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L 98-59

Coordinates: Sky map 08h 18m 07.62s, −68° 18′ 46.8″
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L 98-59
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]
Distance34.599 ± 0.006 ly
(10.608 ± 0.002 pc)
Details[3]
Mass0.273±0.030 M☉
Radius0.303+0.026
−0.023 R☉
Luminosity (bolometric)0.01128±0.00042 L☉
Surface gravity (log g)4.86±0.13 cgs
Temperature3415±135 K
Metallicity [Fe/H]−0.46±0.26 dex
Rotation80.9+5.0
−5.3 d
Age>800 Myr
Other designations
2MASS J08180763-6818468, TOI-175, TYC 9193-2365-1, Gaia DR2 5271055243163629056
Database references
SIMBADdata

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 the Gaia spacecraft.[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]

Planetary system

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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] Transmission spectroscopy by the JWST suggest that L 98-59 d might have a sulfur-rich atmosphere.[14]

Also, ExoFOP list of TESS candidates includes fourth transiter, TOI-175.04 - if confirmed, this sub-earth would be innermost in this system; due to low mass (lighter than L 98-59 b) and intense UV radiation, it probably lacks any kind of thick atmosphere.

The L 98-59 planetary system[3]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
g (unconfirmed) — — 1.048+0.002
−0.002 		0 — 0.68+0.08
−0.05 R🜨
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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Artist's impression of the L 98-59 system, compared to the inner Solar System. Distances are not to scale.

See also

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References

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  1. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c Zacharias, N.; Finch, C. T.; Girard, T. M.; Henden, A.; Bartlett, J. L.; Monet, D. G.; Zacharias, M. I. (1 February 2013). "The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)". The Astronomical Journal. 145 (2): 44. arXiv:1212.6182. Bibcode:2013AJ....145...44Z. doi:10.1088/0004-6256/145/2/44. ISSN 0004-6256. S2CID 119299381.
  3. ^ a b c d Demangeon, Oliver D. S.; Zapatero Osorio, M. R.; Alibert, Y.; Barros, S. C. C.; Adibekyan, V.; Tabernero, H. M.; et al. (July 2021). "A warm terrestrial planet with half the mass of Venus transiting a nearby star" (PDF). Astronomy & Astrophysics. 653: 38. arXiv:2108.03323. Bibcode:2021A&A...653A..41D. doi:10.1051/0004-6361/202140728. S2CID 236957385.
  4. ^ Cloutier, R.; Astudillo-Defru, N.; Bonfils, X.; Jenkins, J. S.; Berdiñas, Z.; Ricker, G.; Vanderspek, R.; Latham, D. W.; Seager, S.; Winn, J.; Jenkins, J. M. (2019-09-01). "Characterization of the L 98-59 multi-planetary system with HARPS - Mass characterization of a hot super-Earth, a sub-Neptune, and a mass upper limit on the third planet". Astronomy & Astrophysics. 629: A111. arXiv:1905.10669. Bibcode:2019A&A...629A.111C. doi:10.1051/0004-6361/201935957. hdl:1721.1/125703. ISSN 0004-6361. S2CID 166228063.
  5. ^ a b Kostov, Veselin B.; Schlieder, Joshua E.; Barclay, Thomas; Quintana, Elisa V.; Colon, Knicole D.; Brande, Jonathan; Collins, Karen A.; Feinstein, Adina D.; Hadden, Samuel; Kane, Stephen R.; Kreidberg, Laura (2019-06-27). "The L 98-59 System: Three Transiting, Terrestrial-Sized Planets Orbiting a Nearby M-dwarf". The Astronomical Journal. 158 (1): 32. arXiv:1903.08017. Bibcode:2019AJ....158...32K. doi:10.3847/1538-3881/ab2459. hdl:1721.1/124742. ISSN 1538-3881. S2CID 118855908.
  6. ^ a b "Comparison of the L 98-59 exoplanet system with the inner Solar System". European Southern Observatory. Retrieved 2021-08-07.
  7. ^ a b "EarthSky | An inner solar system much like ours, 35 light-years away". Earth & Sky. 2021-08-06. Retrieved 2021-08-07.
  8. ^ "New ESO observations show rocky exoplanet has just half the mass of Venus". European Southern Observatory. 5 August 2021. eso2112. Retrieved 8 August 2021.
  9. ^ Pidhorodetska, Daria; et al. (29 September 2021). "L 98-59: A Benchmark System of Small Planets for Future Atmospheric Characterization". The Astronomical Journal. 162 (4): 169. arXiv:2106.00685. Bibcode:2021AJ....162..169P. doi:10.3847/1538-3881/ac1171. S2CID 235293792.
  10. ^ Damiano, Mario; Hu, Renyu; et al. (November 2022). "A Transmission Spectrum of the Sub-Earth Planet L98-59 b in 1.1-1.7 μm". The Astronomical Journal. 164 (5): 225. arXiv:2210.10008. Bibcode:2022AJ....164..225D. doi:10.3847/1538-3881/ac9472.
  11. ^ Zhou, Li; Ma, Bo; et al. (November 2022). "Hubble WFC3 Spectroscopy of the Rocky Planet L 98-59 b: No Evidence for a Cloud-free Primordial Atmosphere". The Astronomical Journal. 164 (5): 203. arXiv:2210.10699. Bibcode:2022AJ....164..203Z. doi:10.3847/1538-3881/ac8fe9.
  12. ^ Zhou, Li; Ma, Bo; et al. (February 2023). "Hubble WFC3 Spectroscopy of the Terrestrial Planets L 98-59 c and d: No Evidence for a Clear Hydrogen Dominated Primary Atmosphere". Research in Astronomy and Astrophysics. 23 (2): 025011. arXiv:2212.09526. Bibcode:2023RAA....23b5011Z. doi:10.1088/1674-4527/acaceb. S2CID 254854167.
  13. ^ Barclay, Thomas; et al. (2023), The transmission spectrum of the potentially rocky planet L 98-59 c, arXiv:2301.10866
  14. ^ Gressier, Amélie; Espinoza, Néstor; Allen, Natalie H.; Sing, David K.; Banerjee, Agnibha; Barstow, Joanna K.; Valenti, Jeff A.; Lewis, Nikole K.; Birkmann, Stephan M. (2024-08-28), Hints of a sulfur-rich atmosphere around the 1.6 R🜨 Super-Earth L98-59 d from JWST NIRSpec G395H transmission spectroscopy, arXiv:2408.15855, doi:10.3847/2041-8213/ad73d1
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