HD 177565

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^[15] and it as an absolute magnitude of +5.00.^[6] A 2017 multiplicity survey failed to detect any stellar companions around the star.^[16]

HD 177565

Location of HD 177565 (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
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 mas/yr[1] Dec.: −367.009 mas/yr[1]
Parallax (π)	58.9860±0.0376 mas[1]
Distance	55.29 ± 0.04 ly (16.95 ± 0.01 pc)
Absolute magnitude (MV)	+5.00[6]
Details
Mass	0.99+0.03 −0.04[7] M☉
Radius	0.985±0.022[8] R☉
Luminosity	0.851±0.005[1] L☉
Surface gravity (log g)	4.44±0.03[9] cgs
Temperature	5,627±19[10] K
Metallicity [Fe/H]	0.08±0.01[10] dex
Rotational velocity (v sin i)	3[11] km/s
Age	4.58±1.51[12] Gyr
Other designations
42 G. Coronae Australis[13], CD−37°13049, CPD−37°8466, GC 26283, GJ 744, HD 177565, HIP 93858, HR 7232, SAO 210937, LTT 7569[14]
Database references
SIMBAD	data

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)^[17] and one source lists it as a G5 subgiant.^[18] 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.^[19]

The HD 177565 planetary system^[19]

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