APOD: 2004 August 27- The Sedna Scenario
Explanation:
The discovery of
Sedna
(
aka
2003 VB12), the most distant known object
orbiting the Sun, presents a
mystery.
Pluto's orbit averages about 40 AU in radius,
where an AU (Astronomical Unit) is the
Earth-Sun distance.
But the closest point in
Sedna's eccentric orbit
scarcely comes within 75 AU, while its farthest point
extends to nearly 1,000 AU.
So how did something
as large as Sedna get so far out there?
Exploring
the problem with computer simulations, astronomers
Alessandro Morbidelli and Harold Levison suggest
that while Sedna was not formed in its current
location, it was also not moved there by encounters with
other
solar
system objects.
Instead, they find it more likely that
Sedna resides in its present orbit because of an
encounter with another star.
In one scenario, objects
like Sedna are yanked out of closer
orbits by the gravitational pull of a
Sun-sized star passing near the solar system
during its
formative years.
Alternatively Sedna could have formed of material
from another system entirely, captured during an early
encounter with a much
smaller
star.
Both Sedna-forming stellar encounter scenarios are consistent
with idea that the Sun itself was born in an ancient, dense,
cluster
of
stars.
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.
