A full transit of v² Lupi d and the search for an exomoon in its Hill sphere with CHEOPS

Abstract

The planetary system around the naked-eye star v2 Lupi (HD 136352; TOI-2011) is composed of three exoplanets with masses of 4.7, 11.2, and 8.6 Earth masses (M⊕). The TESS and CHEOPS missions revealed that all three planets are transiting and have radii straddling the radius gap separating volatile-rich and volatile-poor super-earths. Only a partial transit of planet d had been covered so we re-observed an inferior conjunction of the long-period 8.6 M⊕ exoplanet v2 Lup d with the CHEOPS space telescope. We confirmed its transiting nature by covering its whole 9.1 h transit for the first time. We refined the planet transit ephemeris to P = 107.1361−0.0022+0.0019 days and Tc = 2459009.7759−0.0096+0.0101 BJDTDB, improving by ~40 times on the previously reported transit timing uncertainty. This refined ephemeris will enable further follow-up of this outstanding long-period transiting planet to search for atmospheric signatures or explore the planet’s Hill sphere in search for an exomoon. In fact, the CHEOPS observations also cover the transit of a large fraction of the planet’s Hill sphere, which is as large as the Earth’s, opening the tantalising possibility of catching transiting exomoons. We conducted a search for exomoon signals in this single-epoch light curve but found no conclusive photometric signature of additional transiting bodies larger than Mars. Yet, only a sustained follow-up of v2 Lup d transits will warrant a comprehensive search for a moon around this outstanding exoplanet.

A study of the nonlinear dynamics inside the exoplanetary system Kepler-22 using MATLAB® software

“…where v x , v y , and v z are the velocity components of the test particle (third body), according to the directions x, y and z, respectively, r 1 and r 2 are the distances from the primaries to the test particle, respectively [26][27][28][29]. Astronomers also use the Jacobi constant C = -2E(x, μ) [30,31].…”

“…Lagrange points are points in a binary system on which the test particle (the third body) could reach equilibrium state [27,29]. The position of the Lagrange points is given by the solution of the Equation (1), with:…”

The “Drake Equation” of Exomoons—A Cascade of Formation, Stability and Detection

“…The JWST is capable of detecting super-Titans around isolated planetary-mass objects [134,135], and when the homogeneous surface temperature distribution is taken into account, Titan category exomoons can also be considered [85]. CHEOPS [6] has also attempted to detect large exomoons around long-period planets the large exomoons [136], PLATO will be searching for exomoons from transit photometry [120], while Ariel will also have a program to detect exomoons and rings using photometers in the optical and synthetic spectrophotometry in the infrared [137].…”