Arp 18 is cataloged as a spiral with a Detached Segment. Exactly how this differs from the previous category above I'm not sure. More commonly known as NGC 4088 this galaxy is 42 million light years away as is its companion NGC 4085 at the bottom of the picture. Only 4088 has the detached segment which I take to be the piece at the upper left. Whether this is due to interaction with NGC 4085 I don't know. They have the virtually the same radial velocity which is rarely the case with interacting galaxies. Something disturbed NGC 4088 that's for sure.

The detached part of the galaxy carries a separate designation of SDSS J120543.59+503319.0 ID and has a very different radial velocity. The core of the galaxy is receding at 823 km/s relative to our galaxy but the detached piece of an arm is moving away at only 661 km/s a difference too great to be due to rotation of the galaxy alone. So there's still a mystery here.

The small barred spiral down and left (southeast) of ARP 18 is MCG +09-20-092. It is surprisingly big and bright at magnitude 15.7 for a galaxy with a red shift distance of about 750 million light years! It must be a real giant of a galaxy if that distance is right.

Image with less compression is at:
http://www.spacebanter.com/attachmen...tid=1981&stc=1

14" LX200R @ f/10, L=6x10' binned 2x2 RGB=2x10' binned 3x3, STL-11000XM,
Paramount ME

Rick

Attached Images

NGC4088-85ARP18L6X10RGB2X10X3-7R.jpg (130.5 KB, 22 views)

Wow, twisted blue fuzzies everywhere.

Great image and great science too.

Thanks.

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Observatorio de la Ballona

An Awesome image of the pair and surrounding areas. Very populated area and yet some details could be seen for such a small distant object. A Fantastic image and again great info of what is being seen on the image. Thanks again Rick and Clear Skies

this is another cracker! crisp and clear!
your Arp-series is really astounding, Rick!
super!

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best regards,
Dietmar
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www.stargazer-observatory.com

Great shot and information!