Yintee Cheung
Astronomy II
Professor Acquaviva
Term Project: Extra solar planets
Ever wonder if they were other people out there in the universe? Well humans have been pondering that question at the sky since Galileo looked through his telescope since the ancient time. We’ve come a far way from the days when we thought we were at the center of the universe by divine intervention. Now we are blessed or cursed with technology that’s growing at the exponential pace; we have created more questions than answer the age old questions. How we came to be? Why are we here? And are there aliens out there? We are still asking these questions, but we are getting closer to having an answer. Our advanced telescopes of the modern times have made many new discoveries that we hardly have any time to digest all the news. The Hubble telescope have given us a glimpse of what the outside world looks like, the Kepler telescope’s special mission to search for habitable planets, and the European southern Observatory is building the largest optical/near-infrared telescopes here on earth for the better understanding of our universe. Extra solar planets have made many exciting splash in the media recently. Not too long ago we thought only the solar system had planets orbiting our star. Now the Kepler mission have discover many confirmed planets that are between are smaller than the Earth and those that are more massive than our Jupiter. And still the search is on for the other thousands more candidates that are thought to be planets orbiting their stars.
In December 2011, Astronomers confirmed the first plant in the habitable zone with a radius of 2.4 times the size of the Earth orbiting a sun-like star named Kepler-22b. and later that month two more planets the size of Earth called Kepler-20e and Kepler 20f. Towards the beginning of 2012, Scientists discovered another three small rocky planets by using data from Kepler mission, Palomar Observatory and the W. M. Keck Observatory on Hawaii. These planet are orbiting very close to a star named KOI 961, Barnard’s Star is a red dwarf star and it only takes two days to finish orbiting their parent star. These planets are too close to their star to be in a habitable zone. Most of the planets that confirmed in the universe are mostly gas giants like Jupiter, we have only made a few discoveries of Earth-size planet orbiting a sun-like star.
Sun-like stars may host planet systems that are identical to our solar system as with the discovery of the an Earth mass planet orbiting Alpha Centauri A and B, our closest neighbor in the Milky way on October of 2012. But scientists may also be discovering planets orbiting brown dwarf, the failed stars that never reach the temperature high enough for thermal nuclear reaction. By using the ALMA (Atacam Large Millimeter/submilimeter Array, astronomers found tiny solid grains in the dusty outer regions in the rims of the brown dwarf, it was thought that any microscopic grain that form together by gravity would be hurdle through the center of their star. But surprisingly these grains are forming in the region where it’s icy and cold. These new discoveries would bring a new understanding of how the planets are formed with their stars.
(Artist rendering of a brown dwarf with its rim of dusty particles.)
Discoveries of the planets are so fast and exciting, and if we ever desire or need to colonize the planet, we really need to know what the composition of the planet is. The scientists working at the Very Large Telescope short for LVT in Chile was able to detect the atmosphere of the planet Tau Bootis b by combining the CRIRES high quality infrared instrument and the VLT at ESO’s Paranal Observatory to detect the weak signals from the light reflecting from the planet’s atmosphere. The Tau Bootis was one of the first and closet exoplanets discovered in 1996. The team was able captured the 0.01% of the light coming from Tau Bootis. They discovered that planet has an orbit angle of 44 degrees and a mass that’s six times of Jupiter, and were able to measure Carbon Monoxide was present in the atmosphere. They also discover the fact that temperature is colder in the higher end of the atmosphere; this is the exact opposite of other Jupiter like planets. The feat was a major breakthrough in astronomy, because most of the discoveries were made by the gravitational pull from the star and the planets, thus only big planets like Jupiter would have an effect that is visible in such a long distance. But by using this new technology we are able to find other planets that don’t transit their stars.
We are only just started the hunt for planets, but just how many out there are habitable and can intrigue us to travels light years from home for a visit or migrate? The answer is estimated to be tens of billions of habitable planets in our galaxy alone. New results are ESO HARPS planet finder reveled that rocky planets around the size of the earth are very common in the goldilocks zone of red dwarfs. The team of astronomers estimated that number by using the spectrograph with the 3.6 meter telescope at ESO’s La Silla Observatory in Chile. They have been searching the sky for the most common star in our galaxy, red dwarfs. These stars account for about 80% of the stars in the Milky Way. The Observations noted that 40% of the all red dwarfs stars have super Earth orbiting in the habitable zone where liquor water exists like the on the surface of Earth. They carefully selected dwarfs stars over a six year period and found a total nine super Earths; two were inside the habitable zone named Gilese 581 and Gilese 667 C. By calculating the data from their findings, the team found the occurrence of super-Earths in the habitable zone is around 41% ranging from 28% to 95%. But found that massive planets like Saturn and Jupiter are a rare breed of planets orbiting red dwarfs. These estimates mean we have about a hundred super-earths in the not too hot and not too cold zone at the distance of 30 light years from the sun.
As the technology speeds through time and time again, some day we should be able to visit some of these planets. If humans remind humans in the next thousand years, we would probably visit one with the highest value known to mankind, the rock of that defines richness, the diamond. Recently a team of astrophysicists has plausible evidence that one such planet is made entirely of diamonds, and it’s twice the size of our earth. The planet 55 Cancri e is located 40 light years from earth with a mass of eight times that of Earth. The team used a radio telescope to determine the mass, diameter and the orbit of the 1648 C degree hot planet. They used this data to determine the composition to be of diamonds and graphite on the surface and traces of silicon and carbon.
I would love to visit any other planet in our galaxy, but as of this writing, there’s only a hand of astronauts who have landed on the moon. And rovers landed on Mars and Venus. So I would conclude my chances of ever visiting an exoplanet in the Milky Way is next to nil, but none the less the discoveries provides an exciting portal to another galaxy where science fiction meets astrophysicist. When one day time warp or light speed travel is possible, we can visit the young days of our solar system and answer the fundamental question. Who are we, why are we here?
Bibliography
Eric Hand, Nature Oct 16 2012. http://www.nature.com/news/the-exoplanet-next-door-1.11605
Clark Liat, Wired UK Oct 12 2012. http://www.wired.com/wiredscience/2012/10/diamond-exoplanet/
http://www.eso.org/public/news/eso1214/
http://www.eso.org/public/news/eso1227/
http://www.eso.org/public/news/eso1248/
