Planets outside our solar system

Universe: GJ 1252 B

discovery: Taking a closer look at GJ 1252 b, a rocky “super-Earth” planet discovered in 2020, astronomers have found that an exoplanet could have very little or no atmosphere at all.

The planet, which orbits an M-type star, is “the smallest exoplanet to date with which we have severe restrictions on its atmosphere,” said lead author Ian Crossfield, an astronomer and assistant professor at the University of Kansas.

Key facts: Astronomers often discover and study exoplanets by observing how much light the planets block as they pass in front of their host stars, a technique known as the “transit method.” GJ 1252 b, an exoplanet about 65 light-years away and a radius 1.18 times larger than Earth, was discovered this way by NASA’s Transiting Exoplanet Survey Satellite (TESS) in 2020. In this new study, astronomers observed an exoplanet Solar with the Spitzer Space Telescope before it retired and was able to get a closer look at the planet and its atmosphere.

The team with Spitzer discovered a secondary eclipse that occurs when a planet passes behind a star and the planet’s light, which comes from its own infrared radiation (or heat), as well as reflected light from the star is blocked.

details: Astronomers searching for signs of life in the universe focus on a number of different details in exoplanets. Many of these details serve as a comparison between an exoplanet and Earth, as Earth remains the only planet where we have confirmed the existence of life.

GJ 1252 b isn’t much larger than Earth, but it’s hotter because it’s closer to its star, and as the astronomers found in this study, it lacks a lot of atmosphere.

“We are just beginning to see how often, and under what conditions, rocky planets can maintain their atmospheres,” said astronomer and study co-author Laura Kreidberg, director of atmospheric physics for exoplanets (APEx division of the Max Planck Institute). “This measurement is an indication that for the hottest planets, thicker atmospheres are unlikely to survive.”

To determine what an exoplanet’s atmosphere (if there was one) might be like, astronomers measured infrared radiation from GJ 1252 b as its light was blocked out during a secondary eclipse. These observations revealed the planet’s scorching temperature throughout the day, which is estimated to be as high as 2,242 degrees Fahrenheit (1,228 degrees Celsius). In fact, GJ 1252 b is so hot that gold, silver, and copper would all melt on the planet.

The expected temperatures of an exoplanet, when compared with atmospheric models, indicate that its surface pressure is likely less than 10 bar (for reference, the Earth’s surface pressure is about 1 bar). To be stable for a long time, it is possible for this exoplanet to have an atmosphere as dense as Earth, an atmosphere 10 times as dense as Earth, or even no atmosphere at all.

Due to its extreme temperatures and low surface pressure, the astronomers on this team predicted that GJ 1252 b had no atmosphere at all. This is currently the smallest exoplanet whose atmosphere scientists have a clear idea of.

Fun facts: GJ 1252b is an exoplanet that was first discovered using TESS and then examined more extensively with Spitzer before the telescope’s mission ends in 2020. With further exploration using the James Webb Space Telescope (JWST), the team can put even stricter limits on the atmosphere The atmosphere of the planet, an exciting possibility.

“At the time, Spitzer was the only facility in the known universe that could perform these kinds of measurements. Now, Spitzer is turned off, but JWST is present and at these wavelengths it is much more sensitive than Spitzer. So, what we did as hard as Spitzer we can now Getting started is done easily and for larger numbers of rocky planets using JWST,” Crossfield said.

“The James Webb Space Telescope’s infrared observations have the potential to reveal the surface characteristics of hot, rocky planets like this one. Different types of rocks have different spectral fingerprints, so we can learn what kind of rocks GJ 1252b is made of,” Kreidberg added.

Studying GJ 1252 b further using JWST constitutes an exciting possibility for scientists, as it would be interesting to confirm the existence of an atmosphere on a small and hot exoplanet where it would also be fascinating to explore the formation of a planet like this without an atmosphere at all.

Finders: A team from the University of Kansas, led by Crossfield, led this study that discovered curious new details about GJ 1252b’s atmosphere. In addition, researchers from the University of California, Riverside, NASA’s Jet Propulsion Laboratory, Caltech/IPAC-NASA Institute for Exoplanet Science, University of Maryland, and the Earth and Planetary Laboratory at the Carnegie Institution for Science, Max Planck, participated in the paper. The Astronomy Institute, McGill University, University of New Mexico, Albuquerque, NM, and the Institute for Exoplanet Research at the University of Montreal. The study, published in Astrophysical Journal Letters, can be found here.

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