[P-CG19] 系外惑星

[PCG19-02] The new finding for the planetary system TOI-1883 revealed by radial velocity follow-up observations

*福田 生鵬¹、成田 憲保^1,2、平野 照幸²、福井 暁彦¹、葛原 昌幸²、堀 安範²、幾田 佳¹、生駒 大洋³、jerome de Leon¹、川内 紀代恵⁴、木村 真博³、森 万由子¹、小谷 隆行²、田村 元秀²、IRD intensive team、IRD instrument team (1.東京大学、2.自然科学研究機構 アストロバイオロジーセンター、3.国立天文台 科学研究部、4.立命館大学)

キーワード：系外惑星、視線速度、スーパーネプチューン

Numerous transiting exoplanets have been discovered by space telescopes such as Kepler and TESS, revealing a diversity in their distribution. One of the most notable of these discoveries is that there are fewer Neptune-sized and Jupiter-sized planets than small-radius planets (so called super-Earths and sub-Neptunes) around M dwarfs in the mass-radius diagram. As of February 2024, there are only nine Neptune-sized planets with measured masses orbiting around M dwarfs. TOI-1883 b is a new planet of this type with a radius of around 5.6 Earth radii.

We performed follow-up radial velocity observations to determine the mass of TOI-1883 b using the InfraRed Doppler (IRD) instrument on the Subaru 8.2m Telescope. As a result, we found that this planetary system may contain at least two planets: the inner transiting planet b, with a mass of nearly Neptune, and an outer planet candidate c with a mass of a half of Saturn. However, the true mass of the planet candidate c remains ambiguous since no transit was detected and thus the orbital inclination is uncertain.

In this presentation, we will explain detailed radial velocity analysis, followed by a discussion on the uniqueness of TOI-1883 planetary system by comparing it with other planetary systems.