Revised Architecture and Two New Super-Earths in the HD 134606 Planetary System

April 2024 • 2024AJ....167..155L

Authors • Li, Zhexing • Kane, Stephen R. • Brandt, Timothy D. • Fetherolf, Tara • Robertson, Paul • Zhao, Jinglin • Dalba, Paul A. • Wittenmyer, Robert A. • Butler, R. Paul • Díaz, Matías R. • Howell, Steve B. • Bailey, Jeremy • Carter, Brad • Furlan, Elise • Gnilka, Crystal L. • Horner, Jonathan • Jones, Hugh R. A. • O'Toole, Simon • Tinney, Chris

Abstract • Multiplanet systems exhibit a diversity of architectures that diverge from the solar system and contribute to the topic of exoplanet demographics. Radial velocity (RV) surveys form a crucial component of exoplanet surveys, as their long observational baselines allow for searches for more distant planetary orbits. This work provides a significantly revised architecture for the multiplanet system HD 134606 using both HARPS and UCLES RVs. We confirm the presence of previously reported planets b, c, and d with periods of ${12.0897}_{-0.0018}^{+0.0019}$ , ${58.947}_{-0.054}^{+0.056}$ , and ${958.7}_{-5.9}^{+6.3}$ days and masses of ${9.14}_{-0.63}^{+0.65}$ , 11.0 ± 1, and 44.5 ± 2.9 Earth masses, respectively, with the planet d orbit significantly revised to over double that originally reported. We report two newly detected super-Earths, e and f, with periods of ${4.31943}_{-0.00068}^{+0.00075}$ and ${26.9}_{-0.017}^{+0.019}$ days and masses of ${2.31}_{-0.35}^{+0.36}$ and ${5.52}_{-0.73}^{+0.74}$ Earth masses, respectively. In addition, we identify a linear trend in the RV time series, and the cause of this acceleration is deemed to be a newly detected massive companion with a very long orbital period. HD 134606 now displays four low-mass planets in a compact region near the star, one gas giant further out in the habitable zone, an additional companion in the outer regime, and a low-mass M dwarf stellar companion at large separation, making it an intriguing target for system formation/evolution studies. The location of planet d in the habitable zone proves to be an exciting candidate for future space-based direct imaging missions, whereas continued RV observations of this system are recommended for understanding the nature of the massive, long-period companion.

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• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2024AJ....167..155L
• PDF https://iopscience.iop.org/article/10.3847/1538-3881/ad2461/pdf
• PREPRINT http://arxiv.org/abs/2401.17415
• DATA http://archive.eso.org/bin/ads2eso?2024AJ....167..155L
• DATA https://archive.gemini.edu/searchform/publication=2024AJ....167..155L
• DATA https://irsa.ipac.caltech.edu/bibdata/2024/L/2024AJ....167..155L.html
• ELECTR https://doi.org/10.3847/1538-3881/ad2461