Scientists have proposed many techniques to detect planets revolving around stars millions of light years away from Earth, but few of them are accurate to give us the perfect results. Now a new study suggests using a new technique involving detection of certain molecules that are present in the planet’s atmosphere in order to make it visible, provided that these same molecules are absent from its star.
Researchers have developed a new device that is only sensitive to the selected molecules, making the star invisible and allowing the astronomers to observe the planet directly. The results appear in the journal Astronomy & Astrophysics.
A team of astronomers used archival images taken by the SINFONI instrument of the star Beta Pictoris, which is known to be orbited by a giant planet, Beta Pictoris b. Each pixel in these images contains the spectrum of light received by that pixel. The astronomers then compared the spectrum contained in the pixel with a spectrum corresponding to a given molecule, for example water vapour, to see if there is a correlation. If there is a correlation, it means that the molecule is present in the atmosphere of the planet.
By applying this technique to Beta Pictoris b, researchers noticed that the planet becomes perfectly visible when they looked for water (H2O) or carbon monoxide (CO). However, when the technique was applied to methane (CH4) and ammonia (NH3), the planet remains invisible, suggesting the absence of these molecules in the atmosphere of Beta Pictoris b.
The host star Beta Pictoris remains invisible in all four situations. Indeed, this star is extremely hot and at this high temperature, these four molecules are destroyed.