// Workers AI · dad joke modeIs L 98-59 d a good planet? It's a star student.
 | This article has an unclear citation style. (August 2026) |
 An Artist's impression of L 98-59d | |
| Discovery[1] | |
|---|---|
| Discovery date | March 2019 |
| Transit | |
| Orbital characteristics[2] | |
| 0.0494±0.0016 AU | |
| Eccentricity | 0.006+0.007 −0.004 |
| 7.450729 d | |
| Inclination | 88.44±0.05 |
| Star | L 98-59 |
| Physical characteristics[2] | |
| 1.627±0.041 R | |
| Mass | 1.64±0.07 M |
Mean density | 2.2 g/cm3 |
| Temperature | 1900 C* |
L98-59d or TOI-175 d is an Exoplanet orbiting the star L 98-59 34.6 light years from Earth. L 98-59 d is the third planet potentially fourth planet in its system. [1] Its discovery was announced along with L 98-59 b and c in March 2019. [1] L 98-59 d is a Super-Earth having a mass of 1.64 M🜨 and has a radius of 1.627 R🜨. It takes 7.450729 days to orbit L 98-59 and orbits at a distance of 4.94% earth's orbit and has one of the least eccentric orbits in its system with an eccentricity of 0.006. JWST observations of this planet found an atmosphere made of hydrogen, hydrogen sulfide and sulfur dioxide and also found a lava ocean on its surface.[3]
Atmosphere
[edit]In March 2026 JWST discovered a cloud free atmosphere around L 98-59 d made of hydrogen, hydrogen sulfide and sulfur dioxide. [3]
Magma ocean
[edit]The same study that found an atmosphere around this planet found a molten surface made of lava with a temperature of 1900°C.[4]
Formation
[edit]L 98-59 d formed as a sub-Neptune about 5 billion years ago and its star stripped its atmosphere away. But L 98-59d had an abundance of Hydrogen, Hydrogen sulfide and sulfur dioxide and over time due to Volcanic activity formed an atmosphere with the same elements. L 98-59d has a core mass of 66% earth's total mass. Its core has a radius 55% the radius of earth. [5] The L 98-59d we see today is the dying remnant of a mini-Neptune in process of losing its atmosphere and becoming airless.
References
[edit]- 1 2 3 Kostov, Veselin B.; et al. (June 27, 2019). "The L 98-59 System: Three Transiting, Terrestrial-size Planets Orbiting a Nearby M Dwarf". The Astronomical Journal. 158 (32): 32. doi:10.3847/1538-3881/ab2459.
- 1 2 Demangeon, O. D. S.; Zapatero Osorio, M. R.; Alibert, Y.; et al. (September 2021). "Warm terrestrial planet with half the mass of Venus transiting a nearby star". Astronomy and Astrophysics. 653: A41. doi:10.1051/0004-6361/202140728.
- 1 2 Cheverall, Connor J; Madhusudhan, Nikku; Constantinou, Savvas; McCullough, P R (April 2026). "Ground-based atmospheric characterization of super-Earth L 98-59 d at high spectral resolution". Monthly Notices of the Royal Astronomical Society. 547 (4) stag484. doi:10.1093/mnras/stag484.
- ↑ The Guardian [full citation needed]
- ↑ https://doi.org/10.1038/s41550-026-02815 [full citation needed]