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Designations: NGC 7635, Caldwell 11, H IV 52
Visual
Magnitude: 8.69 (central star)
Size: 15.0 min X 8.0 min
Distance: 11,300 light
years
Discoverer: Unknown
Visual Description: Easy to star-hop
to, easy to find but not easy to see! The open cluster M52 points the way, The
bubble nebula is just one degree away in a south-westerly direction. Observing
from my suburban skies with an 10 inch, the nebula was not seen. The nebula has
a strong O-III emission, an O-III nebula filter should make observation easier.
To find M52, and hence the Bubble Nebula, follow the line Alpha to Beta
Cassiopeiae and on in a straight line for the same distance.
Billed by
the Hubble Heritage Team (Hester et al. 1992), as the "bubble versus the cloud"
. The part we know as the Bubble Nebula is being forced out by a stellar wind of
ionised gas from a massive central star. However next door is a giant molecular
cloud ( a portion of which is visible in the image). The cloud, although able to
contain the expansion of the bubble's gas, gets blasted with intense radiation
from the central star. This radiation heats up denser regions, ionising it and
causing the shell to glow. This interpretation was confirmed by Buckalew et al.
(1999) who, using observations with the Space Telescope Imaging Spectroscope
(STIS), concluded that the characteristic rim was the edge of a shell of ionised
gas that is being "snowploughed" through the surrounding region by the
supersonic wind from the star. The Bubble Nebula is actually the smallest part
of three bubbles surrounding the central star and part of gigantic network known
as s162, created by other massive stars. The Bubble Nebula's central star
BD+602522, is 10 to 20 times more massive than the Sun and is classed as type
O6.5iiif. The Nebula is about 10 light years across and 11,300 light years away
Telescope: TMB 152mm APO
Refractor
Focal
Length: 1200 mm
Mount: Takahashi NJP 160
Camera:
SBIG ST10XME
Exposure:
12 15-minute exposures through a hydrogen alpha filter and 5 8-minute
exposures through each color filter (red, green and blue). (5 hours total)
Other:
SBIG ST402ME
Image Processing: CCDStack and Photoshop CS2
The visual descriptions of NGC7635 was written by David Ratledge in the book "Observing the Caldwell Objects" by David Ratledge. Page 36. ISBN number 0-85233-628-5.
Copyright(c) 2007 Doug Sanqunetti. All rights reserved
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