L 98-59

L 98-59 (TOI-175, TIC 307210830) is a bright M dwarf star, located in the constellation of Volans, at a distance of 10.608 pc, as measured by the Gaia spacecraft.

Broadband photometry shows that it is an M3 dwarf star with three confirmed terrestrial-sized planets in transit, which were announced in March 2019 by TESS, as well as a fourth non-transiting planet and fifth candidate.

In August 2021, new evidence was announced for a fifth, potentially habitable planet, labeled L 98-59 f. Though still unconfirmed, this planet is believed to have 2.46 times Earth's mass, and an orbital period of 23.15 days.

Planetary system
The three inner planets of L 98-59 were discovered in 2019 by TESS. The potential super-Venus planet L 98-59 e was discovered in 2021, along with potentially habitable (located in the middle of the habitable zone) super-Earth candidate L 98-59 f. In September 2021, suggested tests of the abilities of the Hubble Space Telescope and the upcoming James Webb Space Telescope to detect and describe the atmospheric features of the three inner planets were reported.

The two innermost planets, L 98-59 b and c, as well as L 98-59 e are possibly hot rocky worlds. L 98-59 d has a low density, indicating large amounts of water, potentially making up as much as 30% of its entire mass. It may therefore be covered in a deep global ocean. Hubble observations of the three transiting planets in 2022 have found no clear evidence of atmospheres, with high mean molecular weight atmospheres, cloudy or hazy atmospheres, or no atmospheres being consistent with the observed flat spectra. One study found some evidence of an atmosphere on L 98-59 c, which has yet to be confirmed as of 2023.