ASTRO: Ursa Minor Dwarf

The Ursa Minor Dwarf galaxy is a member of the local group of galaxies.
It is about 230,000 to 240,000 light-years distant depending on which
source you look at. It is composed of old stars and has little to no
dust or gas so won't be forming many new stars. In fact it appears that
star formation was confined to a single event some 12 to 14 billion
years ago. This likely is when our galaxy itself was formed. So its
stars are all smaller and fainter than our sun. No wonder it is so
faint. This is based on the paper:
http://iopscience.iop.org/1538-3881/..._118_1_366.pdf .
It was discovered by A. G. Wilson (Albert George) on the POSS 1
survey images in 1954. It is usually classed as dE4.

My field is too small as it extends out the upper part of the image to
the left and lower part to the right so is very elongated. Seems too
elongated for E4 status. My low transparency prevented me from picking
up much of the faint glow from its stars. Though look to the lower left
and upper right to see its edges as the background does get dimmer there
as you move away from the galaxy's boundaries. I need to redo this one
on a far better night though those aren't happening as yet. It might be
easier to see on the half size image where its resolved stars are closer
together better defining its location.

While the area has been covered to some extent by the Sloan Survey Data
Release 9 none of the over 3000 galaxies in it have red shift data.
Though two quasars and the galaxy IC 1110 do have redshift data as well
as one galaxy cluster though that is photographic rather than
spectroscopic. I've marked them on the annotated image. There are
three candidate galaxy clusters listed at NED but seeing nothing at
those positions in my image I didn't include them in the annotated
image. No size nor membership count was available for these possible
clusters and their position was very general. I tend to omit what I
can't find in my image so these were not included making for a very
sparse annotated image.

14" LX200R @ f/10, L=4x10' RG=2x10' B=3x10 (all blue and one R and G
hurt by clouds), STL-11000XM, Paramount ME

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

I managed to grab the wrong 50% size image. Names were too similar. I've attached the correct one (I hope).
Rick

Originally Posted by Rick Johnson[_2_]

The Ursa Minor Dwarf galaxy is a member of the local group of galaxies.
It is about 230,000 to 240,000 light-years distant depending on which
source you look at. It is composed of old stars and has little to no
dust or gas so won't be forming many new stars. In fact it appears that
star formation was confined to a single event some 12 to 14 billion
years ago. This likely is when our galaxy itself was formed. So its
stars are all smaller and fainter than our sun. No wonder it is so
faint. This is based on the paper:
http://iopscience.iop.org/1538-3881/..._118_1_366.pdf .
It was discovered by A. G. Wilson (Albert George) on the POSS 1
survey images in 1954. It is usually classed as dE4.

My field is too small as it extends out the upper part of the image to
the left and lower part to the right so is very elongated. Seems too
elongated for E4 status. My low transparency prevented me from picking
up much of the faint glow from its stars. Though look to the lower left
and upper right to see its edges as the background does get dimmer there
as you move away from the galaxy's boundaries. I need to redo this one
on a far better night though those aren't happening as yet. It might be
easier to see on the half size image where its resolved stars are closer
together better defining its location.

While the area has been covered to some extent by the Sloan Survey Data
Release 9 none of the over 3000 galaxies in it have red shift data.
Though two quasars and the galaxy IC 1110 do have redshift data as well
as one galaxy cluster though that is photographic rather than
spectroscopic. I've marked them on the annotated image. There are
three candidate galaxy clusters listed at NED but seeing nothing at
those positions in my image I didn't include them in the annotated
image. No size nor membership count was available for these possible
clusters and their position was very general. I tend to omit what I
can't find in my image so these were not included making for a very
sparse annotated image.

14" LX200R @ f/10, L=4x10' RG=2x10' B=3x10 (all blue and one R and G
hurt by clouds), STL-11000XM, Paramount ME

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

Rick,

this looks like a star-starved version of the milky way.
I have to admit that I have never heard of th Ursa Minor Dwarf before.
I'd wish we had something like the Magellanic Clouds in the northern sky.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

The Ursa Minor Dwarf galaxy is a member of the local group of galaxies.
It is about 230,000 to 240,000 light-years distant depending on which
source you look at. It is composed of old stars and has little to no
dust or gas so won't be forming many new stars. In fact it appears that
star formation was confined to a single event some 12 to 14 billion
years ago. This likely is when our galaxy itself was formed. So its
stars are all smaller and fainter than our sun. No wonder it is so
faint. This is based on the paper:
http://iopscience.iop.org/1538-3881/..._118_1_366.pdf .
It was discovered by A. G. Wilson (Albert George) on the POSS 1
survey images in 1954. It is usually classed as dE4.

My field is too small as it extends out the upper part of the image to
the left and lower part to the right so is very elongated. Seems too
elongated for E4 status. My low transparency prevented me from picking
up much of the faint glow from its stars. Though look to the lower left
and upper right to see its edges as the background does get dimmer there
as you move away from the galaxy's boundaries. I need to redo this one
on a far better night though those aren't happening as yet. It might be
easier to see on the half size image where its resolved stars are closer
together better defining its location.

While the area has been covered to some extent by the Sloan Survey Data
Release 9 none of the over 3000 galaxies in it have red shift data.
Though two quasars and the galaxy IC 1110 do have redshift data as well
as one galaxy cluster though that is photographic rather than
spectroscopic. I've marked them on the annotated image. There are
three candidate galaxy clusters listed at NED but seeing nothing at
those positions in my image I didn't include them in the annotated
image. No size nor membership count was available for these possible
clusters and their position was very general. I tend to omit what I
can't find in my image so these were not included making for a very
sparse annotated image.

14" LX200R @ f/10, L=4x10' RG=2x10' B=3x10 (all blue and one R and G
hurt by clouds), STL-11000XM, Paramount ME

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