HD 215497

HD 215497 is a single^[4] star in the southern constellation of Tucana. It has an orange hue with an apparent visual magnitude of 8.96,^[2] which is too dim to be viewed with the naked eye. A 2015 survey ruled out the existence of any stellar companions at projected distances from 26 to 300 astronomical units.^[6] Based on parallax measurements,^[1] it is located at a distance of 132 light years from the Sun. The star is drifting further away with a radial velocity of +49 km/s, having come as close as 45 light-years some 774,000 years ago.^[3] The absolute magnitude of this star is 5.77.^[3]

HD 215497

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Tucana
Right ascension	22h 46m 36.75396s[1]
Declination	−56° 35′ 58.3285″[1]
Apparent magnitude (V)	8.96[2]
Characteristics
Spectral type	K3V[2]
Apparent magnitude (B)	9.913[3]
Apparent magnitude (J)	7.339±0.024[3]
Apparent magnitude (H)	6.917±0.053[3]
Apparent magnitude (K)	6.784±0.024[3]
B−V color index	0.953±0.025[3]
Astrometry
Radial velocity (Rv)	+49.31[3] km/s
Proper motion (μ)	RA: −54.660±0.041[1] mas/yr Dec.: −61.028±0.045[1] mas/yr
Parallax (π)	24.6339±0.0324 mas[1]
Distance	132.4 ± 0.2 ly (40.59 ± 0.05 pc)
Absolute magnitude (MV)	5.77[3]
Details[4]
Mass	0.86±0.02 M☉
Radius	0.87±0.02 R☉
Luminosity	0.47±0.02 L☉
Surface gravity (log g)	4.49±0.03 cgs
Temperature	5,128±12 K
Metallicity [Fe/H]	0.23±0.07[2] dex
Rotational velocity (v sin i)	1.67[2] km/s
Age	9.9±2.8 Gyr
Other designations
CPD−57°10139, HD 215497, HIP 112441, SAO 247578, PPM 350516, TYC 8826-00247-1, 2MASS J22463675-5635584[5]
Database references
SIMBAD	data
Exoplanet Archive	data

The stellar classification of HD 215497 is K3V,^[2] indicating this is a K-type main-sequence star that is generating energy through core hydrogen fusion. The star is about ten^[4] billion years old with a low magnetic activity level and is spinning with a projected rotational velocity of 1.67 km/s.^[2] It is smaller than the Sun, with 86% of the Sun's mass and 87% of the radius.^[4] This is a metal-rich star, which means the abundance of heavier elements in the atmosphere is significantly higher than in the Sun.^[2] It is radiating 47% of the luminosity of the Sun from its photosphere at an effective temperature of 5,128 K.^[4]

Planetary system

Announced in 2009, two extrasolar planets were discovered to be orbiting the star.^[2] Both planets are less massive than Jupiter. The inner exoplanet HD 215497 b orbits very close to the star and is termed a "hot super-Earth". The outer exoplanet HD 215497 c is a giant planet that orbits a little bit further from the star than the Earth, at around 1.282 AU, with a high eccentricity. A check for transits of the inner planet did not reveal any passages.^[7]

The HD 215497 planetary system^[2]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥6.6 M🜨	0.047	3.93404 ± 0.00066	0.16 ± 0.09	—	—
c	≥0.33 MJ	1.282	567.94 ± 2.70	0.49 ± 0.04	—	—