14 DAY TRIAL // Extrasolar planets, or exoplanets, a concept that refers to all planet-like celestial bodies orbiting stars in other systems, are very difficult to observe, and even when the telescopes are pointing in the right direction, it takes a certain amount of luck to spot one. Since the first ever such body was discovered, in 1999, only 55 others have been observed. Now, publishing in the journal Astronomy & Astrophysics, two teams of researchers believe they may have made the first Earth-based observations of the atmosphere, or lack thereof, surrounding exoplanets.
The first team of astronomers, made up of University of Leiden scientists Ernst De Mooij and Ignas Snellen, were looking at the star TrES-3, and analyzed its planet, TrES-3b, with the help of the Canary Islands-based William Hershel 4.2 meter telescope.
They noticed the moment when the planet passed in front of the sun, and, by using infrared wavelengths, were able to determine that the temperature on the dark side of the planet had to be approximately 2,000 degrees Kelvin (1,726 Celsius / 3,140 Fahrenheit). This meant that the “day” side of the planet was probably much hotter.
The second research team featured astronomers David Sing and Mercedes Lopez-Morales, from the IAP in France, and the Carnegie Institution in Washington, the United States, respectively. The OGLE-TR-56b star and planet system was their target, and they observed it using two precise instruments – the Chile-based 8 meter Very Large Telescope and 6.5 meter Magellan Telescopes, in Las Campanas. Instead of going for the infrared pictures, the team adopted another method. They waited until the planet passed behind the star, and then used the slight light variation that followed to photograph the region in visible wavelengths.
According to their conclusions, the planet in the OGLE-TR-56b system was so hot that it emitted light visibly, and not just in infrared, as TrES-2 did. The team estimated that the average temperature on the day side of that planet was approximately 2,700 degrees Kelvin (2,426 Celsius / 4,400 Fahrenheit). In regard to its atmosphere, Sing and Lopez-Morales concluded that the planet lacked even the most basic air movements, which would account for why heat was not redistributed across the planet.
Outside of the scientific value of the discoveries, these direct observations prove that it’s possible to catch glimpses of the interactions between other planets and their stars even from Earth and that expensive space observatories are not always required.