Transit timing variations for AU Microscopii b and c
Abstract
We explore the transit timing variations (TTVs) of the young (22 Myr) nearby AU Mic planetary system. For AU Mic b, we introduce three Spitzer (4.5 μm) transits, five TESS transits, 11 LCO transits, one PEST transit, one Brierfield transit, and two transit timing measurements from Rossiter–McLaughlin observations; for AU Mic c, we introduce three TESS transits. We present two independent TTV analyses. First, we use EXOFASTv2 to jointly model the Spitzer and ground-based transits and obtain the midpoint transit times. We then construct an O − C diagram and model the TTVs with Exo-Striker. Second, we reproduce our results with an independent photodynamical analysis. We recover a TTV mass for AU Mic c of 10.8−2.2+2.3 M⊕. We compare the TTV-derived constraints to a recent radial velocity (RV) mass determination. We also observe excess TTVs that do not appear to be consistent with the dynamical interactions of b and c alone or due to spots or flares. Thus, we present a hypothetical nontransiting “middle-d” candidate exoplanet that is consistent with the observed TTVs and candidate RV signal and would establish the AU Mic system as a compact resonant multiplanet chain in a 4:6:9 period commensurability. These results demonstrate that the AU Mic planetary system is dynamically interacting, producing detectable TTVs, and the implied orbital dynamics may inform the formation mechanisms for this young system. We recommend future RV and TTV observations of AU Mic b and c to further constrain the masses and confirm the existence of possible additional planet(s).
Citation
Wittrock , J M , Dreizler , S , Reefe , M A , Morris , B M , Plavchan , P P , Lowrance , P J , Demory , B-O , Ingalls , J G , Gilbert , E A , Barclay , T , Cale , B L , Collins , K A , Collins , K I , Crossfield , I J M , Dragomir , D , Eastman , J D , Mufti , M E , Feliz , D , Gagné , J , Gaidos , E , Gao , P , Geneser , C S , Hebb , L , Henze , C E , Horne , K D , Jenkins , J M , Jensen , E L N , Kane , S R , Kaye , L , Martioli , E , Monsue , T A , Pallé , E , Quintana , E V , Radford , D J , Roccatagliata , V , Schlieder , J E , Schwarz , R P , Shporer , A , Stassun , K G , Stockdale , C , Tan , T-G , Tanner , A M , Vanderburg , A , Vega , L D & Wang , S 2022 , ' Transit timing variations for AU Microscopii b and c ' , Astronomical Journal , vol. 164 , no. 1 , 27 . https://doi.org/10.3847/1538-3881/ac68e5
Publication
Astronomical Journal
Status
Peer reviewed
ISSN
0004-6256Type
Journal article
Rights
Copyright © 2022. The Author(s). Published by the American Astronomical Society.. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Description
P.P.P. acknowledges support from NASA (Exoplanet Research Program award No. 80NSSC20K0251, TESS Cycle 3 Guest Investigator Program award No. 80NSSC21K0349, JPL Research and Technology Development, and Keck Observatory Data Analysis), the NSF (Astronomy and Astrophysics grant Nos. 1716202 and 2006517), and the Mt. Cuba Astronomical Foundation. D.D. acknowledges support from the TESS Guest Investigator Program grant No. 80NSSC21K0108 and NASA Exoplanet Research Program grant No. 18-2XRP18_2-0136. E.G. acknowledges support from NASA Exoplanet Research Program award No. 80NSSC20K0251. The material is based upon work supported by NASA under award No. 80GSFC21M0002. L.D.V. acknowledges funding support from the Heising-Simons Astrophysics Postdoctoral Launch Program through a grant to Vanderbilt University.Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.