Name: VV 248a = Arp 96 NED1 = UGC 3528A = MCG +14-04-010 = CGCG 362-030 = KTG 11A = KPG 116A = PGC 20028
R.A.: 07h 02m 27.4s
Dec.: +86° 34' 46" (J2000)
Con: Cepheus
Type: Sbc
Size: 0.8' x 0.6'
Magnitude: ~15.4B
Name: VV 248b = Arp 96 NED2 = UGC 3536A = MCG +14-04-011 = CGCG 362-031 = KTG 11B = KPG 116B = PGC 20066
R.A.: 07h 03m 22.0s
Dec.: +86° 33' 28" (J2000)
Con: Cepheus
Type: E
Size: 0.7' x 0.6'
Magnitudes: V = 13.6, B = 14.6
After last week's OOTW M41, the "Little Beehive Cluster" (I had never heard of that nickname), I was considering following up with NGC 2516, the "Southern Beehive Cluster" in Carina, which is a much brighter naked-eye cluster (and fantastic in binoculars), but I decided to go in a different direction due to its southern declination of nearly -61°.
So what direction? How about within 3½° of the north celestial pole! VV 248, or perhaps better known as Arp 96, is one of the most northerly interacting pairs. In fact, the only such pair further north that I've observed is UGC 10923, and that only beats out our OOTW by a mere 10'. This is Arp's image (rotated so north is up) using the 200-inch at Palomar.
Arp 96 with 200-inch.jpg
I wrote about this pair (part of a KTG triplet) and a number of other far northern galaxies (all north of +84° dec) in a Sky & Telescope article in February 2016 titled "A Trip to the Northern Frontier". The article was based on observations I made with an 18-inch Starmaster. Here is my description in the article...
"Deep images display long tidal plumes emanating from the spiral arms of UGC 3528A, with the southern extension stretching to UGC 3536A. This interacting pair attracted the attention of Russian astronomer Boris Vorontsov-Velyaminov, who cataloged it as VV 248 in his 1959 Catalogue of Interacting Galaxies (S&T: Sept. 2014, p. 60), as well as Halton Arp, who listed it as Arp 96 in his 1966 Atlas of Peculiar Galaxies. Through the eyepiece, blue magnitude-15.4 UGC 3528A is a hazy patch, about 24" × 18", with no visible core. UGC 3536A (magnitude 13.6), a mere 1.5' southeast, is slightly smaller, but has a higher surface brightness and steadily increases to a quasi-stellar nucleus. A 14.7-magnitude star is pinned against the southwest edge.
This pair shares the field with PGC 20191 [also CGCG 362-033 = MCG +14-04-014] just 7' to the northeast. I found a faint oval, 25" long and 1/2 as wide, with a scarcely brighter core. The trio carries its own designation — KTG 11 from the Karachentseva Isolated Triplets of Galaxies (S&T: May 2015, p. 59) — and is located at a distance of 200 million light-years."
Fritz Zwicky used this pair to illustrate the possible formation of an intergalactic bridge back in a 1956 seminal paper on interacting multiple systems.
Zwicky Arp 96.jpg
There's been very little research on the main pair, except for a 1990 paper by Schombert et al, titled "A multicolor photometric study of the tidal features in interacting galaxies". The authors noted,
"At first glance, the Arp 96 system could easily be mistaken for a chance projection of two galaxies rather than a true interaction. The connecting bridge and northern plume appear to be natural extensions to the primary galaxy's spiral structure. However, on closer examination, the two tidal features show distinct contours separate from the spiral arms. The primary galaxy (SBc type spiral) has slightly higher arms with the bridge and plume originating at the points where the pitch angle changes. The northern plume is a counter-tail under the normal interpretation from collision models. The southern feature is a connecting bridge to the southern elliptical companion. The bridge axis is directly oriented toward the elliptical's center. In addition, there is an extremely faint shell feature to the SW of the elliptical which substantiates the interaction interpretation for this pair."
In his atlas, Arp commented "Faint Diffuse counter arm, and arm leading to companion." The "arm leading to companion" or bridge, as it would be called today, stretches about 1.5' on the sky. At a distance of close to 210 million years based on redshift (assuming H0 = 70), the bridge extends ~90,000 l.y.
So, what about viewing this pair? Neither member was difficult in my 18", although the spiral has a low surface brightness. A 15" should show the spiral, depending on your skies, and certainly a smaller aperture with do for the mag 13.6 elliptical. The bridge itself was not seen. If your skies are cloudy during the next couple of months (we've already had such a stretch in California), no worries --- since this trio is so close to the north celestial pole, you can take a look at any convenient month!
As always,
"Give it a go and let us know!
Good luck and great viewing!"
Arp 96 image.jpg
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