ESA Hubble Image: Cat's Eye Nebula Scanned

An ESA HST image of the Cat's Eye nebula taken with the ACS/WFC (integration time 1.2 h; north is up and east is left). 

The scale of the image is ~1 by ~1 arcminute. 

Middle: the ~84,000 Gaia detections that were made in this area from 25 July to 21 August 2014. 

A superposition of the two images, showing that Gaia is actually able to detect not only stars but also high surface brightness filamentary structures.

HST image credit: NASA, ESA, HEIC, The Hubble Heritage Team (STScI/AURA)

Gaia image credit: ESA/Gaia/DPAC/UB/IEEC

The top image shows a Hubble Space Telescope exposure of the Cat's Eye Nebula, also known as NGC 6543.

This 1000-year old planetary nebula hosts a central, roughly one solar-mass star at a distance of about 1 kpc.

The Cat's Eye Nebula is coincidentally located very close to the north ecliptic pole, which is one of the two areas on the sky which was scanned some 222 times by Gaia during the 4-week period between 25 July and 21 August 2014 (commonly known as the "28 days undisturbed ecliptic-pole scanning law" phase at the beginning of Gaia's nominal life).

In this period, Gaia's on-board detection algorithms registered more than 84,000 detections in the nebula, depicted in the centre image above.

During Operations Rehearsal 5, which is currently being conducted by the Data Processing and Analysis Consortium (DPAC), these on-board detections were mapped on the sky during the cross-matching process at the Data Processing Centre in Barcelona (DPCB), somewhat surprisingly revealing that they accurately trace out gaseous filaments in the nebula (right image).

Various details in the structure of the nebula, as well as the unexplained presence of hard X rays, suggest that the central star may be a double-star system with an accretion disk and precessing jets.

Gaia will carefully monitor this object until 2019 and the end-of-mission micro-arcsecond astrometry may well reveal the binary nature of this enigmatic system.

Hubble Heritage Team: The Cat's Eye Nebula - NGC 6543

Credit: ESA, NASA, HEIC and The Hubble Heritage Team (STScI/AURA)

Three thousand light years from Earth, the Cat's Eye Nebula (NGC 6543) is a sight that draws in the human eye.

In this image from the NASA/ESA Hubble Space Telescope, numerous bubbles are visible – shapes generated by the ejection of glowing gas as the star at its centre approaches the end of its life.

While large stars die in supernova explosions, average Sun-like stars form planetary nebulas as they exhaust their fuel supplies and slowly expire.

The name 'planetary nebula' arose because the round shape, sculpted as layers of material are ejected, looked a little like a planet in small telescopes.

William Herschel

The Cat's Eye Nebula was discovered by William Herschel in 1786, and remains an interesting target for ground-based astronomers.

Amateurs can see the magnitude 8.1 blob in the sky well enough to resolve the Cat's Eye shape, while large telescopes have identified a wider halo extending into space.

Observations of its intricate concentric gas shells and unusual shock-induced knots of gas suggest that the star ejected its mass in a series of pulses at 1500 year intervals.

These convulsions created dust shells that each contain as much mass as all of the planets in our Solar System combined.