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New PODCAST:FINDING EXOPLANETS February 18, 2011

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Sponsored by the Physics Department at Eastern Illinois University

GO TO FINDING EXOPLANETS PART 4

This podcast discusses the topic of Exoplanets and life on other planets out of our solar system

Thomas HofstätterBio: Born in 1993 near Vienna, Austria, Europe. Upper High School with focus on Computer Science.Interested in extreme small and extreme big, devious and uninvestigated things.Thomas Hofstätter main aim is to bring astronomy to public and to establish secular interest in astronomy, physics and mathematics. Host of :: The Hidden Space Project :: at

http://hidden-space.at.tf.”

Earth-sized Exoplanet is in Nearby Star’s Habitable Zone! September 29, 2010

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Gliese 581d

(From Universe Today) An enticing new extrasolar planet found using the Keck Observatory in Hawaii is just three times the mass of Earth and it orbits the parent star squarely in the middle of the star’s “Goldilocks zone,” a potential habitable region where liquid water could exist on the planet‘s surface. If confirmed, this would be the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one. The discoverers also say this finding could mean our galaxy may be teeming with prospective habitable planets.

“Our findings offer a very compelling case for a potentially habitable planet,” said Steven Vogt from UC Santa Cruz. “The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common.”

Vogt and his team from the Lick-Carnegie Exoplanet Survey actually found two new planets around the heavily studied red dwarf star Gliese 581, where planets have been found previously. Now with six known planets, Gliese 581 hosts a planetary system most similar to our own. It is located 20 light years away from Earth in the constellation Libra.

The most interesting of the two new planets is Gliese 581g, with a mass three to four times that of the Earth and an orbital period of just under 37 days. Its mass indicates that it is probably a rocky planet with likely enough gravity to hold on to an atmosphere.

For more go to the rest of the article at Universe Today.

Astronomers find a “Super Earth” with Atmosphere & Water December 17, 2009

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The discovery is to be published today (December 17th) in the Journal Nature. A Super-Earth is a rocky planet between one and ten times the mass of the Earth. The planet was discovered orbiting the star, GJ1214, which is a nearby red dwarf about 40 light years from Earth. This type M star is about 1/5 the size of the Sun. The star is cool at 4,900 degrees F (3000 degrees K) compared to the Sun’s 10,000F (5700 degrees K) and has a luminosity only .003 as bright as the Sun.The planet, GJ1214b, is about 6.5 times as massive as the Earth.

Credit: CNN

The MEarth project spotted the planet using a 16″ telescope, The same size as at Eastern Observatory. However , it is not as simple as looking at a random star to see a planet.

The MEarth (pronounced “mirth”) Project is an array of eight identical 16-inch-diameter RC Optical Systems telescopes that monitor a pre-selected list of 2,000 red dwarf stars. Each telescope perches on a highly accurate Software Bisque Paramount and funnels light to an Apogee U42 charge-coupled device (CCD) chip, which many amateurs also use. The project looks for the signature dimming of a star caused by an orbiting planet  eclipsing the star.

Credit: Dan Brocious, CfA

MEarth telescopes

GJ1214b orbits its star once every 38 hours at a distance of only two million kilometres — 70 times closer to its star than the Earth is to the Sun. “Being so close to its host star, the planet must have a surface temperature of about 200 degrees Celsius, too hot for water to be liquid,” said Charbonneau.

However, computer models show that because of its larger diameter, compared to its mass, it may have an interior made of water ice. Because the planet is nearby, the Hubble space telescope has a good chance of directly observing the atmosphere of the planet and measure its composition.

Tuesday November 10: “Other Star Other Planets” November 9, 2009

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IYA Poster #4a

Poster by J Boshart

IYA Talk: “OTHER STARS, OTHER PLANETS” in one week November 3, 2009

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“OTHER STARS, OTHER PLANETS”  by Jim Kaler Ph.D. , on Tuesday November 10th, 7:00 PM , Phipps Lecture Hall , Physical Science Building. Celebrating the International Year of Astronomy

Take a tour of our Solar System. Then gaze into the heavens and  wonder if it is replicated elsewhere. Are there planets in orbit around other stars? If so, how do we find them, what are they  like? In this talk we will explore not just “extra-solar planets”  (more than 400 found), but extra-solar planetary SYSTEMS, some of
which are beginning to look a lot like our own. Are there then “earths” among the crowd, and is there life? Let the stars themselves tell the story.

exo-planet

Other Stars, Other Planets

Jim Kaler Ph.D. Professor Emeritus of Astronomy at U of I
Past President Astronomical Society of the Pacific, author of over 120 research articles and 20 books,
Asteroid 1998 JK was named 17853 Kaler in honor of his outreach activities, and in 2008 he received the American Astronomical Society’s Education Prize.

Are we still looking for other worlds? July 25, 2009

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What ever happened to extrasolar planets?  They used to make the news.  The search for these distant worlds, however, is as fervent as ever.  As better technology and new techniques have been developed, finding them has become commonplace.  To date, the known number of exoplanets, as they are commonly known, has increased to over 350.  But what are exoplanets, exactly?  How are they detected? And why are we looking for them?

The term extrasolar planet refers to any planet orbiting a star other than our sun.  Though their presence had been predicted for hundreds of years, the first one wasn’t found until 1992.  We didn’t have the technology to detect them.  After all, compared to its parent star, even a Jupiter-sized planet is very small and dim.  Furthermore, most of these planets orbit close to their parent star, making it even harder to distinguish them.  Thus far most exoplanets found have been very large, multiple times larger than Jupiter.

Astronomers use several methods to search for and identify exoplanets.  Each method has its advantages and disadvantages.  Depending on the distance, the size, or the orientation of a planet’s orbital plane one method may be more effective than another.  Sometimes more that one method can be used on the same planet giving a more complete picture of what the planet may be like.

The most successful method for detecting exoplanets is the radial-velocity or Doppler shift method.  In this method, the presence of a planet is detected by measuring tiny changes in the frequency of the star’s light.  As a planet orbits a star it causes it to wobble very slightly about the system’s center of mass (see image below).  As the star is pulled away from us its spectrum is shifted towards the red end, and as it is pulled towards us it is shifted to the blue end.  This method only works if the planet’s orbital plane is aligned parallel to the Earth’s orbit.  It is not possible to determine the size of these planets using this method.

Red/Blue Shift Caused by Star's Wobble

Click here to see an animation of the wobble.

The first planets were detected using pulsar timing.  Pulsars are neutron stars that rotate very quickly.  As they rotate, they emit flashes of radio waves at very regular intervals like a light-house.  These flashes can be detected and timed.  A planet orbiting a pulsar will cause very slight variations in the timing of these flashes which can be used to detect it.

When a planet’s orbital plane is perpendicular to Earth’s, another method known as astrometry works well to detect the star’s tiny wobble.   In this method the star’s position is precisely measured against the background stars.  Tiny shifts in its position indicate the tug of a planet orbiting it.  Astronomers are hopeful that this method will lead to the detection of smaller Earth-sized planets.

In transit photometry the dimming of a star is detected as a planet crosses in front of it.  Using this method, astronomers can measure the size of a planet.  Even more intriguing is that astronomers can sometimes determine the absorption spectrum of a planet’s atmosphere as the star’s light passes through it.  This allows them to determine the composition of the planet’s atmosphere.

As the planet passes in front of the star, it's dims slightly.

For the average person the most exciting method of observation is direct imaging. Unfortunately this requires a rare set of conditions.  The method works best when the planet’s orbital plane is perpendicular to Earth’s, the planet is bright and its star dim, and the star is relatively close to Earth.  So far only a few planets have been found using this method.

In November of 2008 the Hubble telescope imaged a planet orbiting the star Fomalhaut.  The planet is estimated to be about 2 times the size of Jupiter and is extraordinarily bright.  Since then several others have been seen.

A trio of planets (faint dots indicated with arrows) orbits the young, massive star HR 8799, some 130 light-years from Earth. Discovered using the Hawaii Keck telescope. Credit: Marois, National Research Council/Canada, Keck

In recent months, astronomers have been able to identify planets thought to be more Earth-like than the gas giants they have been finding so far.  These large “super-Earths” lack the dense atmosphere of the gas giants and have a dense rocky composition.  So far around 30 such planets have been found, but scientists believe that they probably far outnumber the gas giants.

There are some exciting implications of these recent finds.  If a rocky planet orbits a main sequence star like our sun in the so-called “Goldilocks zone, it is possible that it could support life. In the near future, Astronomers hope to analyze the atmospheres of these super-Earths using new telescopes such as the James Webb Telescope, scheduled for launch in 2013.  If they can find signs of carbon dioxide and water, it could mean that the planet may support life.  On the other hand, if they find oxygen and methane, it may indicate that life already exists there!

Still More Planets! November 17, 2008

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To give an idea of how fast we are discovering exoplanets let’s show you a graph

Exoplanets as of September 2009

Exoplanets as of September 2009

Over 300 and counting! Earlier last week we saw the release of the first photos of a palnet around another star. Now the good people from the Keck telescope have released the first photo of a solar system. Three planets orbiting a star. The star, HR 8799,  in the image was blocked to avoid the glare so you could see the much dimmer planets.

hr8799_keck

This photo was taken in the infra-red part of the spectrum using adaptive optics. The three planets are estimated to be about 10 times the mass of Jupiter. A simiar photo to this was take by th Gemini Telescope.

First Pictures of an Exo-planet! November 14, 2008

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The Hubble space telescope released the first photograph of a planet around another star. Fomalhaut is a main sequence class A3 star about 25 light-years away . It’s the brightest star in the constellation Piscis Austrinus and one of the brightest stars in the night time sky.

fomalhaut_hst_lab

The planet is named Fomalhaut-b. It follows a path along the edge of a vast dust ring that surrounds the star. At a distance of about 17 billion kilometers from Fomalhaut, it takes an estimated 872 years to complete one orbit. The planet is 100,000,000 times fainter than Fomalhaut, so the Hubble team used the Advanced Camera’s coronagraph to block out the star’s glare so that the planet could be seen. The region around Fomalhaut is black becauseof this process. This composite image was taken between 2004 and 2006. Since the dust ring has not been disrupted by the mass of the planet, this constrains Fomalhaute-b to be no more than 3 times the mass of Jupiter.

Weird planet October 13, 2008

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COROT is a mission led by the French Space Agency, with contributions from ESA, Austria, Belgium, Germany, Spain and Brazil. Launched in December 2006, It carries a 27-cm aperture (10.5 inch) telescope designed to detect tiny changes in brightness from nearby stars. The mission’s main objectives are to search for exoplanets and to study stellar interiors. COROT has discovered a massive planet-sized object orbiting its parent star closely, unlike anything ever spotted before. It is so weird, that scientists are unsure as to whether this object is a planet or a failed star.

Called COROT-exo-3b, it is the size of Jupiter, but has over 20 times Jupiter’s mass. This would make a planet that has twice the density of lead

Credit OAMP

Credit OAMP

COROT-exo-3b was discovered by a drop in the brightness of the star each time the object (COROT-exo-3b) passed in front of the parent star. For more information go to the European Space Agency