NGC 4945

High-Res

Object: NGC 4945

NGC 4945 is a relatively nearby galaxy at only 12 million light-years from Earth and is a member of the Centaurus Group, which includes the spectacular Centaurus A. Classified as both a starburst and Seyfert Type II galaxy with an extremely energetic nucleus harboring a large black hole, thick obscuring dust along the equatorial plane of this galaxy hides the lurking monsters environs from view.

Some interesting galaxies are sprinkled across this image. At 7:30 o’clock from NGC 4945, partially obscured by a bright foreground star, is 13th magnitude NGC 4945A (aka ESO 219-28). At 11:00 o-clock, just above NGC 4945 is 16th magnitude galaxy ESO 219-25. Neither of these two galaxies is associated with NGC 4945; in fact they are both background galaxies. At 2 o’clock is the faint, face-on spiral [CFC97] Cen 5 which was originally thought to be a dwarf galaxy associated with the Centaurus Group, but subsequently found using the HST WFPC2 camera to be a distant background spiral. The HIPASS (HI Parkes All Sky Survey) survey suggests that the redshift of this galaxy exceeds ~12,500 km s-1, which was the detection limit of that survey (Publications of the Astronomical Society of the Pacific, Article DOI: 10.1086/426123). Using a Hubble constant of 74.2 and ignoring the margin of error, this means [CFC97] Cen 5 lies at a distance greater than 168.5 Mpc (549 million light-years) from Earth, or over 42 times more distant than NGC 4945.

The very bright bluish-white star right of NGC 4945 is Xi1 Centauri, a 4th magnitude star of spectral class A0V, the same spectral class as the bright Northern Hemisphere star Vega in the constellation Lyra.