Scientists find isotopes on exoplanet for the first time

Thanks to amazing scientific advancements like NASA’s Kepler Space Telescope and the Transiting Exoplanet Monitoring Satellite (TESS), we have confirmed the existence of thousands of exoplanets. Most of these alien worlds are obscured by starlight, limiting what we can learn about them. For the first time, scientists have successfully detected and analyzed elemental isotopes in the atmosphere of an exoplanet. The team says this could lead to new and better ways of understanding planetary formation.

The planet in question has a real name, like most exoplanets. It is called TYC 8998-760-1 b. Eye-catching, right? Unlike most exoplanets, this planet is actually visible from Earth. It’s 300 light years away, but it’s not the distance that makes exoplanets hard to spot, it’s the brightness of their host stars. TYC 8998-760-1 b is a perfect kind of storm for visibility. It’s huge at about twice the diameter of Jupiter and 14 times its mass, and the planet orbits its star at a great distance. You can see a real photo of TYC 8998-760-1 b with its companion planet “c” below.

The new study, led by Yapeng Zhang of Leiden University in the Netherlands, took advantage of this planet’s visibility to learn more about its makeup. The team used the very large telescope of the European Southern Observatory in Chile, in particular a VLT instrument called a spectrograph for integral field observations in the near infrared (SINFONI). As a spectrograph (aka spectrometer), his job is to measure the properties of light. Because TYC 8998-760-1b is so big and insulated, it reflects a lot of visible starlight – that’s why we can see it. By scanning the exoplanet to see which pieces of the optical spectrum are being absorbed, we can determine what is there.

This image, captured by the SPHERE instrument on ESO’s Very Large Telescope, shows the star TYC 8998-760-1 accompanied by two giant exoplanets indicated by arrows, TYC 8998-760-1b (bottom) and TYC 8998-760-1c (top).

TYC 8998-760-1b has large deposits of carbon-13, a version of the ubiquitous element with seven neutrons instead of six, according to the researchers. The team found about twice as much carbon-13 as you would normally expect. These extra neutrons actually tell us something important. TYC 8998-760-1 b is so frigid that it freezes carbon monoxide, and it probably always has been. To have that much carbon-13 in the CO ice, the planet must have formed near its current orbit. It was not closer to the star like all the planets in our solar system are.

This is important data because our solar system is the only one that we have been able to study closely. The detection of isotopes on exoplanets may therefore offer a window into their formation, which may be totally different from what happened here.

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