn@jb.man.ac.uk, Myfanwy.Lloyd@manchester.ac.uk
² Instituto de Astronomia, UNAM, Apdo. Postal 877, Ensenada, B.C. 22800, Mexico
    e-mail: jal@astrosen.unam.mx
³ Institute of Astronomy & Astrophysics, National Observatory of Athens, I. Metaxa & V. Pavlou, P. Penteli, 15236 Athens, Greece
    e-mail: ptb@astro.noa.gr
⁴ Centre for Astronomy, National University of Ireland, Galway, University Road, Galway, Ireland
    e-mail: Matt.Redman@nuigalway.ie

Received 4 February 2009 / Accepted 12 March 2009

Abstract
Optical images and high-dispersion spectra have been obtained of the ejected material surrounding the pulsating AGB star Mira A. The two streams of knots on either side of the star, found in far-ultraviolet (FUV) GALEX images, have now been imaged clearly in the light of H $\alpha$ . Spatially resolved profiles of the same line reveal that the bulk of these knots form a bipolar outflow with radial velocity extremes of $\pm$ 150 km s^-1 with respect to the central star. The south stream is approaching and the north stream receding from the observer. A displacement away from Mira A between the position of one of the south-stream knots in the new H $\alpha$ image and its position in the previous Palomar Observatory Sky Survey (POSS I) red plate was noted. If interpreted as a consequence of expansion proper motions, the bipolar outflow is tilted at 69 $^{\circ}$ $\pm$ 15 $^{\circ}$ to the plane of the sky, has an outflow velocity of 160 $\pm$ 10 km s^-1 and is $\approx$ 1000 y old.

Key words: stars: circumstellar matter -- stars: variables: general -- stars: binaries: general -- stars: individual: Mira

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