FIRST SIGHTING
Nov 13th 2008
Planets are seen outside the Solar System
A FEW grainy smudges and computer-generated blobs are not much to look
at. But these are the first images of planets outside the Solar System,
or exoplanets as they are called. The star they are orbiting, the mass
of blobs seen in the picture, is known only as HR 8799. It is 128 light
years from Earth, and is just visible to the naked eye in the
constellation of Pegasus. The three red dots, marked b, c and d, are
exoplanets.
Since the 1990s more than 300 exoplanets have been found and the number
is growing. However, their presence can usually only be inferred
through the gravitational influences they have on their nearby star.
Images of the three planets at HR 8799, however, were captured directly
using two high-altitude telescopes in Hawaii.
This was quite a feat as the intense light from the star normally
obscures the subtle visual details necessary to distinguish a planet.
However Christian Marois, of the NRC Herzberg Institute of Astrophysics
in Canada and his colleagues, developed a computer processing technique
that was able to separate the light from HR 8799 from the light the
planets are emitting--they are still so young that they are glowing
from heat left over from their formation about 60m years ago. Compared
with Earth, which is about 4.5 billion years old, these are newly
minted.
The three planets are all relatively large, having masses between five
and 13 times that of Jupiter, according to a report published in
SCIENCE this week. The smallest exoplanet is closest to the sun and the
largest is the farthest away, which is interesting to astronomers
because it resembles a scaled up version of the outer part of the Solar
System. This lends support to current theories of planetary formation.
Planets are believed to emerge from the accretion of particles in a
disk of gas and dust as they whirl around the star. The next step is to
look at the chemical composition of these planets, their cloud
structures and their thermal properties.
See this article with graphics and related items at http://www.economist.com/science/displayStory.cfm?source=hptextfeature&story_id=12592240
Planets are seen outside the Solar System
A FEW grainy smudges and computer-generated blobs are not much to look
at. But these are the first images of planets outside the Solar System,
or exoplanets as they are called. The star they are orbiting, the mass
of blobs seen in the picture, is known only as HR 8799. It is 128 light
years from Earth, and is just visible to the naked eye in the
constellation of Pegasus. The three red dots, marked b, c and d, are
exoplanets.
Since the 1990s more than 300 exoplanets have been found and the number
is growing. However, their presence can usually only be inferred
through the gravitational influences they have on their nearby star.
Images of the three planets at HR 8799, however, were captured directly
using two high-altitude telescopes in Hawaii.
This was quite a feat as the intense light from the star normally
obscures the subtle visual details necessary to distinguish a planet.
However Christian Marois, of the NRC Herzberg Institute of Astrophysics
in Canada and his colleagues, developed a computer processing technique
that was able to separate the light from HR 8799 from the light the
planets are emitting--they are still so young that they are glowing
from heat left over from their formation about 60m years ago. Compared
with Earth, which is about 4.5 billion years old, these are newly
minted.
The three planets are all relatively large, having masses between five
and 13 times that of Jupiter, according to a report published in
SCIENCE this week. The smallest exoplanet is closest to the sun and the
largest is the farthest away, which is interesting to astronomers
because it resembles a scaled up version of the outer part of the Solar
System. This lends support to current theories of planetary formation.
Planets are believed to emerge from the accretion of particles in a
disk of gas and dust as they whirl around the star. The next step is to
look at the chemical composition of these planets, their cloud
structures and their thermal properties.
See this article with graphics and related items at http://www.economist.com/science/displayStory.cfm?source=hptextfeature&story_id=12592240
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