LP 944-20: A Failed Star Flares
Explanation:
The tiny spot circled on the right actually represents a big
astronomical discovery -- the first detected
flare from a failed star.
Failed stars, termed
brown dwarfs in astronomers'
parlance,
are too low in mass to ignite nuclear hydrogen burning in their cores,
yet still shine feebly as the energy from
their gravitational collapse is converted to heat and light.
In fact, the
dim brown dwarf cataloged as LP944-20 is
estimated to have only
6 percent the mass of the Sun (60 times the mass of Jupiter) and
one-tenth the Sun's diameter.
A mere 16 light-years distant in the southern constellation Fornax
it is
well studied,
but this failed star recently
startled astronomers
by producing a
flare visible at
x-ray energies.
The above
Chandra X-ray Observatory
images of the
LP944-20 star field were
recorded in December 1999.
Showing nothing (left) for the first
nine hours, the brown dwarf generated a significant x-ray flare during the
final hours of the observation.
How did a failed star produced such a
high-energy flare?
Magnetic fields twisted and broken by turbulent motions near the surface
of the brown dwarf may be the culprit.
Difficult to detect
because they are otherwise faint, brown dwarf stars
are believed to be
common throughout the galaxy.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
