New technique allows astronomers to study the atmosphere of an exoplanet in detail...

....even though it does not pass in front of its parent star. An international team has used ESO's Very Large Telescope to directly catch the faint glow from the planet Tau Boötis b, solving a 15-year-old problem. The team also finds that the planet's atmosphere seems to be cooler higher up, differently from the expected.


An artist’s impression of the exoplanet Tau Boötis b. (ESO/L. Calçada)

The majority of planets around other stars were discovered by their gravitational effects on their parent stars, which limits the information that can be gleaned about their mass: they only allow a lower limit to be calculated for a planet's mass. The new technique pioneered here is much more powerful. Seeing the planet's light directly has allowed the astronomers to measure the angle of the planet's orbit and hence work out its mass precisely. By tracing the changes in the planet's motion as it orbits its star, the team has determined reliably for the first time that Tau Bootis b orbits its host star at an angle of 44 degrees and has a mass six times that of the planet Jupiter in our own Solar System.

"The new VLT observations solve the 15-year old problem of the mass of Tau Bootis b. And the new technique also means that we can now study the atmospheres of exoplanets that don't transit their stars, as well as measuring their masses accurately, which was impossible before", says Ignas Snellen (Leiden Observatory, the Netherlands), co-author of the paper. "This is a big step forward."

Artist's Concept of Extrasolar Planet Tau Bootis B over a Hypothetical Moon

As for the Tau Boötis b, this new technique learnt us:
- That it orbits its host star at an angle of 44 degrees
- That it has a mass six times that of the planet Jupiter in our own Solar System.
- About the amount of carbon monoxide present
- That the temperature at different altitudes were not as expected: the atmosphere has a temperature that falls higher up

Astronomers may even be able to track atmospheric changes between the planet's morning and evening.

"This study shows the enormous potential of current and future ground-based telescopes, such as the E-ELT. Maybe one day we may even find evidence for biological activity on Earth-like planets in this way”, concludes Ignas Snellen.

Yes, it's a new step toward the possible discovery of life outside our solar system!

Source

This research was presented in a paper "The signature of orbital motion from the dayside of the planet τ Boötis b" to appear in the journal Nature on 28 June 2012.

Originally posted by elevenaugust
This research was presented in a paper "The signature of orbital motion from the dayside of the planet τ Boötis b" to appear in the journal Nature on 28 June 2012.

According to the ESO website, the pdf version of that paper is here (with a slightly different name)...
The radial velocity trail from the giant planet orbiting τ Boötis