The exoplanet, TOI-3757 b is a gas giant planet that revolves around a K-type star. The mass of this exoplanet is about 0.27 times more than that of Jupiter and therefore it completes one circle around its star in just 3.4 days. If we talk about its distance, then it is located at approximately 0.038 AU from its K-type star, approx. Furthermore, if we talk about its discovery, then it was in 2022. 

This planet is unique because it has an incredibly low density, similar to that of a marshmallow. Even though red dwarf stars are cooler than stars like our Sun, they can still be very active and produce strong flares that could potentially strip away a planet’s atmosphere.

Planetary scientists suggested two ideas for the planet’s marshmallow-like atmosphere:

Gas giants like Jupiter initially form from rocky cores that are several times more massive than Earth. As the solar system takes shape, these central cores attract surrounding gas. However, in the case of TOI-3757 b, which orbits a red dwarf star with fewer heavy elements than other similar stars, the rocky core formation may have been slower. This delayed the process of accumulating the surrounding gas.

As a result, TOI-3757 b ended up with a less dense and fluffier atmosphere compared to other gas giants like Jupiter that orbit stars with more heavy elements. TOI-3757’s orbit around its red dwarf star could be elliptical.

NOIRLab explains:

“There are times it gets closer to its star than at other times, resulting in substantial excess heating that can cause the planet’s atmosphere to bloat”

The Reason Behind the Low Density of TOI-3757 b:

The exoplanet, TOI-3757 b, is very interesting to astronomers because it possesses unique and distinct characteristics. This makes it one of the relatively few gas giants (around 10 in total) found orbiting M dwarf stars.

What’s particularly intriguing about TOI-3757 b is its low density, which is approximately 0.27 grams per cubic centimeter (g/cm³). The low density provides a valuable chance to study planet formation theories.

Two hypotheses are put forth to explain this low density:

  • Low Metallicity: The star hosting TOI-3757 b has a lower metallicity (around 0.3 dex lower) compared to the average metallicity of M dwarf stars that host gas giants. This lower metallicity might have contributed to the delayed formation of a solid core massive enough to trigger the rapid accumulation of gas.
  • Tidal Heating: It’s also possible that the eccentricity of TOI-3757 b’s orbit (solid estimation at 0.14 +/- 0.06) leads towards tidal heating, which could have expanded the planet’s radius. This, in turn, would result in the lower density observed.

Because of its low density and large scale height, TOI-3757 b is an excellent planet for studying its atmosphere using transmission spectroscopy. This research can reveal details about the atmosphere’s composition and how gases escape, with an estimated measurement of around 190 for transmission spectroscopy.

The Rocky Core & Elliptical Shape of TOI-3757b:

The unusually low density of TOI-3757b can be attributed to two key factors, as explained by astronomers.

Firstly, it’s related to the planet’s rocky core. Gas giants typically start as massive rocky cores, roughly ten times the mass of Earth. Cores quickly gather lots of nearby gas, becoming the gas giants we see now. However, TOI-3757’s host star has a lower concentration of heavy elements compared to other M-dwarf stars with gas giants. This difference may have caused the rocky core of TOI-3757b to form more slowly, delaying the initiation of gas accumulation, and consequently, influencing the planet’s overall density.

Secondly, the planet’s orbit is believed to be somewhat elliptical. At certain points in its orbit, it comes closer to its star than at other times. This proximity results in significant additional heating, causing the planet’s atmosphere to expand or bloat. This expansion contributes to the planet’s lower density.

What is TOI-3757 b?

TOI-3757 b is an exoplanet classified as a gas giant, and it orbits a K-type star. It has a mass approximately equal to 0.26838 times that of Jupiter. This exoplanet orbits its star in just 3.4 days and is very close, about 0.03845 AU away from it.

When was toi-3757 b discovered?

Discovered in 2022, TOI-3757 b is a gas giant orbiting a red dwarf star in the constellation Auriga, located about 580 light-years from Earth. It’s exceptionally low-density, akin to a marshmallow.

Is there a marshmallow planet?

TOI-3757 b, the lowest-density planet ever detected, has a density akin to a marshmallow. The measurement of this exoplanet is just 0.27 grams per cubic centimeter, which is less than half the density of Saturn.

Who discovered TOI-3757 b?

The discovery of TOI-3757b was possible through NASA’s Transiting Exoplanet Survey Satellite (TESS). It was subsequently confirmed using the Habitable-zone Planet Finder (HPF).

What is the diameter of TOI-3757 b?

TESS observed TOI-3757 b as it passed in front of its host star. It is enabling astronomers to determine that the planet’s diameter is approximately 150,000 kilometers (100,000 miles). Which makes it slightly larger than Jupiter.

Is the cotton candy planet real?

“Super-Puffs” might sound like the name of a breakfast cereal. But it’s a term which describes a special and uncommon category of young exoplanets. These planets are as light as cotton candy, and there’s nothing similar to them in our solar system.

Is there a pink planet?

GJ 504b is a fascinating magenta-colored exoplanet. This pinkish planet comprises of gases and looks somewhat like Jupiter, a huge gas giant in our solar system. However, GJ 504b is notably larger, with a mass approximately four times greater than that of Jupiter.

Significant Statements by Authors & Researchers:

TOI-3757b was discovered using NASA’s Transiting Exoplanet Survey Satellite (TESS). It is confirmed with the Habitable-zone Planet Finder (HPF) on the Hobby-Eberly Telescope and the NEID instrument on the WIYN 3.5-m telescope.

Jessica Libby-Roberts is an author of the new research on TOI-3757 b and a postdoctoral researcher at Pennsylvania State University, She says in a statement.

“Potential future observations of the atmosphere of this planet using NASA’s new James Webb Space Telescope could help shed light on its puffy nature,”

Dr. Jessica Libby-Roberts, a postdoctoral researcher at Pennsylvania State University, says:

“Potential future observations of the atmosphere of this planet using the NASA/ESA/CSA James Webb Space Telescope could help shed light on its puffy nature.”

Dr. Kanodia says:

“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.”