What is an exoplanet?
Our universe includes many indefinite stars and planets. All the planets that exist in our solar system orbit around the Sun. The planets that orbit around other stars are called exoplanets. Exoplanets are very hard to see directly even with large telescopes because they are at a few light years far from us. They are concealed by the bright glare of the stars they orbit around. So, astronomers use other ways to detect and study these distant planets. They examine for exoplanets by looking at the effects these planets have on the stars they orbit.
The ESO (European Southern Observatory) has broadcasted the successful observation of an exoplanet using optical interferometry. It’s the first time an exoplanet has been actually seen in this manner and the technique offers a promising example of how we might discern new evidence about the atmospheres of exoplanets. These type of detailed investigations and characterizations are considered critical to discovering other planets in the galaxy that might support earthly life.
The term “Astronomical interferometry“ refers to the process of merging and combining information from multiple separate telescopes to observe a given target in greater in depth and detail than any single telescope could offer. Combining multiple smaller mirrors doesn’t offer all the compensations of a single large telescope, the total amount of light collected is smaller than a single large mirror would be but it consents for very high angular resolutions and avoids the enormous expense associated with casting huge mirrors.
The ESO scientists observed exoplanet HR8799e using the Very Large Telescope (VLT) array in Chile earlier, which combines data from four telescopes using its interferometer. Each individual telescope has an 8.2m meter range. HR8799e is one of the few exoplanets whose movement has been confirmed via direct imaging.
Directly observing the exoplanet led to some astounding discoveries. We already identified that HR8799e is a very young planet, at just 30 million years old. The planet is literally still glowing with leftover heat from its formation and an ambient temperature of ~1,000 C. The new VLT observations improved our understanding of HR8799e’s spectrum by a full order of magnitude, presenting that its atmosphere contains different compounds than expected.
The analysis further exhibited that HR8799e had an atmosphere containing more carbon monoxide than methane, something not expected from equilibrium chemistry. This was explained by team leader Sylvestre Lacour who is a researcher at the Observatoire de Paris, and the Max Planck Institute for Extraterrestrial Physics. “We can best explain this astonishing result with great vertical winds within the atmosphere preventing the carbon monoxide from reacting and retorting with hydrogen to form methane.”
The atmosphere was also found to contain clouds of iron and silicate dust, implying that the entire gas giant is engulfed in a colossal storm. Lacour suggests the planet is lit and ignited from within, with rays of light penetrating stormy, dark clouds. The silicates and iron then “rain” into the interior. This last process isn’t unique to HR8799e as the astronomers believe that diamonds fall like rain within Jupiter and Saturn as well.
Astronomers hope to accomplish more unswerving observations of exoplanet atmospheres in the future. We may have found nearly 3,000 exoplanets, but our understanding of their atmospheres and their composition is still very limited. As this continues, every planet we image and research will likely tell us something we didn’t know before about the likely atmospheric composition of diverse worlds and where to focus our search for life, in the future.