Our Neighbors
-This is a short posting about our closest galactic neighbors, the Alpha Centauri star system. To me Alpha Centauri is the most interesting of all systems because it is the closest one to us. If one is to be a well rounded informed person, it seems to me that a little knowledge about our neighboring star system is required. -
The Alpha
Centauri system is a triple star system which consists of three stars:
Proxima Centauri, Centauri A, and
Centauri B. The Centauri system is located a little more the 25 trillion miles, or 40 trillion kilometers.
This distance takes about 4.36 years for light to
travel. (light-speed per year = 5.88 trillion miles, or 9.46
trillion kilometers) When put into perspective of galactic
distances, this distance can be considered relatively small.
-Keeping in mind that the known universe is 156 billion light-years
across.
It is theorized that all three stars in the Centauri
group where formed together from the same nebula, all around the
same time. This would then indicate that each object in the system
is made up of similar elemental composition. Both stars A and B are
gravitationally bound to one another. "Alpha Centauri A and B orbit
each other at a distance of about 3600 million km, or somewhat more
than the distance of planet Uranus from the Sun. The orbital period
is almost exactly 80 years." (-www.eso.org)
Proxima however, is distinctly distant from the others and so it is still
being debated
whether or not Proxima is gravitationally bound to the others.
Proxima is about 1.5 million km closer to our Sun then it's
sisters. If Proxima is gravitationally attached to Centauri A & B,
it's orbital period is roughly a million years long. (-for a
full orbit
around A & B)
Star Descriptions...
Proxima Centauri -
4.85 Billion years old, 0.123 Solar Masses, 0.145 Solar Radius, Temp
= 3,040 Kelvin, Brightness = 0.000138 Solar Luminosity, Star Type =
Red Dwarf, M5 Class
Centauri A -
4.85 Billion years old, 1.100 Solar Masses, 1.227 Solar
Radius, Temp = 5790 Kelvin, Brightness = 1.519 Solar Luminosity,
Star Type = Main Sequence, Yellow Dwarf, G2 Class
Centauri B -
4.85 Billion years old, 0.907 Solar Masses, 0.865 Solar
Radius, Temp = 5260 Kelvin, Brightness = 0.500 Solar Luminosity,
Star Type = Main Sequence, Orange, K1 Class
Our Sun - 4.65 Billion
Years old, 1.00 Solar Masses, 1.00 Solar Radius, Temp = 5770 Kelvin,
Brightness = 1.00 Solar Luminosity, Star Type = Main Sequence,
Yellow Dwarf, G2 Class
You can see from the table above that there are many similarities between our Sun and
Centauri A & B. Because of this it is being proposed that there may be a high probability
that life exists in the Alpha Centauri system. The two Centauri stars share
similarities of size, temperature, age, luminosity, elemental make
up, and sequence, with the Sun in our system. This all bodes
well for the possibility of existing life.
For life to exist however, there are going to have to
be some orbiting objects in the system besides just stars. It is
generally assumed by many, to be preferable that these satellite
objects be Earth size planets, with similar elemental make up. But, many
microbiologists and astrobiologist point out this criteria is by no
means necessary for the existence of life. See
Microbiology Short,
Looking for Life,
Panspermia Video. It can however, be
commonly agreed upon that the discovery of an Earth-like planet,
dramatically increases the probability of finding life. Whether
there are planets or even Earth-like planets orbiting the Centauri
system is still unclear. But planet finding techniques are improving
and research into the Centauri system is currently underway.
In 2008 researcher Javiera Guedes headed a NASA founded
project to analyze the possibility of detecting an Earthlike planet
in orbit around Alpha Centauri B, and the resulting findings were
positive. "Such a planet would be too small to see, but its gravity
will pull on its host star, making it rock back and forth in a way
that the telescope can detect." -(NASA.gov)
Since that time several teams have begun investigating Alpha
Centauri for signs of planetary bodies. One is a NASA funded team has begun using a telescope in
Chile to closely monitor the star over a three to five year period.
Another group currently
investigating the Centauri system is based at the
High Accuracy Radial velocity Planet Searcher (HARPS) at
the European Southern Observatory. And just recently the University of Canterbury,
working out of Mt. John Observatory has joined the planet hunt. With
three independent professional full-time teams investigating Alpha
Centauri, it
shouldn't be long until we know whether or not there are planets of
any kind in our neighboring star system.
"Being
visible to the naked eye, Alpha Centauri has been known for
centuries, if not millennia, although perhaps not as a double star
until the 1752 observation of the Abbé." (-solstation.com) Proxima,
because of it's small size and dimness (see chart above) was not
official discovered until 1915. At which time it was first
documented by Robert Thorburn Ayton
Innes of Cape Observatory.
Alpha Centauri's closest neighboring stars are as
follows: Sol - 4.36 light years away, Barnard's Star - 6.5
light years away, Ross 154 - 8.1 light years away, Wolf 359 - 8.3
light years away, Sirius 2 - 9.5 light years away,
Epsilon Indi - 9.7
light years away.
Sources
Additional references on this subject can be found :
Reference Links
- http://www.space.com
- http://www.solstation.com
- http://www.nasa.gov
- http://www.jpl.nasa.gov
-
http://www.eso.org/public/
- Parallel Worlds by: Michio Kaku
- Life In Darwin's Universe by: Gene Bylinsky