Sometimes, if you look deep into the twilight of a dying sun, you might see that the rocky remains of small planets are slowly digested. For the first time, astronomers saw a collapsed star separate the remains of something a little more abundant.
An analysis of the spectral fingerprints of the white dwarf WD J0914 + 1914 revealed rare traces of chemistry belonging to a gas giant, revealing a star system quite different from any other we have seen so far.
Using data collected as part of the Sloan Digital Sky Survey (SDSS), researchers from the United Kingdom, Chile and Germany have found signs of a planet similar to Uranus in orbit so close to a distant white dwarf, the planet is being torn apart.
Although technically removed, the bodies of these stars remain hot enough to radiate for hundreds of billions of years. That warm glow, although still quite dull, can provide astronomers with enough information about its chemical composition.
It is not uncommon to find indications of metals that shine in that soft light, telling a story of nearby rocky planets that evaporate in the heat of the white dwarf. However, for that to happen, the solar system has to be a bit messy. The planets must be close enough for the white dwarf to bake, and that usually points to a jolt caused by a nearby heavyweight.
At a distance of about 2,000 light-years, WD J0914 + 1914 is difficult to see even by white dwarf standards. Initially, researchers studying its spectrum thought it was a binary star system, thanks to the signature of its hydrogen component. A closer look soon found clear signs of oxygen, with tentative signs of sulfur.
The fluctuating proportions of hydrogen and oxygen were strange enough to encourage researchers to return to see better, this time using a tool in the Very Large Telescope of the European Southern Observatory called X-Shooter spectrograph.
By executing the spectral data through a simulation program, the team was able to model the conditions we could expect in the immediate environment of WD J0914 + 1914, revealing important details about the types of objects we would expect to see. The mixture of water and hydrogen sulfide suggested that a gaseous planet similar in composition to our own giants, such as Neptune and Uranus, was abandoning its atmosphere.
âIt took a few weeks of very hard thinking to figure out that the only way to make such a disc is the evaporation of a giant planet,â says Matthias Schreiber from the University of Valparaiso in Chile, who computed the past and future evolution of this system.
Even with this evidence of a gas giant in orbit around a white dwarf, it is not clear if it is an anomaly or if we are simply not looking long enough to find other examples. A thorough inspection of some 7,000 white dwarfs in the SDSS data banks could not find something similar to WD J0914 + 1914.
Even so, around 260,000 examples of these collapsed suns have been identified using the Gaia mission of the European Space Agency, so we have a long way to go before we can draw solid conclusions. Since our own Sun is destined to become a white dwarf, it would be interesting to find more examples that could give us an idea of ââthe distant future of our own Solar System.
Also Read: What If Earth Was the Only Planet in the Solar System?