ASTRO: NGC 225 and vdB 4

vdB 4 is a reflection nebula associated with the very young open star
cluster NGC 225. The nebula may be the remains of the cloud that formed
the cluster. The WEBDA puts the distance to the cluster and thus nebula
(if it is related) at about 2000 light-years. But this is quite
uncertain. A very interesting paper on the probable PMS stars in the
cluster illustrates the problems with determining the distance to such
clusters. The paper estimates the cluster is between a half million and
10 million years old based on its study of the PMS stars. No PMS
doesn't mean that. It means Pre Main Sequence. Indicating these are
very young stars still not settled in to getting all their energy from
turning hydrogen to helium which will power the star for most of its
life. The birth process isn't quite complete yet you might say. For
those who want the details the paper is at:
http://www.ncra.tifr.res.in/~basi/06.../200634315.pdf

The cluster was discovered by Caroline Herschel in 1783 as #11 on her
list. A few months later she found it again recording it as #15 in
1784. The Sailboat name seems to be due to Rod Pommier in an article
for Astronomy magazine

vdB 4 is centered on the variable star V594 Cas. The only designation I
find at Simbad for the dark nebula going out of the top of my image is
[LM99] 2. To me vdB 4 looks like an alien standing with his curving
arms to the left. They seem to surround a dark area. Simbad labels the
brighter area just southeast of this dark region LDN 1302. I find this
rather confusing. Simbad also indicates the bright nebula LBN 604 is
near the top edge of my frame a bit left of center. Apparently it
refers to the general glow that fills most of the frame against which
the dark nebulae are seen. I certainly don't see anything but this
general glow in the area.

With only 40 minutes of data the field is rather data starved. At the
time I imaged this last fall (2010) I was imaging NGC 225 as one of the
Herschel 400 objects, another project I have running. Consulting my
visual log of the Herschel 400 I saw no mention of nebulosity nor had I
heard of vdB4 until I later saw Tom Davis' wide angle view of the area
showing a lot of dark and bright nebulae. By then it was too late and
with nothing but clouds and poor seeing this fall I decided to go with
what I had rather than try for more data. I was surprised how well vdB4
itself came through. Sometimes I get lucky.

When I went to process this I found that I'd hit a wrong key in setting
up the imaging file and ended up with the red frame binned 2x2 rather
than 3x3 as the green and blue images were binned. Thanks to
normalization it didn't cause any problems. Just added a minor step in
the processing.

14" LX200R @ f/10, L=4x10' R=2x10' GB=2x10'x3, STL-11000XM, Paramount ME

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

Rick,

I have never heard about this nebula before. Quite a neat bonus for an open
cluster.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
.com...
vdB 4 is a reflection nebula associated with the very young open star
cluster NGC 225. The nebula may be the remains of the cloud that formed
the cluster. The WEBDA puts the distance to the cluster and thus nebula
(if it is related) at about 2000 light-years. But this is quite
uncertain. A very interesting paper on the probable PMS stars in the
cluster illustrates the problems with determining the distance to such
clusters. The paper estimates the cluster is between a half million and
10 million years old based on its study of the PMS stars. No PMS
doesn't mean that. It means Pre Main Sequence. Indicating these are
very young stars still not settled in to getting all their energy from
turning hydrogen to helium which will power the star for most of its
life. The birth process isn't quite complete yet you might say. For
those who want the details the paper is at:
http://www.ncra.tifr.res.in/~basi/06.../200634315.pdf

The cluster was discovered by Caroline Herschel in 1783 as #11 on her
list. A few months later she found it again recording it as #15 in
1784. The Sailboat name seems to be due to Rod Pommier in an article
for Astronomy magazine

vdB 4 is centered on the variable star V594 Cas. The only designation I
find at Simbad for the dark nebula going out of the top of my image is
[LM99] 2. To me vdB 4 looks like an alien standing with his curving
arms to the left. They seem to surround a dark area. Simbad labels the
brighter area just southeast of this dark region LDN 1302. I find this
rather confusing. Simbad also indicates the bright nebula LBN 604 is
near the top edge of my frame a bit left of center. Apparently it
refers to the general glow that fills most of the frame against which
the dark nebulae are seen. I certainly don't see anything but this
general glow in the area.

With only 40 minutes of data the field is rather data starved. At the
time I imaged this last fall (2010) I was imaging NGC 225 as one of the
Herschel 400 objects, another project I have running. Consulting my
visual log of the Herschel 400 I saw no mention of nebulosity nor had I
heard of vdB4 until I later saw Tom Davis' wide angle view of the area
showing a lot of dark and bright nebulae. By then it was too late and
with nothing but clouds and poor seeing this fall I decided to go with
what I had rather than try for more data. I was surprised how well vdB4
itself came through. Sometimes I get lucky.

When I went to process this I found that I'd hit a wrong key in setting
up the imaging file and ended up with the red frame binned 2x2 rather
than 3x3 as the green and blue images were binned. Thanks to
normalization it didn't cause any problems. Just added a minor step in
the processing.

14" LX200R @ f/10, L=4x10' R=2x10' GB=2x10'x3, STL-11000XM, Paramount ME

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