An extragalactic HII region in the Virgo cluster

L.Cortese, G.Gavazzi, A.Boselli, J.Iglesias-Paramo

We present spectroscopic observations for six emission-line objects projected onto the Virgo cluster. These sources have been selected from narrow band (H_alpha+[NII]) images showing faint detectable continuum emission and EW>100 Angstrom. Five of these sources result [OIII]\lambda5007 emitters at z = 0.31, while one 122603+130724 is confirmed to be an HII region belonging to the Virgo cluster. This point-like source has a recessional velocity of 200 km/s, and is associated with the giant galaxy VCC873 (NGC 4402). It has a higher luminosity, star formation rate and metallicity than the extragalactic HII region recently discovered near the Virgo galaxy VCC836 by Gerhard et al. (2002).

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