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ASTRO: NGC 3443, NGC 3454 and NGC 3455 among others



 
 
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  #1  
Old October 30th 13, 06:24 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: NGC 3443, NGC 3454 and NGC 3455 among others

NGC 3454 and NGC 3455 are a pair of galaxies in central Leo. Redshift
puts them at 66 million light-years distant. Tully Fisher
determinations disagree and put them a bit under 100 million light-years
away. I think, in this case, the redshift measurements are likely more
reasonable. Assuming the redshift distance NGC 3454 and NGC 3455 are
both about 52.5 thousand light years across. If the 100 million
light-year figure is used then they are about 80 thousand light-years in
size.

One note at NED say: "Bright spindle with plume, disturbed? by UGC
06028..." while another reads: "Bright bar with knots and dark markings.
Faint, smooth, outer arms. Edge-on. Non-interacting pair with NGC 3455
at 3.8 arcmin." I found no notes on 3455 referencing the apparently
distorted outer arms, especially the western one. About all I can see
for a plume in 3454 is the southeastern ansa seems puffier than the
northwestern one and seems to be off centerline toward 3455. I'd
surmise these features aren't unrelated and some interaction has occurred.

I put these off center to pick up NGC 3443 in the upper right corner.
It's redshift is insignificantly different from the other two (I found
no non redshift measurements of its distance) so it is likely a member
of the same group. Assuming the same distance it is 50,000 light-years
in diameter or 76,000 at the 100,000 light-year distance. It is a
rather low surface brightness spiral compared to the first two.

Also a likely member of the group is ASK 617911.0 on the left edge of
the image. It's redshift is similar. It seems to be quite blue with
two odd star clouds NE and SW of the core though the SW one is below the
major axis of the galaxy. The other small object just above the SW
cloud is most likely a nearby star in our galaxy and not a feature of
this dwarf galaxy. It is only about 11,000 light-years in diameter at
its redshift distance. There's yet a fifth likely member of this group
but my framing missed it. It is about one minute of arc above the upper
left corner of my image. It is NGC 3457?/NGC 3460. There's some debate
over this object's identity. See the NGC Project entries for these two
if interested.

North of the center of the image is an oddly distorted spiral galaxy
that's small in angular size but rather bright in its core though the
outer arms are very faint. NED's only identification of it is SDSS
J105353.23+173041.6. Since it didn't have a redshift distance it wasn't
labeled in the annotated image.

Due to lousy weather this one was taken over two consecutive nights.
The first night was clouded out after 4 luminance frames. The second
night I started again to take the color data but discovered I was taking
more luminance instead. I stopped the run and restarted it for color
data. By then it was too late to get a complete new object so I decided
to take 4 more luminance frames with the time remaining not trusting
those I'd gotten the first night. At the time I didn't realize there
was a very bright asteroid in the field. Turns out I picked it up both
nights. Due to the gap between the first and second luminance frame it
made three trails in the top of the image. The asteroid, discovered by
the German astronomer Joseph Helffrich in 1910 and apparently named
after the far more famous Italian astronomer Galileo (is Galilea the
German spelling of Galileo?) The naming of early asteroids is covered
by a copyright book so the Minor Planet Center can't give out that
information. So this is only a guess on my part. Anyone have better info?

There's a 20th magnitude asteroid in the image which I show in the
annotated version. Since it shows in only 4 (in only the first night's
images) of the 9 frames it is nearly invisible in a mean stack of the
data though very obvious in the raw data. It barely shows up due to
this and the rather poor transparency that first night.

14" LX200R @ f/10, L=9x10' RGB=2x10', STL-11000XM, Paramount ME

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

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  #2  
Old November 13th 13, 10:23 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: NGC 3443, NGC 3454 and NGC 3455 among others

Mighty image Rick.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

NGC 3454 and NGC 3455 are a pair of galaxies in central Leo. Redshift
puts them at 66 million light-years distant. Tully Fisher
determinations disagree and put them a bit under 100 million light-years
away. I think, in this case, the redshift measurements are likely more
reasonable. Assuming the redshift distance NGC 3454 and NGC 3455 are
both about 52.5 thousand light years across. If the 100 million
light-year figure is used then they are about 80 thousand light-years in
size.

One note at NED say: "Bright spindle with plume, disturbed? by UGC
06028..." while another reads: "Bright bar with knots and dark markings.
Faint, smooth, outer arms. Edge-on. Non-interacting pair with NGC 3455
at 3.8 arcmin." I found no notes on 3455 referencing the apparently
distorted outer arms, especially the western one. About all I can see
for a plume in 3454 is the southeastern ansa seems puffier than the
northwestern one and seems to be off centerline toward 3455. I'd
surmise these features aren't unrelated and some interaction has occurred.

I put these off center to pick up NGC 3443 in the upper right corner.
It's redshift is insignificantly different from the other two (I found
no non redshift measurements of its distance) so it is likely a member
of the same group. Assuming the same distance it is 50,000 light-years
in diameter or 76,000 at the 100,000 light-year distance. It is a
rather low surface brightness spiral compared to the first two.

Also a likely member of the group is ASK 617911.0 on the left edge of
the image. It's redshift is similar. It seems to be quite blue with
two odd star clouds NE and SW of the core though the SW one is below the
major axis of the galaxy. The other small object just above the SW
cloud is most likely a nearby star in our galaxy and not a feature of
this dwarf galaxy. It is only about 11,000 light-years in diameter at
its redshift distance. There's yet a fifth likely member of this group
but my framing missed it. It is about one minute of arc above the upper
left corner of my image. It is NGC 3457?/NGC 3460. There's some debate
over this object's identity. See the NGC Project entries for these two
if interested.

North of the center of the image is an oddly distorted spiral galaxy
that's small in angular size but rather bright in its core though the
outer arms are very faint. NED's only identification of it is SDSS
J105353.23+173041.6. Since it didn't have a redshift distance it wasn't
labeled in the annotated image.

Due to lousy weather this one was taken over two consecutive nights.
The first night was clouded out after 4 luminance frames. The second
night I started again to take the color data but discovered I was taking
more luminance instead. I stopped the run and restarted it for color
data. By then it was too late to get a complete new object so I decided
to take 4 more luminance frames with the time remaining not trusting
those I'd gotten the first night. At the time I didn't realize there
was a very bright asteroid in the field. Turns out I picked it up both
nights. Due to the gap between the first and second luminance frame it
made three trails in the top of the image. The asteroid, discovered by
the German astronomer Joseph Helffrich in 1910 and apparently named
after the far more famous Italian astronomer Galileo (is Galilea the
German spelling of Galileo?) The naming of early asteroids is covered
by a copyright book so the Minor Planet Center can't give out that
information. So this is only a guess on my part. Anyone have better info?

There's a 20th magnitude asteroid in the image which I show in the
annotated version. Since it shows in only 4 (in only the first night's
images) of the 9 frames it is nearly invisible in a mean stack of the
data though very obvious in the raw data. It barely shows up due to
this and the rather poor transparency that first night.

14" LX200R @ f/10, L=9x10' RGB=2x10', STL-11000XM, Paramount ME

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

 




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