Astronomers find hints of a 'second-generation' planet born after its star died
In brief
Astronomers led by the University of Warwick say they have found the first strong hints of a "second-generation" planet: a world that formed from material thrown off by a dying star rather than from the dust left over when the star was born. The clue is the element niobium, found in large amounts in the atmosphere of the white dwarf HS 0209+0832, the study in Nature Astronomy reports.
A cold case in old Hubble data
Hubble first looked at this white dwarf in 1999, and the data had about 100 features nobody could identify, NASA says. Lead author Jamie Williams, a doctoral candidate at Warwick, went back with an updated chemical database and found that niobium matched many of them. It is the first time niobium has been seen in a white dwarf. Copper and zinc are also unusually common there. Elements heavier than iron like niobium are not made by normal fusion in a star's core, but in the extreme conditions inside dying stars, so their presence points to material from the star's final stages.
Where the planet comes in
NASA's TESS satellite watched the star for four months and saw its brightness change in a regular pattern every 4.4 days, which the team says fits a planet orbiting about 6 million kilometres away, far closer than Mercury is to the Sun. The researchers think it is a gas giant roughly the size of Jupiter, formed from the star's cast-off layers. The young, very hot white dwarf is stripping its atmosphere, which may leave a comet-like tail that falls onto the star and explains the strange chemistry. The planet is still a candidate, and the team plans more Hubble observations.
VSH take: this is a nice reminder that a star's "death" may not be the end of its story. Curious kids and students can explore real space data on our ISS tracker and Live Earth from space pages, use the scientific calculator to work out how many times farther Mercury is from the Sun (about 58 million km) than this planet is from its star, or revise science topics on our study pages.
This is our own summary of published research and official announcements. ViralScopeHub is not affiliated with NASA, ESA, the University of Warwick or Nature Astronomy.
Why it matters
If confirmed, a planet built from a dead star's debris would show that planet formation can happen twice in a star system's life, changing how astronomers think about the future of systems like our own.
People also ask
What is a second-generation planet?
It is a planet that forms around a stellar remnant, such as a white dwarf, from material the star threw off as it died, instead of from material left over from the star's birth.
Why is niobium important in this discovery?
Niobium is made in the extreme conditions inside dying stars. Finding a lot of it in the white dwarf's atmosphere suggests it is eating material from a planet built from that dying star's debris.
Has the planet been confirmed?
Not yet. It is a strong candidate based on Hubble, FUSE and TESS data, and the team plans more observations.
Related free tools: Scientific Calculator, Unit Converter
Sources
- NASA Science: Suspected Second-generation Planet Solves NASA Hubble Cold Case
- Nature Astronomy: Discovery of a second-generation planet candidate accreting onto a white dwarf
- University of Warwick: Astronomers find a world reborn from its star's ashes
- Eos: White Dwarf Spotted Devouring the Planet It Birthed
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