Exoplanet observed for the first time with optical interferometry

The ESO (European Southern Observatory) announced the successful observation of an exoplanet using optical interferometry. This is the first time that an exoplanet is seen in this way and this technique offers a promising example of how we could discern new information about the atmospheres of exoplanets. Such investigations and characterizations are considered essential for the discovery of other planets in the galaxy that could support life.

Astronomical Interferometry is the process of combining information from several different telescopes to observe a given target with more detail than any single telescope could offer. The combination of several smaller mirrors does not offer all the benefits of a single large telescope – the total amount of light collected is less than that of a single large mirror – but it allows angular resolutions very high and avoids the huge expense associated with huge casting. mirrors.

ESO scientists have observed the exoplanet HR8799e using the Very Large Telescope Network (VLT) in Chile, which combines data from four telescopes using its interferometer. Each telescope has a meter 8.2. Although it has nothing to do with the discovery we are about to discuss, HR8799e is one of the few exoplanets whose motion has been confirmed by direct imaging. You can see it in the GIF below (according to Wikipedia, HR8799e is the point that starts right):

Image by Wikipedia.

Direct observation of the exoplanet has led to some surprising discoveries. We already knew that HR8799e was a very young planet, barely 30 million years old. The planet is literally always illuminated by the heat remnants resulting from its formation and by an ambient temperature of about 1000 ° C. The new VLT observations have improved our understanding of the HR8799e spectrum by a full order of magnitude, showing that its atmosphere contains compounds different from those we expected.

Our analysis showed that HR8799e had an atmosphere containing a lot more carbon monoxide than methane, which is not expected from the chemistry at equilibrium, "explains the team leader, Sylvestre Lacour, researcher at CNRS at the Paris Observatory – PSL and at the Max Planck Institute for Extraterrestrial Physics. "We can better explain this surprising result with strong vertical winds in the atmosphere that prevent carbon monoxide from reacting with hydrogen to form methane."

It was also discovered that the atmosphere contained clouds of iron and silicate dust, which implies that the entire gas giant is engulfed in a colossal storm. Lacour suggests that the planet is illuminated from within, with rays of light penetrating into dark, stormy clouds. Silicates and iron "rain" then inside. This last process is not specific to HR8799e; Astronomers believe that diamonds fall like rain on Jupiter and Saturn.

Astronomers hope to be able to make more direct observations of the atmosphere of the exoplanets in the future, while the new generation observatories will be put on line and that our observation techniques will continue to evolve. improve. We may have found nearly 3,000 exoplanets, but our understanding of their atmosphere is still very limited. At this point, every planet we imagine will probably tell us something we did not know before about the probable atmospheric composition of different worlds and about to focus our search for life.

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