LTT 9779

LTT 9779 is a G-type main-sequence star located 264 light-years (81 pc) 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. 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.

LTT 9779
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
Rotation45 d
Rotational velocity (v sin i)1.06±0.37 km/s
Age1.9+1.7
−1.2 Gyr
Other designations
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

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).[5][6] A study published in 2019, prior to the confirmation of planet b, proposed a second candidate planet in the system based on transit timing variations, but this has not been confirmed.[7]

In August 2022, this planetary system was included among 20 systems to be named by the third NameExoWorlds project.[8]

The LTT 9779 planetary system[3][5]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 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. Vallenari, A.; et al. (Gaia Collaboration) (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. arXiv:2208.00211. doi:10.1051/0004-6361/202243940. Gaia DR3 record for this source at VizieR.
  3. 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. 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.
  6. 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.
  7. 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.
  8. "List of ExoWorlds 2022". nameexoworlds.iau.org. IAU. 8 August 2022. Retrieved 27 August 2022.
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