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ASTRO: NGC 3583, NGC 3577 and companions



 
 
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  #1  
Old May 4th 12, 06:43 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: NGC 3583, NGC 3577 and companions

NGC 3583 is a barred spiral, SB(s)b, in Ursa Major about 110 million
light-years from us. It would fit Arp's category for spiral galaxies
with a high surface brightness companion on its arm. Sometimes the
companion was a true companion but most of the time either we still
don't know or it wasn't a true companion. This time however it is a
true companion and he didn't include it. Both have about the same
redshift indicating they are related. Most sources NED notes call it an
E0 galaxy. I find that odd on two counts. First E0 should be spherical
and it is distinctly oval. Also most E0 galaxies are rather red this
one is blue though when IR is added to the mix by the Sloan survey it
turns white. Still the wrong color. While it doesn't appear to be
interacting I can't help but wonder if its shape indicates interaction
has occurred, likely in the distant past. Something has to have
triggered strong star formation in the last billion years or so for it
to have this blue tint.

On the other side is what to me appears to be a bright knot in NGC
3583's western arm. I have indicated this knot with a question mark.
NED considers it a separate galaxy rather than a part of the galaxy. No
papers I find mention it however as being another companion. They only
refer to the E0 and NGC 3577 5 minutes to the southwest. I still think
it part of the galaxy until more data comes in.

West of NGC 3583 is the galaxy cluster GMBCG J168.46640+48.31697. In
this case the distance to the cluster is shows as being estimated
photographically while the BCG that anchors the cluster and is highly
visible in my image doesn't carry this note. Their distances vary
though not by much. I've listed both though I feel the difference is
due to the difference in error bars between these two measurement
methods. The cluster is listed has having 11 members with no cluster
radius given. It is 3.5 to 3.6 billion light-years away depending on
which estimate you believe.

Southwest of NGC 3583 is NGC 3577. It too is a barred spiral, SB(r)a by
NED and SBb by the NGC project. Arms seem too spread out for for NED's
classification so I prefer that of the NGC project. It is what I call a
lawn sprinkler galaxy. The bar is long and thin like my old walking
lawn sprinkler which spun at high speed and when viewed out my second
story window had water going out in a spiral much like the arms of this
galaxy. It too seems to have a companion on its arm to the northeast.
In this case however I think it likely it is a very distant galaxy.
Unfortunately there's no red shift data to settle the issue. The
companion is SDSS J111346.01+481650.8. NGC 3577, at 250 million
light-years, is over twice as far away as NGC 3583 so they are
unrelated, they just share nearly the same line of sight as seen from earth.

NGC 3577 does have a real companion, MCG +08-21-004, also at 250 million
light-years. It too is a barred spiral and a very blue one. NED however
doesn't classify it or give any more detail on it. Could it have
interacted with NGC 3577? Yes, but that doesn't mean it has. It has a
shape similar to a couple Arp put in his integral sign class though,
like them, I see only a very remote similarity to the sign. How or why
Arp missed this three for one field I don't know.

To the northwest of NGC 3583 is SDSS J111345.41+482405.4, a dwarf galaxy
at 100 million light-years. It could possibly be related to NGC 3583
though I saw nothing indicating this. Since I'm rounding and these
distances are estimates they could be considerably closer than the 10
million light-year difference would indicate.

Southeast of NGC 3583 is another galaxy cluster, GMBCG
J168.76711+48.22342. In this case both the galaxy and BCG have
photographic redshift measurements which agree. Likely because it is a
single measurement. It shows it to be 4.7 billion light-years distant
with 8 members. No radius is given. To its northeast is another
cluster, GMBCG J168.85254+48.25542 at 4.6 billion light-years. The
galaxy just to its north is likely much closer and not part of the
cluster though a few other fuzzies in the area could be members. NED
shows it with 12 members but again, no radius.

Yet another galaxy cluster is in the lower right corner, GMBCG
J168.17596+48.17003 consists of 8 members again in an unknown radius.
Its photographic redshift shows a distance of 4.7 billion light-years.

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

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

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  #2  
Old May 7th 12, 08:10 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: NGC 3583, NGC 3577 and companions

That's a beautiful pair beautifully captured.
I didn't have them on my list, which I now corrected.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
. com...
NGC 3583 is a barred spiral, SB(s)b, in Ursa Major about 110 million
light-years from us. It would fit Arp's category for spiral galaxies
with a high surface brightness companion on its arm. Sometimes the
companion was a true companion but most of the time either we still
don't know or it wasn't a true companion. This time however it is a
true companion and he didn't include it. Both have about the same
redshift indicating they are related. Most sources NED notes call it an
E0 galaxy. I find that odd on two counts. First E0 should be spherical
and it is distinctly oval. Also most E0 galaxies are rather red this
one is blue though when IR is added to the mix by the Sloan survey it
turns white. Still the wrong color. While it doesn't appear to be
interacting I can't help but wonder if its shape indicates interaction
has occurred, likely in the distant past. Something has to have
triggered strong star formation in the last billion years or so for it
to have this blue tint.

On the other side is what to me appears to be a bright knot in NGC
3583's western arm. I have indicated this knot with a question mark.
NED considers it a separate galaxy rather than a part of the galaxy. No
papers I find mention it however as being another companion. They only
refer to the E0 and NGC 3577 5 minutes to the southwest. I still think
it part of the galaxy until more data comes in.

West of NGC 3583 is the galaxy cluster GMBCG J168.46640+48.31697. In
this case the distance to the cluster is shows as being estimated
photographically while the BCG that anchors the cluster and is highly
visible in my image doesn't carry this note. Their distances vary
though not by much. I've listed both though I feel the difference is
due to the difference in error bars between these two measurement
methods. The cluster is listed has having 11 members with no cluster
radius given. It is 3.5 to 3.6 billion light-years away depending on
which estimate you believe.

Southwest of NGC 3583 is NGC 3577. It too is a barred spiral, SB(r)a by
NED and SBb by the NGC project. Arms seem too spread out for for NED's
classification so I prefer that of the NGC project. It is what I call a
lawn sprinkler galaxy. The bar is long and thin like my old walking
lawn sprinkler which spun at high speed and when viewed out my second
story window had water going out in a spiral much like the arms of this
galaxy. It too seems to have a companion on its arm to the northeast.
In this case however I think it likely it is a very distant galaxy.
Unfortunately there's no red shift data to settle the issue. The
companion is SDSS J111346.01+481650.8. NGC 3577, at 250 million
light-years, is over twice as far away as NGC 3583 so they are
unrelated, they just share nearly the same line of sight as seen from
earth.

NGC 3577 does have a real companion, MCG +08-21-004, also at 250 million
light-years. It too is a barred spiral and a very blue one. NED however
doesn't classify it or give any more detail on it. Could it have
interacted with NGC 3577? Yes, but that doesn't mean it has. It has a
shape similar to a couple Arp put in his integral sign class though,
like them, I see only a very remote similarity to the sign. How or why
Arp missed this three for one field I don't know.

To the northwest of NGC 3583 is SDSS J111345.41+482405.4, a dwarf galaxy
at 100 million light-years. It could possibly be related to NGC 3583
though I saw nothing indicating this. Since I'm rounding and these
distances are estimates they could be considerably closer than the 10
million light-year difference would indicate.

Southeast of NGC 3583 is another galaxy cluster, GMBCG
J168.76711+48.22342. In this case both the galaxy and BCG have
photographic redshift measurements which agree. Likely because it is a
single measurement. It shows it to be 4.7 billion light-years distant
with 8 members. No radius is given. To its northeast is another
cluster, GMBCG J168.85254+48.25542 at 4.6 billion light-years. The
galaxy just to its north is likely much closer and not part of the
cluster though a few other fuzzies in the area could be members. NED
shows it with 12 members but again, no radius.

Yet another galaxy cluster is in the lower right corner, GMBCG
J168.17596+48.17003 consists of 8 members again in an unknown radius.
Its photographic redshift shows a distance of 4.7 billion light-years.

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

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



 




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