Jupiters Geist

Planetarischer Nebel
NGC 3242 (Jupiters Geist)
Falschfarbendarstellung einer Beobachtung mittels Linienfilter des Hubble-Weltraumteleskops: 658 nm (rot), 656 nm (grün) und 502 nm (blau).
Falschfarbendarstellung einer Beobachtung mittels Linienfilter des Hubble-Weltraumteleskops: 658 nm (rot), 656 nm (grün) und 502 nm (blau).
AladinLite
SternbildWasserschlange
Position
Äquinoktium: J2000.0
Rektaszension10h 24m 46s [1]
Deklination−18° 38′ 32″[1]
Erscheinungsbild
Scheinbare Helligkeit (visuell)7,7 mag [2]
Scheinbare Helligkeit (B-Band)8,6 mag [2]
Winkelausdehnung2.5´ [2]
Zentralstern
BezeichnungHD 90255 [3]
Scheinbare Helligkeit12,1 mag 
Physikalische Daten
Rotverschiebung+0,000016 [3]
Radialgeschwindigkeit+4,7 km/s [3]
Entfernung4377 ± 296 Lj [4]
Durchmesser3,2 Lj
Geschichte
EntdeckungWilliam Herschel
Datum der Entdeckung7. Februar 1785[5]
Katalogbezeichnungen
 NGC 3242 • PK 261+32.1 • ESO 568-PN5 • GC 2102 • H IV 27 • h 3248 • CS=12.0

Jupiters Geist (auch mit NGC 3242 bezeichnet) ist ein planetarischer Nebel im Sternbild Wasserschlange.

Der Nebel setzt sich aus einem dichteren Bereich mit einem Durchmesser von 16 × 24 Bogensekunden und einer sichtbaren lichtschwächeren Hülle von 40 × 35 Bogensekunden Durchmesser zusammen. Da die äußere Hülle des Nebels im Teleskop etwa die gleiche Ausdehnung wie der Planet Jupiter aufweist, wird er auch als Jupiters Geist (engl.: Ghost of Jupiter) bezeichnet. Die scheinbare Helligkeit des sichtbaren Nebels beträgt 7,7 mag.

Fotografische Aufnahmen zeigen allerdings, dass der Nebel mit 20,8 Bogenminuten wesentlich ausgedehnter ist (zum Vergleich: der Mond besitzt von der Erde aus gesehen einen Durchmesser von etwa 30 Bogenminuten).

Im Zentrum befindet sich ein Weißer Zwergstern mit einer scheinbaren Helligkeit von 12,1 mag. Seine Entfernung zur Sonne konnte bislang nicht eindeutig bestimmt werden, wird aber meist mit 2.500 Lichtjahren angegeben. Eine andere Schätzung geht dagegen von einer Entfernung von 1.400 Lichtjahren aus.

Entdeckt wurde der Nebel am 7. Februar 1785 von William Herschel, der ihn als H IV 27 katalogisierte. John Herschel beobachtete ihn um 1830 vom Kap der Guten Hoffnung aus und nahm ihn 1864 als GC 2102 in den General Catalogue auf. In Dreyers New General Catalogue von 1888 erhielt er die Nummer NGC 3242.

Literatur

  • König, Michael & Binnewies, Stefan (2023): Bildatlas der Sternhaufen & Nebel, Stuttgart: Kosmos, S. 228
Commons: NGC 3242 – Album mit Bildern, Videos und Audiodateien

Einzelnachweise

  1. ↑ NASA/IPAC EXTRAGALACTIC DATABASE
  2. ↑ a b SEDS
  3. ↑ a b SIMBAD
  4. ↑ Astronomy Picture of the Day
  5. ↑ Seligman

Auf dieser Seite verwendete Medien

Extended Region Around the Planetary Nebula NGC 3242.tif
This ultraviolet image from NASA's Galaxy Evolution Explorer shows NGC 3242, a planetary nebula frequently referred to as "Jupiter's Ghost."

The unfortunate name of "planetary nebula" for this class of celestial object is a historical legacy credited to William Herschel during the 18th century -- a time when telescopes where small and objects like these, at least the central region, looked very similar to gas-giant planets such as Saturn and Jupiter. In fact, NGC 3242 has no relation to Jupiter or any other planet.

Telescopes and their detectors have dramatically improved over the past few centuries. Our understanding of what planetary nebulae truly are has improved accordingly.

When stars with a mass similar to our sun approach the end of their lives by exhausting supplies of hydrogen and helium fuel in their cores, they swell up into cool red-giant stars. In a last gasp before death, they expel the layers of gas in their outer atmosphere. This exposes the core of the dying star, a dense hot ball of carbon and oxygen called a white dwarf. The white dwarf is so hot that it shines very brightly in the ultraviolet. The ultraviolet light from the white dwarf, in turn, ionizes the gaseous material expelled by the star causing it to glow. A planetary nebula is really the death of a low-mass star.

Although low-mass stars like our sun live for billions of years, planetary nebulae only last for about ten thousand years. As the central white dwarf quickly cools and the ultraviolet light dwindles, the surrounding gas also cools and fades.

In this image of NGC 3242 from the Galaxy Evolution Explorer, the extended region around the planetary nebula is shown in dramatic detail. The small circular white and blue area at the center of the image is the well-known portion of the famous planetary nebula. The precise origin and composition of the extended wispy white features is not known for certain. It is most likely material ejected during the star's red-giant phase before the white dwarf was exposed. However, it may be possible that the extended material is simply interstellar gas that, by coincidence, is located close enough to the white dwarf to be energized by it, and induced to glow with ultraviolet light.

NGC 3242 is located 1,400 to 2,500 light-years away in the constellation Hydra. It was discovered by William Herschel in 1785.
Ghost of Jupiter Nebula.jpg
This ghostly image from NASA's Spitzer Space Telescope shows the disembodied remains of a dying star, called a planetary nebula. Planetary nebulas are a late stage in a sun-like star's life, when its outer layers have sloughed off and are lit up by ultraviolet light from the central star. The Ghost of Jupiter, also known as NGC 3242, is located roughly 1,400 light-years away in the constellation Hydra. Spitzer's infrared view shows off the cooler outer halo of the dying star, colored here in red. Also evident are concentric rings around the object, the result of material being periodically tossed out in the star's final death throes. In this image, infrared light at wavelengths of 3.6 microns is rendered in blue, 4.5 microns in green, and 8.0 microns in red.
NGC 3242 "Ghost of Jupiter".png
Autor/Urheber: Judy Schmidt, Lizenz: CC BY 2.0

Another planetary nebula. Very similar to <a href="https://www.flickr.com/photos/geckzilla/9667741870">NGC 6826</a> but it's interesting to compare the subtle differences. Why are they so similar? Why are some parts not similar? Are they <a href="http://hubblesite.org/newscenter/archive/releases/2013/37" rel="nofollow">aligned for some reason</a>?

Processing notes: Most of the nebula was on three filters but the edges were cut off around the outer part of the fainter spheroid. Something like <a href="File:NGC_3242_-HST-_R658G656B502.png" rel="nofollow">this</a> but I used a different set for the WFPC2-PC squares. There's more than one way to process a nebula...

Red: hst_08773_13_wfpc2_f658n_pc_sci Green: hst_08773_13_wfpc2_f555w_pc_sci Blue: hst_08773_13_wfpc2_f502n_pc_sci

Extra bits around the edge that were missing from the PC: hst_10822_02_wfpc2_f547m_wf_sci

North is up.
Caldwell Catalogue.jpg
Autor/Urheber: Roberto Mura, Lizenz: CC BY-SA 3.0
Caldwell Catalogue objects.
NGC3242.jpg
Autor/Urheber: Jschulman555, Lizenz: CC BY-SA 3.0
NGC 3242 using 32 inch Schulman telescope on Mt. Lemmon, AZ