Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System

Cale, Bryson L. and Reefe, Michael and Plavchan, Peter and Tanner, Angelle and Gaidos, Eric and Gagne, Jonathan and Gao, Peter and Kane, Stephen R. and Bejar, Victor J. S. and Lodieu, Nicolas and Anglada-Escude, Guillem and Ribas, Ignasi and Palle, Enric and Quirrenbach, Andreas and Amado, Pedro J. and Reiners, Ansgar and Caballero, Jose A. and Zapatero Osorio, Maria Rosa and Dreizler, Stefan and Howard, Andrew W. and Fulton, Benjamin J. and Wang, Sharon Xuesong and Collins, Kevin I. and El Mufti, Mohammed and Wittrock, Justin and Gilbert, Emily A. and Barclay, Thomas and Klein, Baptiste and Martioli, Eder and Wittenmyer, Robert and Wright, Duncan ORCID: https://orcid.org/0000-0001-7294-5386 and Addison, Brett ORCID: https://orcid.org/0000-0003-3216-0626 and Hirano, Teruyuki and Tamura, Motohide and Kotani, Takayuki and Narita, Norio and Vermilion, David and Lee, Rena A. and Geneser, Claire and Teske, Johanna and Quinn, Samuel N. and Latham, David W. and Esquerdo, Gilbert A. and Calkins, Michael L. and Berlind, Perry and Zohrabi, Farzaneh and Stibbards, Caitlin and Kotnana, Srihan and Jenkins, Jon and Twicken, Joseph D. and Henze, Christopher and Kidwell, Richard and Burke, Christopher and Villasenor, Joel and Boyd, Patricia (2021) Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System. The Astronomical Journal, 162 (6):295. pp. 1-32. ISSN 0004-6256


Abstract

We present updated radial-velocity (RV) analyses of the AU Mic system. AU Mic is a young (22 Myr) early-M dwarf known to host two transiting planets - P b ∼ 8.46 days, Rb=4.38-0.18+0.18 R oplus, P c ∼ 18.86 days, R c=3.51-0.16+0.16 R oplus. With visible RVs from Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical echelle Spectrographs (CARMENES)-VIS, CHIRON, HARPS, HIRES, Minerva-Australis, and Tillinghast Reflector Echelle Spectrograph, as well as near-infrared (NIR) RVs from CARMENES-NIR, CSHELL, IRD, iSHELL, NIRSPEC, and SPIRou, we provide a 5σ upper limit to the mass of AU Mic c of M c ≤ 20.13 M ⊕ and present a refined mass of AU Mic b of M b=20.12-1.57+1.72 M oplus. Used in our analyses is a new RV modeling toolkit to exploit the wavelength dependence of stellar activity present in our RVs via wavelength-dependent Gaussian processes. By obtaining near-simultaneous visible and near-infrared RVs, we also compute the temporal evolution of RV 'color' and introduce a regressional method to aid in isolating Keplerian from stellar activity signals when modeling RVs in future works. Using a multiwavelength Gaussian process model, we demonstrate the ability to recover injected planets at 5σ significance with semi-amplitudes down to ≈10 m s-1 with a known ephemeris, more than an order of magnitude below the stellar activity amplitude. However, we find that the accuracy of the recovered semi-amplitudes is ∼50% for such signals with our model.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 14 Jul 2022 04:05
Last Modified: 15 Aug 2022 05:32
Uncontrolled Keywords: Exoplanets (498); Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.3847/1538-3881/ac2c80
URI: http://eprints.usq.edu.au/id/eprint/49485

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