A "white dwarf" -- a small hot white star of low intrinsic brightness -- recently discovered by astronomers in Hawaii is both the smallest and most massive one ever discovered.
The dwarf has a mass greater than the sun, but is in fact only the size of the moon, Ilaria Caiazzo, the Sherman Fairchild postdoctoral scholar research associate in theoretical astrophysics at Caltech (California Institute of Technology), wrote in a newly published study in the journal "Nature."
“It may seem counterintuitive, but smaller white dwarfs happen to be more massive,” Caiazzo told W.M. Keck Observatory News. “This is due to the fact that white dwarfs lack the nuclear burning that keep up normal stars against their own self-gravity, and their size is instead regulated by quantum mechanics.”
White dwarfs are the collapsed remnants of giant stars.
The latest discovery was made by the Zwicky Transient Facility, operator of Caltech’s Palomar Observatory, which has two 10-meter optical/infrared telescopes in Hawaii, W. M. Keck Observatory on Maunakea, Hawaii Island, and the University of Hawaii Institute for Astronomy Panoramic Survey Telescope and Rapid Response System on Haleakala, Maui.
The 200-inch Hale Telescope at Palomar, the European Gaia Space Observatory and NASA’s Neil Gehrels Swift Observatory, also participated in the discovery, according to W.M. Keck Observatory, a private 501(c)3 nonprofit organization that partners with Caltech, the University of California, and the National Aeronautics and Space Administration.
The sun will one day become a white dwarf, but it will take a while -- about 5 billion years, according to the W.M. Keck Observatory News.
“About 97% of all stars become white dwarfs,” W.M. Keck Observatory News said. “While our sun is alone in space without a stellar partner, many stars orbit around each other in pairs. The stars grow old together, and if they are both less than eight solar-masses, they will both evolve into white dwarfs.”
Really massive stars explode into a type of supernova. Smaller ones merge together to make new white dwarfs.
“Astronomers say that the newfound tiny white dwarf, named ZTF J1901+1458, took the latter route of evolution; its progenitors merged and produced a white dwarf 1.35 times the mass of our sun,” W.M. Keck Observatory News said.
Due to COVID-19, the W. M. Keck Observatory Visitor’s Center at the Observatory’s headquarters in Waimea, as well as the Visitor’s Gallery on Maunakea, are closed to the public until further notice, according to the W.M. Keck Observatory's website.