Calabash Nebula

The Calabash Nebula, also known as the Rotten Egg Nebula or by its technical name OH 231.84 +4.22, is a protoplanetary nebula (PPN) 1.4 light years (13 Pm) long and located some 5,000 light years (47 Em) from Earth in the constellation Puppis. The name "Calabash Nebula" was first proposed in 1989 in an early paper on its expected nebular dynamics, based on the nebula's appearance.^[5] The Calabash is almost certainly a member of the open cluster Messier 46, as it has the same distance, radial velocity, and proper motion.^[6] The central star is QX Puppis, a binary composed of a very cool Mira variable and an A-type main-sequence star.

Calabash Nebula

Reflection nebula
Protoplanetary nebula
The Calabash Nebula, as taken by Hubble Space Telescope
Observation data: J2000 epoch
Right ascension	07h 42m 16.83s[1]
Declination	−14° 42′ 52.1″[1]
Distance	4,200[2] ly   (1,300 pc)
Apparent magnitude (V)	9.47[1]
Apparent dimensions (V)	10 × 60 arcsec[3]
Constellation	Puppis
Physical characteristics
Radius	0.7[a] ly
Absolute magnitude (V)	-1.4[b]
Designations	OH 231.84 +4.22,[1] Rotten Egg Nebula[1]
See also: Lists of nebulae

QX Puppis

A near-infrared (I band) light curve for QX Puppis, plotted from AAVSO data[4]
Characteristics
Evolutionary stage	OH/IR star[1]
Spectral type	M10III + A[1]
Variable type	Mira[1]
Database references
SIMBAD	data

Ground-based imagery

NGC 2438 (upper left) and the Calabash Nebula (lower right) taken from the Mount Lemmon SkyCenter using the 0.8 m Schulman Telescope.

In wide field images, the Calabash nebula is visible near the bright planetary nebula NGC 2438 in deep photographs. Although the Calabash Nebula is at the same distance as M46, NGC 2438 is a larger object in the foreground.

Notes

1. ^{^} Radius = distance × sin(angular size / 2) = 5 kly * sin(1′ / 2) = 0.7 ly
2. ^{^} 9.47 apparent magnitude - 5 * (log₁₀(1,500 pc distance) - 1) = -1.4 absolute magnitude