Saturday, March 20, 2021

The Ghost of Jupiter

The Ghost of Jupiter (also known as NGC 3242, or Caldwell 59) is a planetary nebula, located at a distance of around 4,800 light-years in the constellation of Hydra. It was discovered on the 7th of February 1785 by William Herschel.

The nebula is also referred as the Eye Nebula, and it got its name (i.e., Ghost of Jupiter) due to its similar size to the planet. The nebula is around two light years across and at its centre there is a white dwarf. 

From analysis of observations it was estimated that the inner layer of the nebula was formed around 1,500 years ago. Furthermore, the two ends of the nebula display lobes of fast moving gas. This feature is known as Fast Low Ionization Emission Region, which is a gas volume of low ionization, that moves at supersonic speeds. This is observed in many planetary nebulae, and it is observed near the symmetry axis.

Image 1: Composite optical image of the Ghost of Jupiter taken with the Hubble Space Telescope (HST). The image was created using narrow band filters that are focused on the emission of oxygen (blue) and hydrogen (red), together with a broadband filter (green).

Image 2: Ultraviolet image of the Ghost of Jupiter, taken with Galaxy Evolution Explorer (GALEX). The small circular blue and white area at centre of the image is the known part of the nebula. The wispy extended region that we see on this image, is most likely from material ejected by the star during its red giant stage. This has not been clarified yet, thus it could be interstellar gas, located in front of the white dwarf, that gets energized by the latter, emitting in ultraviolet. Note that the field of view in this image is much larger than that of the HST.

Image 1 Credit: NASA/ESA

Image 2 Credit: NASA/JPL-Caltech 

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