Science press release

Cataclysmic Cannibals in the Sky

Embargoed: Not for Release Until 2:00 pm U.S. ET Thursday, 07 December 

Astronomers found a binary star class that had been predicted, but 
not yet seen. Called cataclysmic variables, these flickering binary star 
systems contain a compact white dwarf that sucks material from its larger 
companion star, eventually causing the white dwarf to cease hydrogen 
burning and becomes a brown dwarf. Theory held that most short period 
systems should have already evolved to brown dwarfs. Stuart Paul 
Littlefair and colleagues accurately timed the eclipses in a short period 
cataclysmic variable system and showed that the donor is a brown dwarf 5 
percent of the Sun\uffffs mass. Because the star\uffffs mass is higher 
than its orbital period would suggest, the brown dwarf radii may be 
underestimated by current evolutionary models. Pierre F. L. Maxted 
discusses this in a related Perspective. This research appears in the 08 
December 2006 issue of the journal Science.

Caption for image

Artist's impression of SDSS 1035+0551. The hot white dwarf is the same 
size as the Earth, yet weighs the same as our Sun. The brown dwarf is 
about the same size as Jupiter, but much more massive. The gravity of the 
white dwarf pulls gas from the brown dwarf; this gas spirals down onto the

surface of the white dwarf, like water down a plughole, forming an 
"accretion disc" of hot gas around the white dwarf. Where the falling gas 
from the brown dwarf hits the accretion disc, it creates a hot spot. The 
position of this hot spot depends on the masses of the two stars. The 
authors precisely timed when the white dwarf and hot spot were eclipsed by

the brown dwarf. This allowed them to measure the location of the hot 
spot, and infer the masses of the two stars.