Puffy, Marshmallow-Like Planet Could Float in a Bathtub

This is interesting.  We are slowly building up a spectrum of exo planets, now mostly giants of course and we would have to continously watch a star in order to perhaps build a planet profile.  We actually need to do that with our closer stars to really map a few properly.  Some will be tipped enough to make planet detection unlikely.

What is clear now is that our ability is good enough to look closely at perhaps a hundred stars.  Locking on to them and surveying them breifly every few hours should pick up transits allowing another device to track that object.

We should be able to do this now or certainly soon enough.  such a sample is large enough to say things about planets generally.

Puffy, Marshmallow-Like Planet Could Float in a Bathtub

Scientists found the new exoplanet located in the Auriga constellation 580 light-years away

Sarah Kuta

Daily CorrespondentOctober 25, 2022 4:01 p.m.

https://www.smithsonianmag.com/smart-news/puffy-marshmallow-like-planet-could-float-in-a-bathtub-180980996/?

The exoplanet TOI-3757 b has the same average density as a marshmallow. Pixabay

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Astronomers encounter a lot of intriguing celestial bodies while studying space: a nebula that looks like a tarantula, massive black holes, ice volcanoes and a moon that sounds like dial-up internet, to name a few.

Now, they’ve found a unique exoplanet that’s strikingly similar to a popular sweet treat. The planet, called TOI-3757 b, has the same average density as a marshmallow.

Situated some 580 light-years away from Earth, the exoplanet is orbiting a red dwarf star in the Auriga constellation. Scientists located the distant gas giant using the 3.5-meter telescope at Kitt Peak National Observatory outside of Tucson, Arizona, and recently shared more details about their discovery in The Astronomical Journal.

Though discovering a new exoplanet—a planet outside of our solar system—isn’t uncommon, this one stands out.

For one, with its marshmallow-like fluffiness, TOI-3757 b is the lowest-density planet scientists believe they’ve ever found orbiting a red dwarf star. They calculated its average density to be around 17 grams per cubic feet, which is about one-quarter the density of water. This means it would float if placed in a “planet-sized, cosmic bathtub,” as Chris Young writes for Interesting Engineering.

An artist's rendition of the gas giant planet and the red dwarf star it orbits NOIRLab / NSF / AURA / J. da Silva / Spaceengine / M. Zamani

It’s also unusual for a gas giant to be orbiting a red dwarf star, which can emit flares that are strong enough to strip a planet’s atmosphere and, as Kevin Hurler writes for Gizmodo, “roast it like a s’more.” The planet’s host is a “cool” red dwarf star, also known as an M dwarf. These types of stars, which are very common in the Milky Way and throughout the universe, are the dimmest and smallest of stars that fuse hydrogen into helium in their cores, known as main sequence stars. They are cool compared to other stars, such as our Sun (a yellow dwarf star), but they are still extremely active.

“Finding more such systems with giant planets—which were once theorized to be extremely rare around red dwarfs—is part of our goal to understand how planets form,” says study co-author Shubham Kanodia, an astrophysicist at Carnegie Institution for Science’s Earth and Planets Laboratory, in a statement.

Scientists began taking a closer look at TOI-3757 b after NASA’s Transiting Exoplanet Survey Satellite (TESS) noticed the host star dimmed slightly when the exoplanet passed in front of it. In addition to the 3.5-meter telescope at Kitt Peak, they also observed the planet with ground-based instruments on the Hobby-Eberly Telescope (HET) at the McDonald Observatory in Texas and at the Red Buttes Observatory (RBO) in Wyoming.

From their analyses, they determined TOI-3757 b orbits its red dwarf star every 3.5 days and is slightly larger than Jupiter at roughly 100,000 miles wide. Though they don’t know for certain, scientists suspect the exoplanet has such a low density because its host star has lower-than-normal amounts of heavy elements, which in turn causes the planet’s rocky core to form more slowly. That means the exoplanet isn’t pulling in as much gas as other gas giants do, keeping its density down.

Another possible explanation for the low density is the slightly elliptical shape of the planet’s orbit. When it gets closer to the red dwarf, the star's excess heat may be causing the planet’s atmosphere to “bloat,” per the statement. Scientists now hope the new James Webb Space Telescope will be able to point its sophisticated instruments toward the exoplanet and shed further light on its “puffy nature,” says study co-author Jessica Libby-Roberts, a researcher at Pennsylvania State University, in the statement.