Page last updated June 27, 2017|
A magnitude 14(?) spiral galaxy (type Sm? pec) in Lepus (RA 05 03 20.0, Dec -25 25 25)
Physical Properties: PGC 16643 is part of a study of fifty nearby star-forming galaxies, whence the HST image of the galaxy shown below. In DSS and PanSTARRS images the hot young stars recently formed in it give it a bluish cast, whereas an HST image which emphasizes the clouds of gas and dust out of which those stars formed and new stars will eventually form has a pinkish tone. Based on a recessional velocity of 835 km/sec (and H0 = 70 km/sec/Mpc), PGC 16643 is about 35 to 40 million light years away, in reasonable agreement with a redshift-independent distance estimate (per the press release accompanying the HST image below) of about 30 million light years. Given that and its apparent size of about 1.15 by 0.7 arcmin (from the images below), the galaxy is about 10 to 13 thousand light years across, making it a dwarf spiral (or perhaps, given its peculiar structure, a dwarf irregular) galaxy.
Above, a 12 arcmin wide DSS image centered on PGC 16643
Below, a 1.5 arcmin wide DSS image of the galaxy
Below, a 1.25 arcmin wide PanSTARRS image of the galaxy
Below, a 1.25 arcmin wide HST image of the galaxy (Image Credit ESA/Hubble & NASA)