Page last updated July 31, 2021|
(= ESO 291-024 = MCG -07-48-001)
A magnitude 14.0 spiral? galaxy (type S/Im sp) in Grus (RA 23 23 40.8, Dec -42 24 05)
Note About Classification
: The type is taken from the Spitzer Survey of Stellar Structure in Galaxies
. "sp" indicates that the galaxy is a "spindle" (that is, an "edge-on" galaxy), which makes it more difficult to determine its structure. That and the fact that it is loosely structured (as indicated by the "m") makes it hard to determine whether it's a spiral or an irregular galaxy (hence "S/I").
Above, a 12 arcmin wide DSS image centered on PGC 71309
PGC 71368 (= UGC 12588)
A magnitude 13(?) spiral galaxy (type S(s)dm) in Andromeda (RA 23 24 42.6, Dec +41 20 52)
Physical Properties: Based on a recessional velocity relative to the Cosmic Microwave Background radiation of 110 km/sec (and H0 = 70 km/sec/Mpc), PGC 71368 is about 5 million light years away, in poor agreement with a single redshift-independent distance estimate of about 30 million light years (the HST press release uses an impossibly precise distance of 31 million light years). Given that and its apparent size of about 1.7 by 1.3 arcmin (from the images below), the galaxy is about 15 thousand light years across if about 30 million light years away, which would make it a dwarf spiral galaxy (and also make it unlikely that it is at the Hubble Flow distance, as that would make it only 2500 light years across, because such an extremely small galaxy would probably appear to be merely an amorphous scattering of stars, and not display the rough but still obvious spiral structure displayed by the HST image).
Above, a 12 arcmin wide DSS image centered on PGC 71368
Below, a 2.4 arcmin wide DSS image of the galaxy
Below, a 2 arcmin wide image of the galaxy
(Image Credit ESA/Hubble & NASA, R. Tully; Acknowledgement Gagandeep Anand)