Bibliographic Details
| Title: |
TOI-1438: A rare system with two short-period sub-Neptunes and a tentative long-period Jupiter-like planet orbiting a K0V star |
| Authors: |
Persson, Carina M., Knudstrup, Emil, Carleo, Ilaria, Acuña-Aguirre, Lorena, Nowak, Grzegorz, Muresan, Alexandra, Jankowski, Dawid, Goździewski, Krzysztof, Garcia, Rafael A., Mathur, Savita, Palakkatharappil, Dinil B., Borg, Lina, Mustill, Alexander J., Barrena, Rafael, Fridlund, Malcolm, Gandolfi, Davide, Hatzes, Artie P., Korth, Judith, Luque, Rafael, Martin, Eduardo L., Masseron, Thomas, Morello, Giuseppe, Murgas, Felipe, Orell-Miquel, Jaume, Palle, Enric, Albrecht, Simon H., Bieryla, Allyson, Cochran, William D., Crossfield, Ian J.~M., Deeg, Hans J., Furlan, Elise, Guenther, Eike W., Howell, Steve B., Isaacson, Howard, Lam, Kristine W.~F., Livingston, John, Matson, Rachel A., Matthews, Elisabeth C., Redfield, Seth, Schlieder, Joshua E., Seager, Sara, Smith, Alexis M.~S., Stassun, Keivan G., Twicken, Joseph D., Van Eylen, Vincent, Watkins, Cristilyn N., Weiss, Lauren M. |
| Contributors: |
Lund University, Faculty of Science, Department of Physics, Astrophysics, Lunds universitet, Naturvetenskapliga fakulteten, Fysiska institutionen, Astrofysik, Originator |
| Source: |
Astronomy & Astrophysics. 702 |
| Subject Terms: |
Natural Sciences, Physical Sciences, Astronomy, Astrophysics and Cosmology, Naturvetenskap, Fysik, Astronomi, astrofysik och kosmologi |
| Description: |
We present the detection and characterisation of the TOI-1438 multi-planet system discovered by the Transiting Exoplanet Survey Satellite (TESS). To confirm the planetary nature of the candidates and determine their masses, we collected a series of followup observations including high-spectral resolution observations with HARPS-N and HIRES over a period of 5 years. Our combined modelling shows that the K0V star hosts two transiting sub-Neptunes with Rb = 3.04 ± 0.19 R⊕, Rc = 2.75 ± 0.14 R⊕, Mb = 9.4 ± 1.8 M⊕, and Mc =10.6 ± 2.1 M⊕. The orbital periods of planets b and c are 5.1 and 9.4 days, respectively, corresponding to instellations of 145 ± 10 F⊕ and 65 ± 4 F⊕. The bulk densities are 1.8 ± 0.5 g cm−3 and 2.9 ± 0.7 g cm−3, respectively, suggesting a volatile-rich interior composition. By combining the planet and stellar parameters, we were able to compute a set of planet interior structure models. Planet b presents a high-metallicity envelope that can accommodate up to 2.5% in H/He in mass, while planet c cannot have more than 0.2% as H/He in mass. For any composition of the core considered (Fe-rock or ice-rock), both planets would require a volatile-rich envelope. In addition to the two planets, the radial velocity (RV) data clearly reveal a third signal, likely coming from a non-transiting planet, with an orbital period of 7.6−2.4+1.6 years and an RV semi-amplitude of 35−5+3 m s−1. Our best-fit model finds a minimum mass of 2.1 ± 0.3 MJ and an eccentricity of 0.25−0.11+0.08. However, several RV activity indicators also show strong signals at similar periods, suggesting this signal might (partly) originate from stellar activity. More data over a longer period of time are needed to conclusively determine the nature of this signal. If it is confirmed as a triple-planet system, TOI-1438 would be one of the few detected systems to date characterised by an architecture with two small, short-period planets and one massive, long-period planet, where the inner and outer systems are separated by an orbital period ratio of the order of a few hundred. |
| Access URL: |
https://doi.org/10.1051/0004-6361/202555318 |
| Database: |
SwePub |