Search Publications
Application of time transfer functions to Gaia's global astrometry. Validation on DPAC simulated Gaia-like observations
Bertone, Stefano; Bucciarelli, Beatrice; Lattanzi, Mario G. +5 more
Context. A key objective of the ESA Gaia satellite is the realization of a quasi-inertial reference frame at visual wavelengths by means of global astrometric techniques. This requires accurate mathematical and numerical modeling of relativistic light propagation, as well as double-blind-like procedures for the internal validation of the results, …
Data Timing, Time Transfer and On-board Clock Monitoring for Space Astrometry with Gaia
Butkevich, Alexey G.; Klioner, Sergei A.; Geyer, Robin +1 more
The paper discusses the problematic of data timing in the framework of the space astrometry mission Gaia. For various reasons related both to astrometry and to the measuring principles of the Gaia instrument it is mandatory to assign a highly stable and accurate time tag for each observational point. For this purpose Gaia has a Rb clock on board. …
Energy-banded ions in Saturn's magnetosphere
Thomsen, M. F.; Jackman, C. M.; Kurth, W. S. +3 more
Using data from the Cassini Plasma Spectrometer ion mass spectrometer, we report the first observation of energy-banded ions at Saturn. Observed near midnight at relatively high magnetic latitudes, the banded ions are dominantly H+, and they occupy the range of energies typically associated with the thermal pickup distribution in the in…
Resurfacing event observed in Morpheos basin (Eridania Planitia) and the implications to the formation and timing of Waikato and Reull Valles, Mars
Kostama, V. -P.; Raitala, J.; Kukkonen, S.
The large scale outflow channels of the Hellas impact basin are characteristic to its eastern rim region. Although the majority of the valles are located in the large-scale topographic trough connecting Hesperia Planum and Hellas basin, the most far-reaching of them, Reull Vallis is situated to the south-southeast of this trough cutting through Pr…
The development of magnetic field line wander in gyrokinetic plasma turbulence: dependence on amplitude of turbulence
Howes, Gregory G.; Bourouaine, Sofiane
The dynamics of a turbulent plasma not only manifests the transport of energy from large to small scales, but also can lead to a tangling of the magnetic field that threads through the plasma. The resulting magnetic field line wander can have a large impact on a number of other important processes, such as the propagation of energetic particles th…
An astrometric and spectroscopic study of the δ Scuti variable HD 21190 and its wide companion CPD -83° 64B
Ilyin, I.; Niemczura, E.; Hubrig, S. +4 more
Although pulsations of δ Scuti type are not expected among Ap stars from a theoretical point of view, previous observations of the known δ Scuti star HD 21190 indicated a spectral classification F2 III SrEuSi:, making it the most evolved Ap star known. Our atmospheric chemical analysis based on recent High Accuracy Radial velocity Planet Searcher …
Three-minute Sunspot Oscillations Driven by Magnetic Reconnection in a Light Bridge
Moon, Yong-Jae; Yurchyshyn, Vasyl; Chae, Jongchul +5 more
We report a different type of three-minute chromospheric oscillation above a sunspot in association with a small-scale impulsive event in a light bridge (LB). During our observations, we found a transient brightening in the LB. The brightening was composed of elementary bursts that may be a manifestation of fast repetitive magnetic reconnections i…
Southern Meridiani Planum - A candidate landing site for the first crewed mission to Mars
Smith, H.; Hobbs, S. W.; Clarke, J. D. A. +2 more
Astronauts working on the surface of Mars have the capability to explore efficiently, rapidly, and flexibly, allowing them to perform a wide range of field investigations. NASA has begun an open international process to identify and evaluate candidate locations where crews could land, live and work on the martian surface, beginning with the First …
New Orbits for 18 Binaries
Cvetković, Z.; Pavlović, R.
Orbital elements of 18 visual binaries are computed using the measurements collected in the Fourth Catalog of Interferometric Measurements of Binary Stars; 15 orbits are determined for the first time and three orbits are revised. Eleven of the binaries, denoted as HDS, were discovered during the Hipparcos mission. The remaining binaries were disco…
Gamma-ray observatory INTEGRAL reloaded
van den Heuvel, Edward P. J.
The scientific aims of the European Space Agency's International Gamma-Ray Astrophysics Laboratory are considerably extended because of its unique capability to identify electromagnetic counterparts to sources of gravitational waves and ultra-high-energy neutrinos.