ASTRO: Holmberg V

Phillip Holmberg studied galaxies. Nine of them in enough detail they
have since been named for him. Eight are far enough north I can reach
them from 47N. All were put on my to-do list. I've managed to get a
few of them; II, IV, VIII and IX and now V. The first 4 were all dwarf
galaxies as are most of them. Holmberg II made Arp's list as #268 on
his list of peculiar galaxies. Of the 9 the most "normal is this one,
Holmberg V. It is a rather normal SAB(rs)c spiral galaxy. The surface
brightness is lower than normal but not to a great extent. It does have
an odd straight arm segment south of the core that runs nearly due east
before curving into a normal looking arm. Arp did have a category for
this type feature. Apparently it didn't make the cut. Why it attracted
Holmberg's interest I haven't determined.

It does have a small apparent satellite dwarf galaxy, SDSS
J134039.25+542053.6. With no redshift data I can't be certain it really
is a companion. It is aligned with the the minor axis of Holmberg V.
Holmberg had the idea that such galaxies tended to align with the minor
axis of their galaxy. I assume this means they orbit around the galaxy
at a steep angle to the plane of the galaxy to hold this alignment.
Problem is others can't seem to confirm this as a real situation.
http://www.astro.yale.edu/vdbosch/align.pdf Was this galaxy one he used
to try and support his idea? I just can't track this down as yet.
Considering how different this entry is compared to the other 8 I have
no other idea as to why it made this very short list.

Holmberg V seems to be a rather lonely galaxy but for the possible
companion. No other galaxy in the frame comes within 740,000
light-years. I didn't check for companions out of the frame.

The field contains an above average number of quasars, 9 of them. I
wonder if Arp knew about this? He had a wild idea that quasars were
ejected from peculiar galaxies rather than being distant massive black
holes as we know them today. This high number around a rather normal
looking galaxy (but for that straight arm segment) might have been a
serious problem to his idea.

There are two galaxy clusters in the image. One attracted my interest.
It is close at only 1.8 billion light-years. Above its bright cluster
galaxies is a group of galaxies (and 2 stars) that make a nice "V" shape
pointing to the upper left. Are these part of this cluster? I found no
redshift data for any of them. They seem to small and dim for the 1.8
billion light-year distance to the cluster and are well off center from
the bright cluster galaxy below them. Still to get to the 17 members
mentioned by NED they would need to be included. Below the two galaxies
with redshift data is a third bright one with a large halo. It has no
redshift data but certainly appears to be a disturbed member of the
group that that large, apparently tidal halo that seems to merge with
the much smaller halos of the other two. Though its largest extent
seems to go to the southeast, away from the other two.

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

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

Very good detail Rick.
I feared that Guide 9 would not know Holmberg V but I was able to find it
there.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

Phillip Holmberg studied galaxies. Nine of them in enough detail they
have since been named for him. Eight are far enough north I can reach
them from 47N. All were put on my to-do list. I've managed to get a
few of them; II, IV, VIII and IX and now V. The first 4 were all dwarf
galaxies as are most of them. Holmberg II made Arp's list as #268 on
his list of peculiar galaxies. Of the 9 the most "normal is this one,
Holmberg V. It is a rather normal SAB(rs)c spiral galaxy. The surface
brightness is lower than normal but not to a great extent. It does have
an odd straight arm segment south of the core that runs nearly due east
before curving into a normal looking arm. Arp did have a category for
this type feature. Apparently it didn't make the cut. Why it attracted
Holmberg's interest I haven't determined.

It does have a small apparent satellite dwarf galaxy, SDSS
J134039.25+542053.6. With no redshift data I can't be certain it really
is a companion. It is aligned with the the minor axis of Holmberg V.
Holmberg had the idea that such galaxies tended to align with the minor
axis of their galaxy. I assume this means they orbit around the galaxy
at a steep angle to the plane of the galaxy to hold this alignment.
Problem is others can't seem to confirm this as a real situation.
http://www.astro.yale.edu/vdbosch/align.pdf Was this galaxy one he used
to try and support his idea? I just can't track this down as yet.
Considering how different this entry is compared to the other 8 I have
no other idea as to why it made this very short list.

Holmberg V seems to be a rather lonely galaxy but for the possible
companion. No other galaxy in the frame comes within 740,000
light-years. I didn't check for companions out of the frame.

The field contains an above average number of quasars, 9 of them. I
wonder if Arp knew about this? He had a wild idea that quasars were
ejected from peculiar galaxies rather than being distant massive black
holes as we know them today. This high number around a rather normal
looking galaxy (but for that straight arm segment) might have been a
serious problem to his idea.

There are two galaxy clusters in the image. One attracted my interest.
It is close at only 1.8 billion light-years. Above its bright cluster
galaxies is a group of galaxies (and 2 stars) that make a nice "V" shape
pointing to the upper left. Are these part of this cluster? I found no
redshift data for any of them. They seem to small and dim for the 1.8
billion light-year distance to the cluster and are well off center from
the bright cluster galaxy below them. Still to get to the 17 members
mentioned by NED they would need to be included. Below the two galaxies
with redshift data is a third bright one with a large halo. It has no
redshift data but certainly appears to be a disturbed member of the
group that that large, apparently tidal halo that seems to merge with
the much smaller halos of the other two. Though its largest extent
seems to go to the southeast, away from the other two.

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

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