Astro: Arp 282 with "infall and attraction"

Arp 282 is an interesting interacting pair just under 200 million light
years from us. It consists of a large but distorted spiral, NGC 169 and
a small companion with tidal arms, IC 1559. Ned calls the small
companion a SAB pec though I see no hint of spiral structure. Most
papers I saw classed it as E3 or S0 which makes more sense to me. Arp
classed the pair as Group character: infall and attraction, whatever
that means. He explained a bit saying "Companion appears to rain into
the nucleus of spiral." The famous Whale galaxy, Arp 181/NGC 4631, is
similarly classed by Arp.

Distortions to NGC 169 include a core that is well west (left) of center
as something seems to have drawn the arms on th east side way away from
the core. Likely the companion passed by this side sometime in the
past. While the companion seems to be "falling" into the core it likely
is well in front of the galaxy after looping around the east end. The
orbit is likely unstable and the two will eventually combine sometime in
the future. NGC 169 seems to have a large bulge of halo stars "above"
(north) of the plane of the galaxy. This would indicate the companion
has made several passes at different angles to cause both tidal
distortions.

Note at NED makes the following comments on the pair: "These two
galaxies have dramatically different colors; galaxy A has very blue,
star-forming colors; galaxy B displays the colors of a reddened
elliptical, yet has a disk morphology." I assume A is IC 1559 and B NGC
169. Another note says: "Pair in contact, made up of NGC 0169 and IC
1559 MRK 0341 = IC 1559, a small peculiar lenticular."

The MGC catalog says of IC 1559: "It is of elliptical shape with the
major axis having stubby ends. The continuous spectrum is diffuse in
the blue-violet region and becomes brighter in the ultraviolet.
H{alpha} is observed."

I had a lot of problems processing this image due to the bright star,
SAO 78148, right beside the pair. It is a K2 giant of 6th magnitude and
cast all sorts of junk across the image that was a major pain to deal with.

The third member of this group, 11 arc minutes to the SW (lower right)
is NGC 160. It is at about the same distance as Arp 282. It is classed
as SA0(r) pec. One note says of it: "Very small nucleus, isolated at
center of faint double (R). Non-interacting pair with NGC 0169." That
is, it has a double ring structure. I assume that refers to the inner
yellowish band around the core as well as the bright bluish outer edge
to the galaxy. Normally the outer edge of a spiral fades away but this
one ends abruptly after a narrow suddenly brighter rim. Some stars are
seen outside this bright rim at either end but they also seem to end
abruptly rather than fade into the background. So did it interact with
Arp 282 sometime in the distant past to get this odd structure?

Above NGC 160 and right of the bright star is UGC 354 at 240 million
light years. A bit farther than the others but possibly a group member.
Note that some catalog listings incorrectly show it as NGC 162. The
Sky's data base has this error. The description of NGC 162 however
shows it to be a very different object. It reads: eF, stellar, 160 sp
which translates to extremely Faint, starlike, NGC 160 south preceding.
But UGC 354 certainly isn't starlike, nor extremely faint nor is NGC
160 preceding it across the sky but following it. Thus most feel that
NGC 162 is one of many stars incorrectly thought to be faint galaxies
when seen at the very limit of visibility in scopes of the era. It is
likely the star east (left) of the top edge of NGC 160.

These 4 are the only galaxies in the field that NED shows redshift data.
About 15 more galaxies are cataloged in NED (all IR emitting in the
2MASX catalog) though a few also carry extended LEDA designations. Thus
most of the galaxies in the image are anonymous as far as I can tell.

Arp's photo with the 200" Hale telescope is at:
http://nedwww.ipac.caltech.edu/level...ig_arp282.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10', 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 picture Rick. The dark lane looks very sharp in your image.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Arp 282 is an interesting interacting pair just under 200 million light
years from us. It consists of a large but distorted spiral, NGC 169 and
a small companion with tidal arms, IC 1559. Ned calls the small
companion a SAB pec though I see no hint of spiral structure. Most
papers I saw classed it as E3 or S0 which makes more sense to me. Arp
classed the pair as Group character: infall and attraction, whatever
that means. He explained a bit saying "Companion appears to rain into
the nucleus of spiral." The famous Whale galaxy, Arp 181/NGC 4631, is
similarly classed by Arp.

Distortions to NGC 169 include a core that is well west (left) of center
as something seems to have drawn the arms on th east side way away from
the core. Likely the companion passed by this side sometime in the
past. While the companion seems to be "falling" into the core it likely
is well in front of the galaxy after looping around the east end. The
orbit is likely unstable and the two will eventually combine sometime in
the future. NGC 169 seems to have a large bulge of halo stars "above"
(north) of the plane of the galaxy. This would indicate the companion
has made several passes at different angles to cause both tidal
distortions.

Note at NED makes the following comments on the pair: "These two
galaxies have dramatically different colors; galaxy A has very blue,
star-forming colors; galaxy B displays the colors of a reddened
elliptical, yet has a disk morphology." I assume A is IC 1559 and B NGC
169. Another note says: "Pair in contact, made up of NGC 0169 and IC
1559 MRK 0341 = IC 1559, a small peculiar lenticular."

The MGC catalog says of IC 1559: "It is of elliptical shape with the
major axis having stubby ends. The continuous spectrum is diffuse in
the blue-violet region and becomes brighter in the ultraviolet.
H{alpha} is observed."

I had a lot of problems processing this image due to the bright star,
SAO 78148, right beside the pair. It is a K2 giant of 6th magnitude and
cast all sorts of junk across the image that was a major pain to deal
with.

The third member of this group, 11 arc minutes to the SW (lower right)
is NGC 160. It is at about the same distance as Arp 282. It is classed
as SA0(r) pec. One note says of it: "Very small nucleus, isolated at
center of faint double (R). Non-interacting pair with NGC 0169." That
is, it has a double ring structure. I assume that refers to the inner
yellowish band around the core as well as the bright bluish outer edge
to the galaxy. Normally the outer edge of a spiral fades away but this
one ends abruptly after a narrow suddenly brighter rim. Some stars are
seen outside this bright rim at either end but they also seem to end
abruptly rather than fade into the background. So did it interact with
Arp 282 sometime in the distant past to get this odd structure?

Above NGC 160 and right of the bright star is UGC 354 at 240 million
light years. A bit farther than the others but possibly a group member.
Note that some catalog listings incorrectly show it as NGC 162. The
Sky's data base has this error. The description of NGC 162 however
shows it to be a very different object. It reads: eF, stellar, 160 sp
which translates to extremely Faint, starlike, NGC 160 south preceding.
But UGC 354 certainly isn't starlike, nor extremely faint nor is NGC
160 preceding it across the sky but following it. Thus most feel that
NGC 162 is one of many stars incorrectly thought to be faint galaxies
when seen at the very limit of visibility in scopes of the era. It is
likely the star east (left) of the top edge of NGC 160.

These 4 are the only galaxies in the field that NED shows redshift data.
About 15 more galaxies are cataloged in NED (all IR emitting in the
2MASX catalog) though a few also carry extended LEDA designations. Thus
most of the galaxies in the image are anonymous as far as I can tell.

Arp's photo with the 200" Hale telescope is at:
http://nedwww.ipac.caltech.edu/level...ig_arp282.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10', 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".