Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Volans |
Right ascension | 08h 18m 07.62144s [1] |
Declination | −68° 18′ 46.8054″ [1] |
Apparent magnitude (V) | 11.69±0.05 [2] |
Characteristics | |
Evolutionary stage | Red dwarf (main sequence) |
Spectral type | M3V [3] |
B−V colour index | +1.53 [2] |
R−I colour index | +1.28 [2] |
Variable type | None |
Astrometry | |
Radial velocity (Rv) | −6.10±0.19 [1] km/s |
Proper motion (μ) | RA: 94.794(18) mas/yr [1] Dec.: −340.084(20) mas/yr [1] |
Parallax (π) | 94.2664 ± 0.0155 mas [1] |
Distance | 34.599 ± 0.006 ly (10.608 ± 0.002 pc) |
Details [3] | |
Mass | 0.273±0.030 M☉ |
Radius | 0.303+0.026 −0.023 R☉ |
Luminosity (bolometric) | 0.01128±0.00042 L☉ |
Surface gravity (log g) | 4.86±0.13 cgs |
Temperature | 3415±135 K |
Metallicity [Fe/H] | −0.46±0.26 dex |
Rotation | 80.9+5.0 −5.3 d |
Age | >800 Myr |
Other designations | |
2MASS J08180763-6818468, TOI-175, TYC 9193-2365-1, Gaia DR2 5271055243163629056 | |
Database references | |
SIMBAD | data |
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 parsecs (34.60 light-years ), as measured by Gaia. [4]
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, [5] as well as a fourth non-transiting planet and fifth candidate. [6]
In August 2021, new evidence was announced for a fifth, potentially habitable planet, labeled L 98-59 f. Though still unconfirmed, [6] this planet is believed to have 2.46 times Earth's mass, and an orbital period of 23.15 days. [7] [8]
The three inner planets of L 98-59 were discovered in 2019 by TESS. [5] 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. [3] 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. [9]
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. [7] 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. [10] [11] [12] One study found some evidence of an atmosphere on L 98-59 c, which has yet to be confirmed as of 2023. [13]
Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 0.40+0.16 −0.15 M🜨 | 0.02191+0.00080 −0.00084 | 2.2531136+0.0000012 −0.0000015 | 0.103+0.117 −0.045 | 87.71+1.16 −0.44 ° | 0.85+0.061 −0.047 R🜨 |
c | 2.22+0.26 −0.25 M🜨 | 0.0304+0.0011 −0.0012 | 3.6906777+0.0000016 −0.0000026 | 0.103+0.045 −0.058 | 88.11+0.36 −0.16 ° | 1.385+0.095 −0.075 R🜨 |
d | 1.94±0.28 M🜨 | 0.0486+0.0018 −0.0019 | 7.4507245+0.0000081 −0.0000046 | 0.074+0.057 −0.046 | 88.449+0.058 −0.111 ° | 1.521+0.119 −0.098 R🜨 |
e | ≥3.06+0.33 −0.37 M🜨 | 0.0717+0.0060 −0.0048 | 12.796+0.020 −0.019 | 0.128+0.108 −0.076 | — | — |
f(unconfirmed) | ≥2.46+0.66 −0.82 M🜨 | 0.1034+0.0042 −0.0044 | 23.15+0.60 −0.17 | 0.21+0.17 −0.11 | — | — |
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L 98-59 b is an exoplanet having a size between that of the Earth and Mars and a mass only half that of Venus. It orbits L 98-59, a red dwarf 35 light-years away in the constellation Volans. There are at least 3 other planets in the system: L 98-59 c, d, e, and the unconfirmed L 98-59 f. Its discovery was announced on 27 June 2019 on the NASA website. It was the smallest planet discovered by TESS until the discovery of LHS 1678b, and was the lowest-mass planet whose mass has been measured using radial velocities until Proxima Centauri d was found in 2022.