Prospects for TTV Detection and Dynamical Constraints with TESS

Abstract

We consider the potential for the Transiting Exoplanet Survey Satellite (TESS) to detect transit timing variations (TTVs) during both its nominal and extended mission phases. Building on previous estimates of the overall yield of planetary systems from the TESS mission, we predict that during its nominal two-year mission, TESS will observe measurable TTVs in ∼ 30 systems, from which O(10) planet will get precise mass measurements from TTVs alone, ∼ 5 planets will have significant constraints placed on their masses from TTVs, and over a dozen systems will be singly transiting TTV systems. We consider a number of different extended mission scenarios, and predict that in a typical scenario, an extended mission will allow TESS to increase the number of systems with measurable TTVs to a total of ∼ 90, from which ∼ 15 planets will have precise mass measurements, another ∼ 15 will have significant constraints placed on their masses, and ∼ 60 will be singly transiting TTV systems. We also describe how follow-up transit observations of multiplanet systems discovered by the TESS mission can be optimally planned to maximize TTV mass and eccentricity constraints.

Exploiting the transit timing capabilities of Ariel

“…We can expect about several tens of planets with significant TTV improvements, and a similar number of targets with TTV, whose contribution from Ariel will be important. [18] predicted that about less than 4000 planet systems will be discovered during the nominal mission of TESS and about half of these will be in multi-planet systems. 30 of these multi-planet systems will have a measurable TTV signal and only 10 will be characterised with precise mass measurement from TTV only.…”

Science Extraction from TESS Observations of Known Exoplanet Hosts

“…Some of the most exciting science from Kepler came from systems of multiple transiting planets, particularly those where planet-planet interactions revealed by Transit Timing Variations (TTVs) provided an important source of mass measurements and constraints (e.g., Steffen et al 2013;Hadden & Lithwick 2014). Such observations of TTVs are also true for TESS but to a more limited extent (Goldberg et al 2019;Hadden et al 2019). Kane et al (2019) investigated the degradation of TTV signals when switching from Kepler's 4-year duration to the 6-12 month duration of TESS.…”

The L 98-59 System: Three Transiting, Terrestrial-size Planets Orbiting a Nearby M Dwarf

“…Overall, as multiplanet systems typically have orbital eccentricities of a few percent (Hadden & Lithwick 2016), it is unlikely that TESS will reveal timing variations for this system during its primary mission; doing so would suggest either anomalously large eccentricities (which are unlikely based on dynamical stability consideration) or significantly larger planet masses/densities in this system relative to planets with similar radii in other systems. To explore TTVs using an alternative software framework, we also used the TTV2Fast2Furious package (Hadden et al 2018) to project the expected TTV signals of the planets through Sector 12, again adopting the forecaster masses and, for simplicity, assuming circular orbits. Similar to the TTVFast analysis described above, our results show that it is unlikely TTVs are measurable for this system during the TESS prime mission-the maximum TTV amplitudes are 0.09 minutes for L 98-59 b, 0.17 minutes for L 98-59 c, and 0.56 minutes for L 98-59 d (see Figure 22).…”

“…Following the approach described in Hadden et al (2018), we also used TTV2Fast2Furious to project the precision of mass constraints derived from future TESS transit timing measurements. Planet mass constraints derived from TTVs depend on the precision of transit time measurements, and we adopt the measured scatter in the transit time measurements taken through Sector 2, s = -…”

“…Planets discovered around bright, nearby stars provide ideal targets for mass measurements via Doppler spectroscopy, emission, and transmission spectroscopy for atmospheric characterization, and for precise stellar characterization. Multiplanet systems provide an additional layer of information on planet formation and evolution, orbital dynamics, planetary architectures (e.g., Lissauer et al 2011;Fabrycky et al 2014), and in some cases mass measurements via transit timing variations (TTVs; e.g., Hadden & Lithwick 2016;Hadden et al 2018). While NASA's Kepler and K2 missions successfully discovered thousands of planets around stars in the Kepler field and in the vicinity of the ecliptic plane (e.g., Rowe et al 2014;Morton et al 2016;Livingston et al 2018), TESS will perform a nearly all-sky survey focused on stars in the solar neighborhood and find the touchstone planets that will be prime 59 Sellers Exoplanet Environments Collaboration.…”