|
|
Brown Dwarf LP 944-20:
The Mouse That Roared - Chandra Captures Flare From Brown Dwarf
X-ray image of LP 944-20 before
flare and during flare. For the first 9 hr 36
min of Chandra's observation, no X-rays were detected
from the brown dwarf (left panel). Then the brown dwarf
turned on with a bright X-ray flare (right panel) that
gradually diminished over the last few hours of the
observation. The grainy appearance of the image on the
right is due to a shorter exposure time. The bright
dots in the background are other X-ray sources, 7 of
which have been identified as stars.
This is the first flare at any wavelength detected
from a brown dwarf. The energy emitted in the flare was
comparable to a small solar flare, and was a billion
times greater than observed X-ray flares from Jupiter.
The flaring energy is thought to be produced by a
twisted magnetic field.
Brown dwarfs have too little mass to sustain
significant nuclear reactions in their cores. Their
primary source of energy is the release of
gravitational energy as they slowly contract. Located
in the constellation Fornax in the southern skies, LP
944-20 is one of the best studied brown dwarfs because
it is only 16 light years from Earth. It is about 500
million years old and has a mass that is about 60 times
that of Jupiter, or 6 percent of the Sun's mass. The
brown dwarf's diameter is about one-tenth that of the
Sun and it has a rotation period of less than five
hours.
| Fast Facts for Brown Dwarf LP 944-20: |
| Credit |
NASA/UCB/Caltech/R.Rutledge et al. |
| Scale |
Each panel is 5 arcmin on a side. |
| Category |
Miscellaneous Objects |
| Coordinates (J2000) |
RA 03h 39m 34s | Dec -35° 25' 50" |
| Constellation |
Fornax |
| Observation Dates |
December 15, 1999
|
| Observation Time |
12 hours |
| Obs. IDs |
624
|
| Color Code |
Intensity |
| Instrument |
ACIS |
| References | R. Rutledge et al. Ap.J.Letters (20 July 00, in press) |
| Distance Estimate |
16 light years |
| Release Date |
July 11, 2000 |
|
|
|
