Revisiting the HD 21749 Planetary System with Stellar Activity Modeling
| Autor: | Ward S. Howard, Andrew Vanderburg, Adina D. Feinstein, Fabo Feng, Johanna Teske, Yuri Beletsky, Erin Flowers, Shude Mao, Sharon X. Wang, R. Paul Butler, Benjamin T. Montet, Natasha E. Batalha, Nicholas M. Law, Alan Vasquez, Diana Dragomir, J. B. Haislip, N. Galliher, Jeffrey D. Crane, Avi Shporer, Tianjun Gan, J. Burt, Sangeetha Nandakumar, M. Barbieri, Hank Corbett, Stephen A. Shectman, Jeffrey K. Ratzloff, Chelsea X. Huang, Amy Glazier, Ramses Gonzalez Chavez |
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| Rok vydání: | 2020 |
| Předmět: |
Physics
Earth and Planetary Astrophysics (astro-ph.EP) Stellar rotation FOS: Physical sciences Astronomy and Astrophysics Orbital eccentricity Astrophysics Planetary system Orbital period 01 natural sciences 010309 optics Photometry (optics) Amplitude Astrophysics - Solar and Stellar Astrophysics 13. Climate action Space and Planetary Science Planet 0103 physical sciences Terrestrial planet 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics - Earth and Planetary Astrophysics |
| DOI: | 10.48550/arxiv.2012.04873 |
| Popis: | HD 21749 is a bright ($V=8.1$ mag) K dwarf at 16 pc known to host an inner terrestrial planet HD 21749c as well as an outer sub-Neptune HD 21749b, both delivered by TESS. Follow-up spectroscopic observations measured the mass of HD 21749b to be $22.7\pm2.2\ M_{\oplus}$ with a density of $7.0^{+1.6}_{-1.3}$ g~cm$^{-3}$, making it one of the densest sub-Neptunes. However, the mass measurement was suspected to be influenced by stellar rotation. Here we present new high-cadence PFS RV data to disentangle the stellar activity signal from the planetary signal. We find that HD 21749 has a similar rotational timescale as the planet's orbital period, and the amplitude of the planetary orbital RV signal is estimated to be similar to that of the stellar activity signal. We perform Gaussian Process (GP) regression on the photometry and RVs from HARPS and PFS to model the stellar activity signal. Our new models reveal that HD 21749b has a radius of $2.86\pm0.20\ R_{\oplus}$, an orbital period of $35.6133\pm0.0005$ d with a mass of $M_{b}=20.0\pm2.7\ M_{\oplus}$ and a density of $4.8^{+2.0}_{-1.4}$ g~cm$^{-3}$ on an eccentric orbit with $e=0.16\pm0.06$, which is consistent with the most recent values published for this system. HD 21749c has an orbital period of $7.7902\pm0.0006$ d, a radius of $1.13\pm0.10\ R_{\oplus}$, and a 3$\sigma$ mass upper limit of $3.5\ M_{\oplus}$. Our Monte Carlo simulations confirm that without properly taking stellar activity signals into account, the mass measurement of HD 21749b is likely to arrive at a significantly underestimated error bar. Comment: 20 pages, 16 figures, accepted to MNRAS |
| Databáze: | OpenAIRE |
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