Oct. 15, 2004 — The unidentified corpse of what might have been a brown dwarf star has been found orbiting its suspected murderer: a white dwarf star. Dwarfs killing dwarfs — what's the galaxy coming to?

It appears that a dim and dying white dwarf star three-fifths the mass of our sun has been sucking the life out of its unseen smaller companion for eons.

All that remains of the companion is a dark, still-warm body one-twentieth the mass of our sun. It has spectral features and a composition that match no known type of dwarf star or planet, and so is hard to put in any known category for heavenly objects.

"Maybe somebody will come up with something," said astronomer Steve Howell of the Wisconsin-Indiana-Yale-NOAO telescope and the National Optical Astronomy Observatory in Tucson, regarding what to call the newfound dead celestial body.

All the other good relevant colors have already been assigned to other sorts of dwarf stars, he said.

There are already red, brown and white dwarfs. Maybe a "pink" dwarf is called for, Howell mused, possibly referring to the fact that the object shines only in infrared light.

Because the dead object has lost so much material to the white dwarf, it no longer has the gravity to smash atoms together, trigger nuclear reactions and shine. On the other hand, it's too big to be called a planet, Howell said.

Howell co-authored a paper on the discovery of the unclassifiable dead object in the EF Eridanus star system in the Oct. 20 issue of Astrophysical Journal. EF Eridanus is located 300 light-years from Earth in the constellation Eridanus.

The dead object is about the mass of a brown dwarf, said dwarf star specialist Jonathan Lunine of the University of Arizona's Lunar and Planetary Lab.

"This is the first case where the donor object is a brown dwarf (in size)," said Lunine of known cases where one stellar object is being stripped of material by another.

It may not be the last such case, however. Howell said they are already designing a telescope survey system to search for similar objects. Even before having the survey, Howell and his colleagues have identified 10 to 15 candidate star systems where he wants to look for dead companions, he said.

If more such star systems are found, the new class of dark, dead objects could prove important for figuring out where the galaxy is hiding some of the matter needed to hold the Milky Way together — in other words, dark matter, said Howell.