Celestial Atlas
PGC 37000 - 37499 ←     PGC Objects: PGC 37500 - 37999 Link for sharing this page on Facebook     → PGC 38000 - 38499
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Page last updated Sep 29, 2013

PGC 37639 (with
PGC 101374 = Arp 194)
A magnitude 15 spiral galaxy (type SABb? pec) in Ursa Major (RA 11 57 54.9, Dec +36 23 35)
PGC 37639 has a recessional velocity of 10540 km/sec; its companion has a recessional velocity of 10520 km/sec. Based on their average recessional velocity of 10530 km/sec, a straightforward calculation indicates that they are about 490 million light years away. However, for objects at such distances, we should take into account the Universal expansion during the time it took their light to reach us. Doing that shows that they were about 470 million light years away at the time the light by which we see them was emitted, about 480 million years ago (the difference between the two values being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of 0.8 by 0.65 arcmin (counting its distorted extensions), PGC 37639 is about 110 thousand light years across. Its appearance was caused by a collision with its smaller neighbor (PGC 101374) about a hundred million years before the moment in time at which we see the pair. Material stripped from the larger galaxy is seen as a line of brightly lit star-forming regions lying between the two, and gravitational compression of gases in the galaxies as a result of their collision caused multiple regions of unusually active star formation within each galaxy. The pair was used by the Arp Atlas as an example of a galaxy (PGC 37639) with material ejected from its nucleus (as noted, actually a separate galaxy, PGC 101374).
SDSS image of interacting spiral galaxies PGC 37639 and PGC 101374, which comprise Arp 194
Above, a 2.4 arcmin wide region centered on Arp 194
Below, a roughly 1.2 arcmin wide closeup (Image Credits: NASA/ESA/Hubble Heritage Team (STScI/AURA))
HST image of interacting spiral galaxies PGC 37639 and PGC 101374, which comprise Arp 194
Below, a 12 arcmin wide region centered on the pair
SDSS image of region near interacting spiral galaxies PGC 37639 and PGC 101374, which comprise Arp 194

PGC 101374 (with
PGC 37639 = Arp 194)
Shown here since a companion of PGC 37639, and with it = Arp 194
A magnitude 16 spiral galaxy (type Sc? pec) in Ursa Major (RA 11 57 56.6, Dec +36 23 00)
PGC 101374 is about 470 million light years away (see PGC 37639 for a discussion of how that is determined, and for images and a discussion of the pair's history). Given that and its apparent size of 0.4 by 0.25 arcmin, it is about 55 thousand light years across.

PGC 37772 (= NGC 4027A)
A 15th-magnitude irregular galaxy (type IB(s)m) in
Corvus (RA 11 59 29, Dec -19 19 55)
Thought to be the galaxy whose collision with NGC 4027 (which see) caused the strange appearance of that galaxy (and vice versa). Based on recessional velocity of 1745 km/sec, about 80 million light years away. Given that and apparent size of 0.9 by 0.6 arcmin, about 20 thousand light years across.
Wikisky image of PGC 37772
Above, a 1 arcmin wide closeup of PGC 37772
Below, a 12 arcmin wide region centered on the galaxy
Wikisky image of region near PGC 37772

PGC 37773 (=
NGC 4027 = Arp 22)
Celestial Atlas
PGC 37000 - 37499 ←     PGC Objects: PGC 37500 - 37999     → PGC 38000 - 38499