Starship Asterisk*

Atmospheric gases recede from a “hot Jupiter,” which is a Jupiter-size, egg-shaped planet that orbits close to its own sun, in this artistic rendering. Cornell astronomers have developed a new mathematical model for determining temperatures on different parts of exoplanets, rather than averaging a planet’s temperature. Credit: Matthew Fondeur/Cornell University

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After spotting a curious pattern in scientific papers – they described exoplanets as being cooler than expected – Cornell astronomers have improved a mathematical model to accurately gauge the temperatures of planets from solar systems hundreds of light-years away.

This new model allows scientists to gather data on an exoplanet’s molecular chemistry and gain insight on the cosmos’ planetary beginnings ... Nikole Lewis ... had noticed that over the past five years, scientific papers described exoplanets as being much cooler than predicted by theoretical models. “It seemed to be a trend – a new phenomenon,” Lewis said. “The exoplanets were consistently colder than scientists would expect.”

To date, astronomers have detected more than 4,100 exoplanets. Among them are “hot Jupiters,” a common type of gaseous giant that always orbits close to its host star. Thanks to the star’s overwhelming gravity, hot Jupiters always have one side facing their star, a situation known as “tidal locking.” Therefore, as one side of the hot Jupiter broils, the planet’s far side features much cooler temperatures. In fact, the hot side of the tidally locked exoplanet bulges like a balloon, shaping it like an egg. ...

• Astrophysical Journal Letters 893(2):L43 (2020 Apr 20) DOI: 10.3847/2041-8213/ab8238
• arXiv.org > astro-ph > arXiv:2003.11548 > 25 Mar 2020