LTT 9779 / Uúba
Observation data
Epoch J2000      Equinox J2000
Constellation Sculptor[1]
Right ascension 23h 54m 40.20731s[2]
Declination −37° 37′ 40.5244″[2]
Apparent magnitude (V) 9.76±0.03[3]
Characteristics
Evolutionary stage Main sequence
Spectral type G7V[3]
Apparent magnitude (B) 10.55±0.04[3]
Apparent magnitude (V) 9.76±0.03[3]
Apparent magnitude (G) 9.606±0.003[2]
Apparent magnitude (J) 8.45±0.02[3]
Apparent magnitude (H) 8.15±0.02[3]
Apparent magnitude (K) 8.02±0.03[3]
Astrometry
Radial velocity (Rv)−10.72±0.22[2] km/s
Proper motion (μ) RA: 247.634 mas/yr[2]
Dec.: −69.752 mas/yr[2]
Parallax (π)12.3381 ± 0.0166 mas[2]
Distance264.3 ± 0.4 ly
(81.0 ± 0.1 pc)
Absolute magnitude (MV)5.30±0.07[3]
Details[3]
Mass1.00+0.02
−0.03 M☉
Radius0.949±0.006 R☉
Luminosity (bolometric)0.71±0.01 L☉
Surface gravity (log g)4.51±0.01 cgs
Temperature5443+14
−13 K
Metallicity [Fe/H]0.27±0.03 dex
Rotation≤45 d
Rotational velocity (v sin i)1.06±0.37 km/s
Age1.9+1.7
−1.2 Gyr
Other designations
Uúba, CD−38 15670, CPD−38 8578, HIP 117883, SAO 214854, PPM 304331, LTT 9779, NLTT 58368, TOI-193, TIC 183985250, TYC 8015-1162-1, 2MASS J23544020-3737408, WISEA J235440.43-373741.2[4]
Database references
SIMBADdata

LTT 9779 is a G-type main-sequence star located 264 light-years (81 parsecs) away from the Solar System in the constellation of Sculptor. The star is about 95% the radius and about the same mass as the Sun, but younger than the Sun at 1.7 billion years old, hence its lower luminosity (about 0.7 L☉). It has a temperature of 5,443 K (5,170 °C; 9,338 °F) and a rotation period of 45 days.[3] LTT 9779 is orbited by one known exoplanet.

Nomenclature

The designation LTT 9779 comes from one of Luyten's catalogues of stars with high proper motion.

In August 2022, this planetary system was included among 20 systems to be named by the third NameExoWorlds project.[5] The approved names, proposed by a team from Colombia, were announced in June 2023. LTT 9779 is named Uúba and its planet is named Cuancoá, after the U'wa language word referring to "stars", "seeds", or "eyes" and the name for the morning star, respectively.[6]

Planetary system

The discovery of the exoplanet LTT 9779 b using TESS was published in 2020. It is an ultra-hot Neptune with about 29 times the mass and 4.7 times the radius of Earth and an orbital period of less than a day. These parameters make it one of the very few known planets in the Neptunian desert.[3] Observations using the Spitzer Space Telescope have measured the planet's dayside temperature at 2,305 K (2,032 °C; 3,689 °F),[7][8] and observations by CHEOPS have shown the planet to be highly reflective, with an albedo of 80%.[9][10]

A study published in 2019, prior to the confirmation of LTT 9779 b, proposed a second candidate planet in the system based on transit timing variations, but this has not been confirmed,[11] and the study that confirmed LTT 9779 b found no evidence of transit timing variations.[3]: 23 

The LTT 9779 planetary system[3][7]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b / Cuancoá 29.32+0.78
−0.81 M🜨		 0.01679+0.00014
−0.00012		 0.7920520±0.0000093 <0.01 76.39±0.43° 4.72±0.23 R🜨

References

  1. ↑ "Finding the constellation which contains given sky coordinates". djm.cc. 2 August 2008. Retrieved 30 August 2022.
  2. 1 2 3 4 5 6 7 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.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 Jenkins, James S.; Díaz, Matías R.; et al. (September 2020). "An Ultra-Hot Neptune in the Neptune desert". Nature Astronomy. 4 (12): 1148–1157. arXiv:2009.12832. Bibcode:2020NatAs...4.1148J. doi:10.1038/s41550-020-1142-z. S2CID 256707813.
  4. ↑ "LTT 9779". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 30 August 2022.
  5. ↑ "List of ExoWorlds 2022". nameexoworlds.iau.org. IAU. 8 August 2022. Retrieved 27 August 2022.
  6. ↑ "2022 Approved Names". nameexoworlds.iau.org. IAU. Retrieved 7 June 2023.
  7. 1 2 Dragomir, Diana; Crossfield, Ian J. M.; et al. (November 2020). "Spitzer Reveals Evidence of Molecular Absorption in the Atmosphere of the Hot Neptune LTT 9779b". The Astrophysical Journal Letters. 903 (1): L6. arXiv:2010.12744. Bibcode:2020ApJ...903L...6D. doi:10.3847/2041-8213/abbc70. S2CID 225067568.
  8. ↑ Crossfield, Ian J. M.; Dragomir, Diana; et al. (November 2020). "Phase Curves of Hot Neptune LTT 9779b Suggest a High-metallicity Atmosphere". The Astrophysical Journal Letters. 903 (1): L7. arXiv:2010.12745. Bibcode:2020ApJ...903L...7C. doi:10.3847/2041-8213/abbc71. S2CID 225067727.
  9. ↑ "Cheops shows scorching exoplanet acts like a mirror". ESA. 10 July 2023. Retrieved 10 July 2023.
  10. ↑ Hoyer, S.; Jenkins, J. S.; et al. (July 2023). "The extremely high albedo of LTT 9779 b revealed by CHEOPS". Astronomy & Astrophysics. 675: A81. doi:10.1051/0004-6361/202346117.
  11. ↑ Pearson, Kyle A. (December 2019). "A Search for Multiplanet Systems with TESS Using a Bayesian N-body Retrieval and Machine Learning". The Astronomical Journal. 158 (6): 243. arXiv:1907.03377. Bibcode:2019AJ....158..243P. doi:10.3847/1538-3881/ab4e1c. S2CID 195833716.
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