----------------------- # 1592 - Planets in other Solar Systems
-
- 2013 - There have been over 1,000 planets discovered outside our Solar System. Our Solar System has 8 planets. This review illustrates the diversity of what we have found so far. The 1,000 confirmed are out or over 4,000 candidates leaving many more potential planets under study.
-
- Like looking for your car keys under the lamppost, we tend to find first the larger planets that are orbiting closest to their star. These are simply easier to detect with the methods used to detect planets. ( See the footnotes ). As measurements get more sophisticated we will find smaller, rocky planets in habitable orbits. Much study remains:
-
- 1991 - was the first discovery of an “ exoplanet”. This planet was orbiting a “ pulsar”. A pulsar is a fast rotating neutron star. A rotating beam of radiation is emitted from the poles. If the rotating beam is pointed towards us at times we see it as a pulse of light. A precise pulse of light. If it wobbles the star is being tugged by an orbiting planet.
-
- A neutron star is a dead star. A star that is a remnant from a supernova explosion. Somehow this explosion did not blow away the Jupiter-size planet that also remains.
-
- 1995 - the first planet was discovered orbiting a normal star. 51 Pegasi is a Jupiter size planet orbiting its sun every 4.2 days.
-
- 2012 - Studying these planets have turned up a diversity of solar systems that were not even imagined. This review highlights some of the more fascinating ones:
-
- A planet discovered in 2012 that is only 10% more massive than Earth. It orbits its star that is 93% the mass of our Sun. This planet is located in the closest star system to us just 4.36 lightyears away. However, it is orbiting very close to its star. 0.042 Astronomical Units. That is 0nly 4.2% of the Earth-Sun distance making it far to hot to support life, 1,200 C.
-
- It is not the hottest planet discovered. Kepler - 70b orbits just 0.6% AU from its star that was a Red Giant just 18 million years ago. At that time the planet was inside the bloated atmosphere of the Red Giant Star. Today it is a hot cinder with a surface temperature of 6,930 C.
-
- Not all planets are so close to their star. They are harder to detect in distant orbits but a planet orbiting the star Formalhaut takes 876 years to complete one revolution. The is 5 times longer than for the planet Neptune.
-
- The oldest planet discovered is 13 billion years old. The Universe is only 13.72 years old. It has been around for a long time orbiting a binary system. The two star system consists of a Pulsar and a White Dwarf star. It takes the planet 100 years to orbit the pair and it s 2.5 times the size of Jupiter.
-
- 2008 - In the same star system where the first planet was discovered orbiting a normal star a companion planet is in orbit around the same star that is 1.4 times the size of Jupiter. It takes only 1.1 days to orbit its star that super heats it to 2,650 C. The planet is so hot its atmosphere has nearly all evaporated. It is close enough for spectrums of light passing through the remaining atmosphere to have absorption lines that identify the gases. The molecules that have been detected include water, methane, carbon monoxide, aluminum, magnesium, tin and vanadium existing in the steamy atmosphere.
-
- So far 4 stars have a system of at least 6 planets.
-
- 2013 - June - a star was discovered with 3 planets in its “ habitable zone”. Habitable zone orbits are defined as those where conditions allow liquid water to exist on their surface. The system consists of 6 planets with the 3 habitable planets orbiting at 13% and 21% AU. The planets are orbiting closer but the star is a Red Dwarf Star about 30% the mass of our Sun. The system is 22 lightyears away.
-
- Kepler- 11 system star is 95% the mass of our Sun. But all 5 inner planets are orbiting so close to the star they could all fit inside the orbit of Mercury.
-
- There is a lot more diversity to add to the list. The list keeps growing and more about planet candidates is discovered every day. There are 36 planets under study that could be habitable under our definition. 12 of these are confirmed. They could have the same size ,temperature, elements and age that life could have evolved. Looking at all the twists and turns of our own evolution it seems unlikely that even under similar conditions life will be what we are familiar with. It is a fascinating exploration. Stay tuned, and announcement will be made shortly.
-------------------------------- -------------------------------------------------------------------
- Radial Velocity change is one method of planet detection. In this case orbiting planets cause the host star to wobble around the system’s common center of gravity. When the star orbits towards us it is blue shifted a slight amount. When it is moving away from us it is redshifted. The velocity change is only 1 meter per second resolution for today’s technology. We need 0.1 centimeters / second resolution to detect a single Earth-size planet.
-
- The transit method of planet detection requires the planet to pass in front of the star in our line of sight. When this happens the planet blocks a slight amount of light from the star. In essence the planets shadow sweeps across the telescope. A Jupiter size planet might dim the brightness by 1%. To detect an Earth size planet it would be 0.01% and we would need one part per million brightness resolution to measure it.
-
------------------------------------------------------------------------------------------------------
RSVP, please reply with a number to rate this review: #1- learned something new. #2 - Didn’t read it. #3- very interesting. #4- Send another review #___ from the index. #5- Keep em coming. #6- I forwarded copies to some friends. #7- Don‘t send me these anymore! #8- I am forwarding you some questions? Index is available with email upon request. Some reviews are at http://jdetrick.blogspot.com Please send feedback, corrections, or recommended improvements to: jamesdetrick@comcast.net. ---- “Jim Detrick” -- www.facebook.com, -- www.twitter.com, -- 707-536-3272 Wednesday, September 25, 2013
No comments:
Post a Comment