ASTRO: The Medusa Galaxies

Arp 160 has been in the news recently as an image of it combining white
light data from Hubble and X-ray data from Chandra has been recently
released. I imaged it the week before the image was released rushed it
to the top of the processing list when I finally saw the Chandra release.
http://chandra.harvard.edu/photo/2009/medusa/

Arp 160 is known as the Medusa Galaxies though Arp apparently didn't
know it was two galaxies. He considered it one and classed it as under
"Galaxies not classifiable as elliptical or spiral that are disturbed
with interior absorption". In fact it is two galaxies that are in the
process of merging. The fan shaped blue object above and the spiral
like, mostly reddish object below. Using Chandra's X ray vision (better
than Superman's?) the black hole that was at the core of the upper
galaxy has been spotted. Its accretion disk is should say.

I had a heck of a time processing this image as there was a 5th
magnitude star just out of frame at the top right that must have hit
something reflective in the camera. It sent ghost images all over the
field. Many overlapped. It took me a couple days work to remove them.
In doing so I lost faint parts of the image but none involving Arp 160
which is also known as NGC 4194 and is in Ursa Major.

Arp's image with the 200" Palomar scope is at:
http://nedwww.ipac.caltech.edu/level...ig_arp160.jpeg
Film has far less dynamic range than today's digital sensors so the core
is burned out in Arp's image loosing the spiral nature of that region in
an attempt to show the fainter parts.

While looking at the image you will see a ton of galaxies, some "big and
bright" but most are very faint and very red indicating great distance.
While they are all on the Sloan Digital Sky Survey I found most didn't
have distance measurements but some did. Those that did surprised me.
The size and brightness in my image had little to do with distance.
Without checking the annotated image below the main one, estimate the
distance to the largest field galaxy, a spiral 2/3rds of the way from
Arp 160 to the upper left corner. I found its distance to be very
surprising.

There is only one quasar in the image. It is the one over 9 billion
light years away and is blue. One clue to distance of the galaxies is
the red color of the most distant. Only one other galaxy in the field
is blue, thus likely close enough not to be dust reddened. It turns out
to have almost exactly the same red shift as Arp 160. Note that while
red shift says Arp 160 is 120 million light years away, the
Hubble/Chandra photo caption says 110 million. I used the 120 million
on the annotated image to be consistent with all the other distance
measurements. A difference of less than 10% is actually pretty good as
distance measurements go. Which is closer to correct is hard to say.
Checking the SDSS data the faintest field galaxies in my image are about
magnitude 23.4. Unfortunately none had red shift data other than those
I've shown. Looking at the raw data with the horrid ghosts show some a
magnitude fainter than this were found but they were lost when "ghost
busting" the image. The label is right of the object.

14" LX200R @ f/10, L=4x10' RGB=2x10' all binned 2x2, STL-11000XM,
Paramount ME

Yes my camera really is an "XM" model even if someone at SBIG says they
never made one.

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

That is a very disturbed galaxy, thanks for sharing!

Rick Johnson wrote:
Arp 160 is known as the Medusa Galaxies though Arp apparently didn't
know it was two galaxies.

14" LX200R @ f/10, L=4x10' RGB=2x10' all binned 2x2, STL-11000XM,
Paramount ME


--
Adriano
34°14'11.7"N

Wow, this is a good one. I was quite lazy in recent years and only saved a
few images I saw online to my harddisk, but this was a "must" have. Amazing
object and great image.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Arp 160 has been in the news recently as an image of it combining white
light data from Hubble and X-ray data from Chandra has been recently
released. I imaged it the week before the image was released rushed it
to the top of the processing list when I finally saw the Chandra release.
http://chandra.harvard.edu/photo/2009/medusa/

Arp 160 is known as the Medusa Galaxies though Arp apparently didn't
know it was two galaxies. He considered it one and classed it as under
"Galaxies not classifiable as elliptical or spiral that are disturbed
with interior absorption". In fact it is two galaxies that are in the
process of merging. The fan shaped blue object above and the spiral
like, mostly reddish object below. Using Chandra's X ray vision (better
than Superman's?) the black hole that was at the core of the upper
galaxy has been spotted. Its accretion disk is should say.

I had a heck of a time processing this image as there was a 5th
magnitude star just out of frame at the top right that must have hit
something reflective in the camera. It sent ghost images all over the
field. Many overlapped. It took me a couple days work to remove them.
In doing so I lost faint parts of the image but none involving Arp 160
which is also known as NGC 4194 and is in Ursa Major.

Arp's image with the 200" Palomar scope is at:
http://nedwww.ipac.caltech.edu/level...ig_arp160.jpeg
Film has far less dynamic range than today's digital sensors so the core
is burned out in Arp's image loosing the spiral nature of that region in
an attempt to show the fainter parts.

While looking at the image you will see a ton of galaxies, some "big and
bright" but most are very faint and very red indicating great distance.
While they are all on the Sloan Digital Sky Survey I found most didn't
have distance measurements but some did. Those that did surprised me.
The size and brightness in my image had little to do with distance.
Without checking the annotated image below the main one, estimate the
distance to the largest field galaxy, a spiral 2/3rds of the way from
Arp 160 to the upper left corner. I found its distance to be very
surprising.

There is only one quasar in the image. It is the one over 9 billion
light years away and is blue. One clue to distance of the galaxies is
the red color of the most distant. Only one other galaxy in the field
is blue, thus likely close enough not to be dust reddened. It turns out
to have almost exactly the same red shift as Arp 160. Note that while
red shift says Arp 160 is 120 million light years away, the
Hubble/Chandra photo caption says 110 million. I used the 120 million
on the annotated image to be consistent with all the other distance
measurements. A difference of less than 10% is actually pretty good as
distance measurements go. Which is closer to correct is hard to say.
Checking the SDSS data the faintest field galaxies in my image are about
magnitude 23.4. Unfortunately none had red shift data other than those
I've shown. Looking at the raw data with the horrid ghosts show some a
magnitude fainter than this were found but they were lost when "ghost
busting" the image. The label is right of the object.

14" LX200R @ f/10, L=4x10' RGB=2x10' all binned 2x2, STL-11000XM,
Paramount ME

Yes my camera really is an "XM" model even if someone at SBIG says they
never made one.

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".