One year of AU Mic with HARPS: I -- measuring the masses of the two transiting planets
| Autor: | Norbert Zicher, Oscar Barragán, Baptiste Klein, Suzanne Aigrain, James E Owen, Davide Gandolfi, Anne-Marie Lagrange, Luisa Maria Serrano, Laurel Kaye, Louise Dyregaard Nielsen, Vinesh Maguire Rajpaul, Antoine Grandjean, Elisa Goffo, Belinda Nicholson |
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| Přispěvatelé: | The Royal Society, Commission of the European Communities |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
FOS: Physical sciences
stars: starspots ZODIACAL EXOPLANETS Astronomy & Astrophysics DEBRIS DISK HOT JUPITER ATMOSPHERIC ESCAPE techniques: radial velocities stars: activity 0201 Astronomical and Space Sciences planets and satellites: fundamental parameters TESS HUNT Solar and Stellar Astrophysics (astro-ph.SR) Earth and Planetary Astrophysics (astro-ph.EP) Science & Technology RADIAL-VELOCITY Astronomy and Astrophysics stars: individual: AU Microscopii GIANT IMPACTS Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science SUPER-EARTHS Physical Sciences YOUNG MAIN-SEQUENCE STAR techniques: spectroscopic Astrophysics - Earth and Planetary Astrophysics |
| Popis: | The system of two transiting Neptune-sized planets around the bright, young M-dwarf AU Mic provides a unique opportunity to test models of planet formation, early evolution, and star-planet interaction. However, the intense magnetic activity of the host star makes measuring the masses of the planets via the radial velocity (RV) method very challenging. We report on a 1-year, intensive monitoring campaign of the system using 91 observations with the HARPS spectrograph, allowing for detailed modelling of the $\sim 600\, \rm{m\,s^{-1}}$ peak-to-peak activity-induced RV variations. We used a multidimensional Gaussian Process framework to model these and the planetary signals simultaneously. We detect the latter with semi-amplitudes of $\rm{K_b} = 5.8 \pm 2.5\, \rm{m\,s^{-1}}$ and $\rm{K_c} = 8.5 \pm 2.5\, \rm{m\, s^{-1}}$, respectively. The resulting mass estimates, $\rm{M_b} = 11.7 \pm 5.0\, \rm{M_{\rm \oplus}}$ and $\rm{M_c} = 22.2 \pm 6.7\, \rm{M_{\rm \oplus}}$, suggest that planet b might be less dense, and planet c considerably denser than previously thought. These results are in tension with the current standard models of core-accretion. They suggest that both planets accreted a H/He envelope that is smaller than expected, and the trend between the two planets' envelope fractions is the opposite of what is predicted by theory. |
| Databáze: | OpenAIRE |
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