ASTRO: An interesting galaxy group

NGC 5275 and NGC 5280 are located in a rich galaxy field in Canes
Venatici about 1.5 degrees north of the far more famous M3. While the 5
largest galaxies constitute the WBL 464 galaxy group I couldn't
determine exactly what cluster the vast majority of these belong to.
There appear to be three main groups, one about 500 million light-years,
another at 600 million light-years and a third at 850 million
light-years. There's lots of overlap here. The most distant group are
likely members of the ABELL 7181 galaxy cluster listed at 830 million
light-years. It is a very large but sparse cluster with a center about
a minute beyond the left border about midline.

The reason I imaged the field was NGC 5275, also known as VV 543E, An E
or maybe S0 galaxy that's quite compact so of rather high mass. It has
an apparent companion, VV 543W, a blue spiral that's somewhat distorted
with a detached blue star cloud at its south end. This makes the
illusion that is it highly warped into a curve around NGC 5275. However
it is an illusion. While it appears distorted it isn't warped after
all. The Sloan Survey image clearly shows the arms that appear drawn
toward NGC 5275 and the detached piece. My seeing was too poor to show
this very clearly. So are they interacting? I found nothing in the
literature on this pair addressing this. Redshift puts them about 70
million light-years apart. If correct they are members of two different
groups and thus not interacting. Could the difference be due to a high
speed difference between the two. I find this unlikely as such a big
speed difference would mean they were within interaction range for far
too short of a time to create this distortion.

UGC 8682 to the northeast of NGC 5275 has a warped south east end. At
500 million light-years it is another 70 million light-years closer than
NGC 5275 so again it is doubtful NGC 5275 had anything to do with its
distortion. But it is the same distance as NGC 5280. They could have
interacted in the past. Unfortunately, I found nothing on these two
either. The field is very poorly researched from what I could determine.

The annotated image lists all galaxies NED had redshift data on as well
as a couple quasars. The quasar to the northeast was listed twice with
a position difference of only 0.02" of arc and with a slightly different
redshift. This is why it is listed with two z values. When converted
to light travel time those values were the same within the three digit
accuracy I use so only one light travel distance is shown.

If the galaxy had an entry in a common catalog it is listed by that
catalog name, otherwise just a G is used. Why some bright galaxies were
missed by LEDA or others but but such catalogs picked up much smaller
and fainter galaxies that were very close in position to each other I
can't fathom.

I've included the SDSS image of 5275 showing the companion more clearly.

This is my last April 2013 image, on to May.

14" LX200R @ f/10, L=4x10' RGB=2x10' STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

Great image Rick. The blue "companion" gives a nice contrast to the
elliptical galaxy.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

NGC 5275 and NGC 5280 are located in a rich galaxy field in Canes
Venatici about 1.5 degrees north of the far more famous M3. While the 5
largest galaxies constitute the WBL 464 galaxy group I couldn't
determine exactly what cluster the vast majority of these belong to.
There appear to be three main groups, one about 500 million light-years,
another at 600 million light-years and a third at 850 million
light-years. There's lots of overlap here. The most distant group are
likely members of the ABELL 7181 galaxy cluster listed at 830 million
light-years. It is a very large but sparse cluster with a center about
a minute beyond the left border about midline.

The reason I imaged the field was NGC 5275, also known as VV 543E, An E
or maybe S0 galaxy that's quite compact so of rather high mass. It has
an apparent companion, VV 543W, a blue spiral that's somewhat distorted
with a detached blue star cloud at its south end. This makes the
illusion that is it highly warped into a curve around NGC 5275. However
it is an illusion. While it appears distorted it isn't warped after
all. The Sloan Survey image clearly shows the arms that appear drawn
toward NGC 5275 and the detached piece. My seeing was too poor to show
this very clearly. So are they interacting? I found nothing in the
literature on this pair addressing this. Redshift puts them about 70
million light-years apart. If correct they are members of two different
groups and thus not interacting. Could the difference be due to a high
speed difference between the two. I find this unlikely as such a big
speed difference would mean they were within interaction range for far
too short of a time to create this distortion.

UGC 8682 to the northeast of NGC 5275 has a warped south east end. At
500 million light-years it is another 70 million light-years closer than
NGC 5275 so again it is doubtful NGC 5275 had anything to do with its
distortion. But it is the same distance as NGC 5280. They could have
interacted in the past. Unfortunately, I found nothing on these two
either. The field is very poorly researched from what I could determine.

The annotated image lists all galaxies NED had redshift data on as well
as a couple quasars. The quasar to the northeast was listed twice with
a position difference of only 0.02" of arc and with a slightly different
redshift. This is why it is listed with two z values. When converted
to light travel time those values were the same within the three digit
accuracy I use so only one light travel distance is shown.

If the galaxy had an entry in a common catalog it is listed by that
catalog name, otherwise just a G is used. Why some bright galaxies were
missed by LEDA or others but but such catalogs picked up much smaller
and fainter galaxies that were very close in position to each other I
can't fathom.

I've included the SDSS image of 5275 showing the companion more clearly.

This is my last April 2013 image, on to May.

14" LX200R @ f/10, L=4x10' RGB=2x10' STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net