Astronomy:HD 177565

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Short description: G-dwarf star w. a planet; Corona Australis
HD 177565
Location of HD 177565 (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Corona Australis
Right ascension  19h 06m 52.46439s[1]
Declination −37° 48′ 38.3734″[1]
Apparent magnitude (V) 6.16[2]
Characteristics
Spectral type G6 V[3]
U−B color index +0.27[4]
B−V color index +0.70[4]
Astrometry
Radial velocity (Rv)60.9±0.8[5] km/s
Proper motion (μ) RA: −187.700[1] mas/yr
Dec.: −367.009[1] mas/yr
Parallax (π)58.9860 ± 0.0376[1] mas
Distance55.29 ± 0.04 ly
(16.95 ± 0.01 pc)
Absolute magnitude (MV)+5.00[6]
Details
Mass0.99+0.03−0.04[7] M☉
Radius0.985±0.022[8] R☉
Luminosity0.851±0.005[1] L☉
Surface gravity (log g)4.44±0.03[9] cgs
Temperature5,627±19[10] K
Metallicity [Fe/H]0.08±0.01[10] dex
Rotational velocity (v sin i)3[11] km/s
Age4.58±1.51[12] Gyr
Other designations
CD−37°13049, CPD−37°8466, GC 26283, GJ 744, HD 177565, HIP 93858, HR 7232, SAO 210937, LTT 7569[13]
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,[2] 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,[1] but it is receding rapidly with a heliocentric radial velocity of 60.9 km/s.[5] At its current distance, HD 177565's brightness is diminished by interstellar extinction of 0.07 magnitudes[14] and it has an absolute magnitude of +5.00.[6] A 2017 multiplicity survey failed to detect any stellar companions around the star.[15]

HD 177565 has a stellar classification of G6 V,[3] indicating that it is an ordinary G-type main-sequence star like the Sun. The object has also be given a later class of G8 V (Houk 1982)[16] and one source lists it as a G5 subgiant.[17] It has 99% the mass of the Sun[7] and 98.5% the Sun's radius.[8] It radiates 85.1% the luminosity of the Sun[1] from its photosphere at an effective temperature of 5,627 K,[10] making it slightly cooler than the Sun. HD 177565 is slightly metal enriched with an iron abundance at [Fe/H] = +0.08 (120% solar)[10] and it is estimated to be 4.58 billion years old.[12] HD 177565 spins slightly faster than the Sun with a projected rotational velocity of 3 km/s[11] 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.[18] 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.[19]

The HD 177565 planetary system[18]
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[20] R⊕
Size comparison of the planet HD 177565 b (artistic concept) with Earth and Neptune

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 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.
  2. ↑ 2.0 2.1 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. 
  3. ↑ 3.0 3.1 Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2 June 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample". The Astronomical Journal 132 (1): 161–170. doi:10.1086/504637. ISSN 0004-6256. Bibcode: 2006AJ....132..161G. 
  4. ↑ 4.0 4.1 Cousins, A. W. J. (January 1973). "UBV Photometry of Some Southern Stars (Second List)". Monthly Notes of the Astronomical Society of South Africa 32: 11. ISSN 0024-8266. Bibcode: 1973MNSSA..32...11C. 
  5. ↑ 5.0 5.1 Valenti, Jeff A.; Fischer, Debra A. (July 2005). "Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs". The Astrophysical Journal Supplement Series 159 (1): 141–166. doi:10.1086/430500. ISSN 0067-0049. Bibcode: 2005ApJS..159..141V. 
  6. ↑ 6.0 6.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 Ramírez, I.; Fish, J. R.; Lambert, D. L.; Allende Prieto, C. (13 August 2012). "Lithium Abundances in nearby FGK Dwarf and Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, and Exoplanets". The Astrophysical Journal 756 (1): 46. doi:10.1088/0004-637X/756/1/46. ISSN 0004-637X. Bibcode: 2012ApJ...756...46R. 
  8. ↑ 8.0 8.1 Masana, E.; Jordi, C.; Ribas, I. (10 April 2006). "Effective temperature scale and bolometric corrections from 2MASS photometry". Astronomy & Astrophysics 450 (2): 735–746. doi:10.1051/0004-6361:20054021. ISSN 0004-6361. Bibcode: 2006A&A...450..735M. 
  9. ↑ Aguilera-Gómez, Claudia; Ramírez, Iván; Chanamé, Julio (June 2018). "Lithium abundance patterns of late-F stars: an in-depth analysis of the lithium desert". Astronomy & Astrophysics 614: A55. doi:10.1051/0004-6361/201732209. ISSN 0004-6361. Bibcode: 2018A&A...614A..55A. 
  10. ↑ 10.0 10.1 10.2 10.3 Sousa, S. G.; Santos, N. C.; Mayor, M.; Udry, S.; Casagrande, L.; Israelian, G.; Pepe, F.; Queloz, D. et al. (4 June 2008). "Spectroscopic parameters for 451 stars in the HARPS GTO planet search program". Astronomy & Astrophysics 487 (1): 373–381. doi:10.1051/0004-6361:200809698. ISSN 0004-6361. Bibcode: 2008A&A...487..373S. 
  11. ↑ 11.0 11.1 Nordström, B.; Mayor, M.; Andersen, J.; Holmberg, J.; Pont, F.; Jørgensen, B. R.; Olsen, E. H.; Udry, S. et al. (16 April 2004). "The Geneva-Copenhagen survey of the Solar neighbourhood". Astronomy & Astrophysics 418 (3): 989–1019. doi:10.1051/0004-6361:20035959. ISSN 0004-6361. Bibcode: 2004A&A...418..989N. 
  12. ↑ 12.0 12.1 Gomes da Silva, J.; Santos, N. C.; Adibekyan, V.; Sousa, S. G.; Campante, T. L.; Figueira, P.; Bossini, D.; Delgado-Mena, E. et al. (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. doi:10.1051/0004-6361/202039765. ISSN 0004-6361. Bibcode: 2021A&A...646A..77G. 
  13. ↑ "HD 177565". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+177565. 
  14. ↑ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society 472 (4): 3805–3820. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
  15. ↑ Fuhrmann, K.; Chini, R.; Kaderhandt, L.; Chen, Z. (February 14, 2017). "Multiplicity among Solar-type Stars". The Astrophysical Journal (American Astronomical Society) 836 (1): 139. doi:10.3847/1538-4357/836/1/139. ISSN 1538-4357. Bibcode: 2017ApJ...836..139F. 
  16. ↑ Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. 3. Bibcode: 1982mcts.book.....H. 
  17. ↑ 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. doi:10.1093/mnras/119.6.638. ISSN 0035-8711. Bibcode: 1959MNRAS.119..638E. 
  18. ↑ 18.0 18.1 Feng, F.; Tuomi, M.; Jones, H. R. A. (May 16, 2017). "Agatha: disentangling periodic signals from correlated noise in a periodogram framework". Monthly Notices of the Royal Astronomical Society (Oxford University Press (OUP)) 470 (4): 4794–4814. doi:10.1093/mnras/stx1126. ISSN 0035-8711. Bibcode: 2017MNRAS.470.4794F. 
  19. ↑ "Extreme Lithium Depletion in Solar Twins: Challenging Non-Standard Mixing Models". August 2025. arXiv:2508.16513 [astro-ph.SR].
  20. ↑ Foster, G.; Poppenhaeger, K.; Ilic, N.; Schwope, A. (2022). "Exoplanet X-ray irradiation and evaporation rates with eROSITA". Astronomy & Astrophysics (EDP Sciences) 661: A23. doi:10.1051/0004-6361/202141097. ISSN 0004-6361. Bibcode: 2022A&A...661A..23F. 
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