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Irregular Galaxy NGC 4449

Date:25.3.1998 + 8.3.1997 Time:01h UT + 0h UT Exposure:B: 42m, V: 12m, I: 9m, Ha: 20m
Field of View:11' x 9' Receiver: HoLiCam, 20482 CCD Filter:B, V, I+Ha
Instrument: 1m, f=3680mm Observatory: Hoher List Observer:S. Kohle, T. Credner

© Copyright by the observers

Astronomical Institutes of the University of Bonn

From Colors to Astrophysics:

This three color composit consists of exposures with B, V, I, and H-alpha filters that are represented in blue (B), green (V) and red (I + H-alpha).

This dwarf galaxy is a member of the Canes Venatici group of galaxies and has a distance of about 4 Mpc (12 million lightyears).
The morphology and absolute size is remarkebly similar to our neighbour galaxy LMC (Large Magellanic Cloud). The bar consists of a population of stars with an age older than five million years.The red regions in the upper northern part of the image which emit most of their light in the H-alpha line are HII regions with embedded ongoing star formation. There are several bluish white star clusters visible, some of them near filaments of dust which provide the fuel for future star formation. In the western part of the image (right hand side) there is an isolated supergiant shell of H-alpha emission which probably is ionized by the central cluster of stars.
Radio observations in the HI line show that NGC 4449 is embedded in a huge gaseous halo with a diameter of 14 times the optical one.