Discovery[1] | |
---|---|
Discovered by | Montalto et al. |
Discovery site | TESS |
Discovery date | 13 October 2021 |
Transit | |
Orbital characteristics[1] | |
Periastron | 0.049 AU (7,300,000 km) |
Apoastron | 0.052 AU (7,800,000 km) |
0.051 ± 0.002 AU (7,630,000 ± 300,000 km) | |
Eccentricity | 0.03 ± 0.02 |
3.660028 ± 0.000006 d | |
Inclination | 86.0°±0.7° |
2,458,708.9983 ± 0.0003 JD | |
Semi-amplitude | 74±3 m/s |
Star | TOI-4138 |
Physical characteristics[1] | |
Mean radius | 1.49 ± 0.04 RJ |
Mass | 0.67 ± 0.03 MJ |
Mean density | 250 ± 20 kg/m3 (421 ± 34 lb/cu yd) |
Temperature | 1,762 ± 21 K (2,711.9 ± 37.8 °F; 1,488.8 ± 21.0 °C) |
TOI-4138 b is a transiting exoplanet orbiting the G-type subgiant TOI-4138 1,674 light years away in the northern circumpolar constellation Ursa Minor.
The planet was discovered by TESS using the transit method, which involves measuring light curves during a planet’s eclipse. The paper states that it’s inflated due to heating from its host star, which has a high luminosity.[2] Its discovery was announced in October 2021.
TOI-4138 b has an orbital period of 3.6 days, typical for a hot Jupiter. This corresponds to a separation from its host close to one eighth of the distance of Mercury from the Sun. Since the inclination is known, doppler spectroscopy measurements give the planet a mass only 67% that of Jupiter.[1] Its separation is comparable with HD 209458 b, but is much larger due to the evolved state of the host star.[1]
TOI-4138 b’s transit gives it a radius 1.49 times that of Jupiter; this combined with its low mass of 0.67 MJ gives it a density only 25% that of water.[1]
TOI-4138 b orbits TOI-4138, a subgiant star[1] located in the constellation Ursa Minor. The star has an enlarged radius of 1.82 R☉, a luminosity of 4.37 L☉ and an effective temperature of 6,128 K (5,855 °C).[1] It has 1.32 times the Sun's mass, and it has an intermediate age of around 3.5 billion years.[1] The apparent magnitude of the star is 11.8, making it not visible to the naked eye.[3]