Water maser emission in IC 342
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
Corresponding author: A. Tarchi, email@example.com
Accepted: 4 February 2002
The detection of 22 GHz water vapor emission from IC 342 is reported, raising the detection rate among northern galaxies with IRAS point source fluxes Jy to 16%. The maser, associated with a star forming region ~10–15´´ west of the nucleus, consists of a single 0.5 km s-1 wide feature and reaches an isotropic luminosity of 10-2 ( Mpc). If the time variability is intrinsic, the maser size is cm (0.5 mas) which corresponds to a brightness temperature of 109 K. The linewidth, luminosity, and rapid variability are reminiscent of the 8 km s-1 super maser in Orion-KL. A velocity shift of 1 km s-1 within two weeks and subsequent rapid fading is explained in terms of a chance alignment of two dense molecular clouds. Observations at 22 GHz toward Maffei 2 are also reported, yielding a 5σ upper limit of 25 mJy for a channel spacing of 1.05 km s-1.
Key words: galaxies: individual: IC 342, Maffei 2 / galaxies: starburst / ISM: molecules / masers / radio lines: ISM
© ESO, 2002