Volunteer Discovers Record-Setting White Dwarf Star
A citizen scientist working with the NASA-led Backyard Worlds: Planet 9 project has found the oldest and coldest known white dwarf — an Earth-sized remnant of a Sun-like star that has died — ringed by dust and debris. Astronomers suspect this could be the first known white dwarf with multiple dust rings.
The star, LSPM J0207+3331 or J0207 for short, is located around 145 light-years away in the constellation Triangulum. White dwarfs slowly cool as they age, and calculations show J0207 is about 3 billion years old based on a temperature just over 10,500 degrees Fahrenheit (5,800 degrees Celsius). A strong infrared signal picked up by NASA’s Wide-field Infrared Survey Explorer mission — which mapped the entire sky in infrared light — suggested the presence of dust, making J0207 the oldest and coldest white dwarf with dust yet known. Previously, dust disks and rings had only been observed surrounding white dwarfs about one-third J0207’s age.
The dust in the disks and rings around white dwarfs is supplied by the break-up of asteroids by the stars’ powerful gravity. In J0207’s case, the ring may even be multiple rings, one thin ring just at the point where the star’s tides break up the asteroids and a wider ring closer to the white dwarf. Follow-up with future missions like NASA's James Webb Space Telescope may help astronomers tease apart the ring’s constituent parts.
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