Search Publications
Revisiting Ulysses electron data with a triple fit of velocity distributions
Fichtner, H.; Scherer, K.; Lazar, M. +1 more
Context. Given their uniqueness, the Ulysses data can still provide us with valuable new clues about the properties of plasma populations in the solar wind, and especially about their variations with heliographic coordinates. In the context of kinetic waves and instabilities in the solar wind plasma, the electron temperature anisotropy plays a cru…
Auroral kilometric radiation—The electron cyclotron maser paradigm
Treumann, R. A.; Baumjohann, Wolfgang
Auroral kilometric radiation (AKR) is the paradigm of intense radio emission from planetary magnetospheres. Being close to the electron gyro frequency and/or its lower harmonics, its observation indicates the non-thermal state of the source plasma. Emission is produced when the plasma enters a state of energetic excitation which results in deforma…
A Search for Predicted Astrometric Microlensing Events by Nearby Brown Dwarfs
Lu, Jessica R.; McGill, Peter; Leauthaud, Alexie +3 more
Gravitational microlensing has the potential to provide direct gravitational masses of single, free-floating brown dwarfs, independent of evolutionary and atmospheric models. The proper motions and parallaxes of nearby brown dwarfs can be used to predict close future alignments with distant background stars that cause a microlensing event. Targete…
K2-99 revisited: a non-inflated warm Jupiter, and a temperate giant planet on a 522-d orbit around a subgiant
Fridlund, M.; Guenther, E. W.; García, R. A. +29 more
We report new photometric and spectroscopic observations of the K2-99 planetary system. Asteroseismic analysis of the short-cadence light curve from K2's Campaign 17 allows us to refine the stellar properties. We find K2-99 to be significantly smaller than previously thought, with R⋆ = 2.55 ± 0.02 R⊙. The new light curve also…
Subarcsecond Imaging of a Solar Active Region Filament With ALMA and IRIS
Heinzel, P.; Gunár, S.; Leenaarts, J. +4 more
Quiescent filaments appear as absorption features on the solar disk when observed in chromospheric lines and at continuum wavelengths in the millimeter (mm) range. Active region (AR) filaments are their small-scale, low-altitude analogues, but they could not be resolved in previous mm observations. This spectral diagnostic can provide insight into…
AMBITION - comet nucleus cryogenic sample return
Henri, Pierre; Bianchi, Eleonora; Codella, Claudio +27 more
We describe the AMBITION project, a mission to return the first-ever cryogenically-stored sample of a cometary nucleus, that has been proposed for the ESA Science Programme Voyage 2050. Comets are the leftover building blocks of giant planet cores and other planetary bodies, and fingerprints of Solar System's formation processes. We summarise some…
Discovery of two bright high-redshift gravitationally lensed quasars revealed by Gaia
McMahon, Richard G.; Auger, Matthew W.; Anguita, Timo +4 more
We present the discovery and preliminary characterisation of two high-redshift gravitationally lensed quasar systems in Gaia Data Release 2 (DR2). Candidates with multiple close-separation Gaia detections and quasar-like colours in WISE, Pan-STARRS, and DES are selected for follow-up spectroscopy with the New Technology Telescope. We confirm DES J…
The lithified aeolian dune field adjacent to the Apollinaris Sulci, Mars: Geological history and paleo-wind record
Chojnacki, Matthew; Edgett, Kenneth S.; Day, Mackenzie +1 more
A lithified aeolian dune field in the Apollinaris Sulci region of Mars presents a unique opportunity to study ancient aeolian processes and paleo-wind conditions during an earlier episode of martian climate history. The ancient dunes occur inside an eroded, partly-filled impact structure. The petrified dune field retains its original geomorphology…
Rotation of hot normal, peculiar and Be stars from space photometry
Balona, L. A.
The periods of 34 376 main-sequence stars hotter than 6000 K are derived from Kepler, K2, and TESS light curves. From the effective temperatures and GAIA DR3 luminosities, the radii, and hence the equatorial rotational velocities, can be estimated. Comparison with the projected rotational velocities shows that the photometric periods are indisting…
Stellar Loci. VI. An Updated Catalog of the Best and Brightest Metal-poor Stars
Huang, Yang; Beers, Timothy C.; Li, Haining +3 more
We employ Gaia, Two Micron All Sky Survey, and ALLWISE photometry, as well as astrometric data from Gaia, to search for relatively bright very metal-poor (VMP; [Fe/H] < -2.0) giant star candidates using three different criteria: (1) the derived Gaia photometric metallicities from Xu et al., (2) the lack of stellar molecular absorption near 4.6 …