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Topic Name: Astronomers have Found 10 new Planets Outside Solar System Using a System of Robotic Cameras

Category: STAR (Space, Telecommunications & Radioscience)

Research persons: Don Pollaco

Location: University of California, Santa Barbara, United States

Details

An international team of astronomers has found 10 new “extra solar” planets, planets that orbit stars other than our sun. The team used a system of robotic cameras that yield a great deal of information about these other worlds, some of which are quite exotic. The system is expected to revolutionize scientific understanding of how planets form.

Two participating astronomers from the U.S. are Rachel Street and Tim Lister. Street is a postdoctoral fellow at the University of California, Santa Barbara and the Las Cumbres Observatory Global Telescope Network (LCOGTN) located in Santa Barbara. Lister is a project scientist with LCOGTN.

Team leader, Don Pollaco of Queen’s University, Belfast, Northern Ireland, will announce the findings in his talk at the Royal Astronomical Society’s national astronomy meeting in the U.K. on Wednesday, April 2.

The new international collaboration is called “SuperWASP,” for Wide Area Search for Planets.

This technique of locating the planets gives more information about the formation and evolution of the planets than the gravitational technique. Astronomers look for “transits,” moments when the planets pass in front of the star, like an eclipse, as viewed from the Earth.

In the last six months the SuperWASP team has used two batteries of cameras, one in Spain’s Canary Islands and one in South Africa, to discover the 10 new extra solar planets.

With the gravitational technique, scientists have discovered around 270 extra solar planets since the early 1990s. They measured the gravitational pull on the star that is exerted by the orbiting planet. As the planet moves, it pulls on the star, tugging it back and forth. However, making these discoveries depends on looking at each star over a period of weeks or months, so the pace of discovery is slow.

The SuperWASP technique involves two sets of cameras to watch for events known as transits, where a planet passes directly in front of a star and blocks out some of the star's light. From the Earth the star temporarily appears a little fainter. The

SuperWASP cameras work as robots, surveying a large area of the sky at once. Each night astronomers receive data from millions of stars. They can then check for transits and hence planets. The transit technique also allows scientists to deduce the size and mass of each planet.

A team of collaborators around the world follows up each possible planet found by SuperWASP with more detailed observations to confirm or reject the discovery.

The astronomers working at the Las Cumbres Observatory Global Telescope Network (LCOGTN), affiliated with UC Santa Barbara, use robotically controlled telescopes in Arizona, Hawaii, and Australia. These telescopes provide high quality data used to select the best targets for intense observation. This, together with data from the Nordic Optical Telescope in La Palma, Spain; the Swiss Euler Telescope in Chile; and the Observatoire de Haute Provence in Southern France; provides the final confirmation of the new discoveries.

A total of 46 planets have been found to transit their stars. Since they started operation in 2004, the SuperWASP cameras have found 15 of these. SuperWASP is the most successful transit survey in the world.

The planets discovered by SuperWASP have masses between a middle weight of half the size of Jupiter to more than eight times the size of Jupiter, the largest planet in our solar system.

A number of these new worlds are very exotic. For example, a year, or one orbit, on WASP-12b, is just a bit over one day. This planet is so close to its star that its daytime temperature could reach a searing 2300 degrees Celsius.

Lister and Street from LCOGTN/UCSB are delighted with the results. Street described the discovery as a “very big step forward for the field.”

Lister said, “The flood of new discoveries from SuperWASP will revolutionize our understanding of how planets form. LCOGTN's flexible global network of telescopes is an indispensable part of the worldwide effort to learn about the new planets.”

Note for SuperWASP
SuperWASP (Wide Angle Search for Planets) is performing an ultra-wide angle search for transiting extrasolar planets with the aim of covering the entire sky down to ~15th magnitude.

SuperWASP consists of two robotic observatories; SuperWASP-North at Roque de los Muchachos Observatory on the island of La Palma in the Canaries and SuperWASP-South at the South African Astronomical Observatory, South Africa. Each observatory consists of an array of eight Canon 200mm f1.8 lenses backed by high quality 2k x 2k science grade CCDs. The large field of view of the Canon lenses gives each observatory a massive sky coverage of just under 500 square degrees per pointing.

The observatories continually monitor the sky, taking a set of images approximately once per minute, resulting in a total of up to 100 gigabytes of data per night. By measuring the brightness of each star, in each image, small dips in brightness caused by Jupiter sized planets passing in front of their parent stars (transits) can be searched for.

SuperWASP is operated by a consortium of eight academic institutions which include the Instituto de Astrofisica de Canarias, the Isaac Newton Group of Telescopes, Keele University, the University of Leicester, the Open University, Queen's University Belfast and St. Andrews University. It is hoped that SuperWASP will revolutionize our understanding of planet formation paving the way for future space missions searching for 'Earth'-like worlds.

On September 26, 2006, the team reported the discovery of two extrasolar planets: WASP-1b (orbiting 6 million km from star once every 2.5 days) and WASP-2b (orbiting 4.5 million km from star once every 2 days)

On October 31, 2007, the team reported the discovery of three extrasolar planets: WASP-3b, WASP-4b and WASP-5b. All three planets are similar to Jovian mass and are so close to their respective stars that their orbital periods are all less than two days. These are among the shortest orbital periods discovered. The surface temperatures of the planets should be more than 2000 degrees Celsius, owing to their short distances from their respective stars. The discoveries make the SuperWASP team the first and only one to detect planets in both the northern and southern hemispheres using the transit detection technique. The WASP-4b and WASP-5b planets are the first planets discovered by the WASP project's cameras in South Africa, while WASP-3b is the third planet discovered by the WASP project's cameras in La Palma.

About Las Cumbres Observatory Global Telescope
Las Cumbres Observatory Global Telescope (LCOGT) is a non-profit private operating foundation directed by the technologist Wayne Rosing. It aims to build a global network of longitudinally spaced robotic telescopes for scientific and educational use. At present, the nascent network comprises two fully operational, science-grade telescopes, the 2m Faulkes Telescopes North and South.

Although the final telescope breakdown is presently in flux, it is likely that the network will have approximately:

~forty 0.4 meter telescopes arranged in clusters of 4 that are primarily for educational uses, but also science capable.
~twenty 1-meter telescopes that are primarily for science use, but also capable of educational use, in clusters of 3 at 6 sites around the world in the North & South hemispheres
two or more 2-meter telescopes allowing 24/7 high quality observations of time variable astrophysical and solar system phenomena for both scientific research and education.
At any time, any object of interest should be accessible from 2-4 of the planned site-clusters.

Examples of current science being performed with the network includes extra-solar planet work, particularly transit timing and followup and microlensing followup (in collaboration with the RoboNet-1.0 project).

Accompanying the educational network will be a vast library of resources and projects. The goal of the educational arm of the project is not to make more astronomers, but to create an awareness for science and technology, and to foster the ability to think critically about the world around us.

LCOGT will concentrate on time-varying astronomy. Initially, LCOGT started with a strong concentration of astronomers studying extra solar planets. Science Director Timothy Brown was on the team that observed the first transiting extra solar planet, and has been a leader in transiting planet research. LCOGT's first staff astronomer, Stuart Taylor, established LCOGT's still ongoing project on transit timing variations (TTVs), now led by Marton Hidas.

Having a world-wide network of telescopes will mean there will be a telescope available for time-certain events. The flexibility to measure transits from multiple longitudes are an example of the advantage of having telescopes spaced around the earth, hence TTV research is an early priority.

About Nordic Optical Telescope
The Nordic Optical Telescope (NOT) is an astronomical telescope located at Roque de los Muchachos Observatory, La Palma in the Canary Islands. First light came in 1988, with regular observing beginning in 1989. It is funded by Denmark, Sweden, Iceland, Norway and Finland. Access is provided to astronomers of all nationalities through international time allocation committees.
The NOT was the first major telescope facility designed to use active optics to correct the shape of a thin, lightweight primary mirror supported on actuators.
The NOT is a 2.56m telescope with the following instrumentation:
ALFOSC -- CCD (visible light) faint object spectrograph and 4 Megapixel camera
NOTCam -- 1 Megapixel HgCdTe Hawaii infrared camera and spectrograph
MOSCA -- 16 Megapixel CCD camera
SOFIN -- High resolution CCD spectrograph (up to R=170000)
StanCam -- Stand-by 1 Megapixel CCD camera
LuckyCam -- High frame rate, low noise L3Vision CCD camera for lucky imaging
TURPOL -- UBVRI Photopolarimeter
FIES -- cross-dispersed high-resolution (up to R=60000) echelle spectrograph, isolated from thermal and mechanical instability.