Mauna Kea
telescopes find stellar
object ‘in limbo’

HILO >> Astronomers using two telescopes on Mauna Kea have discovered a new type of stellar object never seen before, a cross between a huge planet and a dead star, Gemini North observatory announced yesterday.

The object, part of a pair of objects known as a binary system, was discovered and investigated in 2002-2003 by astronomers Steve B. Howell of Tucson, Ariz., and Thomas Harrison of Las Cruces, N.M., according to the announcement.

The astronomers used the Gemini and the Keck II telescope on Mauna Kea to investigate the binary called EF Eridanus, about 300 light-years from earth.

What they discovered was a small, dense white dwarf star that over the course of 500 million years sucked most of the matter and energy out of its companion star.

The larger but less massive donor star "gave, and gave, and gave some more until it had nothing left to give," Howell said.

"Now the donor star has reached a dead end. It is far too massive to be considered a superplanet, its composition does not match brown dwarfs (large, warm objects that aren't quite stars), and it is far too low in mass to be a star. There's no true category for an object in such limbo," Howell said.

The dead donor object is about the same distance from the white dwarf as the moon is from the earth, but instead of orbiting once every 28 day like the moon does, it spins around the dwarf every 81 hours.

The dwarf has a magnetic field about 14 million times as strong as that of the earth, Gemini said.