ASTRO: NGC 147

NGC 147 is a low surface brightness dwarf elliptical galaxy and well
known satellite of M31. Oddly, I found a wide range of distance
measurements to this one. Apparently it doesn't have any Cepheids as
all distance measurements used other methods including a relative of
Cepheids, RR Lyra stars. The estimates ranged from 2.2 to 2.8 million
light-years. The average is about 2.5 million light-years which is
pretty much the accepted distance to M31. One paper said star formation
ended over a billion years ago in NGC 147. Another said there's been
little star formation for the last 3 billion years. I expected it to be
more orange than it came out.

I noticed a nice "small" edge on disk galaxy on the NE edge of the
galaxy. I then collected redshift data from NED on the field. Oddly
that galaxy (marked by a question mark in the annotated image) wasn't in
NED at all. NED identified less than 20 galaxies in the field even
though I see far more in my image. Of those only 5 had red shift data.
I'm not counting NGC 147 since it is bound to M31 which is heading our
way. Thus NGC 147 has a blue shift, worthless for determining distance.
One of the 5 is about 130 million light-years away and is southeast
(lower left) of NGC 147. It is listed at NED as being a starburst
galaxy though rather red in my image. Not unexpected as the new stars
of such galaxies are often hidden near the core behind a dense dust
cloud. Heating of the cloud by these stars is often the key to
identifying them as being starburst galaxies. Still it is nearly
star-like and faint at magnitude 19.7 so a low surface brightness dwarf
galaxy.

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, 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".

Rick,

the small edge on is a nice feature of this otherwise rather featureless
galaxy.
At least it is bigger than the average Arp galaxy ;-)

Stefan



"Rick Johnson" schrieb im Newsbeitrag
.com...
NGC 147 is a low surface brightness dwarf elliptical galaxy and well
known satellite of M31. Oddly, I found a wide range of distance
measurements to this one. Apparently it doesn't have any Cepheids as
all distance measurements used other methods including a relative of
Cepheids, RR Lyra stars. The estimates ranged from 2.2 to 2.8 million
light-years. The average is about 2.5 million light-years which is
pretty much the accepted distance to M31. One paper said star formation
ended over a billion years ago in NGC 147. Another said there's been
little star formation for the last 3 billion years. I expected it to be
more orange than it came out.

I noticed a nice "small" edge on disk galaxy on the NE edge of the
galaxy. I then collected redshift data from NED on the field. Oddly
that galaxy (marked by a question mark in the annotated image) wasn't in
NED at all. NED identified less than 20 galaxies in the field even
though I see far more in my image. Of those only 5 had red shift data.
I'm not counting NGC 147 since it is bound to M31 which is heading our
way. Thus NGC 147 has a blue shift, worthless for determining distance.
One of the 5 is about 130 million light-years away and is southeast
(lower left) of NGC 147. It is listed at NED as being a starburst
galaxy though rather red in my image. Not unexpected as the new stars
of such galaxies are often hidden near the core behind a dense dust
cloud. Heating of the cloud by these stars is often the key to
identifying them as being starburst galaxies. Still it is nearly
star-like and faint at magnitude 19.7 so a low surface brightness dwarf
galaxy.

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, 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".