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Kinematics of coronal rain in a transversely oscillating loop: Ponderomotive force and rain-excited oscillations
Kohutova, P.; Verwichte, E.; Neukirch, T. +2 more
Context. Coronal rain is composed of cool dense blobs that form in solar coronal loops and are a manifestation of catastrophic cooling linked to thermal instability. Once formed, rain falls towards the solar surface at sub-ballistic speeds, which is not well understood. Pressure forces seem to be the prime candidate to explain this. In many observ…
Power spectra based Planck constraints on compensated isocurvature, and forecasts for LiteBIRD and CORE space missions
Väliviita, Jussi
Compensated isocurvature perturbations (CIP), where the primordial baryon and cold dark matter density perturbations cancel, do not cause total matter isocurvature perturbation. Consequently, at the linear order in the baryon density contrast Δ, a mixture of CIP and the adiabatic mode leads to the same CMB spectra as the pure adiabatic mode. Only …
Late-time observations of the relativistic tidal disruption flare candidate Swift J1112.2-8238
Cenko, S. B.; Krühler, T.; Levan, A. J. +6 more
We present late-time follow-up of the relativistic tidal disruption flare (rTDF) candidate Swift J1112.2-8238. We confirm the previously determined redshift of z = 0.8900 ± 0.0005 based on multiple emission line detections. Hubble Space Telescope imaging of the host galaxy indicates a complex and distorted morphology with at least two spatially di…
Sensitivity and fragmentation calibration of the time-of-flight mass spectrometer RTOF on board ESA's Rosetta mission
Mall, Urs; Fiethe, Björn; Wurz, Peter +8 more
The European Space Agency's Rosetta spacecraft, with the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) onboard, has been following and observing comet 67P/Churyumov-Gerasimenko since summer 2014. Prior to this period, and due to a technical failure also during this period, optimization and calibration campaigns have been condu…
An eccentric companion at the edge of the brown dwarf desert orbiting the 2.4 M⊙ giant star HIP 67537
Wittenmyer, R. A.; Jones, M. I.; Drass, H. +5 more
We report the discovery of a substellar companion around the giant star HIP 67537. Based on precision radial velocity measurements from CHIRON and FEROS high-resolution spectroscopic data, we derived the following orbital elements for HIP 67537 b: mb sin I = 11.1+0.4-1.1Mjup, a =4.9+0.14-…
Gaia Data Release 1. Validation of the photometry
Jordi, C.; Evans, D. W.; Brown, A. G. A. +12 more
Aims: The photometric validation of the Gaia DR1 release of the ESA Gaia mission is described and the quality of the data shown.
Methods: This is carried out via an internal analysis of the photometry using the most constant sources. Comparisons with external photometric catalogues are also made, but are limited by the accuracies and sys…
LOFAR observations of decameter carbon radio recombination lines towards Cassiopeia A
van Weeren, R. J.; Tielens, A. G. G. M.; Röttgering, H. J. A. +6 more
We present a study of carbon radio recombination lines towards Cassiopeia A using low frequency array (LOFAR) observations in the frequency range 10-33 MHz. Individual carbon α lines are detected in absorption against the continuum at frequencies as low as 16 MHz. Stacking several Cα lines we obtain detections in the 11-16 MHz range. These are the…
Constraints on AGN feedback from its Sunyaev-Zel'dovich imprint on the cosmic background radiation
Sijacki, Debora; Efstathiou, George; Puchwein, Ewald +2 more
We derive constraints on feedback by active galactic nuclei (AGN) by setting limits on their thermal Sunyaev-Zel'dovich (SZ) imprint on the cosmic microwave background. The amplitude of any SZ signature is small and degenerate with the poorly known sub-mm spectral energy distribution of the AGN host galaxy and other unresolved dusty sources along …
Hard X-ray variability of V404 Cygni during the 2015 outburst
Motta, S. E.; Sánchez-Fernández, C.; Kuulkers, E. +1 more
Aims: Hard X-ray spectra of black hole binaries (BHB) are produced by Comptonization of soft seed photons by hot electrons near the black hole. The slope of the resulting energy spectra is governed by two main parameters: the electron temperature (Te) and optical depth (τ) of the emitting plasma. Given the extreme brightness of V40…
Evidence for depletion of heavy silicon isotopes at comet 67P/Churyumov-Gerasimenko
Wurz, P.; Altwegg, K.; Balsiger, H. +17 more
Context. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) was designed to measure the composition of the gas in the coma of comet 67P/Churyumov-Gerasimenko, the target of the European Space Agency's Rosetta mission. In addition to the volatiles, ROSINA measured refractories sputtered off the comet by the interaction of solar …