Object of the Week Mar 11, 2012 - The Boomerang Nebula

[Jim Chandler]

ESO 172-7 aka the Boomerang Nebula

J2000 R.A. 12h 44m 46.1s Dec -54°31'10"

Size (from NED): 1.45’ x .73’

Magnitude (from NED): 12.4V

A bipolar protoplanetary nebula in Centaurus, discovered in 1977-78 in the ESO Quick Blue survey. One interesting tidbit about the Boomerang is that it is currently the coldest known region in the universe, with a temperature of only one degree Kelvin. No emission lines are apparent, but there is sufficient dust reflecting light from the central star to allow the nebula to be seen.

I observed the Boomerang with a 20" f/4 dob in 2006 at the Texas Star Party. From my log notes:

The southern-most object I've observed from my usual latitude, 30 degrees north.

My 25" wouldn't point low enough without dismantling the altitude drive, so I enlisted Barbara Wilson's 20". The Boomerang shared the field of view with a tree, which stuck down from the top of the fov. The viewing position consisted of lying stretched out on the ground, head propped up on one arm to reach the eyepiece.

At 120x, seen with averted vision only.
At 182x, seen intermittently with direct vision, held easily with averted vision.
At 290x, dim but held steadily with direct vision.

The nebula was elongated in appearance, but no detail was visible due to the atmospheric effects of viewing with the telescope pointed almost horizontally; it could easily have been mistaken for a galaxy.

121

GIVE IT A GO AND LET US KNOW

GOOD LUCK AND GOOD VIEWING


Jim Chandler

[Uwe Glahn]

Very cool object.
My quick and dirty notes from Namibia:

12", 375x, Seeing II , fst 7m+
bright, 4:1 elongated with bright stellar peak in the middle, south side brighter, no conical structure

24", 687x, Seeing IV, fst 7m+
very bright Proto PN, brighter to its middle (CS), from the middle two conical structures to the south and north, southern gas cloud seems to be a little bit brighter, no structure within the structures, poor seeing

[Steve Gottlieb]

I finally had an opportunity to observe the Boomerang Nebula after it was listed by Jim Chandler as an OOTW more than 4 years ago. This protoplanetary is famous for being only 1 degree above absolute zero -- at the OzSky Star Party last week in Coonabarabran, Australia! I actually observed it on two nights with both 14.5" and 18" f/4.5 scopes, but not the large 25" or 30". As this object shines by reflected light, no filter was used. It was fun to observe a celestial boomerang in Australia.

14.5" (4/3/16 - Coonabarabran, 238x): the Boomerang Nebula (protoplanetary) was easily picked up as a fairly bright, quasi-stellar glow (central star) with small faint "wings" extending north and south (no obvious "flaring"). The south wing appeared brighter and larger and the total size was roughly 25"x8". A mag 9.8 star lies 2.3' SW

18" (4/4/16 - Coonabarabran, 296x): more structure was seen through the 18" with the central star easier to pick out within an elongated, high surface brightness haze. The south lobe or cone was clearly brighter and larger and flared out towards the south, dimming near the end. The north extension was small and less prominent. The dimensions were estimated as ~30"x10" (at south end). Located 13' NW of mag 6.7 HD 110924.