Transit Timing Variations for AU Microscopii b and c

Wittrock, Justin M.; Dreizler, Stefan; Reefe, Michael A.; Morris, Brett M.; Plavchan, Peter P.; Lowrance, Patrick J.; Demory, Brice-Olivier; Ingalls, James G.; Gilbert, Emily A.; Barclay, Thomas; Cale, Bryson L.; Collins, Karen A.; Collins, Kevin I.; Crossfield, Ian J. M.; Dragomir, Diana; Eastman, Jason D.; Mufti, Mohammed El; Feliz, Dax; Gagné, Jonathan; Gaidos, Eric; Gao, Peter; Geneser, Claire S.; Hebb, Leslie; Henze, Christopher E.; Horne, Keith D.; Jenkins, Jon M.; Jensen, Eric L. N.; Kane, Stephen R.; Kaye, Laurel; Martioli, Eder; Monsue, Teresa A.; Pallé, Enric; Quintana, Elisa V.; Radford, Don J.; Roccatagliata, Veronica; Schlieder, Joshua E.; Schwarz, Richard P.; Shporer, Avi; Stassun, Keivan G.; Stockdale, Christopher; Tan, Thiam-Guan; Tanner, Angelle M.; Vanderburg, Andrew; Vega, Laura D.; Wang, Songhu
Bibliographical reference

The Astronomical Journal

Advertised on:
7
2022
Number of authors
45
IAC number of authors
1
Citations
10
Refereed citations
8
Description
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).
Related projects
Projects' name image
Exoplanets and Astrobiology

The search for life in the universe has been driven by recent discoveries of planets around other stars (known as exoplanets), becoming one of the most active fields in modern astrophysics. The growing number of new exoplanets discovered in recent years and the recent advance on the study of their atmospheres are not only providing new valuable

Enric
Pallé Bago