Celestial Atlas
PGC 45500 - 45999 ←PGC Objects: PGC 46000 - 46499 Link for sharing this page on Facebook→ PGC 46500 - 46999
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Page last updated June 26, 2021
Completely updated all entries

PGC 46225 (with
PGC 1457659 = Arp 57)
(= CGCG 101-019 = MCG +03-34-012)

(Other than the PGC designations, all the catalog "names" refer to the pair of galaxies)
A magnitude 15.1 spiral galaxy (type SABbc?) in Coma Berenices (RA 13 16 47.2, Dec +14 25 41)
Note About The PGC Designations: Aside from the designations for the individual galaxies, PGC also has an entry for the pair (as Arp 57 = CGCG 101-019), namely PGC 3167645; however, a search of the LEDA database for that PGC designation returns no result, so it can be thought of as merely a "place-keeper", and of no other use.
Usage By The Arp Atlas: PGC 46225 is used by the Arp Atlas as an example of a spiral galaxy with a small high-brightness companion (PGC 1457659), with the note "Small companion connected to end of arm."
Physical Information: Since this galaxy and its companion are interacting, they must be at about the same distance, and the best number to use for an estimate of their Hubble Flow distance is the average of their individual recessional velocities. For PGC 46225, the recessional velocity relative to the Cosmic Microwave Background is about 18345 km/sec, while for its companion, the measured value is about 18195 km/sec (all astronomical data have at least a small range of uncertainty, so "about" is more accurate than any specific number), yielding an average of about 18270 km/sec (the 150 km/sec difference between the two values is the "peculiar velocity", or actual motion of the objects relative to each other, and has nothing to do with the Universal Expansion). Given that average (and H0 = 70 km/sec/Mpc), a straightforward calculation indicates that Arp 57 is about 850 million light-years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was about 790 to 795 million light-years away at the time the light by which we see it was emitted, about 815 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 0.69 by 0.43 arcmin (from the images below), PGC 46225 is about 160 thousand light-years across.
 Aside from its obvious companion, PGC 46225 is in the same direction and at nearly the same distance as PGC 46234. The difference in their recessional velocities is small enough that it could be due to peculiar (non-Hubble Expansion) velocities, so although the two galaxies may be unrelated, they may be part of a triple system of gravitationally bound objects.
SDSS image of region near spiral galaxy PGC 46225 and its companion, PGC 1457659, which comprise Arp 57; also shown is PGC 46234
Above, a 12 arcmin wide SDSS image centered on PGC 46225 and its interacting companion, PGC 1457659
Also shown is a possible companion, PGC 46234
Below, the same image with additional labels for PGC objects 1455622, 1458619, and 1459772
SDSS image of spiral galaxy PGC 46225 and its companion, PGC 1457659, which comprise Arp 57; also labeled are PGC 46234, and PGC Objects 1455622, 1458619 and 1459772
Below, a 2.4 arcmin wide SDSS image of Arp 57, also showing PGC 46234
SDSS image of spiral galaxy PGC 46225 and its companion, PGC 1457659, which comprise Arp 57; also shown is spiral galaxy PGC 46234
Below, a 0.75 by 1.0 arcmin wide SDSS image of Arp 57
SDSS image of spiral galaxy PGC 46225 and its companion, PGC 1457659, which comprise Arp 574

PGC 1457659 (with
PGC 46225 = Arp 57)
(= CGCG 101-019 = MCG +03-34-012)

(Other than the PGC designations, all the catalog "names" refer to the pair of galaxies)
Listed here since an almost certain companion of PGC 46225 (which see for images)
A magnitude 17.2 lenticular galaxy (type S0?) in Coma Berenices (RA 13 16 47.9, Dec +14 25 15)
Usage By The Arp Atlas: See PGC 46225 for a note about that.
Physical Information: As discussed in the entry for PGC 46225, Arp 57 was about 790 to 795 million light-years away at the time the light by which we see it was emitted, about 815 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 0.21 by 0.14 arcmin (from the images shown in the previous entry), PGC 1457659 is about 45 to 50 thousand light-years across (or was, about 815 million years ago; the interaction between the two galaxies during that interval may have slightly changed its appearance and dimensions).

PGC 46234
(= MCG +03-34-013)

A magnitude 16.0 spiral galaxy (type SAbc?) in
Coma Berenices (RA 13 16 51.8, Dec +14 24 55)
Note About Error In HyperLEDA: In the LEDA database, PGC 46234 is shown as part of Arp 57 and CGCG 101-019 (which is Arp 57). This is a blunder. Although it is possible that PGC 46234 is a companion of Arp 57, and it is shown in the photograph in the Arp Atlas, it is definitely not part of the Arp object.
Physical Information: Based on a recessional velocity of about 17940 km/sec relative to the Cosmic Microwave Background of 17940 km/sec (and H0 = 70 km/sec/Mpc), a straightforward calculation indicates that PGC 46234 is about 835 million light-years away. However, for objects as such distances we should take into account the Universal expansion during the time it took their light to reach us. Doing that shows that the galaxy was about 780 million light-years away at the time the light by which we see it was emitted, about 800 to 805 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of 0.5 by 0.25 arcmin (from the images below), the galaxy is about 110 to 115 thousand light-years across.
 As noted in the entry for PGC 46225, it is possible that PGC 46234 and Arp 57 are more closely related than their slightly different recessional velocities might imply, as the roughly 400 km/sec difference in their recessional velocities is only slightly larger than typical "peculiar velocities" (random motions of galaxies relative to each other that are not related to the Universal Expansion), but whether they are part of a gravitationally bound triple system cannot be known, and they are most likely not gravitationally bound companions; but if nothing else, the slightly peculiar appearance of PGC 46234 might be explained by a moderately close passage of the galaxy with the now (apparently) more distant pair at some time in the past.
SDSS image of region near spiral galaxy PGC 46234, also showing PGC 46225 and its companion, PGC 1457659, which comprise Arp 57
Above, a 12 arcmin wide SDSS image centered on PGC 46234, also showing the pair of galaxies that comprise Arp 57
Below, a 0.75 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy PGC 46234, also showing PGC 46225 and its apparent companion, PGC 1457659, which comprise Arp 57

PGC 46423
(= ESO 508-043)

A magnitude 14.5(?) spiral galaxy (type Sb?) in
Hydra (RA 13 19 05.7, Dec -24 25 05)
Physical Information: Based on a recessional velocity relative to the Cosmic Background Radiation of 10450 km/sec (and H0 = 70 km/sec/Mpc), a straightforward calculation indicates that PGC 46423 is about 485 to 490 million light-years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was about 465 to 470 million light-years away at the time the light by which we see it was emitted, about 475 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 1.4 by 0.25 arcmin (from the images below), the galaxy is about 190 thousand light-years across. The galaxy is classified as an HII emitter, indicating that it has regions of relatively rapid formation of hot, bright stars that are heating up the gases out of which they formed.
 The faint galaxy to its west, PGC 790153, is a probable companion, as it has a similar recessional velocity, but the north-south galaxy on its eastern side, PGC 790216, has an unknown distance, and is probably merely a background galaxy. Nothing is known about 6dFJ1319096-242505 ("PGC 4681588"), the small galaxy immediately to its east, so whether it is in any way related to PGC 46423 is also unknown.
PanSTARRS image of region near spiral galaxy 46423, also showing PGC 46461
Above, a 12 arcmin wide PanSTARRS image centered on PGC 46423, also showing PGC 46461
Below, a 2.75 arcmin wide PanSTARRS image of the region near PGC 46423, also showing the other galaxies mentioned above
PanSTARRS image of spiral galaxy 46423, also showing apparently nearby galaxies
Below, a 1.75 arcmin wide PanSTARRS image of the galaxy
PanSTARRS image of spiral galaxy 46423

PGC 46461
(with PGC 46464 = ESO 508-045 = AM 1316-241)

A magnitude 15(?) elliptical galaxy (type E0?) in
Hydra (RA 13 19 32.0, Dec -24 29 03)
Physical Information: Since PGC 46461 and 46464 are an interacting pair, they must be at essentially the same distance, so the best Hubble Flow recessional velocity is the average of their individual measurements. For PGC 46461, that is about 10135 km/sec, and for PGC 46464, it is about 10795 km/sec. Note that if those velocities were only related to the Universal Expansion, its higher recessional velocity would place PGC 46464 behind PGC 46461; but since the image of the pair clearly shows that PGC 46464 is in front of its companion (as seen from our location), the difference of nearly 600 km/sec in their recessional velocities must represent a real motion (a "peculiar velocity") of the spiral galaxy toward its elliptical companion, so they will be even closer together (and probably "collide" with each other) at some future date.
 Based on their average recessional velocity relative to the Cosmic Background Radiation of about 10465 km/sec (and H0 = 70 km/sec/Mpc), a straightforward calculation indicates that PGC 46461 and 46464 are about 485 to 490 million light-years away, in reasonable agreement with a single redshift-independent distance estimate of about 465 million light-years (which, as shown below, is probably very close to their actual distance). However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the pair was about 465 to 470 million light-years away at the time the light by which we see it was emitted, just over 475 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 1.05 by 1.05 arcmin (from the images below), PGC 46461 is about 140 to 145 thousand light-years across.
PanSTARRS image of region near elliptical galaxy PGC 46461 and spiral galaxy PGC 46464, which comprise an interacting pair
Above, a 12 arcmin wide PanSTARRS image centered on PGC 46461 and PGC 46464, also showing PGC 46423
Below, a 1.3 arcmin wide PanSTARRS image of the interacting pair
PanSTARRS image of elliptical galaxy PGC 46461 and spiral galaxy PGC 46464, which comprise an interacting pair
Below, the same region as shown above, in an HST image
(Image Credit NASA/ESA/Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, & W. Keel (U. of Alabama, Tuscaloosa))
HST image of elliptical galaxy PGC 46461 and spiral galaxy PGC 46464, which comprise an interacting pair
Below, a 1.7 by 2.25 arcmin wide version of the HST image, rotated 30° anti-clockwise to show more detail
HST image of elliptical galaxy PGC 46461 and spiral galaxy PGC 46464, which comprise an interacting pair

PGC 46464
(with
PGC 46461 = ESO 508-045 = AM 1316-241)
See PGC 46461 for images of the pair
A magnitude 15.5(?) spiral galaxy (type Sbc pec) in Hydra (RA 13 19 33.2, Dec -24 29 25)
Physical Information: Based on the discussion in the entry for PGC 46461, the pair of interacting galaxies must have been about 465 to 470 million light-years away at the time the light by which we see it was emitted, just over 475 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of 1.45 by 0.45 arcmin (from the images above), PGC 46464 is about 195 to 200 thousand light-years across, counting the extended dust lanes silhouetted against its elliptical companion.
Celestial Atlas
PGC 45500 - 45999 ←PGC Objects: PGC 46000 - 46499→ PGC 46500 - 46999