The TOI-2427 system: Two close-in planets orbiting a late K-dwarf star

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Title: The TOI-2427 system: Two close-in planets orbiting a late K-dwarf star
Authors: Schmerling, H., Goffo, E., Grziwa, S., Persson, Carina, 1964, Gandolfi, D., Pätzold, Martin, Hatzes, A., Hellier, Coel, Livingston, J.H., Acuña, L., Aguichine, A., Costanza, E., Deeg, H., Masseron, T., Palle, Enric, Cochran, William D., Nowak, G., Jankowski, D., Goździewski, K., Luque, R., Mathur, S., Palakkatharappil, Dinil B., García, R. A.
Source: Astronomy and Astrophysics. 699
Subject Terms: techniques: radial velocities, planets and satellites: atmospheres, planets and satellites: detection, instrumentation: photometers, planets and satellites: interiors
Description: Using high-precision photometry, NASA’s TESS space mission has discovered many intriguing transiting planet candidates. These discoveries require ground-based follow-up observations, including high-precision Doppler spectroscopy, to rule out false positive scenarios and measure the mass of the transiting planets. In this study, we present an intensive Doppler follow-up campaign of the TESS object of interest TOI-2427, carried out with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph to determine the mass of the previously validated transiting planet (TOI-2427 b) and search for additional orbiting companions. By analyzing TESS transit photometry alongside our HARPS radial velocity measurements, we spectroscopically confirmed the transiting planet TOI-2427 b, which orbits its host star every ~1.3 d. We also discovered the presence of a second non-transiting planetary companion with an orbital period of ~5.15 d, which is very close to four times the orbital period of the inner transiting planet. We found that TOI-2427 b is a short-period, high-density super-Earth with a mass of Mb = 5.69 + − 0 0 51 50 Mand a radius of Rb = 1.64 + − 0 0 12 11 R, implying a mean density of b = 7.1 + − 1 1 8 4 g cm −3 . Its interior seems to be composed of a predominantly iron core and a silicate mantle and crust. Despite its high density, it is unlikely that TOI-2427 b can sustain any atmosphere composed of lighter gases; however, it could still retain heavier gases. The outer non-transiting planet TOI-2427 c has a minimum mass of Mc sin ic = 6.46 + − 0 0 79 78 M. Assuming that TOI-2427 b and c are coplanar, a statistical analysis suggests that planets with a mass of ~6.5 M tend to have radii around 2.7 + − 1 0 1 8 R. This would place TOI-2457 c near the sub-Neptune regime, while also leaving open the possibility of it being a super-Earth.
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Access URL: https://research.chalmers.se/publication/547605
https://research.chalmers.se/publication/547605/file/547605_Fulltext.pdf
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Abstract:Using high-precision photometry, NASA’s TESS space mission has discovered many intriguing transiting planet candidates. These discoveries require ground-based follow-up observations, including high-precision Doppler spectroscopy, to rule out false positive scenarios and measure the mass of the transiting planets. In this study, we present an intensive Doppler follow-up campaign of the TESS object of interest TOI-2427, carried out with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph to determine the mass of the previously validated transiting planet (TOI-2427 b) and search for additional orbiting companions. By analyzing TESS transit photometry alongside our HARPS radial velocity measurements, we spectroscopically confirmed the transiting planet TOI-2427 b, which orbits its host star every ~1.3 d. We also discovered the presence of a second non-transiting planetary companion with an orbital period of ~5.15 d, which is very close to four times the orbital period of the inner transiting planet. We found that TOI-2427 b is a short-period, high-density super-Earth with a mass of Mb = 5.69 + − 0 0 51 50 Mand a radius of Rb = 1.64 + − 0 0 12 11 R, implying a mean density of b = 7.1 + − 1 1 8 4 g cm −3 . Its interior seems to be composed of a predominantly iron core and a silicate mantle and crust. Despite its high density, it is unlikely that TOI-2427 b can sustain any atmosphere composed of lighter gases; however, it could still retain heavier gases. The outer non-transiting planet TOI-2427 c has a minimum mass of Mc sin ic = 6.46 + − 0 0 79 78 M. Assuming that TOI-2427 b and c are coplanar, a statistical analysis suggests that planets with a mass of ~6.5 M tend to have radii around 2.7 + − 1 0 1 8 R. This would place TOI-2457 c near the sub-Neptune regime, while also leaving open the possibility of it being a super-Earth.
ISSN:00046361
14320746
DOI:10.1051/0004-6361/202452620