Object of the Week, April 13 2014 – NGC 4676A/B “The Mice”

NGC 4676A/B (IC 819/IC 820)
= VV 224, Arp 242

Interacting Galaxy Pair

Coma Berenices
RA 12h 46.2m
DEC +66° 43.7’

Magnitude 13.5v/13.8v


First known description came from Herschel at March 1785. Although he only cataloged one object trough his 18,7” Reflector, he described it as faint, extended and binuclear. In 1892 Spitaler cataloged two objects through his huge 27” Refractor. The Index Catalog named both objects as IC 819 and IC 820.
The situation behind this object became really exciting with the publication and distribution of the POSS plates. Fastest astronomer was as often the Russian Astronomer Vorontsov-Velyaminov (VV) who mentioned in 1957 the abnormal spirals and the bright comet-like tail and assumed that both galaxies have to be a colliding pair. VV named the new class of galaxies “mice” for his compilation of unusual galaxies. But the pair became his famous name “The Mice” two years later when Burbidge and Burbidge refer to a detailed prime-focus plate of the 82” McDonald Reflector (maybe someone knows this instrument here?)

Now we know much more details about the colliding pair. Lots of simulations of the collision started. First contact has taken place 150 million years. This cosmic dance should last another 400 million years. Then, this pair should look like a normal elliptical galaxy and is not worth as another OOTW here.

The pair should be in reach for 8” class telescopes. Under good but not perfect conditions I could see hints of the brighter tail in my old 16”. The 20” showed this without problems and with 24” it was a direct vision detail. Much more difficult is the fainter tail to the south and the bridge between both galaxies. A quick view in the past through an 24” telescope doesn’t show both fainter details, but I know of positive observations with 20” under perfect conditions.

What are your experiences with this pair, both tails and the bridge?

SDSS image
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sketch: 24", 315x, NELM 6m7
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“GIVE IT A GO AND LET US KNOW”
GOOD LUCK AND GREAT VIEWING!

My log notes for The Mice, from June 2, 2008 at the Texas Star Party using a 30" f/4.5 at 304x:

Bright tail easily seen. Interaction between the two galaxies obvious.
Dim tail seen as a fat plume emitting from the right [(east] side of the upper galaxy [4676B], then curving upward [south].

"the 82” McDonald Reflector (maybe someone knows this instrument here?)"

Oh yeah, we know the 82". In addition to being a research instrument, it's also an incredible visual telescope that quite a few DSF members have experience with. We amateurs don't get as much time on it as we used to, due to new instrumentation that keeps it busier than ever with research, but the few opportunities we do get to view with it are still exciting.

Jim

Hi Jim,

thanks for the description of the dim tail. I have definitely revisit the pair with the 27" under better conditions.

I forgot to set I smily behind my question about the 82". You guys are absolutely privileged to use this giant telescope visually. I wish one day, that I get a chance too.

Quote:

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Originally Posted by Uwe Glahn

Hi Jim,

You guys are absolutely privileged to use this giant telescope visually. I wish one day, that I get a chance too.

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I, too, hope that you get that chance. It would be great to see you again.

Jim

I had bad luck getting a decent look at The Mice under decent conditions with my 28 inch, but had a memorable view of them through Jimi's 48 inch last spring. It was a brief look because it was a windy night, but here's my observation:

"What a cool tidal tail! Long, slightly curved - it really looks like a tail. 488x, 21.71 SQM"
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This was a very good object. It was one of the first object I looked at TSP 2006 with my 30" Stamaster under NELM 7.2 skies.

Here are my notes:

30" f/4.3 reflector @ 252, 364 and 468x

Phenomenal!! – Looks like the Hubble picture! The Mice!

The two very bright 2:1 elongated halos are equally bright with significantly brighter cores. Both are about 30” long. The position angle of NGC 4676A is 0 degrees and 4676B is 45 degrees. NGC 4676A is about 40” NW of 4676B.
The “Ray” starting at the north edge and pointing north of NGC 4676A is easily visible as an even surface brightness spike of about 1.4’ long. The last 40” of the spike is a little thicker than the rest of it. A 16th magnitude star is just west of the tip of the spike.
The hook from NGC 4676B is barely visible with averted vision. It starts on the SE edge of 4676B and hooking counterclockwise to the SE, ending to the SW. About 50” long.

30" at 364x
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Hi Uwe,

great Object of the week. I haven't observed this pair for some time, so my notes are from a few years ago:

With my 22" Dob, the tidal streamer to the North is not particularly difficult and extends over roughly twice the diameter of the northern component. At the opposite side, there is as well an extremely faint brightening. This is presumably the inner arm of the southern galaxy.

Therefore, from position and extent of the southern extension, I have likely not seen the very faint southern tail, but the brightening in the southern part of the halo of the B galaxy, presumably a spiral arm or another closer and brighter tidal stream.

OK, I managed a go over the Mice on two consecutive nights from the (very) dark site at Lysos, Cyprus. Unfortunately, conditions were not as good as they usually are there, apparently there was some high level moisture in the upper atmosphere making the sky ver dark, but certainly not pitch-black as is the norm there.

Anyway, I did manage to see both components with my 18". At low to medium powers they were just an undefined blur, but increasing the magnification to 275X showed them both clearly as two separate entities. The southern component seemed a touch brighter than the north one, but I could not see the southern "tidal tail". The northern tidal tail was visible, initially intermittently with averted vision, and by spending more time on it steadily with averted vision and intermittently with direct vision. I could not though confirm that the norternmost part was thicker than the rest. I certainly believe that this tail may be visible even with less than 16 inches...

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