Space Telescopes See Born-Again Planetary Nebula

Astronomers have used NASA’s Hubble Space Telescope, ESA’s XMM-Newton and NASA’s Chandra X-ray observatories to peer at the heart of the planetary nebula Abell 30.

The planetary nebula Abell 30, located about 5,500 light years from Earth, as seen in X-rays and optical light by ESA’s XMM-Newton and KPNO (X-ray: ESA / XMM-Newton; optical: NSF / NOAO / KPNO). The inset shows a close-up view of Abell 30 as seen by NASA’s Hubble Space Telescope and Chandra X-ray Observatory (X-ray: NASA / CXC / IAA-CSIC / M.Guerrero et al; optical: NASA / STScI)

A planetary nebula – so called because it looks like a planet when viewed with a small telescope – is formed in the late stage of the evolution of a Sun-like star. Astronomers now know that as a star with less than eight times the mass of the Sun swells into a red giant towards the end of its life, its outer layers are expelled via pulsations and winds. Ultraviolet radiation shining out from the stripped-down hot stellar core then lights up the ejected shells, resulting in intricate artworks that can be seen by modern telescopes.

Abell 30, one of a small number of planetary nebulae known as born-again planetary nebula, is located in the constellation Cancer some 5,500 light-years away.

A Sun-like star at the heart of Abell 30 experienced its first brush with death 12,500 years ago when its outer shell was stripped off by a slow and dense stellar wind. The remnant of this evolutionary stage is seen in optical light as a large, near-spherical shell of glowing material expanding out into space.

The star suddenly came back to life about 850 years ago, coughing out knots of helium and carbon-rich material in a violent event. Its outer envelope briefly expanded during this born-again episode, but then very rapidly contracted again within 20 years. This had the knock-on effect of accelerating the wind from the star to its present speed of 4,000 km per second. These findings appear in the Astrophysical Journal ( version).

As this fast stellar wind catches up and interacts with the slower wind and clumps of previously ejected material, complex structures are formed, including the delicate comet-like tails seen near the central star in this image. The stellar wind bombarding dense clumps of material provides a chilling look at the possible fate of Earth and its fellow planets in our own Solar System in a few billion years’ time.


Bibliographic information: M. A. Guerrero et al. 2012. Rebirth of X-Ray Emission from the Born-again Planetary Nebula A30. ApJ, vol. 755, no. 2, 129; doi: 10.1088/0004-637X/755/2/129