ASTRO: NGC 2775 A Flocculent Galaxy

NGC 2775 is a flocculent galaxy in southeastern Cancer. Redshift puts
it about 76 million light-years distant by redshift and 55 million
light-years by a Tully estimate. NED classes it as SA(r)ab AGN? The
NGC Project says simply Sa. Other papers have yet other opinions
including Sa(r), S0/a. It is a strange galaxy in that the core region
is nearly featureless with a star-like point at the core. After a
rather evenly bright, featureless disk there's a dust ring followed by
flocculent arms. Then another dust ring separates these rings from a
featureless outer band that fades away. Longer exposure time would
likely trace this area out further but add no detail. The contrast of
the galaxy seems very low as if viewed through a mist. Could this be
due to a huge spherical halo of stars around it? Seems quite possible
but I found nothing much about this in the literature I read. If its
distance is about 76 million light-years it is some 110,000 light-years
across, a large spiral

An odd red object is seen in the middle of the flocculent rings to the
southwest. It is listed by the Sloan survey as SDSS J091019.53+070141.2
and at a redshift distance of 82 million light-years. NED lists it as a
separate galaxy rather than part of NGC 2775 but gives it a maximum size
of 0.04 minutes. This translates to a galaxy of only about 950 light
years in size! A dwarf galaxy indeed. The red color in the blue of the
flocculent arms certainly would indicate it could be a background (or
foreground) dwarf galaxy of old stars. Unusual to see a red dwarf
however. Could the red be due to seeing it through a lot of dust in NGC
2775? Nope turns out there is a much simpler solution. I found this HST
image of the galaxy:
http://cseligman.com/text/atlas/ngc2775hst.jpg It is oriented the same
as mine. Note it is just a foreground star. Apparently the redshift
comes from NGC 2775's spiral arm not the object/star. Sometimes the
pros get it wrong it would appear.

NGC 2775 has a small companion, NGC 2777 to the northeast. It has a
similar redshift to NGC 2775 so likely a true companion. NED classes it
as Sab? NGC project says Sb-. Seeing was poor for this image making NGC
2777 look rather odd. Better image show its arms are made of mostly
very large star knots. It's these knots that give it the very odd
appearance in my low resolution image. I need to revisit this one under
better seeing conditions than the near 4" of this one. Then it would
look more like a spiral. If the distance is 83 million light-years it
is a dwarf spiral only 15,000 light-years in diameter.

Also in my image is NGC 2773. It has a redshift putting it three times
more distant than the other two so it is not related. The distance also
makes it hard to see any detail. Both NED and the NGC project class it
as S?

North of NGC 2775 is the odd galaxy LEDA 213577. NED has the essential
note about it saying: "May be an interacting pair." That certainly
appears reasonable. The two parts of this object are very different
shades of blue. It has the same redshift as nearby NGC 2777 but even
smaller. If two galaxies they are really dwarfs. End to end the object
is only 11,000 light-years long at 84 million light-years with the
bright blue object being less than 5000 light-years across. These sizes
would argue against this being two interacting galaxies. A small dwarf
with a large bright star knot at one end may be a more likely
explanation. I'd sure like to see a high resolution image of this one.

There are two objects IXO 32 and IXO 33 that NED shows as a quasar, Xray
Source and an AGN. One, south of NGC 2775 has a distance of only 3
billion light-years and is not star-like but shows a disk like other
galaxies at this distance. On the other had the other, north of NGC
2775, is over 11 billion light-years distant and is star-like. It is
also blue which is rather expected of such objects rather than the
slightly red color of the close one that matches typical galaxies at
this distance. I can't explain why this difference.

Near the bottom of the image is a very odd looking galaxy at 1.63
billion light-years, 2MASX J09104935+0653231. I put the label well to
the right as there's faint fuzz between the label and the core of the
galaxy and more fuzz doing up and a bit left of the core. This north
piece is far brighter than the one going west. NED gives no clue as to
what is going on here. The north going fuzz looks a lot like a faint
disk galaxy seen somewhat edge on that has no core as it is rather oval
in shape. The west one appears more round. Is this three objects, the
result of two interacting galaxies or something else? I haven't a clue
but it sure is strange. It appears to be part of a group of galaxies
that fall into the 1.63 to 1.66 billion light-year distance range.
Though I didn't see any listed at NED. Also there are quite a few
galaxies at about 1.8 to 1.85 million light-years in the image. They
would appear to be part of some galaxy group but I didn't find one
listed in NED either.

While NED has distance estimates for dozens of galaxies too faint to get
through my poor seeing and transparency this night there are galaxies in
the image NED doesn't even list. Three of them form an interesting knot
inside the north edge of NGC 2775. Are they three interacting galaxies?
Not only doesn't NED have any redshift data on any of them, it doesn't
list anything at their position though far fainter galaxies (too faint
for my image) are listed. I've noted them with a question mark.

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

Rick


--
Prefix is correct. Domain is arvig dot net

Rick,

I have this one on my list with the remark "tight spiral, not a lot of
detail". Apparently I have to remove the part about detail, but I don't
think I could get as much detail as you did.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

NGC 2775 is a flocculent galaxy in southeastern Cancer. Redshift puts
it about 76 million light-years distant by redshift and 55 million
light-years by a Tully estimate. NED classes it as SA(r)ab AGN? The
NGC Project says simply Sa. Other papers have yet other opinions
including Sa(r), S0/a. It is a strange galaxy in that the core region
is nearly featureless with a star-like point at the core. After a
rather evenly bright, featureless disk there's a dust ring followed by
flocculent arms. Then another dust ring separates these rings from a
featureless outer band that fades away. Longer exposure time would
likely trace this area out further but add no detail. The contrast of
the galaxy seems very low as if viewed through a mist. Could this be
due to a huge spherical halo of stars around it? Seems quite possible
but I found nothing much about this in the literature I read. If its
distance is about 76 million light-years it is some 110,000 light-years
across, a large spiral

An odd red object is seen in the middle of the flocculent rings to the
southwest. It is listed by the Sloan survey as SDSS J091019.53+070141.2
and at a redshift distance of 82 million light-years. NED lists it as a
separate galaxy rather than part of NGC 2775 but gives it a maximum size
of 0.04 minutes. This translates to a galaxy of only about 950 light
years in size! A dwarf galaxy indeed. The red color in the blue of the
flocculent arms certainly would indicate it could be a background (or
foreground) dwarf galaxy of old stars. Unusual to see a red dwarf
however. Could the red be due to seeing it through a lot of dust in NGC
2775? Nope turns out there is a much simpler solution. I found this HST
image of the galaxy:
http://cseligman.com/text/atlas/ngc2775hst.jpg It is oriented the same
as mine. Note it is just a foreground star. Apparently the redshift
comes from NGC 2775's spiral arm not the object/star. Sometimes the
pros get it wrong it would appear.

NGC 2775 has a small companion, NGC 2777 to the northeast. It has a
similar redshift to NGC 2775 so likely a true companion. NED classes it
as Sab? NGC project says Sb-. Seeing was poor for this image making NGC
2777 look rather odd. Better image show its arms are made of mostly
very large star knots. It's these knots that give it the very odd
appearance in my low resolution image. I need to revisit this one under
better seeing conditions than the near 4" of this one. Then it would
look more like a spiral. If the distance is 83 million light-years it
is a dwarf spiral only 15,000 light-years in diameter.

Also in my image is NGC 2773. It has a redshift putting it three times
more distant than the other two so it is not related. The distance also
makes it hard to see any detail. Both NED and the NGC project class it
as S?

North of NGC 2775 is the odd galaxy LEDA 213577. NED has the essential
note about it saying: "May be an interacting pair." That certainly
appears reasonable. The two parts of this object are very different
shades of blue. It has the same redshift as nearby NGC 2777 but even
smaller. If two galaxies they are really dwarfs. End to end the object
is only 11,000 light-years long at 84 million light-years with the
bright blue object being less than 5000 light-years across. These sizes
would argue against this being two interacting galaxies. A small dwarf
with a large bright star knot at one end may be a more likely
explanation. I'd sure like to see a high resolution image of this one.

There are two objects IXO 32 and IXO 33 that NED shows as a quasar, Xray
Source and an AGN. One, south of NGC 2775 has a distance of only 3
billion light-years and is not star-like but shows a disk like other
galaxies at this distance. On the other had the other, north of NGC
2775, is over 11 billion light-years distant and is star-like. It is
also blue which is rather expected of such objects rather than the
slightly red color of the close one that matches typical galaxies at
this distance. I can't explain why this difference.

Near the bottom of the image is a very odd looking galaxy at 1.63
billion light-years, 2MASX J09104935+0653231. I put the label well to
the right as there's faint fuzz between the label and the core of the
galaxy and more fuzz doing up and a bit left of the core. This north
piece is far brighter than the one going west. NED gives no clue as to
what is going on here. The north going fuzz looks a lot like a faint
disk galaxy seen somewhat edge on that has no core as it is rather oval
in shape. The west one appears more round. Is this three objects, the
result of two interacting galaxies or something else? I haven't a clue
but it sure is strange. It appears to be part of a group of galaxies
that fall into the 1.63 to 1.66 billion light-year distance range.
Though I didn't see any listed at NED. Also there are quite a few
galaxies at about 1.8 to 1.85 million light-years in the image. They
would appear to be part of some galaxy group but I didn't find one
listed in NED either.

While NED has distance estimates for dozens of galaxies too faint to get
through my poor seeing and transparency this night there are galaxies in
the image NED doesn't even list. Three of them form an interesting knot
inside the north edge of NGC 2775. Are they three interacting galaxies?
Not only doesn't NED have any redshift data on any of them, it doesn't
list anything at their position though far fainter galaxies (too faint
for my image) are listed. I've noted them with a question mark.

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

Rick


--
Prefix is correct. Domain is arvig dot net

I don't know how much of the "fog" that made detail so faint was due to
poor seeing and how much is due to the galaxy itself, likely its halo
stars hiding detail. I need to revisit this one under better seeing
conditions.

It's PhotoShop's High Pass filter that allows me to cut through the fog
and bring out detail. Can set it to work on fine detail or course
detail. Somewhat like the wavelet tool does in other packages. Usually
takes several applications adjusting a little at a time otherwise it can
turn "unnatural" very quickly and look over processed. Takes some
practice how to use it. Best to mask stars seen against the object or
they get hard edges that are very unnatural looking. Once the high pass
has done its thing then a light unsharp mark helps. I usually do a
single run of CCDSharp's deconvolution (really ten iterations I've been
told) before moving into Photoshop as this gives the High Pass something
to work on. The unsharp mask something to work on. It's amazing how
that will pop out detail. Have to work slowly or it can turn harsh if
you try to do to much at one time.

Rick


On 1/29/2013 2:01 PM, Stefan Lilge wrote:
Rick,

I have this one on my list with the remark "tight spiral, not a lot of
detail". Apparently I have to remove the part about detail, but I don't
think I could get as much detail as you did.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

NGC 2775 is a flocculent galaxy in southeastern Cancer. Redshift puts
it about 76 million light-years distant by redshift and 55 million
light-years by a Tully estimate. NED classes it as SA(r)ab AGN? The
NGC Project says simply Sa. Other papers have yet other opinions
including Sa(r), S0/a. It is a strange galaxy in that the core region
is nearly featureless with a star-like point at the core. After a
rather evenly bright, featureless disk there's a dust ring followed by
flocculent arms. Then another dust ring separates these rings from a
featureless outer band that fades away. Longer exposure time would
likely trace this area out further but add no detail. The contrast of
the galaxy seems very low as if viewed through a mist. Could this be
due to a huge spherical halo of stars around it? Seems quite possible
but I found nothing much about this in the literature I read. If its
distance is about 76 million light-years it is some 110,000 light-years
across, a large spiral

An odd red object is seen in the middle of the flocculent rings to the
southwest. It is listed by the Sloan survey as SDSS J091019.53+070141.2
and at a redshift distance of 82 million light-years. NED lists it as a
separate galaxy rather than part of NGC 2775 but gives it a maximum size
of 0.04 minutes. This translates to a galaxy of only about 950 light
years in size! A dwarf galaxy indeed. The red color in the blue of the
flocculent arms certainly would indicate it could be a background (or
foreground) dwarf galaxy of old stars. Unusual to see a red dwarf
however. Could the red be due to seeing it through a lot of dust in NGC
2775? Nope turns out there is a much simpler solution. I found this HST
image of the galaxy:
http://cseligman.com/text/atlas/ngc2775hst.jpg It is oriented the same
as mine. Note it is just a foreground star. Apparently the redshift
comes from NGC 2775's spiral arm not the object/star. Sometimes the
pros get it wrong it would appear.

NGC 2775 has a small companion, NGC 2777 to the northeast. It has a
similar redshift to NGC 2775 so likely a true companion. NED classes it
as Sab? NGC project says Sb-. Seeing was poor for this image making NGC
2777 look rather odd. Better image show its arms are made of mostly
very large star knots. It's these knots that give it the very odd
appearance in my low resolution image. I need to revisit this one under
better seeing conditions than the near 4" of this one. Then it would
look more like a spiral. If the distance is 83 million light-years it
is a dwarf spiral only 15,000 light-years in diameter.

Also in my image is NGC 2773. It has a redshift putting it three times
more distant than the other two so it is not related. The distance also
makes it hard to see any detail. Both NED and the NGC project class it
as S?

North of NGC 2775 is the odd galaxy LEDA 213577. NED has the essential
note about it saying: "May be an interacting pair." That certainly
appears reasonable. The two parts of this object are very different
shades of blue. It has the same redshift as nearby NGC 2777 but even
smaller. If two galaxies they are really dwarfs. End to end the object
is only 11,000 light-years long at 84 million light-years with the
bright blue object being less than 5000 light-years across. These sizes
would argue against this being two interacting galaxies. A small dwarf
with a large bright star knot at one end may be a more likely
explanation. I'd sure like to see a high resolution image of this one.

There are two objects IXO 32 and IXO 33 that NED shows as a quasar, Xray
Source and an AGN. One, south of NGC 2775 has a distance of only 3
billion light-years and is not star-like but shows a disk like other
galaxies at this distance. On the other had the other, north of NGC
2775, is over 11 billion light-years distant and is star-like. It is
also blue which is rather expected of such objects rather than the
slightly red color of the close one that matches typical galaxies at
this distance. I can't explain why this difference.

Near the bottom of the image is a very odd looking galaxy at 1.63
billion light-years, 2MASX J09104935+0653231. I put the label well to
the right as there's faint fuzz between the label and the core of the
galaxy and more fuzz doing up and a bit left of the core. This north
piece is far brighter than the one going west. NED gives no clue as to
what is going on here. The north going fuzz looks a lot like a faint
disk galaxy seen somewhat edge on that has no core as it is rather oval
in shape. The west one appears more round. Is this three objects, the
result of two interacting galaxies or something else? I haven't a clue
but it sure is strange. It appears to be part of a group of galaxies
that fall into the 1.63 to 1.66 billion light-year distance range.
Though I didn't see any listed at NED. Also there are quite a few
galaxies at about 1.8 to 1.85 million light-years in the image. They
would appear to be part of some galaxy group but I didn't find one
listed in NED either.

While NED has distance estimates for dozens of galaxies too faint to get
through my poor seeing and transparency this night there are galaxies in
the image NED doesn't even list. Three of them form an interesting knot
inside the north edge of NGC 2775. Are they three interacting galaxies?
Not only doesn't NED have any redshift data on any of them, it doesn't
list anything at their position though far fainter galaxies (too faint
for my image) are listed. I've noted them with a question mark.

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

Rick




--
Prefix is correct. Domain is arvig dot net