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A proximity, rocky exoplanet may be just an ordinary rock without atmosphere – supporting a theory that planets orbiting small stars are more likely to lack atmosphere.
Astronomers using NASA Spitzer telescope observed the planet, named LHS 3844b, while looking for signs of an atmosphere. Instead, they found indications that the planet is a bare rock. The results corroborate the theory that planets revolve around smaller stars (about 60% smaller radius than the Sun) lack substantial atmospheres – probably because of the radiation of their dwarf star, according to the study.
The radius of the LHS 3844b is 1.3 times larger than that of the Earth and it completes an orbit around its host star in just 11 hours.
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The study tested the atmosphere of the planet, indicating whether or not it can sustain life, by observing the light from its surface for a period of 100 hours. Through observations, scientists have discovered that one side of the planet is constantly facing its star in what is called "aLocked"orbit. (Earth's moon is also locked, which is why we never see the far side.)
One of the sides of the planet, the "side of the day," is a scorching temperature of 1,710 degrees Fahrenheit (770 degrees Celsius). If there was a substantial atmosphere on the planet, then warm air from one side would generate winds that transfer heat to the surface of the planet. But with a lack of atmosphere, there would be no air to transfer the heat. (The temperature of the "night side" of the planet could not be measured by the Spitzer telescope because it is an infrared telescope).
"The temperature contrast on this planet is about as large as possible," said Laura Kreidberg, researcher at the Harvard and Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and lead author of the new study, said in a statement. "This fits perfectly with our model of bare rock without atmosphere."
According to the statement, the surface of the planet could be covered with the same dark lava rocks called "mares" found in the darkest areas of the moon.
The rocky exoplanet was discovered in 2018 by NASA Satellite survey on exoplanets in transit, who found LHS 3844b in orbit around a Dwarf star M – the most common type of star in the Milky Way.
The discovery of the exoplanet marks the first time that scientists have observed an exoplanet orbiting a dwarf M without atmosphere.
"We have a lot of theories about planetary atmospheres around Mains, but we have not been able to study them empirically," Kreidberg said. "Now, with LHS 3844b, we have a terrestrial planet outside our solar system where, for the first time, we can determine observatively that an atmosphere is not present."
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