Analyzing light

A team of scientists and engineers at Princeton University just gave exoplanet research a long-needed boost. Using a new Earth-bound instrument, the scientists were able to isolate light reflecting from far-out exoplanets.

This new instrument is known as CHARIS, an acronym for Coronagraphic High Angular Resolution Imaging Spectrograph. It was built by a team led by N. Jeremy Kasdin, professor of mechanical and aerospace engineering at Princeton. CHARIS features nine mirrors, five filters, two prism assemblies, and a microlens array. It weighs 226.8 kg (500 lbs), and is maintained at -223.15 C (50 Kelvin, -369 F).

According to the team, CHARIS was able to isolate light reflecting from an exoplanet — a fairly difficult feat, given that these planets are dimmer than the stars they orbit.

“By analyzing the spectrum of a planet, we can really understand a lot about the planet. You can see specific features that can allow you to understand the mass, the temperature, the age of the planet,” researcher Tyler Groff explained.

Understanding exoplanets

Exoplanets are planets found outside of the solar system, orbiting another star. We owe most of our success at finding exoplanets to the Kepler space telescope. But apart from where they are located, there really isn’t much we know about them.

CHARIS can help change that.

It has only been three decades since the first known exoplanets were discovered in the 1990s. That’s right, just 30 years ago, we didn’t have confirmed evidence of any planets outside our solar system. Today, we know of thousands of them. But we aren’t just getting observational evidence of these foreign worlds, we are actually seeing them, and our fascination with them has only increased since we passed that revolutionary juncture and saw our first alien worlds – especially since these worlds could potentially support life (as a future home for us or a current one for extraterrestrial civilizations).

Notably, these new updates help advance our understanding of exoplanets and see them as never before.

“With CHARIS spectra we can now do a lot more than simply detect planets: we can measure their temperatures and atmosphere compositions,” said Olivier Guyon, faculty member at the University of Arizona and head of the adaptive optics program at the Subaru Telescope in Hawaii, with which CHARIS works in conjunction.

Exoplanet research is bound to get even better in the next couple of years, with the capabilities of CHARIS, together with the Subaru Telescope, and with the James Webb Space Telescope’s scheduled launch in 2018.

“There is a lot of excitement,” said Tyler Groff, a member of the Princeton research team currently working in NASA. “[CHARIS] is going to open for science in February to everyone.”