Transit detection of the long-period volatile-rich super-Earth ν² Lupi d with CHEOPS

Author(s)

L. Delrez, David Ehrenreich, Yann Alibert, A. Bonfanti, Luca Borsato, Manuel Güdel

Abstract

Exoplanets transiting bright nearby stars are key objects for advancing our knowledge of planetary formation and evolution. The wealth of photons from the host star gives detailed access to the atmospheric, interior and orbital properties of the planetary companions. ν² Lupi (HD 136352) is a naked-eye (V = 5.78) Sun-like star that was discovered to host three low-mass planets with orbital periods of 11.6, 27.6 and 107.6 d via radial-velocity monitoring. The two inner planets (b and c) were recently found to transit, prompting a photometric follow-up by the brand new Characterising Exoplanets Satellite (CHEOPS). Here, we report that the outer planet d is also transiting, and measure its radius and mass to be 2.56 ± 0.09 R_⊕ and 8.82 ± 0.94 M_⊕, respectively. With its bright Sun-like star, long period and mild irradiation (~5.7 times the irradiation of Earth), ν² Lupi d unlocks a completely new region in the parameter space of exoplanets amenable to detailed characterization. We refine the properties of all three planets: planet b probably has a rocky mostly dry composition, while planets c and d seem to have retained small hydrogen-helium envelopes and a possibly large water fraction. This diversity of planetary compositions makes the ν² Lupi system an excellent laboratory for testing formation and evolution models of low-mass planets.

Organisation(s)

Department of Astrophysics

External organisation(s)

Université de Genève, Osservatorio Astronomico, Université de Liège, Universität Bern, Österreichische Akademie der Wissenschaften (ÖAW)

Journal

Nature Astronomy

Volume

5

Pages

775-787

No. of pages

13

DOI

https://doi.org/10.1038/s41550-021-01381-5

Publication date

08-2021

Peer reviewed

Yes

Austrian Fields of Science 2012

103003 Astronomy, 103004 Astrophysics

Keywords

ASJC Scopus subject areas

Astronomy and Astrophysics

Portal url

https://ucrisportal.univie.ac.at/en/publications/transit-detection-of-the-longperiod-volatilerich-superearth-2-lupi-d-with-cheops(c34c3683-21cc-4b32-8dbc-70373d4015c7).html