Across the Universe
In the first week of Dec., Waikoloa hosted the Extreme Solar System III conference. Astronomers from around the globe specializing in exoplanets, or planets orbiting other stars, attended the conference to discuss the cutting edge research topic.
One of the discoveries presented at the conference came from Thayne Currie, an astronomer at the Subaru Observatory headquartered in Hilo. Dr. Currie and his team discovered at least one, possibly two, baby Jupiter sized planets still forming around their host star, HD 100546. The team used the Gemini Planet Imager (GPI) at the Gemini South Observatory in Chile to take key data for the discovery. The newly discovered system resembles the first directly imaged planetary system, HR 8779, discovered in 2008 by the Gemini North Telescope on Maunakea. The new discovery looks back into time and shows astronomers what other more developed systems like HR 8779 may have looked like when they formed.
“Now, seven years later, we can for the first time see what this (HR 8779) planetary system may have looked like while the planets were just coming into existence,” Dr. Currie says.
The conference also celebrated the 20th anniversary of the discovery of an exoplanet around the star 51 Pegasus by Michel Mayor and Didier Queloz. While it was not the first exoplanet discovered, the planet was the first discovered around a star like our sun.
Thanks to the Kepler Space mission and ground based telescopes, like those on Maunakea, our understanding of exoplanets has grown by leaps and bounds in the past 20 years. As of Dec. 3, astronomers have confirmed the discovery of 1,916 exoplanets. In all likelihood, more planets will have been added to the list by the time this article is published.
Astronomers have several methods to discover planets. The most obvious is to take a picture like Dr. Currie and his team did with GPI. Kepler uses another method — transits. When a planet passes in front of its host star, a small portion of the star’s light is blocked by the planet’s shadow. This was demonstrated in our own solar system in 2012 when millions watched the Venus transit. From earth, we watch the disk of Venus move across the sun blocking a small amount of the sun’s light. Kepler does not take a picture of the star; instead it analyzes the light from the star looking for tiny dips in brightness. Transits are only seen when the exoplanetary system is in almost perfect alignment with our own solar system. According to the Kepler website, a planet in an earth sized orbit has less than a 1 percent chance of being aligned well enough to produce a transit visible to Kepler. In other words, it’s very unlikely that Kepler could have detected a Venus-like transit in a foreign solar system.
At Canada-France-Hawaii Telescope, we are in the process of building a new instrument, called SPIRou, that will allow astronomers to find earthlike planets around distant stars. SPIRou will arrive in 2017.