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.
Undetrended and detrended light curves are only available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/671/A154- Publication:
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Astronomy and Astrophysics
- Pub Date:
- March 2023
- DOI:
- 10.1051/0004-6361/202244790
- arXiv:
- arXiv:2302.01853
- Bibcode:
- 2023A&A...671A.154E
- Keywords:
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- planets and satellites: detection;
- planets and satellites: individual: HD 136352;
- planets and satellites: general;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 16 pages, 9 figures. Accepted for publication in Astronomy &