Science and Tech

Astronomers discover the ‘marshmallow’ planet: it would float in a bathtub

Recreation of TOI-3757b,

Recreation of TOI-3757b, – NOIRLAB

Oct. 21 () –

A gas giant exoplanet with the same density as a marshmallowwas discovered orbiting a cool red dwarf star, thanks to a set of scientific devices.

Identified as TOI-3757b, the object is located about 580 light years from Earth, in the constellation of Auriga (the Coachman), and is the planet with the lowest density detected around a red dwarf star.

Red dwarf stars are the smallest and faintest members of the so-called “main sequence stars”; stars that in their cores convert hydrogen into helium at a constant rate. Although cool compared to stars like our Sun, red dwarf stars can be extremely active and can erupt with powerful flares capable of stripping a planet of its atmosphere and turning them into inhospitable places.

“Traditionally, giant planets around red dwarf stars have been thought to be difficult to form,” he explains. it’s a statement Shubham Kanodia, a researcher at the Carnegie Institution for Science and lead author of the scientific article published in The Astronimcal Journal. “Until now, this type of phenomenon has been observed in Doppler scan samples, which have generally found giant planets further away from these red dwarf stars. So far we haven’t gotten a large enough sample of planets to consistently find nearby gas planets.”

One of the biggest unexplained mysteries around TOI-3757b is how a gas giant planet could form around a red dwarf star, and especially one with such a low density. Kanodia’s team, however, believes that they might have a solution to this mystery.

The researchers propose that TOI-3757b’s extremely low density could be the result of two factors: The first is related to the planet’s rocky core. Gas giants are thought to start out as massive rocky cores that would be about ten times more massive than Earth, at which point they rapidly draw in large amounts of surrounding gas to form the gas giants we see today. TOI-3757b’s star has a lower abundance of heavy elements compared to other M-type dwarfs with gas giants, and this may have caused the rocky core to form at a slower rate, delaying the start of gas accumulation and thus affecting the overall density of the planet.

The second factor may be the planet’s orbit, which is believed to be elliptical. There are times when it is closer to its star than others, resulting in a substantial excess of temperature. which can cause the planet’s atmosphere to “inflate”.

The planet was initially detected by NASA’s Transiting Exoplanet Survey Satellite (TESS). The Kanodia team then made follow-up observations using ground-based instruments, including NEID and NN-EXPLORE Exoplanet Stellar Speckle Imager (NESSI), both located on the WIYN 3.5-meter Telescope; the Habitable-zone Planet Finder (HPF), located on the Hobby-Eberly Telescope; and the Red Buttes Observatory (RBO) in Wyoming.

The TESS satellite tracked the crossing that this planet made in front of its star, which allowed astronomers to calculate the planet’s diameter, which turned out to be approximately 150,000 kilometers, just slightly larger than Jupiter. This gas giant takes just 3.5 days to complete its orbit around its host star. 25 times less than the closest planet to the Sun in our Solar System, Mercury, which takes 88 days to complete one orbital period.

I WOULD FLOAT IN A BATHTUB

Astronomers then used NEID and HPF to measure the star’s apparent motion along the line of sight, also known as radial velocity. These measurements provide the planet’s mass, which was estimated to be one-fourth the mass of Jupiter, or about 85 times the mass of Earth. Both data allowed the Kanodia team to calculate the average density of TOI-3757b, which turned out to be 0.27 grams per cubic centimeter (about 17 grams per cubic foot), which would be less than half the density of Saturn (the planet with the lowest density in the Solar System), which corresponds to a quarter of the density of water (which means that could perfectly float in a bathtub big enough to pose the planet), or also, a density similar to that of a marshmallow

Jessica Libby-Roberts, Pennsylvania State University researcher and second author of the scientific article, pointed out that “future observations of this planet’s atmosphere using the James Webb Space Telescope could help us learn more about its nature.”

“Finding more such systems with giant planets, once thought to be extremely rare around red dwarfs, is part of our goal to understand how planets formKanodia added.

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