NGC 4845 A Warped Galaxy?

NGC 4845 is an apparently warped, rather red, spiral galaxy in central Virgo. Redshift puts it about 72 million light-years distant and Tully Fisher estimates agree rather closely. William Herschel discovered it on February 24, 1786. It is a rather flat galaxy lacking much of a central bulge. In fact a significant part of its core is hidden behind a rather thin dust lane indicating how small the core is. The galaxy is thought to have a rather small black hole in its core to go along with its small central bulge being only 300,000 times that of our sun. Still in January of 2011 it is thought it's black hole might have devoured a rogue planet that got too close to its core. You can read about it at this link: http://www.universetoday.com/101172/...e-%20%20101172 which contains a link to the paper the article is based on.

NGC 4845 has another mystery. It might be long lost NGC 4910. It was found by William Herschel prior to NGC 4845 on January 24, 1784 but he admitted his coordinates were poor. Here's what the NGC Project says on this matter:

"NGC 4910 may possibly be NGC 4845. There is nothing in WH's place, and Dreyer
quotes WH's note in the Scientific Papers: "The place of this neb. is not
determined with accuracy." Dreyer adds, "No modern observations known."

"WH referred two other nebulae -- NGC 4420 and NGC 4772 -- to the same
comparison star (75 Leo). For N4772, Dreyer notes, "RA 40 seconds too
great." This suggests that WH's RA for N4910 might also be too large. In
that case, NGC 4845 would be a candidate for WH's object. It is a large
galaxy at about the right declination. However, WH describes his nebula as
"eF, vL, er, R. 7 or 8 arcmin d[iameter]." N4845 is not quite that large,
nor is it round. It is, however, the only reasonable candidate, so I've
adopted the identity, though with a query. - Dr. Harold G. Corwin, Jr."

What caused the warping of NGC 4845? I found no papers even mentioning it is warped let alone discussing its warped nature. That mystery will remain unsolved for a while longer it appears. NGC 4845 is one of the original Herschel 400 objects. All this gave me many reasons for putting it on my to-do list.

To the northeast is FGC 1530 a really flat blue galaxy seen edge on. Though no dust lane is seen. Redshift puts it 140 million light-years distant or twice the distance of NGC 4845. In this case the Tully Fisher distance estimates for it are wildly discordant. One estimate from 2000 says it is only 5 million light-years away. Obviously something is wrong with that estimate. Another from 2010 comes up with three results depending on interpretation of the results. It gives 91, 92, 94 million light-years. That's only 65% of the distance redshift comes up with.

There were 5 asteroids in the image though 2 are so faint they didn't survive the JPEG compression. I left their location marked as some faint hint is still seen of them. Their details are on the annotated image. This field is one not covered well by catalogs other than those that reference galaxies by their coordinates. For those I just use G or Q for Galaxy or Quasar without including their coordinate name as that is available by plate solving my image. UvES objects are listed as being quasar candidates with only photographic redshift measurements.

Conditions were poor for this one. While seeing was only somewhat below average this night, like the previous one had rapidly falling temperatures. So rapid that tube currents developed again flattening stars though not as much as the previous night. This put a lot of ice crystals into the air which dimmed the image as well as creating huge halos around bright stars, especially the brilliant F2 HD 112542. Even though it was only 7th magnitude it's glow covered one third of the image making for processing nightmare.

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

Rick

Rick,

that's a good one. Currently too low for me to image, but I will be moving
to a new flat in October that has a largely unobstructed view of the
southern horizon.
Skies won't be much darker though as it still is well within Berlin city
limits.

Stefan


"WA0CKY" schrieb im Newsbeitrag ...


NGC 4845 is an apparently warped, rather red, spiral galaxy in central
Virgo. Redshift puts it about 72 million light-years distant and Tully
Fisher estimates agree rather closely. William Herschel discovered it
on February 24, 1786. It is a rather flat galaxy lacking much of a
central bulge. In fact a significant part of its core is hidden behind
a rather thin dust lane indicating how small the core is. The galaxy is
thought to have a rather small black hole in its core to go along with
its small central bulge being only 300,000 times that of our sun. Still
in January of 2011 it is thought it's black hole might have devoured a
rogue planet that got too close to its core. You can read about it at
this link: http://tinyurl.com/cr24qnp which contains a link to the paper
the article is based on.

NGC 4845 has another mystery. It might be long lost NGC 4910. It was
found by William Herschel prior to NGC 4845 on January 24, 1784 but he
admitted his coordinates were poor. Here's what the NGC Project says on
this matter:

"NGC 4910 may possibly be NGC 4845. There is nothing in WH's place,
and Dreyer
quotes WH's note in the Scientific Papers: "The place of this neb.
is not
determined with accuracy." Dreyer adds, "No modern observations
known."

"WH referred two other nebulae -- NGC 4420 and NGC 4772 -- to the
same
comparison star (75 Leo). For N4772, Dreyer notes, "RA 40 seconds
too
great." This suggests that WH's RA for N4910 might also be too
large. In
that case, NGC 4845 would be a candidate for WH's object. It is a
large
galaxy at about the right declination. However, WH describes his
nebula as
"eF, vL, er, R. 7 or 8 arcmin d[iameter]." N4845 is not quite that
large,
nor is it round. It is, however, the only reasonable candidate, so
I've
adopted the identity, though with a query. - Dr. Harold G. Corwin,
Jr."

What caused the warping of NGC 4845? I found no papers even mentioning
it is warped let alone discussing its warped nature. That mystery will
remain unsolved for a while longer it appears. NGC 4845 is one of the
original Herschel 400 objects. All this gave me many reasons for
putting it on my to-do list.

To the northeast is FGC 1530 a really flat blue galaxy seen edge on.
Though no dust lane is seen. Redshift puts it 140 million light-years
distant or twice the distance of NGC 4845. In this case the Tully
Fisher distance estimates for it are wildly discordant. One estimate
from 2000 says it is only 5 million light-years away. Obviously
something is wrong with that estimate. Another from 2010 comes up with
three results depending on interpretation of the results. It gives 91,
92, 94 million light-years. That's only 65% of the distance redshift
comes up with.

There were 5 asteroids in the image though 2 are so faint they didn't
survive the JPEG compression. I left their location marked as some
faint hint is still seen of them. Their details are on the annotated
image. This field is one not covered well by catalogs other than those
that reference galaxies by their coordinates. For those I just use G or
Q for Galaxy or Quasar without including their coordinate name as that
is available by plate solving my image. UvES objects are listed as
being quasar candidates with only photographic redshift measurements.

Conditions were poor for this one. While seeing was only somewhat below
average this night, like the previous one had rapidly falling
temperatures. So rapid that tube currents developed again flattening
stars though not as much as the previous night. This put a lot of ice
crystals into the air which dimmed the image as well as creating huge
halos around bright stars, especially the brilliant F2 HD 112542. Even
though it was only 7th magnitude it's glow covered one third of the
image making for processing nightmare.

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

Rick


--
WA0CKY