akarsh
June 1st, 2025, 02:11 AM
IC 1101 = UGC 9752 = CGCG 049-023
Lenticular Galaxy in Virgo
RA (ICRS): 15 10 56
Dec (ICRS): 05 44 41
Mag: 13.70 (Steinicke NGC/IC catalog)
Size: 0.87 × 0.49
(Brightest Cluster Galaxy)
PGC 54178
Galaxy in Virgo
RA (ICRS): 15 11 00
Dec (ICRS): 05 46 58
Mag (B): 16.88
Size: 0.27 × 0.20
(Cluster member)
Abell 2029
Galaxy Cluster in Virgo
Coordinates same as IC 1101
LEDA 5057632
?????? Galaxy in Virgo
RA (ICRS): 15 10 55
Dec (ICRS): 05 43 15
Mag: ~17.8
Size: 0.62 × 0.62
(Foreground Galaxy)
Looks like I'm continuing on a theme of Abell clusters! IC 1101 was discovered in 1890 by Edward Swift (according to Prof. Courtney Seligman). It is the cD (center dominant) and BCG (Brightest Cluster Galaxy) of the distant galaxy cluster Abell 2029. IC 1101 is a formidable monster -- this supergiant lenticular galaxy harbors one of the largest super-massive black holes that astrophysicists are aware of, exceeded by Ton 618 and Phoenix A.
5722
HST Image of IC 1101
I tried doing some research on what made IC 1101 so massive and gigantic, that we are able to clearly see its disk from over a billion light years away: It's redshift of 0.0778 translates to over a billion light years of light-travel time according to present cosmological models. I could not find exactly what led to the growth of IC 1101, and ChatGPT only produced some hallucinated responses! If anyone knows, I would love to know.
For a fascinating account of how cluster galaxies are transformed by their environment -- both through gravitational interactions as well as ram-pressure stripping, I recommend Prof. Chris Mihos' article in Sky & Telescope Jan 2025 issue, on the "Tumultous Lives of Galaxies". He explains that in denser cluster environments, there are more elliptical, lenticular, and dwarf ellipsoidal galaxies than spirals and dwarf irregulars, which are only found on the outer fringes of such clusters where there is a lower density. This is due to the increased likelihood of mergers in more dense environments, as well as ram-pressure stripping removing gas from spirals and turning them into lenticulars. This is perhaps the reason why IC 1101 is surrounded by tiny lenticular and elliptical galaxies.
Dynamical friction eventually causes the nearby galaxies to merge into the central elliptical/lenticular galaxy making it larger and larger. Thus, IC 1101 is expected to have grown to its size due to galactic cannibalism, and the black hole at the center has therefore also grown in mass. For those with arachnophobia, perhaps the environment of a cD galaxy appears eerie, as it is reminiscent of a mother spider with many babies around her in a web, except here, the process is played in reverse -- the cD galaxy is cannibalizing the smaller dwarfs nearby rather than the other way around. The cluster Abell 2029 is devoid of Milky Way-sized galaxies, and I didn't exactly understand what implication this has.
That brings me to the second target here: PGC 54178 seems to be the second brightest galaxy in the region. Looking at how it stood out from the rest of the cluster, I suspected it may be a foreground galaxy, but the SDSS has a spectrum on it which shows that it is also at a similar redshift. SIMBAD lists it as a 100% probable member of Abell 2029. So now the challenge is to see not one but two galaxies in this distant cluster, or even better, as many of the tiny "baby spider" galaxies as possible.
Finally, there is a strange-looking galaxy in the cluster with perfectly collimated "jets", which bears the designation LEDA 5057632. At first, it looked like a plate defect on the DSS2 image, but you can see it on the SDSS and Legacy images as well. Is it an edge-on galaxy or a polar-ring galaxy? In any case, it does seem to be foreground from the cluster, both from its appearance and from the redshift SIMBAD has on it. This may be a good observing challenge for large telescopes.
5721
DSS2 Color image of Abell 2029, annotated
5723
Legacy Survey image of Abell 2029
Visual Observation
The smallest aperture I've attempted and successfully seen IC 1101 with happens to be a 24-inch, although I imagine it may be visible under excellent conditions in an 18- or 20-inch telescope. Recently, in my 28-inch telescope, I was able to clearly see IC 1101 as a slightly elongated diffuse low-surface brightness galaxy. I looked hard for any other cluster members, and the only one I could confirm was PGC 54178. A nearby fuzzy spot that caught my eye turned out to be a double star. PGC 54178 was continuously visible with averted vision.
Well, I was very satisfied to see not one but two galaxies of this distant cluster. I wonder, how many can be seen with larger telescopes or under better conditions. So, when you get a chance,
GIVE IT A GO AND LET US KNOW!
Lenticular Galaxy in Virgo
RA (ICRS): 15 10 56
Dec (ICRS): 05 44 41
Mag: 13.70 (Steinicke NGC/IC catalog)
Size: 0.87 × 0.49
(Brightest Cluster Galaxy)
PGC 54178
Galaxy in Virgo
RA (ICRS): 15 11 00
Dec (ICRS): 05 46 58
Mag (B): 16.88
Size: 0.27 × 0.20
(Cluster member)
Abell 2029
Galaxy Cluster in Virgo
Coordinates same as IC 1101
LEDA 5057632
?????? Galaxy in Virgo
RA (ICRS): 15 10 55
Dec (ICRS): 05 43 15
Mag: ~17.8
Size: 0.62 × 0.62
(Foreground Galaxy)
Looks like I'm continuing on a theme of Abell clusters! IC 1101 was discovered in 1890 by Edward Swift (according to Prof. Courtney Seligman). It is the cD (center dominant) and BCG (Brightest Cluster Galaxy) of the distant galaxy cluster Abell 2029. IC 1101 is a formidable monster -- this supergiant lenticular galaxy harbors one of the largest super-massive black holes that astrophysicists are aware of, exceeded by Ton 618 and Phoenix A.
5722
HST Image of IC 1101
I tried doing some research on what made IC 1101 so massive and gigantic, that we are able to clearly see its disk from over a billion light years away: It's redshift of 0.0778 translates to over a billion light years of light-travel time according to present cosmological models. I could not find exactly what led to the growth of IC 1101, and ChatGPT only produced some hallucinated responses! If anyone knows, I would love to know.
For a fascinating account of how cluster galaxies are transformed by their environment -- both through gravitational interactions as well as ram-pressure stripping, I recommend Prof. Chris Mihos' article in Sky & Telescope Jan 2025 issue, on the "Tumultous Lives of Galaxies". He explains that in denser cluster environments, there are more elliptical, lenticular, and dwarf ellipsoidal galaxies than spirals and dwarf irregulars, which are only found on the outer fringes of such clusters where there is a lower density. This is due to the increased likelihood of mergers in more dense environments, as well as ram-pressure stripping removing gas from spirals and turning them into lenticulars. This is perhaps the reason why IC 1101 is surrounded by tiny lenticular and elliptical galaxies.
Dynamical friction eventually causes the nearby galaxies to merge into the central elliptical/lenticular galaxy making it larger and larger. Thus, IC 1101 is expected to have grown to its size due to galactic cannibalism, and the black hole at the center has therefore also grown in mass. For those with arachnophobia, perhaps the environment of a cD galaxy appears eerie, as it is reminiscent of a mother spider with many babies around her in a web, except here, the process is played in reverse -- the cD galaxy is cannibalizing the smaller dwarfs nearby rather than the other way around. The cluster Abell 2029 is devoid of Milky Way-sized galaxies, and I didn't exactly understand what implication this has.
That brings me to the second target here: PGC 54178 seems to be the second brightest galaxy in the region. Looking at how it stood out from the rest of the cluster, I suspected it may be a foreground galaxy, but the SDSS has a spectrum on it which shows that it is also at a similar redshift. SIMBAD lists it as a 100% probable member of Abell 2029. So now the challenge is to see not one but two galaxies in this distant cluster, or even better, as many of the tiny "baby spider" galaxies as possible.
Finally, there is a strange-looking galaxy in the cluster with perfectly collimated "jets", which bears the designation LEDA 5057632. At first, it looked like a plate defect on the DSS2 image, but you can see it on the SDSS and Legacy images as well. Is it an edge-on galaxy or a polar-ring galaxy? In any case, it does seem to be foreground from the cluster, both from its appearance and from the redshift SIMBAD has on it. This may be a good observing challenge for large telescopes.
5721
DSS2 Color image of Abell 2029, annotated
5723
Legacy Survey image of Abell 2029
Visual Observation
The smallest aperture I've attempted and successfully seen IC 1101 with happens to be a 24-inch, although I imagine it may be visible under excellent conditions in an 18- or 20-inch telescope. Recently, in my 28-inch telescope, I was able to clearly see IC 1101 as a slightly elongated diffuse low-surface brightness galaxy. I looked hard for any other cluster members, and the only one I could confirm was PGC 54178. A nearby fuzzy spot that caught my eye turned out to be a double star. PGC 54178 was continuously visible with averted vision.
Well, I was very satisfied to see not one but two galaxies of this distant cluster. I wonder, how many can be seen with larger telescopes or under better conditions. So, when you get a chance,
GIVE IT A GO AND LET US KNOW!