New Method May Expedite Search for Exoplanets with Atmospheres

Kate S. Petersen | Sky & Telescope
Monday, December 2, 2019

A team of astronomers propose screening exoplanets by their temperatures to determine whether they host an atmosphere — and are worth following up.

Read the full story at Sky & Telescope

There are thousands of confirmed exoplanets and many more to come in the years leading up to when the next-generation of telescopes comes online. Once that happens, astronomers will be vying for access to observe many of them, but time availability will be limited. 

Now a group of scientists led by MIT EAPS postdoctoral fellow Daniel Koll has found a way "to quickly detect atmospheres on rocky exoplanets, just by using daytime temperatures readings," Kate S. Petersen writes for Sky & Telescope. Their work was published in four Astrophysical Journal papers.

When a planet has an atmosphere, daytime heat from its star is redistributed throughout the planet by atmospheric winds, reducing overall daytime temperatures. This limits how hot the day side can get. If the telescope detects a day side that's cooler than that limit, “this is an indication for an atmosphere,” says Daniel Koll (MIT), a lead author on one of the papers. “It's not a solid detection—it's an inference. But the good thing is, an inference is very cheap. You can make it fast.” Koll says the method will allow researchers to scan exoplanets quickly and then double back for more information if they find one with a potential atmosphere.

The new technique is aimed at exoplanets orbiting closely to their dim, red M-dwarf stars.

The new technique is limited to evaluating exoplanets inside the inner edge of the so-called habitable zone — those that are probably too hot to support liquid water, and thus life. These hot planets, close to the star, are also thought to be most vulnerable to atmospheric stripping due to the duration and intensity of radiation produced by M dwarfs when they are young. However, Koll notes that if these hot planets have atmospheres that survived the star’s violent youth, then it’s likely cooler, farther-out planets would also retain their atmospheres.


Kate S. Petersen is a master’s student in the Graduate Program in Science Writing at the Massachusetts Institute of Technology (MIT) who specializes in reporting on earth and planetary sciences. 

Story Image: Artist’s impression of a cool, red star surrounded by planets. (Credit: NASA / JPL-Caltech)

Links:

Daniel Koll

Paper: Daniel D. B. Koll et al. “Identifying Candidate Atmospheres on Rocky M Dwarf Planets via Eclipse Photometry,” 2019, Astrophysical Journal [preprint available: https://arxiv.org/abs/1907.13138].

Paper: Megan Mansfield et al. “Identifying Atmospheres on Rocky Exoplanets Through Inferred High Albedo,” 2019, Astrophysical Journal [preprint availabile: https://arxiv.org/abs/1907.13150].

Paper: Matej Malik et al. “Analyzing Atmospheric Temperature Profiles and Spectra of M Dwarf Rocky Planets,” 2019, Astrophysical Journal [preprint available: https://arxiv.org/abs/1907.13135].

Paper: Daniel D. B. Koll. “A Scaling Theory for Atmospheric Heat Redistribution on Rocky Exoplanets,” 2019, Astrophysical Journal [preprint available: https://arxiv.org/abs/1907.13145]

 

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