Sunday, September 05, 2004

M76, The Little Dumbell, Butterfly, Cork, Barbell Nebula

A lot of names for one object but this planetary nebula is known
by all four: the Little Dumbell, the Butterfly, the Cork, and the
Barbell Nebula. It is the faintest and smallest object among the
'M' or Messier objects.

It is made up of two parts: the central rectangle and two faint
wispy butterfly wings. My imaging equipment only allowed me to
bring out just the beginning features of each wing but you can
see them a little better in the grayscale image on the right.
If you were to search for NGC-650 and NGC-651 in a planetarium
program you would probably be directed to M76 each time. The
two numbers refer to each 'wing' because they were thought by
William Herschel to be two independent nebula that were in
contact. At each end of the rectangle there are condensed
gaseous features that appear to be the hottest and brightest
areas of the nebula. The rectangle is very similar to what we
see when viewing M57, the Ring Nebula, except in this case we
are actually viewing the cylinder of gas from the side rather
than the end. And as in the case of M57, M76's central star is
visible. You can see this faint 16.5 mag star at the very
center of the rectangle. It really consists of two stars with
the star that created the nebula itself appearing as a hot
blue star. Take a look at this stunning image of M76 taken by
Adam Block with a 20' scope which shows the butterfly wings
and the hot blue central star located at the top of the two
stars: Adam Block M76 Image

The Little Dumbell is 3-5 thousand light years away with a length
of about one light year across. It's cylinder is expanding at the
rate of 42 km/sec and it is moving towards Earth at 24 km/sec (15
miles per/sec). The central star is approximately 90% of the mass
of our sun and eventually, as is the fate of our sun, will cool
down to become a white dwarf.

Note: The type of nebulae that I have been imaging are, for the
most part, planetary nebula (three other types are emission,
reflection and dark). The first ingredient necessary to form
one of these unique objects is a sun about the size of our own
but no more than eight solar masses. After several billions of
years, when most of the hydrogen has been burned, the core will
contract, the temperature will rise and the star will become
much larger and redder. Once the helium in the core ignites
and becomes exhausted, the star begins to shed its gaseous
envelope and enters a super red giant phase with most of the
stars inner planets burnt and stripped of their atmospheres
(nice thought huh?). Over thousands of years, the stars gas
is shed even further through a process of stellar winds and
'helium shell flashes' (don't ask) to eventually form a
planetary nebula. What shape this will take is anybody's
guess which is part of the fascination in viewing and
imaging these interesting objects. After 50,000 years or so
the nebula will begin to dissipate into space leaving behind
the stars old core which will transform into a white dwarf.

Techno Stuff: 8" SCT, Mogg 0.6 fr with extension for FL 3.3,
Baader IR filter, Toucam SC1.5 normal mode, Alt 79 deg, 40.5
sec x 90, 70 frames used, dark subtract (11 frames) , 5fps,
Brightness 40%, Gamma 35%, Saturation 40%, White Balance Auto,
Gain 70%, Processed in K3CCDTools, Registax, Photoshop

Who says I don't have good taste in jewelry?
Scroll your mouse over the ring and watch it light up!