Page last updated Oct 21, 2018|
PGC 51214 (with PGC 200317 = Arp 45)
PGC 51214 = A magnitude 15.0(?) spiral galaxy (type SAB(rs)b?) in Bo÷tes (RA 14 19 55, Dec +51 53 38)
PGC 200317 = A magnitude 15.5(?) spiral galaxy (type Scd? pec) in Bo÷tes (RA 14 20 01, Dec +51 52 53)
PGC 51214 and PGC 200317 comprise Arp 45, an example of a spiral galaxy with a fainter companion.
PGC Designation Note: The current LEDA catalog lists the fainter galaxy as PGC 51214 and the brighter as PGC 200317, while NED reverses the PGC designations. A Vizier catalog search states that the brighter galaxy is PGC 51214, so that is more likely to be correct and the current LEDA listing a transposition error, and I have used that interpretation to label the images below (it also makes more sense, as the first 77141 PGC listings belong to the original catalog and are generally brighter than those with larger numbers, which represent supplementary catalogs).
Physical Information: (Note to self: Need to update for relativistic corrections, Hubble constant, etc). Given the designations as stated, PGC 51214 has a recessional velocity of 8705 km/sec, and an apparent size of 0.7 by 0.5 arcmin. PGC 200317 has a recessional velocity of 8770 km/sec, and an apparent size of 0.4 by 0.3 arcmin. These numbers imply that the pair is about 410 million light years away, probably gravitationally bound, and that the larger galaxy is about 85 thousand light years across and the smaller about 45 thousand light years across.
Above, a 12 arcmin wide SDSS image centered on PGC 51214 and 200317, which comprise Arp 45
Below, a 2.4 arcmin wide SDSS image of the pair
Note: the exaggeratedly red star which dominates the image is magnitude 10.5
PGC 51472 (= PGC 2246250 = "DDO 190")
Discovered (1959) by Sidney van den Bergh
A magnitude 12.8 dwarf irregular galaxy (type IAm?) in Bo÷tes (RA 14 24 43.6, Dec +44 31 34)
Note About DDO Designation: The press release for the HST image shown below only refers to the galaxy as DDO 190, referring to its inclusion in a catalog of dwarf galaxies observed at the David Dunlap Observatory in Canada.
Warning About Possible Misidentification: This object is also known as UGC 9240, but I was alerted to its existence by a question about a mislabeled image which called it UGC 2940; so it is possible that similar errors may exist.
Physical Information: The galaxy's recessional velocity of 150 km/sec is too small to be a reliable indicator of its Hubble distance, but redshift-independent distances estimates range from 9 to 12 million light years, the lower value being the one used in the HST press release. Given that and its apparent size of about 2.0 by 1.9 arcmin (from the images below), it is about 5 thousand light years across (hence its classification as a dwarf galaxy). It is thought to be a loosely bound member of the M94 group of galaxies, with its nearest neighbor (DDO 187) being about 3 million light years from PGC 51472. While most of the stars in the galaxy are red dwarfs, there are a substantial number of younger, hot blue young stars scattered throughout it, and even a notable region of ionized gas heated by young star clusters on its southern rim.
Above, a 12 arcmin wide SDSS image centered on PGC 51472
Below, a 2.5 arcmin wide SDSS image of the galaxy
Below, a 2.5 arcmin wide HST image of the galaxy (Image Credit ESA/Hubble & NASA)