Kavli Affiliate: Andrew Vanderburg
| First 5 Authors: Justin M. Wittrock, Stefan Dreizler, Michael A. Reefe, Brett M. Morris, Peter P. Plavchan
| Summary:
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 $mu$m)
transits, five TESS transits, 11 LCO transits, one PEST transit, one Brierfield
transit, and two transit timing measurements from Rossiter-McLaughlin
observations; for aumic c, we introduce three tess Cycle transits. We present
two independent TTV analyses. First, we use EXOFASTv2 to jointly model the
Spitzer and ground-based transits and to 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$^{+2.3}_{-2.2}$ M$_{E}$. 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, and do not appear to be due to spots or flares.
Thus, we present a hypothetical non-transiting "middle-d" candidate exoplanet
that is consistent with the observed TTVs, the candidate RV signal, and would
establish the AU Mic system as a compact resonant multi-planet 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 to confirm the existence of possible additional planet(s).
| Search Query: ArXiv Query: search_query=au:”Andrew Vanderburg”&id_list=&start=0&max_results=10