[P-CG19] Exoplanet

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

*Izuru Fukuda¹, Norio Narita^1,2, Teruyuki Hirano², Akihiko Fukui¹, Masayuki Kuzuhara², Yasunori Hori², Kai Ikuta¹, Masahiro Ikoma³, Jerome Pitogo de Leon¹, Kiyoe Kawauchi⁴, Tadahiro Kimura³, Mayuko Mori¹, Takayuki Kotani², Motohide Tamura², IRD intensive team, IRD instrument team (1.The University of Tokyo, 2.Astrobiology Center, NINS, 3.Division of Science, NAOJ, 4.Ritsumeikan University)

Keywords:Exoplanet, Radial Velocity, Super Neptune

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.