For the very first time, scientists have found evidence of a giant planet associated with a white dwarf star.
Professor of Public Understanding of Science at the University of Brighton, Hal Sosabowski, told LBC News the planet offers us a glimpse at the potential future of our own solar system.
The global team behind the study examined 7,000 white dwarfs that were observed as part of the Sloan Digital Sky Survey. "We knew that there had to be something exceptional going on in this system, and speculated that it may be related to some type of planetary remnant".
Using the Very Large Telescope of the European Southern Observatory in Chile to obtain more observations of this star, they found that the shape of the hydrogen, oxygen, and sulphur features are typical indicators of a ring of gas. "However, our observations show that it is a single white dwarf with a disk around it roughly 10 times the size of our sun, made exclusively of hydrogen, oxygen, and sulfur". The VLT turned its gaze on the odd white dwarf, and with the help of a powerful spectrograph instrument called X-shooter created a detailed spectrum, or breakdown, of the star's light.
"We were stunned when we realized that when observing hot white dwarfs, we are potentially seeing signatures from extrasolar planet atmospheres", Schreiber says.
The giant planet takes just 10 days to orbit the star and it leaves a trail of gas comprised of hydrogen, oxygen and sulfur.
But the radiation emitted by the Sun, once it becomes a white dwarf, will be powerful enough to evaporate the atmospheres of Jupiter, Saturn and Uranus where they are orbiting now. "Such a system has never been seen before, and it was immediately clear to me that this was a unique star". But Mars, the asteroid belt, Jupiter and the rest of the planets in the Solar System will expand out on their orbits, as the Sun loses mass because it will have less of a gravitational pull on those planets. By contrast, the planet is icy and large-at least twice as large as the star. "But because the star is so hot, it is evaporating the planet, and we detect the atmosphere it is losing".
It is pulling its lost mass into a gas disc around the star at a rate of more than 3,000 tonnes per second.
The insignificant sun exerts its diminishing force on the planet, stripping its atmosphere and spinning an elegant disk of gas around it in the process.
Stars like our Sun burn hydrogen in their cores for most of their lives. In the case of the Solar System, this will include Mercury, Venus, and even Earth, which will all be consumed by the red-giant Sun in about 5 billion years.
"It will then contract to a white dwarf, like we have seen with the star in question".
Dead stars can have planets, too.
An global team used observational data from multiple telescopes and theoretical models to conclude that while the white dwarf star is ancient, it's five times hotter than our sun.
Researchers say the star is around 2,000 light years from Earth. This time around, researchers in the United Kingdom, Chile, and Germany took a closer look at what they thought was a pair of white dwarfs in a system called J0914+1914. The unusual position of the planet implies that at some point after the host star became a white dwarf, the planet moved closer to it.
While the astronomers could not directly observe the planet, the extreme heat of the 28,000 C star is causing it to slowly evaporate. It will be reduced to a handful of large planets orbiting a small, very dense star that once used to a glowing ball of burning hydrogen and helium. "This discovery of a planet orbiting closely around a burnt-out stellar core forcefully demonstrates that the Universe is time and again challenging our minds to step beyond our established ideas", concludes the lead author.
The discovery by astronomers from the University of Warwick's Department of Physics and the Millennium Nucleus for Planet Formation (NPF) at the University of Valparaiso is published in the journal Nature.