Publications (110)
Insight into atmospheres of extrasolar planets through plasma processes
Ch. Helling, I. Vorgul
Extrasolar planets appear in a chemical diversity unseen in our own solar system. Despite their atmospheres being cold, continuous and transient plasma processes do affect these at…
Revisiting fundamental properties of TiO nanoclusters as condensation seeds in astrophysical environments
J. P. Sindel, D. Gobrecht, Ch. Helling +1
The formation of inorganic cloud particles takes place in several atmospheric environments including those of warm, hot, rocky and gaseous exoplanets, brown dwarfs, and AGB stars.…
Transit Timing Variations in HIP 41378: CHEOPS and TESS confirm a non-transiting sixth planet in the system
P. Leonardi, L. Borsato, L. Pagliaro +89
In multiple-planet systems, gravitational interactions of exoplanets could lead to transit timing variations (TTVs), whose amplitude becomes significantly enhanced when planets are…
A four-planet system orbiting the old thick disk star TOI-1203
D. Gandolfi, A. Alnajjarine, L. M. Serrano +120
TOI-1203 is a bright (V=8.6) G3 V star known to host a transiting warm sub-Neptune on a 25.5 d orbit. Here we report on an intensive high-precision radial velocity and photometric…
MOVES III. Simultaneous X-ray and ultraviolet observations unveiling the variable environment of the hot Jupiter HD 189733b
V. Bourrier, P. J. Wheatley, A. Lecavelier des Etangs +8
In this third paper of the MOVES (Multiwavelength Observations of an eVaporating Exoplanet and its Star) programme, we combine Hubble Space Telescope far-ultraviolet observations w…
The KELT-7b atmospheric thermal-inversion conundrum revisited with CHEOPS, TESS, and additional data
Z. Garai, A. Krenn, P. E. Cubillos +84
Ultrahot Jupiters are predicted to show inverted temperature-pressure (T-P) profiles in the presence of optical absorbers such as TiO and VO. An inverted T-P profile of KELT-7b was…
Transit-timing variations in the AU Mic system observed with CHEOPS
Ã. Boldog, Gy. M. Szabó, L. Kriskovics +86
AU Mic is a very active M dwarf with an edge-on debris disk and two transiting sub-Neptunes with a possible third planetary companion. The two transiting planets exhibit significan…
Infrared spectra of TiO2 clusters for hot Jupiter atmospheres
J. P. Sindel, Ch. Helling, D. Gobrecht +2
Context. Clouds seem unavoidable in cool and dense environments, and hence, are necessary to explain observations of exoplanet atmospheres, most recently of WASP 96b with JWST. Und…
HARPS-N, TESS, and CHEOPS discover a transiting sub-Neptune and two outer companions around the bright solar analogue HD 85426
F. Lienhard, A. Mortier, A. Collier Cameron +96
We provide a detailed characterisation of the planetary system orbiting HD 85426 (TOI-1774). This bright G-type star (: 0.99 ; : 1.13 $\text{R…
Dust in brown dwarfs and extra-solar planets II. Cloud formation for cosmologically evolving abundances
S. Witte, Ch. Helling, P. H. Hauschildt
Substellar objects have extremely long life-spans. The cosmological consequence for older objects are low abundances of heavy elements, which results in a wide distribution of obje…
Searching for Hot Water World Candidates with CHEOPS: Refining the radii and analysing the internal structures and atmospheric lifetimes of TOI-238 b and TOI-1685 b
J. A. Egger, D. Kubyshkina, Y. Alibert +85
Studying the composition of exoplanets is one of the most promising approaches to observationally constrain planet formation and evolution processes. However, this endeavour is com…
The Influence of Galactic Cosmic Rays on Ion-Neutral Hydrocarbon Chemistry in the Upper Atmospheres of Free-Floating Exoplanets
P. B. Rimmer, Ch. Helling, C. Bilger
Cosmic rays may be linked to the formation of volatiles necessary for prebiotic chemistry. We explore the effect of cosmic rays in a hydrogen-dominated atmosphere, as a proof-of-co…
Prospects for Detection of Exoplanet Magnetic Fields Through Bow-Shock Observations During Transits
A. A. Vidotto, M. Jardine, Ch. Helling
An asymmetry between the ingress and egress times was observed in the near-UV light curve of the transit planet WASP-12b. Such asymmetry led us to suggest that the early ingress in…
The multi-planet system TOI-5624: Four transiting sub-Neptunes with an outer companion revealed by transit-timing variations
A. Bonfanti, D. Gandolfi, P. Leonardi +96
Following the 2022 alert of a TESS object of interest transiting TOI-5624 (a G7 V star 100 pc away), a CHEOPS campaign in 2023 detected four planetary signals at $P_b\approx3…
The CHEOPS view on the climate of WASP-3 b
G. Scandariato, L. Carone, P. E. Cubillos +83
Hot Jupiters are giant planets subject to intense stellar radiation. The physical and chemical properties of their atmosphere makes them the most amenable targets for the atmospher…
Dust in brown dwarfs and extra-solar planets IV. Assessing TiO2 and SiO nucleation for cloud formation modeling
E. K. H. Lee, Ch. Helling, H. Giles +1
Clouds form in atmospheres of brown dwarfs and planets. The cloud particle formation processes are similar to the dust formation process studied in circumstellar shells of AGB star…
Ionisation in atmospheres of Brown Dwarfs and extrasolar planets II Dust-induced collisional ionization
Ch. Helling, M. Jardine, F. Mokler
Observations have shown that continuous radio emission and also sporadic H-alpha and X-ray emission are prominent in singular, low-mass objects later than spectral class M. These a…
No random transits in CHEOPS observations of HD 139139
R. Alonso, S. Hoyer, M. Deleuil +78
HD 139139 (a.k.a. 'The Random Transiter') is a star that exhibited enigmatic transit-like features with no apparent periodicity in K2 data. The shallow depth of the events (2…
Robust detection of quasi-periodic variability: A HAWKI mini survey of late T dwarfs
S. P. Littlefair, B. Burningham, Ch. Helling
We present HAWK-I J-band light curves of five late-type T dwarfs (T6.5-T7.5) with a typical duration of four hours, and investigate the evidence for quasi-periodic photometric vari…
Ionisation in atmospheres of brown dwarfs and extrasolar planets VI: Properties of large-scale discharge events
R. L. Bailey, Ch. Helling, G. Hodosán +2
Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electricall…
Mass Transfer, Transiting Stream and Magnetopause in Close-in Exoplanetary Systems with Applications to WASP-12
Dong Lai, Ch. Helling, E. P. J. van den Heuvel
We study mass transfer by Roche lobe overflow in close-in exoplanetary systems. The planet's atmospheric gas passes through the inner Lagrangian point and flows along a narrow stre…
A possible misaligned orbit for the young planet AU Mic c
H. Yu, Z. Garai, M. Cretignier +98
The AU Microscopii planetary system is only 24 Myr old, and its geometry may provide clues about the early dynamical history of planetary systems. Here, we present the first measur…
CHEOPS observations confirm nodal precession in the WASP-33 system
A. M. S. Smith, Sz. Csizmadia, V. Van Grootel +86
Aims: We aim to observe the transits and occultations of WASP-33b, which orbits a rapidly-rotating Scuti pulsator, with the goal of measuring the orbital obliquity via the gra…
The sulphur species in hot rocky exoplanet atmospheres
L. J. Janssen, P. Woitke, O. Herbort +4
The first JWST observations of hot Jupiters showed an unexpected detection of SO2 in their hydrogen-rich atmospheres. We investigate how much sulphur can be expected in the atmosph…
Mineral cloud and hydrocarbon haze particles in the atmosphere of the hot Jupiter JWST target WASP-43b
Ch. Helling, Y. Kawashima, V. Graham +5
Having a short orbital period and being tidally locked makes WASP-43b an ideal candidate for JWST observations. Phase curve observations of an entire orbit will enable the mapping…
Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets
Ch. Helling, P. B. Rimmer, I. M. Rodriguez-Barrera +3
Brown dwarfs and giant gas extrasolar planets have cold atmospheres with a rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes…
Shock formation around planets orbiting M-dwarf stars
A. A. Vidotto, J. Llama, M. Jardine +2
Bow shocks can be formed around planets due to their interaction with the coronal medium of the host stars. The net velocity of the particles impacting on the planet determines the…
MOVES V. Modelling star-planet magnetic interactions of HD 189733
A. Strugarek, R. Fares, V. Bourrier +10
Magnetic interactions between stars and close-in planets may lead to a detectable signal on the stellar disk. HD 189733 is one of the key exosystems thought to harbor magnetic inte…
The influence of non-isotropic scattering of thermal radiation on spectra of brown dwarfs and hot exoplanets
R. J. de Kok, Ch. Helling, D. M. Stam +2
(abridged) We calculate near-infrared thermal emission spectra using a doubling-adding radiative transfer code, which includes scattering by clouds and haze. Initial temperature pr…
The energetic particle environment of a GJ 436 b-like planet
D. Rodgers-Lee, P. B. Rimmer, A. A. Vidotto +8
A key first step to constrain the impact of energetic particles in exoplanet atmospheres is to detect the chemical signature of ionisation due to stellar energetic particles and Ga…
Early UV Ingress in WASP-12b: Measuring Planetary Magnetic Fields
A. A. Vidotto, M. Jardine, Ch. Helling
Recently, Fossati et al. observed that the UV transit of WASP-12b showed an early ingress compared to the optical transit. We suggest that the resulting early ingress is caused by…
Coexistence of CH4, CO2 and H2O in exoplanet atmospheres
P. Woitke, O. Herbort, Ch. Helling +4
We propose a classification of exoplanet atmospheres based on their H, C, O, N element abundances below about 600 K. Chemical equilibrium models were run for all combinations of H,…
Rain and clouds in brown dwarf atmospheres: A coupled problem from small to large
Ch. Helling, P. Woitke
The large scale structure of a brown dwarf atmosphere is determined by an interplay of convection, radiation, dust formation, and gravitational settling, which possibly provides an…
Ionisation in atmospheres of Brown Dwarfs and extrasolar planets III. Breakdown conditions for mineral clouds
Ch. Helling, M. Jardine, C. Stark +1
Electric discharges were detected directly in the cloudy atmospheres of Earth, Jupiter and Saturn, are debatable for Venus, and indirectly inferred for Neptune and Uranus in our so…
Unveiling the internal structure and formation history of the three planets transiting HIP 29442 (TOI-469) with CHEOPS
J. A. Egger, H. P. Osborn, D. Kubyshkina +91
Multiplanetary systems spanning the radius valley are ideal testing grounds for exploring the proposed explanations for the observed bimodality in the radius distribution of close-…
Transit Variability in Bow Shock-Hosting Planets
A. A. Vidotto, M. Jardine, Ch. Helling
We investigate the formation of bow shocks around exoplanets as a result of the interaction of the planet with the coronal material of the host star, focusing on physical causes th…
Characterising TOI-732 b and c: New insights into the M-dwarf radius and density valley
A. Bonfanti, M. Brady, T. G. Wilson +88
TOI-732 is an M dwarf hosting two transiting planets that are located on the two opposite sides of the radius valley. By doubling the number of available space-based observations a…
An Ultra-Short Period Super-Earth and a Sub-Neptune Orbiting the K dwarf TOI-4311
Yoshi Nike Emilia Eschen, Thomas G. Wilson, Andrew Collier Cameron +95
We report the discovery and characterisation of the multi-planetary system around TOI-4311, a K dwarf kinematically between the Galactic thick disk and Hercules stream. TOI-4311 ho…
Dust in brown dwarfs and extra-solar planets. VIII. TiO seed formation: 3D Monte Carlo versus kinetic approach
C. Köhn, Ch. Helling, M. Bødker Enghoff +4
We aim to understand the onset of cloud formation {and study the formation of} TiO-CCNs. The formation of (TiO) clusters as precursors to extrasolar cloud formati…
Dust in brown dwarfs and extra-solar planets V. Cloud formation in carbon- and oxygen-rich environment
Ch. Helling, D. Tootill, P. Woitke +1
Recent observations indicate potentially carbon-rich exoplanet atmospheres. Spectral fitting methods for brown dwarfs and exoplanets have invoked the C/O ratio as additional parame…
The effect of stellar magnetic activity on measurements of morning and evening asymmetry of planetary terminator
N. Kostogryz, A. I. Shapiro, L. Carone +9
Differences in the ingress and egress shapes of transit light curves can indicate morning-evening temperature contrasts on transiting planets. Here, we pinpoint an alternative mech…
Planetary host stars: Evaluating uncertainties in ultra-cool model atmospheres
I. Bozhinova, Ch. Helling, A. Scholz
M-dwarfs are emerging in the literature as promising targets for detecting low-mass, Earth-like planets. An important step in this process is to determine the stellar parameters of…
Simulating the cloudy atmospheres of HD 209458 b and HD 189733 b with the 3D Met Office Unified Model
S. Lines, N. J. Mayne, Ian A. Boutle +9
To understand and compare the 3D atmospheric structure of HD 209458 b and HD 189733 b, focusing on the formation and distribution of cloud particles, as well as their feedback on t…
A resonant sextuplet of sub-Neptunes transiting the bright star HD 110067
R. Luque, H. P. Osborn, A. Leleu +149
Planets with radii between that of the Earth and Neptune (hereafter referred to as sub-Neptunes) are found in close-in orbits around more than half of all Sun-like stars. Yet, thei…
The Influence of Dust Formation Modelling on Na I and K I Line Profiles in Substellar Atmospheres
C. M. S. Johnas, Ch. Helling, M. Dehn +2
We aim to understand the correlation between cloud formation and alkali line formation in substellar atmospheres.We perform line profile calculations for Na I and K I based on the…
The K2-24 planetary system revisited by CHEOPS
V. Nascimbeni, L. Borsato, P. Leonardi +82
K2-24 is a planetary system composed of two transiting low-density Neptunians locked in an almost perfect 2:1 resonance and showing large TTVs, i.e., an excellent laboratory to sea…
CHEOPS in-flight performance: A comprehensive look at the first 3.5 years of operations
A. Fortier, A. E. Simon, C. Broeg +128
CHEOPS is a space telescope specifically designed to monitor transiting exoplanets orbiting bright stars. In September 2023, CHEOPS completed its nominal mission and remains in exc…
Precise characterisation of HD 15337 with CHEOPS: a laboratory for planet formation and evolution
N. M. Rosário, O. D. S. Demangeon, S. C. C. Barros +90
We aim to constrain the internal structure and composition of HD 15337 b and c, two short-period planets situated on opposite sides of the radius valley, using new transit photomet…
CHEOPS observations of KELT-20 b/MASCARA-2 b: An aligned orbit and signs of variability from a reflective dayside
V. Singh, G. Scandariato, A. M. S. Smith +87
Occultations are windows of opportunity to indirectly peek into the dayside atmosphere of exoplanets. High-precision transit events provide information on the spin-orbit alignment…
Careers in astronomy in Germany and the UK
J. Fohlmeister, Ch. Helling
We discuss the outcomes of surveys addressing the career situation of astronomers in Germany and the UK, finding social and cultural differences between communities as well as gend…
Modelling the local and global cloud formation on HD 189733b
E. K. H. Lee, Ch. Helling, I. Dobbs-Dixon +1
Context. Observations suggest that exoplanets such as HD 189733b form clouds in their atmospheres which have a strong feedback onto their thermodynamical and chemical structure, an…
M dwarf stars in the light of (future) exoplanet searches
B. Rojas-Ayala, E. J. Hilton, A. W. Mann +8
We present a brief overview of a splinter session on M dwarf stars as planet hosts that was organized as part of the Cool Stars 17 conference. The session was devoted to reviewing…
The mineral clouds on HD 209458b and HD189733b
Ch. Helling, G. Lee, I. Dobbs-Dixon +7
3D atmosphere model results are used to comparatively study the kinetic, non-equilibrium cloud formation in the atmospheres of two example planets guided by the giant gas planets H…
Career situation of female astronomers in Germany
J. Fohlmeister, Ch. Helling
We survey the job situation of women in astronomy in Germany and of German women abroad and review indicators for their career development. Our sample includes women astronomers fr…
Rosseland and Planck Mean Opacities for Protoplanetary Discs
D. Semenov, Th. Henning, Ch. Helling +2
In this paper, we present mean gas and dust opacities relevant to the physical conditions typical of protoplanetary discs. As the principal absorber for temperatures below ~1,500 K…
Characterising exoplanets and their environment with UV transmission spectroscopy
L. Fossati, V. Bourrier, D. Ehrenreich +36
Exoplanet science is now in its full expansion, particularly after the CoRoT and Kepler space missions that led us to the discovery of thousands of extra-solar planets. The last de…
In-situ observations of resident space objects with the CHEOPS space telescope
Nicolas Billot, Stephan Hellmich, Willy Benz +80
The CHaracterising ExOPlanet Satellite (CHEOPS) is a partnership between the European Space Agency and Switzerland with important contributions by 10 additional ESA member States.…
A joint effort to discover and characterize two resonant mini Neptunes around TOI-1803 with TESS, HARPS-N and CHEOPS
T. Zingales, L. Malavolta, L. Borsato +130
We present the discovery of two mini Neptunes near a 2:1 orbital resonance configuration orbiting the K0 star TOI-1803. We describe their orbital architecture in detail and suggest…
A comparison of chemistry and dust cloud formation in ultracool dwarf model atmospheres
Ch. Helling, A. Ackerman, F. Allard +8
The atmospheres of substellar objects contain clouds of oxides, iron, silicates, and other refractory condensates. Water clouds are expected in the coolest objects. The opacity of…
MOVES II. Tuning in to the radio environment of HD189733b
R. D. Kavanagh, A. A. Vidotto, D. à Fionnagáin +7
We present stellar wind modelling of the hot Jupiter host HD189733, and predict radio emission from the stellar wind and the planet, the latter arising from the interaction of the…
TOI-757 b: an eccentric transiting mini-Neptune on a 17.5-d orbit
A. Alqasim, N. Grieves, N. M. Rosário +129
We report the spectroscopic confirmation and fundamental properties of TOI-757 b, a mini-Neptune on a 17.5-day orbit transiting a bright star ( mag) discovered by the TESS…
The Impact of Stellar Model Spectra in Disk Detection
J. A. Sinclair, Ch. Helling, J. S. Greaves
We present a study of the impact of different model groups in the detection of circumstellar debris disks. Almost all previous studies in this field have used Kurucz model spectra…
An Ultra-Short Period Super-Earth and Sub-Neptune Spanning the Radius Valley Orbiting the Kinematic Thick Disk Star TOI-2345
Yoshi Nike Emilia Eschen, Thomas G. Wilson, Andrea Bonfanti +94
A crucial chemical link between stars and their orbiting exoplanets is thought to exist. If universal, this connection could affect the formation and evolution of all planets. Ther…
Tuning in to the radio environment of HD189733b
R. D. Kavanagh, A. A. Vidotto, D. à Fionnagáin +7
The hot Jupiter HD189733b is expected to be a source of strong radio emission, due to its close proximity to its magnetically active host star. Here, we model the stellar wind of i…
Understanding the atmospheric properties and chemical composition of the ultra-hot Jupiter HAT-P-7b: I. Cloud and chemistry mapping
Ch. Helling, N. Iro, L. Corrales +10
Ultra-hot Jupiters have recently attracted interest from observers and theoreticians alike, as they provide observationally accessible test cases. We apply a hierarchical modelling…
Gas phase mean opacities for varying [M/H], N/O, and C/O
Ch. Helling, W. Lucas
We present a set of gas-phase Planck mean and Rosseland mean opacity tables applicable for simulations of star and planet formation, stellar evolution, disk modelling at various me…
Dark skies of the slightly eccentric WASP-18 b from its optical-to-infrared dayside emission
A. Deline, P. E. Cubillos, L. Carone +86
We performed a joint analysis of phase-curve observations of the ultra-hot Jupiter WASP-18 b from the visible to the mid-infrared, using data from CHEOPS, TESS and Spitzer. We aim…
HIP 41378 observed by CHEOPS: Where is planet d?
S. Sulis, L. Borsato, S. Grouffal +84
HIP 41378 d is a long-period planet that has only been observed to transit twice, three years apart, with K2. According to stability considerations and a partial detection of the R…
The impact of M-dwarf atmosphere modelling on planet detection
I. Bozhinova, Ch. Helling, C. Stark
Being able to accurately estimate stellar parameters based on spectral observations is important not only for understanding the stars themselves but it is also vital for the determ…
First spectroscopic observations of the sub-stellar companion of the young debris disk star PZ Telescopii
T. O. B. Schmidt, M. Mugrauer, R. Neuhäuser +5
In 2010 a sub-stellar companion to the solar analog pre-main sequence star PZ Tel and member of the about 12 Myr old Beta Pic moving group was found by high-contrast direct imaging…
The EBLM Project XI. Mass, radius and effective temperature measurements for 23 M-dwarf companions to solar-type stars observed with CHEOPS
M. I. Swayne, P. F. L. Maxted, A. H. M. J. Triaud +104
Observations of low-mass stars have frequently shown a disagreement between observed stellar radii and radii predicted by theoretical stellar structure models. This ``radius inflat…
Improved characterization of the TOI-2141 system: a dense sub-Neptune with non-transiting inner and outer companions
R. Luque, K. W. F. Lam, J. Cabrera +87
We aim to refine the fundamental parameters of the TOI-2141 planetary system, which includes a transiting sub-Neptune orbiting a Sun-like star in a relatively long orbit of 18.26 d…
Aspects of Multi-Dimensional Modelling of Substellar Atmospheres
Ch. Helling, E. Pedretti, S. Berdyugina +6
Theoretical arguments and observations suggest that the atmospheres of Brown Dwarfs and planets are very dynamic on chemical and on physical time scales. The modelling of such subs…
Photo-dynamical characterisation of the TOI-178 resonant chain
A. Leleu, J. -B. Delisle, L. Delrez +104
The TOI-178 system consists of a nearby late K-dwarf transited by six planets in the super-Earth to mini-Neptune regime, with radii ranging from 1.2 to 2.9 earth radius and orbital…
A search for transit timing variations in the HATS-18 planetary system
John Southworth, A. J. Barker, T. C. Hinse +23
HATS-18b is a transiting planet with a large mass and a short orbital period, and is one of the best candidates for the detection of orbital decay induced by tidal effects. We pres…
The dark days are overcast: Iron-bearing clouds on HD 209458 b and WASP-43 b can explain low dayside albedos
K. L. Chubb, D. Samra, Ch. Helling +2
We simulate the geometric albedo spectra of hot Jupiter exoplanets HD 209458 b and WASP-43 b, based on global climate model (GCMs) post-processed with kinetic cloud models. We pred…
Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30
T. O. B. Schmidt, R. Neuhäuser, C. Briceño +11
We surveyed the 25 Ori association for direct-imaging companions. This association has an age of only few million years. Among other targets, we observed CVSO 30, which has recentl…
Atmospheric electrification in dusty, reactive gases in the solar system and beyond
Ch. Helling, R. G. Harrison, F. Honary +7
Detailed observations of the solar system planets reveal a wide variety of local atmospheric conditions. Astronomical observations have revealed a variety of extrasolar planets non…
Disk evolution, element abundances and cloud properties of young gas giant planets
Ch. Helling, P. Woitke, P. B. Rimmer +3
We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemic…
Direct evidence of a sub-stellar companion around CT Cha
T. O. B. Schmidt, R. Neuhäuser, A. Seifahrt +5
In our ongoing search for close and faint companions around T Tauri stars, we found a very faint (Ks=14.9mag, Ks_0=14.4mag) object, just ~2.67" northwest of the Chamaeleon star-for…
Dust in Brown Dwarfs IV. Dust formation and driven turbulence on mesoscopic scales
Ch. Helling, R. Klein, P. Woitke +2
Dust formation in brown dwarf atmospheres is studied by utilising a model for driven turbulence in the mesoscopic scale regime. We apply a pseudo-spectral method where waves are cr…
Exploring terrestrial lightning parameterisations for exoplanets and brown dwarfs
G. Hodosán, Ch. Helling, I. Vorgul
Observations and models suggest that the conditions to develop lightning may be present in cloud-forming extrasolar planetary and brown dwarf atmospheres. Whether lightning on thes…
Cloud formation in metal-rich atmospheres of hot super-Earths like 55 Cnc e and CoRot7b
G. Mahapatra, Ch. Helling, Y. Miguel
Clouds form in the atmospheres of planets where they can determine the observable spectra, the albedo and phase curves. Cloud properties are determined by the local thermodynamical…
Detailed cool star flare morphology with CHEOPS and TESS
G. Bruno, I. Pagano, G. Scandariato +79
Context. White-light stellar flares are proxies for some of the most energetic types of flares, but their triggering mechanism is still poorly understood. As they are associated wi…
Understanding the atmospheric properties and chemical composition of the ultra-hot Jupiter HAT-P-7b: III. Changing ionisation and the emergence of an ionosphere
Ch. Helling, M. Worters, D. Samra +2
Ultra-hot Jupiters are the hottest close-in exoplanets discovered so far, and present a unique possibility to explore hot and cold chemistry on one object. The tidally locked ultra…
Equilibrium chemistry down to 100 K - Impact of silicates and phyllosilicates on carbon/oxygen ratio
P. Woitke, Ch. Helling, G. H. Hunter +5
We introduce a fast and versatile computer code, GGchem, to determine the chemical composition of gases in thermo-chemical equilibrium down to 100 K, with or without equilibrium co…
Reference study to characterise plasma and magnetic properties of ultra-cool atmospheres
M. I. Rodriguez-Barrera, Ch. Helling, C. R. Stark +1
Radio and X-ray emission from brown dwarfs suggest that an ionised gas and a magnetic field with a sufficient flux density must be present. We perform a reference study for late M-…
Cloud property trends in hot and ultra-hot giant gas planets (WASP-43b, WASP-103b, WASP-121b, HAT-P-7b, and WASP-18b)
Ch. Helling, D. Lewis, D. Samra +8
Ultra-hot Jupiters are the hottest exoplanets discovered so far. Observations begin to provide insight into the composition of their extended atmospheres and their chemical day/nig…
Multiwaveband photometry of the irradiated brown dwarf WD0137-349B
S. L. Casewell, K. A. Lawrie, P. F. L. Maxted +7
WD0137-349 is a white dwarf-brown dwarf binary system in a 116 minute orbit. We present radial velocity observations and multiwaveband photometry from V, R and I in the optical, to…
Characterisation of the Warm-Jupiter TOI-1130 system with CHEOPS and photo-dynamical approach
L. Borsato, D. Degen, A. Leleu +93
Among the thousands of exoplanets discovered to date, approximately a few hundred gas giants on short-period orbits are classified as "lonely" and only a few are in a multi-planet…
Constraining the reflective properties of WASP-178b using Cheops photometry
I. Pagano, G. Scandariato, V. Singh +79
Multiwavelength photometry of the secondary eclipses of extrasolar planets is able to disentangle the reflected and thermally emitted light radiated from the planetary dayside. Thi…
Architecture of TOI-561 planetary system
G. Piotto, T. Zingales, L. Borsato +89
We present new observations from CHEOPS and TESS to clarify the architecture of the planetary system hosted by the old Galactic thick disk star TOI-561. Our global analysis, which…
Dynamic mineral clouds on HD 189733b I. 3D RHD with kinetic, non-equilibrium cloud formation
E. K. H. Lee, I. Dobbs-Dixon, Ch. Helling +2
Observations of exoplanet atmospheres have revealed the presence of cloud particles in their atmospheres. 3D modelling of cloud formation in atmospheres of extrasolar planets coupl…
The tidal deformation and atmosphere of WASP-12b from its phase curve
B. Akinsanmi, S. C. C. Barros, M. Lendl +85
Ultra-hot Jupiters present a unique opportunity to understand the physics and chemistry of planets at extreme conditions. WASP-12b stands out as an archetype of this class of exopl…
Exonephology: Transmission spectra from a 3D simulated cloudy atmosphere of HD209458b
S. Lines, J. Manners, N. J. Mayne +8
We present high resolution transmission spectra, calculated directly from a 3D radiative-hydrodynamics simulation that includes kinetic cloud formation, for HD209458b. We find that…
The First Millimeter Detection of a Non-Accreting Ultracool Dwarf
P. K. G. Williams, S. L. Casewell, C. R. Stark +3
The well-studied M9 dwarf TVLM 513-46546 is a rapid rotator (P_rot ~ 2 hr) hosting a stable, dipolar magnetic field of ~3 kG surface strength. Here we report its detection with ALM…
The shocking transit of WASP-12b: Modelling the observed early ingress in the near ultraviolet
J. Llama, K. Wood, M. Jardine +4
Near ultraviolet observations of WASP-12b have revealed an early ingress compared to the optical transit lightcurve. This has been interpreted as due to the presence of a magnetosp…
Sparkling nights and very hot days on WASP-18b: the formation of clouds and the emergence of an ionosphere
Ch. Helling, P. Gourbin, P. Woitke +1
WASP-18b is an utra-hot Jupiter with a temperature difference of upto 2500K between day and night. Such giant planets begin to emerge as planetary laboratory for understanding clou…
MOVES I. The evolving magnetic field of the planet-hosting star HD189733
R. Fares, V. Bourrier, A. A. Vidotto +9
HD189733 is an active K dwarf that is, with its transiting hot Jupiter, among the most studied exoplanetary systems. In this first paper of the Multiwavelength Observations of an e…
The CHEOPS view of HD 95338b: refined transit parameters, and a search for exomoons
Sz. Kálmán, A. E. Simon, A. Deline +90
Despite the ever-increasing number of known exoplanets, no uncontested detections have been made of their satellites, known as exomoons. The quest to find exomoons is at the forefr…