Astronomy:LTT 9779

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Short description: Star in the constellation Sculptor
LTT 9779 / Uúba
Observation data
Equinox J2000.0]] (ICRS)
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[2] mas/yr
Dec.: −69.752[2] mas/yr
Parallax (π)12.3381 ± 0.0166[2] mas
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, TYC 8015-1162-1, 2MASS J23544020-3737408[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". 2 August 2008. http://djm.cc/constellation.html. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 Jenkins, James S. et al. (September 2020). "An Ultra-Hot Neptune in the Neptune desert". Nature Astronomy 4 (12): 1148–1157. doi:10.1038/s41550-020-1142-z. Bibcode: 2020NatAs...4.1148J. 
  4. ↑ "LTT 9779". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=LTT+9779. 
  5. ↑ "List of ExoWorlds 2022". IAU. 8 August 2022. https://www.nameexoworlds.iau.org/2022exoworlds. 
  6. ↑ "2022 Approved Names". IAU. https://www.nameexoworlds.iau.org/2022approved-names?pgid=lieirelz-3a427f17-9066-4236-a40c-86b55aead81d. 
  7. ↑ 7.0 7.1 Dragomir, Diana 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. doi:10.3847/2041-8213/abbc70. Bibcode: 2020ApJ...903L...6D. 
  8. ↑ Crossfield, Ian J. M. et al. (November 2020). "Phase Curves of Hot Neptune LTT 9779b Suggest a High-metallicity Atmosphere". The Astrophysical Journal Letters 903 (1): L7. doi:10.3847/2041-8213/abbc71. Bibcode: 2020ApJ...903L...7C. 
  9. ↑ "Cheops shows scorching exoplanet acts like a mirror". ESA. 10 July 2023. https://www.esa.int/Science_Exploration/Space_Science/Cheops/Cheops_shows_scorching_exoplanet_acts_like_a_mirror. 
  10. ↑ Hoyer, 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. doi:10.3847/1538-3881/ab4e1c. Bibcode: 2019AJ....158..243P. 



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