ASTRO: Arp 245 with wild plume

Arp 245/NGC 2992-3 is a great pair of interacting galaxies in Hydra.
Red shift puts them at about 125 million light-years but most papers are
going with the Tully-Fisher distance of 100 million light-years. In any
case they are close and large enough to actually make an interesting
pair to image. Arp put them in his category galaxies with the
appearance of fission. I think he only meant they appeared to be
dividing not that they really were. Of course they are now known to be
interacting galaxies that may be merging rather than splitting. Arp's
comment on these is; "Very faint diffuse connection from both ends of N
spiral to S spiral."

The N spiral is NGC 2992 and the S spiral is NGC 2993. While NGC 2992
appears quite red in my image and is indeed a strong IR source it is
also a very strong UV source and well seen in the X-ray spectrum as
well. It has a highly variable Seyfert Core. Papers argue between
Seyfert 1, 1.9 and 2 status with 1.9 being seen most. All of this is
rather expected from such a strongly interacting pair. I don't know if
its overall red color is due to stars or dust absorption. I suspect the
latter. NED classes it as Sa pec while the NGC project just says Pec.
NED gives the northern plume the designation of Arp 245N listing it as a
tidal tail.

NGC 2993 is a near face on spiral with a large bright core, some say is
double though I was unable to see this. It is much bluer than its
companion. It too has a lot of star birth going on in its core. NED
also says it is Sa Pec with HII emissions. The NGC project again says
simply Pec. Of the tidal plume between the two galaxies it is hard to
say which galaxy it come from, possibly both I would suspect. I say
this because the plume seems to change from slightly reddish to slightly
blue as you get closer to the blue galaxy. The change is rather abrupt
in fact. I'd love to see this pair from another angle to see what these
tidal plumes are doing. Is the "connecting" plume really connecting or
does it go behind or in front of NGC 2992? There is a lot of papers
listed at NED, I could take a month to read them all, maybe the answer
is in them someplace my quick overview missed.

While this field is not covered by the Sloan survey a couple of unusual
objects are among the few NED has data on. One is the very blue star
just to the east of the tip of the northern plume of NGC 2992. NED
gives it catalog listings. UITBOC 1574 (Ultraviolet Imaging Telescope
Bright Object Catalog) saying it is a visual source which tells us
nothing useful. Another name for it is [BOB94] 0943-1403
(Bowen+Osmer+Blades catalog of galaxies and quasars) which lists it as a
quasar. So far so good. Many quasars are very blue. In fact when they
were still a mystery one name for the blue ones was blue stellar object.
But then we come to its red shift which say it is only 20 million
light-years distant. Normally we'd easily see the galaxy it was in at
that distance and the quasar itself should be exceedingly bright not
magnitude 17.5. I've imaged quasars that bright 5 billion light years
distant! Yet I found no notes on this object. Maybe it is just a super
blue star? Red shift error? (I had to go back and correct my typo for
"shift" -- I left out the "f" -- maybe I was trying to tell myself
something.)

Less confusing is the third galaxy in the group, the thin flat one to
the southwest (lower right). It is FGC 938/RFGC 1621. Either indicate
it is an extremely flat galaxy (FGC=Flat Galaxy Catalog). It's red
shift is also about 125 million light-years so it may be a member of the
same group as Arp 245, just not close enough to be interacting. It is
classed Scd (as are most entries to these catalogs). How some spirals
get to be so flat with virtually no central bulge is still a mystery.
Since the size of the bulge seems related to the size of the black hole
at a spiral galaxy's core does this mean it has no black hole in its
core? Just an unusually small one? I don't know. Anyone out there
seen anything on this?

Only 2 other objects, both galaxies, are listed in NED with red shift
data. Both can be seen near Arp 245. Directly above the blue
star/quasar is a small smudge of a galaxy. It is somewhat blue in
color. It is [DBS2000] J094545.55-141623.7 at 1.44 billion light-years.
That's the only designation NED has; DBS stands for
Duc+Brinks+Springel. The other galaxy is up and to the left of the last
one. It is the third (bottom) object of a small arc of two stars and
the orange galaxy. The upper star is orange while the middle star is
white. The galaxy is quite orange. It is 2MASX J09455121-1415430 with
precisely the same red shift (z=0.111000) as the other galaxy and thus
also 1.44 billion light-years distant. None of the other galaxies in
the image have red shift data and most aren't even listed at NED.

Arp's image:
http://nedwww.ipac.caltech.edu/level...ig_arp245.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

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".

Great object and image Rick.
I just wanted to add it to my list when I noticed that it is at -14
degrees...

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Arp 245/NGC 2992-3 is a great pair of interacting galaxies in Hydra.
Red shift puts them at about 125 million light-years but most papers are
going with the Tully-Fisher distance of 100 million light-years. In any
case they are close and large enough to actually make an interesting
pair to image. Arp put them in his category galaxies with the
appearance of fission. I think he only meant they appeared to be
dividing not that they really were. Of course they are now known to be
interacting galaxies that may be merging rather than splitting. Arp's
comment on these is; "Very faint diffuse connection from both ends of N
spiral to S spiral."

The N spiral is NGC 2992 and the S spiral is NGC 2993. While NGC 2992
appears quite red in my image and is indeed a strong IR source it is
also a very strong UV source and well seen in the X-ray spectrum as
well. It has a highly variable Seyfert Core. Papers argue between
Seyfert 1, 1.9 and 2 status with 1.9 being seen most. All of this is
rather expected from such a strongly interacting pair. I don't know if
its overall red color is due to stars or dust absorption. I suspect the
latter. NED classes it as Sa pec while the NGC project just says Pec.
NED gives the northern plume the designation of Arp 245N listing it as a
tidal tail.

NGC 2993 is a near face on spiral with a large bright core, some say is
double though I was unable to see this. It is much bluer than its
companion. It too has a lot of star birth going on in its core. NED
also says it is Sa Pec with HII emissions. The NGC project again says
simply Pec. Of the tidal plume between the two galaxies it is hard to
say which galaxy it come from, possibly both I would suspect. I say
this because the plume seems to change from slightly reddish to slightly
blue as you get closer to the blue galaxy. The change is rather abrupt
in fact. I'd love to see this pair from another angle to see what these
tidal plumes are doing. Is the "connecting" plume really connecting or
does it go behind or in front of NGC 2992? There is a lot of papers
listed at NED, I could take a month to read them all, maybe the answer
is in them someplace my quick overview missed.

While this field is not covered by the Sloan survey a couple of unusual
objects are among the few NED has data on. One is the very blue star
just to the east of the tip of the northern plume of NGC 2992. NED
gives it catalog listings. UITBOC 1574 (Ultraviolet Imaging Telescope
Bright Object Catalog) saying it is a visual source which tells us
nothing useful. Another name for it is [BOB94] 0943-1403
(Bowen+Osmer+Blades catalog of galaxies and quasars) which lists it as a
quasar. So far so good. Many quasars are very blue. In fact when they
were still a mystery one name for the blue ones was blue stellar object.
But then we come to its red shift which say it is only 20 million
light-years distant. Normally we'd easily see the galaxy it was in at
that distance and the quasar itself should be exceedingly bright not
magnitude 17.5. I've imaged quasars that bright 5 billion light years
distant! Yet I found no notes on this object. Maybe it is just a super
blue star? Red shift error? (I had to go back and correct my typo for
"shift" -- I left out the "f" -- maybe I was trying to tell myself
something.)

Less confusing is the third galaxy in the group, the thin flat one to
the southwest (lower right). It is FGC 938/RFGC 1621. Either indicate
it is an extremely flat galaxy (FGC=Flat Galaxy Catalog). It's red
shift is also about 125 million light-years so it may be a member of the
same group as Arp 245, just not close enough to be interacting. It is
classed Scd (as are most entries to these catalogs). How some spirals
get to be so flat with virtually no central bulge is still a mystery.
Since the size of the bulge seems related to the size of the black hole
at a spiral galaxy's core does this mean it has no black hole in its
core? Just an unusually small one? I don't know. Anyone out there
seen anything on this?

Only 2 other objects, both galaxies, are listed in NED with red shift
data. Both can be seen near Arp 245. Directly above the blue
star/quasar is a small smudge of a galaxy. It is somewhat blue in
color. It is [DBS2000] J094545.55-141623.7 at 1.44 billion light-years.
That's the only designation NED has; DBS stands for
Duc+Brinks+Springel. The other galaxy is up and to the left of the last
one. It is the third (bottom) object of a small arc of two stars and
the orange galaxy. The upper star is orange while the middle star is
white. The galaxy is quite orange. It is 2MASX J09455121-1415430 with
precisely the same red shift (z=0.111000) as the other galaxy and thus
also 1.44 billion light-years distant. None of the other galaxies in
the image have red shift data and most aren't even listed at NED.

Arp's image:
http://nedwww.ipac.caltech.edu/level...ig_arp245.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

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".

It was on my list for three years until I finally had a night I could go
that low and that faint and I'm at 47N. You're several further north.

Rick

On 2/27/2011 1:44 PM, Stefan Lilge wrote:
Great object and image Rick.
I just wanted to add it to my list when I noticed that it is at -14
degrees...

Stefan

"Rick schrieb im Newsbeitrag
ster.com...
Arp 245/NGC 2992-3 is a great pair of interacting galaxies in Hydra.
Red shift puts them at about 125 million light-years but most papers are
going with the Tully-Fisher distance of 100 million light-years. In any
case they are close and large enough to actually make an interesting
pair to image. Arp put them in his category galaxies with the
appearance of fission. I think he only meant they appeared to be
dividing not that they really were. Of course they are now known to be
interacting galaxies that may be merging rather than splitting. Arp's
comment on these is; "Very faint diffuse connection from both ends of N
spiral to S spiral."

The N spiral is NGC 2992 and the S spiral is NGC 2993. While NGC 2992
appears quite red in my image and is indeed a strong IR source it is
also a very strong UV source and well seen in the X-ray spectrum as
well. It has a highly variable Seyfert Core. Papers argue between
Seyfert 1, 1.9 and 2 status with 1.9 being seen most. All of this is
rather expected from such a strongly interacting pair. I don't know if
its overall red color is due to stars or dust absorption. I suspect the
latter. NED classes it as Sa pec while the NGC project just says Pec.
NED gives the northern plume the designation of Arp 245N listing it as a
tidal tail.

NGC 2993 is a near face on spiral with a large bright core, some say is
double though I was unable to see this. It is much bluer than its
companion. It too has a lot of star birth going on in its core. NED
also says it is Sa Pec with HII emissions. The NGC project again says
simply Pec. Of the tidal plume between the two galaxies it is hard to
say which galaxy it come from, possibly both I would suspect. I say
this because the plume seems to change from slightly reddish to slightly
blue as you get closer to the blue galaxy. The change is rather abrupt
in fact. I'd love to see this pair from another angle to see what these
tidal plumes are doing. Is the "connecting" plume really connecting or
does it go behind or in front of NGC 2992? There is a lot of papers
listed at NED, I could take a month to read them all, maybe the answer
is in them someplace my quick overview missed.

While this field is not covered by the Sloan survey a couple of unusual
objects are among the few NED has data on. One is the very blue star
just to the east of the tip of the northern plume of NGC 2992. NED
gives it catalog listings. UITBOC 1574 (Ultraviolet Imaging Telescope
Bright Object Catalog) saying it is a visual source which tells us
nothing useful. Another name for it is [BOB94] 0943-1403
(Bowen+Osmer+Blades catalog of galaxies and quasars) which lists it as a
quasar. So far so good. Many quasars are very blue. In fact when they
were still a mystery one name for the blue ones was blue stellar object.
But then we come to its red shift which say it is only 20 million
light-years distant. Normally we'd easily see the galaxy it was in at
that distance and the quasar itself should be exceedingly bright not
magnitude 17.5. I've imaged quasars that bright 5 billion light years
distant! Yet I found no notes on this object. Maybe it is just a super
blue star? Red shift error? (I had to go back and correct my typo for
"shift" -- I left out the "f" -- maybe I was trying to tell myself
something.)

Less confusing is the third galaxy in the group, the thin flat one to
the southwest (lower right). It is FGC 938/RFGC 1621. Either indicate
it is an extremely flat galaxy (FGC=Flat Galaxy Catalog). It's red
shift is also about 125 million light-years so it may be a member of the
same group as Arp 245, just not close enough to be interacting. It is
classed Scd (as are most entries to these catalogs). How some spirals
get to be so flat with virtually no central bulge is still a mystery.
Since the size of the bulge seems related to the size of the black hole
at a spiral galaxy's core does this mean it has no black hole in its
core? Just an unusually small one? I don't know. Anyone out there
seen anything on this?

Only 2 other objects, both galaxies, are listed in NED with red shift
data. Both can be seen near Arp 245. Directly above the blue
star/quasar is a small smudge of a galaxy. It is somewhat blue in
color. It is [DBS2000] J094545.55-141623.7 at 1.44 billion light-years.
That's the only designation NED has; DBS stands for
Duc+Brinks+Springel. The other galaxy is up and to the left of the last
one. It is the third (bottom) object of a small arc of two stars and
the orange galaxy. The upper star is orange while the middle star is
white. The galaxy is quite orange. It is 2MASX J09455121-1415430 with
precisely the same red shift (z=0.111000) as the other galaxy and thus
also 1.44 billion light-years distant. None of the other galaxies in
the image have red shift data and most aren't even listed at NED.

Arp's image:
http://nedwww.ipac.caltech.edu/level...ig_arp245.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

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".





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