L 98-59 d
 Artist's impression of L 98-59 d | |
| 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 | 1,900 °C (3,450 °F) |
L 98-59 d (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, potentially fourth, planet in its system.[1] Its discovery was announced along with L 98-59 b and c in 2019 by the Transiting Exoplanet Survey Satellite (TESS).[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. The James Webb Space Telescope (JWST) observations of a planet found with an atmosphere made of hydrogen, hydrogen sulfide, and sulfur dioxide and also found a lava ocean on its surface.[3]
Atmosphere
In 2026, the JWST discovered a cloud-free atmosphere around L 98-59 d made of hydrogen, hydrogen sulfide and sulfur dioxide.[3]
Magma ocean
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
L 98-59 d formed as a sub-Neptune about 5 billion years ago and its star stripped its atmosphere away. L 98-59 d has an abundance of hydrogen, hydrogen sulfide and sulfur dioxide and over time due to volcanic activity formed an atmosphere with the same elements. L 98-59 d has a core mass of 66% Earth's total mass. Its core has a radius 55% the radius of Earth.[5] The planet L 98-59 d we see today is the dying remnant of a mini-Neptune in the process of losing its atmosphere and becoming airless.
References
- 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. arXiv:1903.08017. 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. arXiv:2108.03323. 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. arXiv:2603.02209. doi:10.1093/mnras/stag484.
- ↑ The Guardian
- ↑ https://doi.org/10.1038/s41550-026-02815
