Transit Timing Variations for AU Microscopii b and c
Author:
Wittrock Justin M.ORCID, Dreizler StefanORCID, Reefe Michael A.ORCID, Morris Brett M.ORCID, Plavchan Peter P.ORCID, Lowrance Patrick J.ORCID, Demory Brice-OlivierORCID, Ingalls James G.ORCID, Gilbert Emily A.ORCID, Barclay ThomasORCID, Cale Bryson L.ORCID, Collins Karen A.ORCID, Collins Kevin I.ORCID, Crossfield Ian J. M.ORCID, Dragomir DianaORCID, Eastman Jason D.ORCID, Mufti Mohammed ElORCID, Feliz DaxORCID, Gagné JonathanORCID, Gaidos EricORCID, Gao PeterORCID, Geneser Claire S.ORCID, Hebb LeslieORCID, Henze Christopher E., Horne Keith D.ORCID, Jenkins Jon M.ORCID, Jensen Eric L. N.ORCID, Kane Stephen R.ORCID, Kaye LaurelORCID, Martioli EderORCID, Monsue Teresa A.ORCID, Pallé EnricORCID, Quintana Elisa V.ORCID, Radford Don J.ORCID, Roccatagliata VeronicaORCID, Schlieder Joshua E.ORCID, Schwarz Richard P.ORCID, Shporer AviORCID, Stassun Keivan G.ORCID, Stockdale ChristopherORCID, Tan Thiam-GuanORCID, Tanner Angelle M.ORCID, Vanderburg AndrewORCID, Vega Laura D.ORCID, Wang SonghuORCID
Abstract
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).
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
8 articles.
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