KELT-24

KELT-24 (HD 93148, MASCARA-3) is a multiple star system in the constellation Ursa Major at a distance of approximately 316 light-years (about 96.9 parsecs) from Sun. The apparent magnitude of the primary star is +8.33. The star's age is estimated to be about 2.8 billion years. As an F-type main-sequence star, it is similar to the Sun, but slightly hotter, larger, and more luminous.

KELT-24

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Ursa Major[1]
KELT-24
Right ascension	10h 47m 38.35063s[2]
Declination	+71° 39′ 21.1525″[2]
Apparent magnitude (V)	8.33[3]
KELT-24B
Right ascension	10h 47m 38.38264s[4]
Declination	+71° 39′ 19.1482″[4]
Characteristics
KELT-24
Evolutionary stage	main sequence[2]
Spectral type	F5[5]
Variable type	planetary transit
KELT-24B
Evolutionary stage	main sequence[6]
Spectral type	M + M?[6]
Variable type	eclipsing[6]
Astrometry
KELT-24
Radial velocity (Rv)	−5.54±0.24[2] km/s
Proper motion (μ)	RA: −56.061 mas/yr[2] Dec.: −34.526 mas/yr[2]
Parallax (π)	10.3218±0.0180 mas[2]
Distance	316.0 ± 0.6 ly (96.9 ± 0.2 pc)
Absolute magnitude (MV)	+3.47[1]
KELT-24B
Proper motion (μ)	RA: −49.897 mas/yr[4] Dec.: −37.516 mas/yr[4]
Parallax (π)	10.6799±0.0892 mas[4]
Distance	305 ± 3 ly (93.6 ± 0.8 pc)
Details[6]
KELT-24
Mass	1.31 M☉
Radius	1.51 R☉
Luminosity	3.54 L☉
Surface gravity (log g)	4.19 cgs
Temperature	6,437 K
Metallicity [Fe/H]	0.17 dex
Rotation	~4 days
Rotational velocity (v sin i)	19.7 km/s
Age	2.8 Gyr
B
Mass	0.52 M☉
Radius	0.48 R☉
Luminosity	0.037 L☉
Surface gravity (log g)	4.78 cgs
Temperature	3,630 K
Metallicity [Fe/H]	0.30 dex
Age	2.8 Gyr
C
Mass	0.51 M☉
Radius	0.49 R☉
Luminosity	0.038 L☉
Surface gravity (log g)	4.77 cgs
Temperature	3,640 K
Metallicity [Fe/H]	−0.31 dex
Age	2.8 Gyr
Other designations
MASCARA-3, KELT-24, HD 93148, HIP 52796[7]
Database references
SIMBAD	data
	B

KELT-24 has a single known exoplanet, a hot Jupiter only 11 R_☉ from the star.

Nomenclature

This star was first catalogued in the Henry Draper Catalogue as HD 93148. The Henry Draper Catalogue gave stars visible to the naked eye in suitable conditions a designation, indicating that this star can be seen with the naked eye. But in 2019, the Multi-site All-Sky Camera and the Kilodegree Extremely Little Telescope announced the discovery of the exoplanet KELT-24b/MASCARA-3b around this star. Thus, it is most commonly known as KELT-24, although the star is sometimes catalogued as MASCARA-3.^[6]

The common proper motion companion is referred to as HD 93148B or KELT-24B,^[7] or KELT-24BC when it is being treated as a spectroscopic binary.^[6]

Star system

KELT-24 is an 8th-magnitude F-type star with a faint companion separated by 2″. The companion is over-luminous for a normal star of its colour and is suspected to be a binary consisting of two red dwarfs.

KELT-24 is a yellow-white star with a spectral class of F5. Its mass is about 1.3 M_☉, its radius is about 1.5 R_☉, and its luminosity is about 3.5 L_☉. Its effective temperature is about 6,437 K. An age of 2.8 billion years has been calculated, but the 68% confidence interval ranges from 2.0 to 6.9 billion years.^[6] Age estimates in the original discovery papers were 0.78 and 2.8 billion years respectively.^[8][9]

KELT-24B, or KELT-24BC when both components are being referred to, is suspected of being an eclipsing binary although only a single "transit-like event" has been observed. The best model fit is two near-identical red dwarfs each with a mass about half the Sun's and a luminosity less than 4% of the Sun's.^[6]

Planetary system

In 2019, the discovery of the Hot Jupiter type planet KELT-24b/MASCARA-3b was announced by the Multi-site All-Sky CAmeRA and the Kilodegree Extremely Little Telescope. TESS data confirmed that no additional companions are orbiting this star.^[10][11]

The KELT-24^[6] planetary system

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	4.6 MJ	0.0501	5.5515	0.032	89.7°	1.1 RJ