T. O. Winterhalder
A5092849820- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Atmospheric Ozone and Climate
- Spacecraft and Cryogenic Technologies
- Astronomical Observations and Instrumentation
- Planetary Science and Exploration
- Adaptive optics and wavefront sensing
- Chemical Thermodynamics and Molecular Structure
- History and Developments in Astronomy
- Solar and Space Plasma Dynamics
European Southern Observatory
2023-2024
University of Cologne
2024
Heidelberg University
2021-2023
European Space Research and Technology Centre
2021
Leiden University
2021
With four companions at separations from 16 to 71 au, HR 8799 is a unique target for direct imaging, presenting an opportunity the comparative study of exoplanets with shared formation history. Combining new VLTI/GRAVITY observations obtained within ExoGRAVITY program archival data, we perform systematic atmospheric characterisation all planets. We explore different levels model flexibility understand temperature structure, chemistry and clouds each planet using both petitRADTRANS retrievals...
Context. Since 2019, GRAVITY has provided direct observations of giant planets and brown dwarfs at separations down to 95 mas from the host star. Some these have first confirmation companions previously detected by indirect techniques (astrometry radial velocities). Aims. We want improve observing strategy data reduction in order lower inner working angle dual-field on-axis mode. also determine current limitations instrument when faint with 30–150 range. Methods. To angle, we propose a fiber...
The companion GL229B was recently resolved by Xuan et al. (2024) as a tight binary of two brown dwarfs (Ba and Bb) through VLTI-GRAVITY interferometry VLT-CRIRES+ RV measurements. Here, we present Bayesian models the interferometric data in additional detail, along with an updated outer orbit dwarf pair about primary. To create model inner robust uncertainties, apply kernel phases to GRAVITY address baseline redundancy raw closure phases. Using parallel tempering, constrain binary's using...
Abstract The companion GL229B was recently resolved by Xuan et al. as a tight binary of two brown dwarfs (Ba and Bb) through VLTI-GRAVITY interferometry Very Large Telescope-CRIRES+ radial velocity (RV) measurements. Here, we present Bayesian models the interferometric RV data in additional detail, along with an updated outer orbit dwarf pair about primary. To create model inner robust uncertainties, apply kernel phases to GRAVITY data, address baseline redundancy raw closure phases. Using...
Context . Dual-field interferometric observations with VLTI/GRAVITY sometimes require the use of a binary calibrator. This is star whose individual components remain unresolved by interferometer, separation between 400 and 2000 mas for Unit Telescopes (UTs), or 1200–3000 Auxiliary (ATs). The vector also needs to be predictable within 10 proper pointing instrument. Aims No list properly vetted calibrators was available so far dual-field on UTs. Our objective compile such make it community....
Abstract Direct imaging observations are biased toward wide-separation, massive companions that have degenerate formation histories. Although the majority of exoplanets expected to form via core accretion, most directly imaged not been convincingly demonstrated follow this pathway. We obtained new interferometric giant planet AF Lep b with VLTI/GRAVITY instrument. present three epochs ∼50 μ as relative astrometry and K -band spectrum for first time at a resolution R = 500. Using only these...
Abstract Tension remains between the observed and modeled properties of substellar objects, but objects in binary orbits, with known dynamical masses, can provide a way forward. HD 72946 B is recently imaged brown dwarf companion to nearby, solar-type star. We achieve ∼100 μ as relative astrometry K band using VLTI/GRAVITY, unprecedented for benchmark dwarf. fit an ensemble measurements orbit orbitize! derive strong mass constraint M = 69.5 ± 0.5 Jup assuming prior on host star A 0.97 0.01 ⊙...
Abstract Giant exoplanets have been directly imaged over orders of magnitude orbital separations, prompting theoretical and observational investigations their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data HIP 65426 b, a cold, giant exoplanet which is particular challenge for most theories at projected separation 92 au from its primary. Leveraging GRAVITY’s precision, an updated eccentricity posterior that disfavors large eccentricities. The still prior...
Abstract Young, low-mass brown dwarfs orbiting early-type stars, with low mass ratios ( q ≲ 0.01), appear to be intrinsically rare and present a formation dilemma: could handful of these objects the highest-mass outcomes “planetary” channels (bottom up within protoplanetary disk), or are they more representative lowest-mass “failed binaries” (formed via disk fragmentation core fragmentation)? Additionally, their orbits can yield model-independent dynamical masses, when paired wide wavelength...
Precise mass constraints are vital for the characterisation of brown dwarfs and exoplanets. Here we present how combination data obtained by Gaia GRAVITY can help enlarge sample substellar companions with measured dynamical masses. We show Non-Single-Star (NSS) two-body orbit catalogue contained in DR3 be used to inform high-angular-resolution follow-up observations GRAVITY. Applying method presented this work eight candidate systems, detect all predicted companions, seven which were...
Europa's subsurface ocean is a potential candidate for life in the outer solar system. It thought that plumes may exist which eject material out into space, be detected by spacecraft flyby. Previous work on feasibility of these detections has assumed collisionless model plume particles. New models including particle collisions have shown shock can develop interior as rising particles collide with falling back to moon's surface, limiting plume's altitude. Results show region over surface...
Precise mass constraints are vital for the characterisation of brown dwarfs and exoplanets. Here we present how combination data obtained by Gaia GRAVITY can help enlarge sample substellar companions with measured dynamical masses. We show Non-Single-Star (NSS) two-body orbit catalogue contained in DR3 be used to inform high-angular-resolution follow-up observations GRAVITY. Applying method presented this work eight candidate systems, detect all predicted companions, seven which were...
ESA's upcoming JUpiter Icy moons Explorer (JUICE) is scheduled to perform two flybys of Jupiter's moon Europa. Here, we present the results our investigation into JUICE's capability detect plumes and separate them from background water in atmosphere as a function their source's location mass flux on Europan surface using neutral spectrometer NIM. For both currently planned evaluate different scenarios estimate how feasible such detection is, Monte Carlo particle tracing model plume. We also...
Dual-field interferometric observations with VLTI/GRAVITY sometimes require the use of a "binary calibrator", binary star whose individual components remain unresolved by interferometer, separation between 400 and 2000 mas for Units Telescopes (UTs), or 1200 to 3000 Auxiliary (ATs). The vector also needs be predictable within 10 proper pointing instrument. Up until now, no list properly vetted calibrators was available dual-field on UTs. Our objective is compile such list, make it community....
With four companions at separations from 16 to 71 au, HR 8799 is a unique target for direct imaging, presenting an opportunity comparative study of exoplanets with shared formation history. Combining new VLTI/GRAVITY observations obtained within the ExoGRAVITY program archival data, we performed systematic atmospheric characterisation across all planets. We explored different levels model flexibility understand temperature structure, chemistry, and clouds each planet using both petitRADTRANS...
Since 2019, GRAVITY has provided direct observations of giant planets and brown dwarfs at separations down to 95 mas from the host star. Some these have first confirmation companions previously detected by indirect techniques (astrometry radial velocities). We want improve observing strategy data reduction in order lower inner working angle dual-field on-axis mode. also determine current limitations instrument when faint with 30-150 range. To angle, we propose a fiber off-pointing during...
Direct imaging observations are biased towards wide-separation, massive companions that have degenerate formation histories. Although the majority of exoplanets expected to form via core accretion, most directly imaged not been convincingly demonstrated follow this pathway. We obtained new interferometric giant planet AF Lep b with VLTI/GRAVITY instrument. present three epochs 50$\mu$as relative astrometry and K-band spectrum for first time at a resolution R=500. Using only these...
Europa's subsurface ocean is a potential candidate for life in the outer solar system. It thought that plumes may exist which eject material out into space, be detected by spacecraft flyby. Previous work on feasibility of these detections has assumed collisionless model plume particles. New models including particle collisions have shown shock can develop interior as rising particles collide with falling back to moon's surface, limiting plume's altitude. Results show region over surface...
The repeated eruptions of water plumes on Europa have been suggested based Hubble observations, Keck observations and in-situ magnetic field data from Galileo (Roth et al., 2014; Sparks 2016, 2017, 2019; Jia 2018; Arnold Paganini 2019). possibility that such could transport material Europa’s subsurface, or reservoirs contained in the ice layer (Vorbuger Wurz 2021), far above surface creates an unprecedented opportunity to sample subsurface environment investigate its habitability....
Tension remains between the observed and modeled properties of substellar objects, but objects in binary orbits, with known dynamical masses can provide a way forward. HD 72946 B is recently imaged brown dwarf companion to nearby, solar type star. We achieve $\sim100~\mu\mathrm{as}$ relative astrometry K-band using VLTI/GRAVITY, unprecedented for benchmark dwarf. fit an ensemble measurements orbit orbitize! derive strong mass constraint $\mathrm{M_B}=69.5\pm0.5~\mathrm{M_{Jup}}$ assuming...
Giant exoplanets have been directly imaged over orders of magnitude orbital separations, prompting theoretical and observational investigations their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data HIP 65426 b, a cold, giant exoplanet which is particular challenge for most theories at projected separation 92 au from its primary. Leveraging GRAVITY's precision, an updated eccentricity posterior that disfavors large eccentricities. The still prior-dependent,...
Young, low-mass Brown Dwarfs orbiting early-type stars, with low mass ratios ($q\lesssim0.01$), appear intrinsically rare and present a formation dilemma: could handful of these objects be the highest outcomes ``planetary" channels (bottom up within protoplanetary disk), or are they more representative lowest ``failed binaries" (formed via disk fragmentation, core fragmentation)? Additionally, their orbits can yield model-independent dynamical masses, when paired wide wavelength coverage...
<p>The repeated eruptions of water plumes on Europa have been suggested based Hubble observations, Keck observations and in-situ magnetic field data from Galileo (Roth et al., 2014; Sparks 2016, 2017, 2019; Jia 2018; Arnold Paganini 2019). The possibility that such could transport material Europa’s subsurface, or reservoirs contained in the ice layer (Vorbuger Wurz 2021), creates an unprecedented opportunity to sample subsurface environment investigate its...
ESA's JUpiter Icy moons Explorer (JUICE) will arrive at the Jupiter System in 2029 and perform two flybys of Europa. Here, we present results our investigation into JUICE's capability to detect plumes separate them from background water atmosphere as a function their source's location mass flux on Europan surface using neutral spectrometer NIM. For both currently planned evaluate different scenarios estimate how feasible such detection is, Monte Carlo particle tracing model plume. We also...