Transit detection of the long-period volatile-rich super-Earth ${\nu }^2$ Lupi d with $CHEOPS$

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. ${\nu }^2$ 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 days via radial velocity monitoring (Udry et al. 2019). The two inner planets (b and c) were recently found to transit (Kane et al. 2020), prompting a photometric follow-up by the brand-new $CHaracterisingExOPlanetsSatellite(CHEOPS)$. Here, we report that the outer planet d is also transiting, and measure its radius and mass to be $2.56\pm 0.09$ $R_{\oplus }$ and $8.82\pm 0.94$ $M_{\oplus }$, respectively. With its bright Sun-like star, long period, and mild irradiation ($\sim$5.7 times the irradiation of Earth), ${\nu }^2$ 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 likely 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 ${\nu }^2$ Lupi system an excellent laboratory for testing formation and evolution models of low-mass planets.

Published in Nature Astronomy. 60 pages, 18 Figures, 6 Tables. This is the authors' version of the manuscript. The final authenticated version is available online at https://www.nature.com/articles/s41550-021-01381-5

References in corpus (47)

• Array Programming with NumPy
• The Transiting Exoplanet Survey Satellite
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Bayes in the sky: Bayesian inference and model selection in cosmology
• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• Spectroscopic parameters for 451 stars in the HARPS GTO planet search program. Stellar [Fe/H] and the frequency of exo-Neptunes
• Growth Model Interpretation of Planet Size Distribution
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• Can we constrain interior structure of rocky exoplanets from mass and radius measurements?
• A new code for automatic determination of equivalent widths: Automatic Routine for line Equivalent widths in stellar Spectra (ARES)
• The CHEOPS mission
• The connection between stellar granulation and oscillation as seen by the Kepler mission
• CLES, Code Liegeois d'Evolution Stellaire
• The Extreme Ultraviolet and X-Ray Sun in Time: High-Energy Evolutionary Tracks of a Solar-Like Star
• A Sub-Neptune Exoplanet with a Low-Metallicity Methane-Depleted Atmosphere and Mie-Scattering Clouds
• Stellar Winds on the Main-Sequence II: the Evolution of Rotation and Winds
• ARES v2 - new features and improved performance
• A generalized bayesian inference method for constraining the interiors of super Earths and sub-Neptunes
• Hubble PanCET: An extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470 b
• Satellite dynamics on the Laplace surface
• AQUA: A Collection of H${}_2$O Equations of State for Planetary Models
• On Correlated-noise Analyses Applied To Exoplanet Light Curves
• Theoretical Emission Spectra of Atmospheres of Hot Rocky Super-Earths
• Revising the ages of planet-hosting stars
• Radial-Velocity Fitting Challenge. II. First results of the analysis of the data set
• The hot dayside and asymmetric transit of WASP-189b seen by CHEOPS
• A super-Earth and a sub-Neptune orbiting the bright, quiet M3 dwarf TOI-1266
• From planetesimals to planets: volatile molecules
• Search for water vapor in the high-resolution transmission spectrum of HD189733b in the visible
• Two massive rocky planets transiting a K-dwarf 6.5 parsecs away
• Radial Velocity Data Analysis with Compressed Sensing Techniques
• A He I upper atmosphere around the warm Neptune GJ 3470b
• TRADES: A new software to derive orbital parameters from observed transit times and radial velocities. Revisiting Kepler-11 and Kepler-9
• Kinematics of planet-host stars and their relation with dynamical streams in the solar neighbourhood
• HARPS-N radial velocities confirm the low densities of the Kepler-9 planets
• GJ 273: On the formation, dynamical evolution and habitability of a planetary system hosted by an M dwarf at 3.75 parsec
• Improving transit characterisation with Gaussian process modelling of stellar variability
• K2-111: an old system with two planets in near-resonance
• Mass determinations of the three mini-Neptunes transiting TOI-125
• Close-in sub-Neptunes reveal the past rotation history of their host stars: atmospheric evolution of planets in the HD3167 and K2-32 planetary systems
• The Kepler-11 system: evolution of the stellar high-energy emission and {initial planetary} atmospheric mass fractions
• Transits of Known Planets Orbiting a Naked-Eye Star
• Mitigating flicker noise in high-precision photometry. I -- Characterization of the noise structure, impact on the inferred transit parameters, and predictions for CHEOPS observations
• GJ357: A low-mass planetary system uncovered by precision radial-velocities and dynamical simulations
• On the impact of tides on the transit-timing fits to the TRAPPIST-1 system
• Two NIRCam channels are Better than One: How JWST Can Do More Science with NIRCam's Short-Wavelength Dispersed Hartmann Sensor
• Studying tidal effects in planetary systems with Posidonius. A N-body simulator written in Rust

Cited by in corpus (54)

• Warm terrestrial planet with half the mass of Venus transiting a nearby star
• Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops
• Two temperate super-Earths transiting a nearby late-type M dwarf
• A resonant sextuplet of sub-Neptunes transiting the bright star HD 110067
• A pair of Sub-Neptunes transiting the bright K-dwarf TOI-1064 characterised with CHEOPS
• The Ariel Target List: The Impact of TESS and the Potential for Characterising Multiple Planets Within a System
• Spi-OPS: Spitzer and CHEOPS confirm the near-polar orbit of MASCARA-1 b and reveal a hint of dayside reflection
• A detailed analysis of the Gl 486 planetary system
• Uncovering the true periods of the young sub-Neptunes orbiting TOI-2076
• Investigating the architecture and internal structure of the TOI-561 system planets with CHEOPS, HARPS-N and TESS
• An unusually low-density super-Earth transiting the bright early-type M-dwarf GJ 1018 (TOI-244)
• HD 23472: A multi-planetary system with three super-Earths and two potential super-Mercuries
• The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc
• Doppler Constraints on Planetary Companions to Nearby Sun-like Stars: An Archival Radial Velocity Survey of Southern Targets for Proposed NASA Direct Imaging Missions
• The geometric albedo of the hot Jupiter HD 189733b measured with CHEOPS
• A super-Earth and a mini-Neptune near the 2:1 MMR straddling the radius valley around the nearby mid-M dwarf TOI-2096
• TOI-836: A super-Earth and mini-Neptune transiting a nearby K-dwarf
• Unveiling the internal structure and formation history of the three planets transiting HIP 29442 (TOI-469) with CHEOPS
• TOI-5678 b: A 48-day transiting Neptune-mass planet characterized with CHEOPS and HARPS
• Investigating the visible phase-curve variability of 55 Cnc e
• Two super-Earths at the edge of the habitable zone of the nearby M dwarf TOI-2095
• 55 Cancri e's occultation captured with CHEOPS
• Resonant sub-Neptunes are puffier
• TOI-969: a late-K dwarf with a hot mini-Neptune in the desert and an eccentric cold Jupiter
• Heating and ionization by non-thermal electrons in the upper atmospheres of water-rich exoplanets
• CHEOPS finds KELT-1b darker than expected in visible light: Discrepancy between the CHEOPS and TESS eclipse depths
• The SOPHIE search for northern extrasolar planets-XIX. A system including a cold sub-Neptune potentially transiting a V = 6.5 star HD88986
• Precise mass determination for the keystone sub-Neptune planet transiting the mid-type M dwarf G 9-40
• GJ 3090 b: one of the most favourable mini-Neptune for atmospheric characterisation
• The HD 93963 A transiting system: A 1.04d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS
• The SHERLOCK pipeline: new exoplanet candidates in the WASP-16, HAT-P-27, HAT-P-26, and TOI-2411 systems
• The GAPS Programme at TNG XL: A puffy and warm Neptune-sized planet and an outer Neptune-mass candidate orbiting the solar-type star TOI-1422
• A full transit of ${\nu }^2$ Lupi d and the search for an exomoon in its Hill sphere with CHEOPS
• Refined parameters of the HD 22946 planetary system and the true orbital period of planet d
• Luminaries in the Sky: The TESS Legacy Sample of Bright Stars. I. Asteroseismic detections in naked-eye main-sequence and sub-giant solar-like oscillators
• TESS and CHEOPS Discover Two Warm Sub-Neptunes Transiting the Bright K-dwarf HD 15906
• ATREIDES I. Embarking on a trek across the exo-Neptunian landscape with the TOI-421 system
• Two warm Earth-sized exoplanets and an Earth-sized candidate in the M5V-M6V binary system TOI-2267
• TOI-908: a planet at the edge of the Neptune desert transiting a G-type star
• The GAPS programme at TNG LXIV: An inner eccentric sub-Neptune and an outer sub-Neptune-mass candidate around BD+00 444 (TOI-2443)
• Discovery of TOI-1260d and the characterisation of the multi-planet system
• Dark skies of the slightly eccentric WASP-18 b from its optical-to-infrared dayside emission
• The "Drake equation" of exomoons -- a cascade of formation, stability and detection
• Radii, masses, and transit-timing variations of the three-planet system orbiting the naked-eye star TOI-396
• Variability of Known Exoplanet Host Stars Observed by TESS
• Tidally Heated Sub-Neptunes, Refined Planetary Compositions, and Confirmation of a Third Planet in the TOI-1266 System
• Planetary system architectures with low-mass inner planets: Direct imaging exploration of mature systems beyond 1 au
• Transit Duration and Timing Variations from Binary Planets
• Null transit detections of 68 radial velocity exoplanets observed by TESS
• Glancing through the debris disk: Photometric analysis of DE Boo with CHEOPS
• SPORES-HWO. II. Companion Mass Limits and Updated Planet Properties for 120 Future Exoplanet Imaging Targets from 35 yr of Precise Doppler Monitoring
• Gas-depleted planet formation occurred in the four-planet system around the red dwarf LHS 1903
• Hidden water in magma ocean exoplanets
• Constraining stellar rotation and planetary atmospheric evolution of a dozen systems hosting sub-Neptunes and super-Earths