| Nov 15, 2012 | |
Born-again star foreshadows fate of Solar System |
|
| (Nanowerk News) Astronomers have found evidence for a dying Sun-like star coming briefly back to life after casting its gassy shells out into space, mimicking the possible fate our own Solar System faces in a few billion years ("Rebirth of X-ray Emission from the Born-again Planetary Nebula Abell 30"). | |
| This new picture of the planetary nebula Abell 30, located 5500 light-years from Earth, is a composite of visible images from the NASA/ESA Hubble Space Telescope and X-ray data from ESA’s XMM-Newton and NASA’s Chandra space telescopes. | |
 |
|
| Abell 30: a born-again planetary nebula. Credits: Main image: X-ray: ESA/XMM-Newton; optical: NSF/NOAO/KPNO; inset: NASA/CXC/IAA-CSIC/M. Guerrero et al; optical: NASA/STScI | |
| ‘Planetary nebula’ is the name given to the often-concentric shells of stellar material cast into space by dying stars. To astronomers of the 18th century, these objects looked like the colourful ‘blob’ of a planet through their telescopes, and the name stuck. | |
| 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. | |
| The star at the heart of Abell 30 experienced its first brush with death 12 500 years ago – as seen from Earth – when its outer shell was stripped off by a slow and dense stellar wind. | |
| Optical telescopes see the remnant of this evolutionary stage as a large, near-spherical shell of glowing material expanding out into space. | |
| Then, about 850 years ago, the star suddenly came back to life, coughing out knots of helium and carbon-rich material in a violent event. | |
| The star’s outer envelope briefly expanded during this born-again episode, but then very rapidly contracted again witin 20 years. | |
| This had the knock-on effect of accelerating the wind from the star to its present speed of 4000 kilometres per second – over 14 million kilometres per hour. | |
| 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. | |
| When our Sun emits its final gasps of life at the heart of a planetary nebula, its strong stellar wind and harsh radiation will blast and evaporate any planets that may have survived the red giant phase of stellar evolution. | |
| If any distant civilisation is watching with high-power telescopes at the time, they might see the glowing embers of the planets light up in X-rays as they are engulfed in the stellar wind. |
| Source: European Space Agency | |
|
Subscribe to a free copy of one of our daily Nanowerk Newsletter Email Digests with a compilation of all of the day's news. |