Gemini Planet Imager Begins Search for Exoplanets Via Direct Imaging

March 24, 2014

Gemini South telescope in Chile has been upgraded with Gemini Planet Imager (GPI) instrument, capable of direct imaging of extrasolar gas giants. This marks the beginning of search for exoplanets via direct imaging.

Gemini South telescope in Chile where Gemini Planet Imager was deployed.

Gemini South telescope in Chile where Gemini Planet Imager was deployed.

When detecting exoplanets, we are mostly relying on either measuring dips in distant stars' brightness as planets pass in font of them, or by measuring the way the stars wobble as gravity from planets that orbit them slightly puts them "off balance". With the development of highly advanced instruments, however, we enter a new era when we are able to directly image exoplanets.

For the time being, best we can do is detect large Jupiter-like gas giants, but it is a significant step toward one day directly imaging Earth-like rocky exoplanets.

A new instrument called Gemini Planet Imager (GPI), which enables us such direct imaging, has been installed on Gemini South telescope in Chile. It detects infrared radiation from gas giants in other solar system and can give us information about their atmosphere. In addition, it will be able to study protoplanetary disks around young stars. Protoplanetary disk is a disk made of gas and dust around a young star where planets are presumably being formed.

"Most planets that we know about to date are only known because of indirect methods that tell us a planet is there, a bit about its orbit and mass, but not much else," says Bruce Macintosh of the Lawrence Livermore National Laboratory, Livermore, USA. "With GPI we directly image planets around stars – it's a bit like being able to dissect the system and really dive into the planet's atmospheric makeup and characteristics."

In order to perform such measurements, GPI has to be incredibly accurate. "Each individual mirror inside GPI has to be smooth to within a few times the size of an atom," says Leslie Saddlemyer, one of GPI's system engineers.

The team started their observations with known systems like Beta Pictoris and obtained the spectrum of gas giant Beta Pictoris b, first such observation of the planet. It is only the beginning of a large survey that will encompass 600 young stars in search for gas giants around them. In the future, we hope that GPI-like instruments will accompany space telescopes that, without an atmosphere to hinder the instrument's resolution, will be able to detect smaller planets similar to Earth.

"Some day, there will be an instrument that will look a lot like GPI, on a telescope in space," adds Macintosh. "And the images and spectra that will come out of that instrument will show a little blue dot that is another Earth."



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