The oldest and coldest white dwarf star found

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

A citizen scientist working for NASA has found the coldest and the oldest white dwarf star ringed by dust and debris. It is the remnant of a sun-like star and is as big as our earth in size. Astronomers believe that this is perhaps the first time that a white dwarf is found with surrounding rings of dust and gases.

Designated as LSPM J0207+3330 or simply J0207, the star has forced researchers to reconsider the conventional model of a planetary system. It could also help in understanding the distant future of our own solar system.

"The white dwarf is so old that whatever process is feeding material into its rings must operate on a billion-year timescale", said John Debes - an astronomer at the Space Telescope Science Institute at Baltimore, who is working with Nasa-led Backyard Worlds: Planet 9 project.

"Most of the models that scientists have created so far, to explain rings around a white dwarf work only upto 100 million years, so this star is really challenging our assumptions of how planetary systems evolve", Debes added. The findings were published in the Astrophysical Journal Letters.

J0207 is located 145 light years away from our planet in the Capriocornus constellation. White dwarfs slowly cool as they age, and based on the calculations, Debes' team found out that J0207 is about 3 billion years old, with a temperature of just over 5,800 degrees Celsius. Earlier, dust rings have been found around white dwarfs, but they were just one-third as old as J0207. 

Scientists also believe that there may be not just one, but multiple rings around this star. They suggest that there are possibly two distinct components - first, a thin ring just at the point where the star's tides breakup the asteroids and the second, a wider ring closer to the white dwarf.

Future missions like NASA's James Webb Space Telescope may reveal much about these rings.