ASTRO: Palomar 13

Palomar 13, found in Pegasus, is located about 85 million light-years
away and about 88 million light-years from the center of the galaxy.
While SIMBAD and a note at NED says it is an intergalactic cluster this
is likely incorrect. SEDS has this to say about it: "Palomar 13 was
discovered by A.G. Wilson (1955) and named by him the Pegasus Globular
Cluster, together with globular clusters Palomar 3, Palomar 4 and
Palomar 5, and two new Local Group galaxies. That naming was certainly
not essentially a happy choice, as Pegasus also contains the prominent
globular M15. G.O. Abell (1955) cataloged them with their Palomar numbers."

Note that it has an unusual number of very blue stars. These are likely
high mass stars that are the result of the union of smaller, dying red
stars. The merger has given them twice the mass causing them to turn
into hot blue stars -- for a short time at least. It's orbit about our
galaxy, according to the paper below, shows it dives in rather close to
the galaxy's core then out into the halo again where we see it is today.
This will tend to strip it of its less massive stars leaving mostly
the more massive stars, many of which are blue stragglers. Their
calculations indicate that it is now so depleted of stars and thus mass
that its next nose dive into the core will be its last as there's not
enough left to resist the tidal forces of our galaxy's core.
http://xxx.lanl.gov/pdf/astro-ph/0011220v1.pdf

An image of it taken at the Las Campanas Observatory in the Atacama
Desert of Chile is at APOD. http://apod.nasa.gov/apod/ap001130.html
They don't say which scope took it. It is rotated so west as at the top
rather than north in my image. It appears to be a somewhat false color
image.

Interestingly, three of the 4 entries in NED call it a galaxy. I assume
they saw it as a nearby dwarf galaxy. Apparently, if you look for
galaxies you find them even when they are something else.

There are a couple asteroids in my image. (287071) 2002 RZ28 at an
estimated magnitude of 19.3 is east of Pal 13 while (170485) 2003 UC277
at an estimated magnitude of 18.4 is toward the upper right corner.

For reasons now lost to my memory and not in my notes, I went back the
next night and retook my normal 2 frames in each color. While the first
night wasn't quite as transparent of a night as the second I did use all
four of each in composing the image.

I've not prepared an annotated image. Most of my data for such images
comes from the Sloan data base at NED. That starts at 13 degrees which
is the very top of my image so except for the top minute of arc, the
image is out of their data at NED.

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

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

Make that 85 thousand light years rather than million.

Rick

On 9/9/2012 2:09 AM, Rick Johnson wrote:
Palomar 13, found in Pegasus, is located about 85 million light-years
away and about 88 million light-years from the center of the galaxy.
While SIMBAD and a note at NED says it is an intergalactic cluster this
is likely incorrect. SEDS has this to say about it: "Palomar 13 was
discovered by A.G. Wilson (1955) and named by him the Pegasus Globular
Cluster, together with globular clusters Palomar 3, Palomar 4 and
Palomar 5, and two new Local Group galaxies. That naming was certainly
not essentially a happy choice, as Pegasus also contains the prominent
globular M15. G.O. Abell (1955) cataloged them with their Palomar numbers."

Note that it has an unusual number of very blue stars. These are likely
high mass stars that are the result of the union of smaller, dying red
stars. The merger has given them twice the mass causing them to turn
into hot blue stars -- for a short time at least. It's orbit about our
galaxy, according to the paper below, shows it dives in rather close to
the galaxy's core then out into the halo again where we see it is today.
This will tend to strip it of its less massive stars leaving mostly
the more massive stars, many of which are blue stragglers. Their
calculations indicate that it is now so depleted of stars and thus mass
that its next nose dive into the core will be its last as there's not
enough left to resist the tidal forces of our galaxy's core.
http://xxx.lanl.gov/pdf/astro-ph/0011220v1.pdf

An image of it taken at the Las Campanas Observatory in the Atacama
Desert of Chile is at APOD. http://apod.nasa.gov/apod/ap001130.html
They don't say which scope took it. It is rotated so west as at the top
rather than north in my image. It appears to be a somewhat false color
image.

Interestingly, three of the 4 entries in NED call it a galaxy. I assume
they saw it as a nearby dwarf galaxy. Apparently, if you look for
galaxies you find them even when they are something else.

There are a couple asteroids in my image. (287071) 2002 RZ28 at an
estimated magnitude of 19.3 is east of Pal 13 while (170485) 2003 UC277
at an estimated magnitude of 18.4 is toward the upper right corner.

For reasons now lost to my memory and not in my notes, I went back the
next night and retook my normal 2 frames in each color. While the first
night wasn't quite as transparent of a night as the second I did use all
four of each in composing the image.

I've not prepared an annotated image. Most of my data for such images
comes from the Sloan data base at NED. That starts at 13 degrees which
is the very top of my image so except for the top minute of arc, the
image is out of their data at NED.

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

Rick


--
Prefix is correct. Domain is arvig dot net

Rick,

in spite of the faintness of this glob you managed to get good star colours.
It seems to have some very bright blue stars.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

Make that 85 thousand light years rather than million.

Rick

On 9/9/2012 2:09 AM, Rick Johnson wrote:
Palomar 13, found in Pegasus, is located about 85 million light-years
away and about 88 million light-years from the center of the galaxy.
While SIMBAD and a note at NED says it is an intergalactic cluster this
is likely incorrect. SEDS has this to say about it: "Palomar 13 was
discovered by A.G. Wilson (1955) and named by him the Pegasus Globular
Cluster, together with globular clusters Palomar 3, Palomar 4 and
Palomar 5, and two new Local Group galaxies. That naming was certainly
not essentially a happy choice, as Pegasus also contains the prominent
globular M15. G.O. Abell (1955) cataloged them with their Palomar
numbers."

Note that it has an unusual number of very blue stars. These are likely
high mass stars that are the result of the union of smaller, dying red
stars. The merger has given them twice the mass causing them to turn
into hot blue stars -- for a short time at least. It's orbit about our
galaxy, according to the paper below, shows it dives in rather close to
the galaxy's core then out into the halo again where we see it is today.
This will tend to strip it of its less massive stars leaving mostly
the more massive stars, many of which are blue stragglers. Their
calculations indicate that it is now so depleted of stars and thus mass
that its next nose dive into the core will be its last as there's not
enough left to resist the tidal forces of our galaxy's core.
http://xxx.lanl.gov/pdf/astro-ph/0011220v1.pdf

An image of it taken at the Las Campanas Observatory in the Atacama
Desert of Chile is at APOD. http://apod.nasa.gov/apod/ap001130.html
They don't say which scope took it. It is rotated so west as at the top
rather than north in my image. It appears to be a somewhat false color
image.

Interestingly, three of the 4 entries in NED call it a galaxy. I assume
they saw it as a nearby dwarf galaxy. Apparently, if you look for
galaxies you find them even when they are something else.

There are a couple asteroids in my image. (287071) 2002 RZ28 at an
estimated magnitude of 19.3 is east of Pal 13 while (170485) 2003 UC277
at an estimated magnitude of 18.4 is toward the upper right corner.

For reasons now lost to my memory and not in my notes, I went back the
next night and retook my normal 2 frames in each color. While the first
night wasn't quite as transparent of a night as the second I did use all
four of each in composing the image.

I've not prepared an annotated image. Most of my data for such images
comes from the Sloan data base at NED. That starts at 13 degrees which
is the very top of my image so except for the top minute of arc, the
image is out of their data at NED.

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

Rick


--
Prefix is correct. Domain is arvig dot net