Ein Planet aus einer fremden Galaxie | Unser Universum

Uploaded by WissensMagazin on 12.12.2010

Cannibalism is proscribed ... on Earth!
In outer space, an act of cosmic cannibalism
has brought an exoplanet —
a planet from another galaxy — within astronomers reach
and into our galaxy, the Milky Way.
A European team of astronomers has detected
a Jupiter-like planet, orbiting a dying star.
The star, nearing the end of its life, may engulf the planet.
This could give us breath-taking clues about the fate and the future
of our solar system in the distant future.
Until now, astronomers have detected about
500 planets orbiting stars in our galaxy,
but none from outside the Milky Way.
Now a planet and its star,
both of extragalactic origin,
have been found and confirmed inside our galaxy.
The star, known as HIP 13044, is about 2000 light-years away from earth.
It is part of the Helmi stream –
a stream of stars originally belonging to a dwarf galaxy
which was devoured in an act of cosmic cannibalism
by the Milky Way billions of years ago.
The new planet was detected by astronomers
who were looking for wobbles of the star,
caused by the gravitational tug of the orbiting planet.
These observations were made with a
high-resolution spectrograph named FEROS
at ESO’s La Silla Observatory in Chile.
The planet named HIP 13044 b is one of only a few exoplanets
which survived the huge expansion of its sun.
When all the hydrogen in the core of a star was exhausted, the star became a Red Giant,
one step in its stellar evolution. HIP 13044 b is very close to its sun now.
At the closest point in its orbit its distance to the star
is only as long as 5.5 percent of the distance between earth and sun.
One circumnavigation takes only 16 days.
Astronomers think that the planet’s orbit has been much larger in the past.
They think it moved inwards during the Red Giant phase of the star.
Other planets located closer to the dying star
may not have been so lucky.
They might have been swallowed by the Red Giant,
and this evolution is not complete yet. Another expansion will happen,
and now that the planet is so close to the star, it may be doomed in the end, too.
Astronomers are searching for more planets orbiting dying stars,
because one day our sun will become a Red Giant too,
to our planetary system when this occurs.
and we want to know what might happen
We still got time to learn ... about four to five billion years!