Planet appears to have formed around a white dwarf after its star died

Mixed · 2Astronomers report a gas-giant exoplanet, HS0209+0832b, that appears to have formed after its host star died, in a paper published in Nature Astronomy. 1 2 Mixed · 2The planet orbits HS0209+0832, a white dwarf, which is the compact remnant left when a star like the sun dies; the team has nicknamed it a "phoenix planet". 1 2 Mixed · 2Lead author Jamie Williams, a doctoral student at the University of Warwick, said it is the first example of a planet forming around a white dwarf; such second-generation planets had previously been found only around neutron stars such as pulsars. 2 1

Mixed · 2The evidence is chemical: the planet and star appear to share similar chemistry, and the planet is rich in niobium, copper and zinc, elements that dying stars expel. Metro adds that niobium had never before been detected in a white dwarf. 2 1 Mixed · 2The planet is a gas giant, perhaps slightly more massive than Jupiter, with a 4.4-day orbit at about 4 per cent of the Earth–sun distance. CNA reports that the white dwarf's extreme ultraviolet radiation is evaporating its outer atmosphere, with some of that material falling onto the star. 2 1 Mixed · 2The researchers used data from the Hubble, TESS and FUSE space telescopes and hope to use the James Webb Space Telescope to confirm their conclusions. Metro says the finding could be the first observational evidence of such a planet, if confirmed. 2 1

Left · 1Williams suspects that a companion star spun the white dwarf's leftover layers into a disc, which gravity then clumped into a planet. The planet is too hot for life, at over 1,500°C according to Williams. 1 Centre · 1Williams said other second-generation planets, such as rocky ones, could stay in a white dwarf's habitable zone for billions of years, making them candidates in the search for life. More than 95 per cent of Milky Way stars will become white dwarfs, so such planets could outnumber those around pulsars. 2 Left · 1Metro says that because the white dwarf's progenitor star resembled the sun, Williams thinks a second-generation planet could form after the sun dies in about five billion years. 1

Centre · 1CNA also covers a second Nature Astronomy study, led by MIT's Aaron Householder, of a red dwarf in an 87-minute orbit with a brown dwarf in Taurus. The star appears to be siphoning material from the brown dwarf. 2