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Astron. Astrophys. 361, 1-4 (2000)

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The filament of ionized gas in the outskirt of M87 *

G. Gavazzi 1, A. Boselli 2, J.M. Vílchez 3, J. Iglesias-Paramo 4 and C. Bonfanti 1

1 Università degli Studi di Milano - Bicocca, Piazza dell'Ateneo Nuovo 1, 20126 Milano, Italy
2 Laboratoire d'Astronomie Spatiale, Traverse du Siphon, 13376 Marseille Cedex 12, France
3 Instituto de Astrofsica de Andaluca, CSIC, Apdo. 3004, 18080 Granada, Spain
4 Instituto de Astrofisica de Canarias, 38200 La Laguna, Tenerife, Spain

Received 22 June 2000 / Accepted 3 July 2000


We report on the filament of ionized gas found at the NE periphery of M87, the second brightest elliptical galaxy in the Virgo cluster. The object lies at 3.16 arcmin (15.7 kpc) projected distance of the nucleus of M87, and it coincides in position with the Eastern radio lobe of M87. Long slit spectroscopy confirmed the gaseous nature of this object, showing [FORMULA], [OIII], [OI], [NII], [FORMULA] and [SII] lines, without any underlying continuum. The redshift of the object, [FORMULA], agrees with the velocity of M87 itself ([FORMULA]), and with the bulk of the ionized material found near the center of M87. The [FORMULA] flux of this filament corresponds to [FORMULA] of the ionized material in M87. The radio-optical coincidence together with the spectral characteristics suggest that the filament is ionized by a shock.

Key words: galaxies: individual: M87 – galaxies: interactions – galaxies: ISM

* Based on observations taken at INT and OHP. The INT is operated by the I.N.G. at the Spanish Observatorio del Roque de Los Muchachos of the I.A.C.. The OHP is operated by the French CNRS.

Send offprint requests to: G. Gavazzi (gavazzi@jarrett.uni.mi.astro.it)

© European Southern Observatory (ESO) 2000

Online publication: September 5, 2000