Helixnebulosan
| Helixnebulosan | |
.jpg) Foto i infrarött taget med NASAs Spitzerteleskop | |
| Observationsdata | |
|---|---|
| Typ | Planetarisk nebulosa |
| Stjärnbild | Vattumannen |
| Rektascension | 22t 29m 39s |
| Deklination | -20° 50′ 14″ |
| Avstånd | ~695 ljusår |
| Skenbar storlek | 25 |
| Skenbar magnitud | +7,6 |
| Noterbart | En av de närmaste planetariska nebulosorna |
| Fysiska egenskaper | |
| Radie | 2,87 ljusår |
| Absolut magnitud | 6,58 |
| Upptäckt | |
| Upptäcktsår | 1824 |
| Upptäckare | Karl Ludwig Harding |
| Andra beteckningar | |
| NGC 7293, Caldwell 63, Bennett 129, PK 36-57.1, ESO 602-PN22, GC 4795, BD -21 6239 | |
| Se även: Nebulosor, Lista över nebulosor | |
Helixnebulosan, också känd som Helix och NGC 7293, är en stor planetarisk nebulosa i stjärnbilden Vattumannen.
Den upptäcktes av Karl Ludwig Harding, troligtvis före 1824 och är ett av de objekt som är närmast jorden bland de planetariska nebulosorna. Det uppskattade avståndet är ungefär 700 ljusår.[1][2]
Helixnebulosan är snarlik Ringnebulosan och Hantelnebulosan, men har på grund av den vinkel vi betraktar den i fått smeknamnet ”Eye of God” (Guds öga).[3]
Excitationstemperaturen varierar i nebulosan, från 1800 kelvin i de inre regionerna av nebulosan till ungefär 900 kelvin i de yttre.[4]
Referenser
- ^ ”Helix”. SIMBAD Astronomical Database. http://simbad.u-strasbg.fr/simbad/. Läst 5 augusti 2013.
- ^ Hora, Latter, Smith & Marengo (2006). ”Infrared Observations of the Helix Planetary Nebula”. The Astrophysical Journal (652): sid. 426-441.
- ^ ”Helix - Urban Legends”. Snopes.com. http://www.snopes.com/photos/space/eyeofgod.as. Läst 5 augusti 2013.
- ^ Matsuura, Speck, Smith, Zijlstra, Viti, Lowe, Redman, Wareing & Lagadec (2007). ”VLT/near-infrared integral field spectrometer observations of molecular hydrogen lines in the knots of the planetary nebula NGC 7293 (the Helix Nebula)”. Monthly Notices of the Royal Astronomical Society (382): sid. 1447-1459.
Externa länkar
Wikimedia Commons har media som rör Helixnebulosan.- NASA APOD – 31 december 2009 - Helixnebulosan - Picture of the Day
- NASA APOD – 10 maj 2003 - Helixnebulosan - Picture of the Day
- NASA/JPL-Caltech - Helix Nebula - Unraveling at the Seams
- SEDS - The Helix Nebula (NGC 7293)
- NightSkyInfo – Beskrivning för dig som vill titta med teleskop
- Beskrivning i Constellation Guide av Helixnebulosan
Media som används på denna webbplats
This infrared image from NASA's Spitzer Space Telescope shows the Helix Nebula, a cosmic starlet often photographed by amateur astronomers for its vivid colors and eerie resemblance to a giant eye.
The nebula, located about 700 light-years away in the constellation Aquarius, belongs to a class of objects called planetary nebulae. Discovered in the 18th century, these colorful beauties were named for their resemblance to gas-giant planets like Jupiter.
Planetary nebulae are the remains of stars that once looked a lot like our sun. When sun-like stars die, they puff out their outer gaseous layers. These layers are heated by the hot core of the dead star, called a white dwarf, and shine with infrared and visible colors. Our own sun will blossom into a planetary nebula when it dies in about five billion years.
In Spitzer's infrared view of the Helix nebula, the eye looks more like that of a green monster's. Infrared light from the outer gaseous layers is represented in blues and greens. The white dwarf is visible as a tiny white dot in the center of the picture. The red color in the middle of the eye denotes the final layers of gas blown out when the star died.
The brighter red circle in the very center is the glow of a dusty disk circling the white dwarf (the disk itself is too small to be resolved). This dust, discovered by Spitzer's infrared heat-seeking vision, was most likely kicked up by comets that survived the death of their star. Before the star died, its comets and possibly planets would have orbited the star in an orderly fashion. But when the star blew off its outer layers, the icy bodies and outer planets would have been tossed about and into each other, resulting in an ongoing cosmic dust storm. Any inner planets in the system would have burned up or been swallowed as their dying star expanded.
So far, the Helix nebula is one of only a few dead-star systems in which evidence for comet survivors has been found.
This image is made up of data from Spitzer's infrared array camera and multiband imaging photometer. Blue shows infrared light of 3.6 to 4.5 microns; green shows infrared light of 5.8 to 8 microns; and red shows infrared light of 24 microns.Författare/Upphovsman: ESO/VISTA/J. Emerson, Licens: CC BY 4.0
ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) has captured this unusual view of the Helix Nebula (NGC 7293), a planetary nebula located 700 light-years away. The coloured picture was created from images taken through Y, J and K infrared filters. While bringing to light a rich background of stars and galaxies, the telescope's infrared vision also reveals strands of cold nebular gas that are mostly obscured in visible images of the Helix.