HD 177565

HD 177565
Location of HD 177565 (circled)
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Corona Australis
Right ascension 19h 06m 52.46439s
Declination −37° 48′ 38.3734″
Apparent magnitude (V) 6.16
Characteristics
Evolutionary stage main sequence
Spectral type G6 V
U−B color index +0.27
B−V color index +0.70
Astrometry
Radial velocity (Rv)60.9±0.8 km/s
Proper motion (μ) RA: −187.700 mas/yr
Dec.: −367.009 mas/yr
Parallax (π)58.9860±0.0376 mas
Distance55.29 ± 0.04 ly
(16.95 ± 0.01 pc)
Absolute magnitude (MV)+5.00
Details
Mass0.99+0.03
−0.04 M☉
Radius0.985±0.022 R☉
Luminosity0.851±0.005 L☉
Surface gravity (log g)4.44±0.03 cgs
Temperature5,627±19 K
Metallicity [Fe/H]0.08±0.01 dex
Rotational velocity (v sin i)3 km/s
Age4.58±1.51 Gyr
Other designations
42 G. Coronae Australis, CD−37°13049, CPD−37°8466, GC 26283, GJ 744, HD 177565, HIP 93858, HR 7232, SAO 210937, LTT 7569
Database references
SIMBADdata
Exoplanet Archivedata

HD 177565 (HR 7232; LTT 7569; Gliese 744) is a yellow-hued star located in the southern constellation Corona Australis. It has an apparent magnitude of 6.16, placing it near the limit for naked eye visibility, even under ideal conditions. The object is located relatively close at a distance of 55.3 light-years based on Gaia DR3 parallax measurements, but it is receding rapidly with a heliocentric radial velocity of 60.9 km/s. At its current distance, HD 177565's brightness is diminished by interstellar extinction of 0.07 magnitudes and it has an absolute magnitude of +5.00. A 2017 multiplicity survey failed to detect any stellar companions around the star.

HD 177565 has a stellar classification of G6 V, indicating that it is an ordinary G-type main-sequence star like the Sun. The object has also been given a later class of G8 V (Houk 1982) and one source lists it as a G5 subgiant. It has 99% the mass of the Sun and 98.5% the Sun's radius. It radiates 85.1% the luminosity of the Sun from its photosphere at an effective temperature of 5,627 K, making it slightly cooler than the Sun. HD 177565 is slightly metal enriched with an iron abundance at [Fe/H] = +0.08 (120% solar) and it is estimated to be 4.58 billion years old. HD 177565 spins slightly faster than the Sun with a projected rotational velocity of 3 km/s compared to the Sun's rotational velocity of 2 km/s.

Planetary system

In 2017, an exoplanet was discovered orbiting the star after observations of HARPS data. HD 177565 b is a hot Neptune that takes 44.5 days to revolve around its host star in a relatively circular orbit. However, a 2025 study proposed a completely different planet "b" with a period of 767 days and a minimum mass of 23.5 M🜨, with no mention of the previously published planet.

The HD 177565 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination
(°)		 Radius
b ≥15.10+6.40
−6.05 M🜨		 0.246±0.019 44.5+0.6
−0.3		 0.059+0.172
−0.058		 — ~4.1 R🜨
Size comparison of the planet HD 177565 b (artistic concept) with Earth and Neptune

References

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  2. 1 2 3 4 5 6 7 8 9 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 Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99–110. Bibcode:1966CoLPL...4...99J.
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  12. 1 2 Gomes da Silva, J.; Santos, N. C.; Adibekyan, V.; Sousa, S. G.; Campante, T. L.; Figueira, P.; Bossini, D.; Delgado-Mena, E.; Monteiro, M. J. P. F. G.; de Laverny, P.; Recio-Blanco, A.; Lovis, C. (February 2021). "Stellar chromospheric activity of 1674 FGK stars from the AMBRE-HARPS sample. I. A catalogue of homogeneous chromospheric activity". Astronomy & Astrophysics. 646: A77. arXiv:2012.10199. Bibcode:2021A&A...646A..77G. doi:10.1051/0004-6361/202039765. eISSN 1432-0746. ISSN 0004-6361. S2CID 229331727.
  13. ↑ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
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  17. ↑ Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. Vol. 3. Bibcode:1982mcts.book.....H.
  18. ↑ Evans, D. S.; Menzies, A.; Stoy, R. H. (1 December 1959). "Fundamental Data for Southern Stars (Second List)". Monthly Notices of the Royal Astronomical Society. 119 (6): 638–647. Bibcode:1959MNRAS.119..638E. doi:10.1093/mnras/119.6.638. eISSN 1365-2966. ISSN 0035-8711.
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  20. ↑ Winnick, Isabelle; Galarza, Jhon Yana; et al. (August 2025). "Extreme Lithium Depletion in Solar Twins: Challenging Non-Standard Mixing Models". arXiv:2508.16513 [astro-ph.SR].
  21. ↑ Foster, G.; Poppenhaeger, K.; Ilic, N.; Schwope, A. (2022). "Exoplanet X-ray irradiation and evaporation rates with eROSITA". Astronomy & Astrophysics. 661. EDP Sciences: A23. arXiv:2106.14550. Bibcode:2022A&A...661A..23F. doi:10.1051/0004-6361/202141097. ISSN 0004-6361.