TOI-3757 b

TOI-3757 b

Discovery[1]
Discovered by	Kanodia et al.
Discovery date	2022
Detection method	Transit
Orbital characteristics[1]
Semi-major axis	0.03845±0.00043 AU
Eccentricity	0.14±0.06
Orbital period (sidereal)	3.438753±0.000004 d
Inclination	86.76+0.20 −0.23°
Argument of perihelion	130±23°
Star	TOI-3757
Physical characteristics[1]
Mean radius	12.0+0.4 −0.5 R🜨
Mass	85.3+8.8 −8.7 M🜨
Mean density	0.27+0.05 −0.04 g/cm^3
Temperature	759±13 K[a]

TOI-3757 b is a gas giant exoplanet located in the constellation of Auriga^[2] 578 light years, or 177 parsecs, away from Earth.^[3] It is well known for having a low density; as a result, it has been monikered the 'fluffiest planet ever'^[4] and the 'marshmallow world'.^[5] Its density is 0.27+0.05
−0.04 g/cm³,^[3] so low that it could float in a bathtub large enough to hold it.^[6] It is the least dense planet discovered around a red dwarf star, and also has the lowest metallicity of an gas giant around a red dwarf.^[7][3]

Physical characteristics

Mass and radius

The planet has a mass of only 0.27 Jupiter masses but a radius of 1.07 Jupiter radii, resulting in its extremely low density.

Host star

TOI-3757 is a M0 red dwarf star, which are very rare hosts for gas giant planets.^[3]

Orbit

TOI-3757b has a small orbit, having a semimajor axis at 0.04 astronomical units and an orbital period of just 3 days.^[1]

See also

• List of exoplanets discovered in 2022

Notes

1. assuming the planet is a black body and albedo is 0 with perfect energy redistribution

References

1. Martin, Pierre-Yves (2022). "Planet TOI-3757 b". exoplanet.eu. Retrieved 2026-02-20.
2. "Find the constellation which contains given sky coordinates". djm.cc. Retrieved 2025-05-01.
3. Kanodia, Shubham; Libby-Roberts, Jessica; Cañas, Caleb I.; Ninan, Joe P.; Mahadevan, Suvrath; Stefansson, Gudmundur; Lin, Andrea S. J.; Jones, Sinclaire; Monson, Andrew; Parker, Brock A.; Kobulnicky, Henry A.; Swaby, Tera N.; Powers, Luke; Beard, Corey; Bender, Chad F. (2022-09-01). "TOI-3757 b: A Low-density Gas Giant Orbiting a Solar-metallicity M Dwarf". The Astronomical Journal. 164 (3): 81. doi:10.3847/1538-3881/ac7c20. ISSN 0004-6256.
4. "Astronomers discover 'fluffiest planet ever' with the density of a marshmallow". The Independent. Archived from the original on 2025-03-04. Retrieved 2025-05-01.
5. Lea, Robert (2022-10-20). "'Marshmallow' world defies expectations for planets orbiting red dwarf stars". Space. Retrieved 2025-05-01.
6. Carter, Jamie. "We've Found A 'Marshmallow' Planet That Would Float In A Bathtub, Say Scientists". Forbes. Retrieved 2025-05-02.
7. [e-mail]. "'Marshmallow' World Orbiting a Cool Red Dwarf Star - Kitt Peak National Observatory telescope helps determines that Jupiter-like Planet is lowest-density gas giant ever detected around a red dwarf". www.noirlab.edu. Retrieved 2025-05-02.