Astronomers Spot Free-Floating Titanium in an Ultra-Hot Exoplanet's Atmosphere

Thursday, 16 August 2018 - 11:34AM
Astronomy
Space
Thursday, 16 August 2018 - 11:34AM
Astronomers Spot Free-Floating Titanium in an Ultra-Hot Exoplanet's Atmosphere
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The exoplanet KELT-9b is hot. Extremely hot. Almost star-level hot. For comparison, the hottest planet in our solar system, Venus, has a temperature of about 864 degrees Fahrenheit, and our Sun's chromosphere (one of the upper layers of the atmosphere) is about 7,800 degrees. KELT-9b's surface temp is about the same as that chromosphere, which means it actually resembles a star more than a planet in some ways. Astronomers recently took a close look at KELT-9b and found something unique: for the first time, they found free-floating titanium in an exoplanet's atmosphere, along with iron.

One of the consistently mind-blowing things about exoplanet astronomy is that no scientist is peering at the surface of, say, Trappist-1 with a high-powered optical telescope and making notes about what they see. Instead, most astronomers are using the transit method, in which a telescope picks up on an exoplanet's properties when the planet moves between its star and the telescope. The light from the star illuminates the planet and lets astronomers figure out its size, the composition of its atmosphere, and other properties.

 

With the right tools, scientists can study the wavelengths of light coming from the planet and figure out what kind of matter would leave that signature. In an email to Space.com, Kevin Heng, an astrophysicist at the University of Bern explained. "Different atoms or molecules have a fingerprint when you split the light into a spectrum," Heng said. "Given enough resolution, given good enough data, every molecule has a unique fingerprint." In this case, the data from KELT-9b was high-quality enough to spot titanium in its atmosphere, which has never been seen before on its own (scientists have spotted titanium dioxide on an exoplanet called Kepler-13A, however).

What's especially exciting about the method Heng and his colleagues used is that the same process can be applied to the search for life. According to Heng: "This is the same technique that we will use to detect signatures of biology, or biosignatures. On Earth, we think it's oxygen and a few other obscure molecules, but we don't know what biosignatures are in general. If you knew what they were...you could use exactly the same technique to detect these molecules in cooler, smaller planets."
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