Calabash Nebula
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| Protoplanetary nebula | Lists of nebulae |
|---|---|
Calabash Nebula |
|
| Observation data (Epoch J2000) |
|
| Right ascension | 07h 42m 16.83s[1] |
| Declination | -14° 42′ 52.1″[1] |
| Distance | 4.2 kly (1.3 kpc)[2] |
| Apparent magnitude (V) | 9.47[1] |
| Apparent dimensions (V) | 1′[citation needed] |
| Constellation | Puppis |
| Physical characteristics | |
| Radius | 0.7 ly[a] |
| Absolute magnitude (V) | -1.4[b] |
| Notable features | - |
| Other designations | OH 231.84 +4.22,[1] Rotten Egg Nebula[1] |
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.
Violent gas collisions that produced supersonic shock fronts in a dying star are seen in a new, detailed image from NASA's Hubble Space Telescope.
The object is sometimes called the Rotten Egg Nebula because it contains a lot of sulfur, which would produce an awful odor if one could smell in space. The densest parts of the nebula are composed of material ejected recently by the central star and accelerated in opposite directions. This material, shown as yellow in the image, is zooming away at speeds up to one and a half million kilometers per hour (one million miles per hour). Most of the star's original mass is now contained in these bipolar gas structures.
A team of Spanish and US astronomers used NASA's Hubble Space Telescope to study how the gas stream rams into the surrounding material, shown in blue. They believe that such interactions dominate the formation process in planetary nebulae. Due to the high speed of the gas, shock-fronts are formed on impact and heat the surrounding gas. Although computer calculations have predicted the existence and structure of such shocks for some time, previous observations have not been able to prove the theory.
This new Hubble image used filters that only let through light from ionized hydrogen and nitrogen atoms. Astronomers were able to distinguish the warmest parts of the gas heated by the violent shocks and found that they form a complex double-bubble shape. The bright yellow-orange colors in the picture show how dense, high-speed gas is flowing from the star, like supersonic speeding bullets ripping through a medium in opposite directions. The central star itself is hidden in the dusty band at the center.
Much of the gas flow observed today seems to stem from a sudden acceleration that took place only about 800 years ago. The astronomers believe that 1,000 years from now, the Calabash Nebula will become a fully developed planetary nebula, like a butterfly emerging from its chrysalis.
[edit] External links
- PIA04228: Rotten Egg Nebula, NASA Planetary Photojournal
- The Rotten Egg Planetary Nebula, APOD 1999 November 1
- The Making of the Rotten Egg Nebula, APOD 2001 September 3
[edit] Notes
- ^ Radius = distance × sin(angular size / 2) = 5 kly * sin(1′ / 2) = 0.7 ly
- ^ 9.47 apparent magnitude - 5 * (log10(1,500 pc distance) - 1) = -1.4 absolute magnitude
- ^ a b c d e (SIMBAD 2007)
- ^ (Kastner et al. 1998)
[edit] References
- Kastner, Joel H.; David A. Weintraub & K. M. Merrill et al. (1998), "Direct Detection of the Mira at the Heart of OH 231.8+4.2", The Astronomical Journal 116(3): 1412-1418
- SIMBAD (January 4, 2007), Results for Red Rectangle, SIMBAD, Centre de Données Astronomiques de Strasbourg
