Doomed Worlds. II. Reassessing Suggestions of Orbital Decay for TrES-5 b

Abstract TrES-5 b is one of only three ultrahot Jupiters with suggestions of a possibly decreasing orbital period that have persisted through multiple independent analyses. While WASP-12 b’s decreasing period is well explained by tidally induced orbital decay, and stellar acceleration has been proposed for WASP-4 b, the cause of the apparent trend for TrES-5 b has not been satisfactorily explained. This work extends the previous observations with 14 new ground-based transits from 2016 to 2024 and two newly published midtimes for data from 2007 and 2009. Four TESS sectors (75, 77, 82, and 84) have also been included for the first time. With the new data, the case for a decreasing orbital period is much weaker than before. The revised rate of period change, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mi>P</mml:mi> <mml:mo>̇</mml:mo> </mml:mover> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>5.3</mml:mn> <mml:mo>±</mml:mo> <mml:mn>2.2</mml:mn> <mml:mspace width="0.25em"/> <mml:mi>ms</mml:mi> <mml:mspace width="0.25em"/> <mml:msup> <mml:mi>yr</mml:mi> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> , is less than half that found in previous work, and the preference for a quadratic over a linear model, as measured through ΔBIC LQ , has been falling since 2020, with a current value of 11. Furthermore, these results are not robust to outliers; removing a single early transit midtime causes the effect to vanish (ΔBIC LQ = −1). Additionally, no significant periodic signals in the transit timing data are identified. The current data are well explained by a linear ephemeris.