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Modeling irregular small bodies gravity field via extreme learning machines and Bayesian optimization
Reddy, Vishnu; Le Corre, Lucille; Furfaro, Roberto +4 more
Close proximity operations around small bodies are extremely challenging due to their uncertain dynamical environment. Autonomous guidance and navigation around small bodies require fast and accurate modeling of the gravitational field for potential on-board computation. In this paper, we investigate a model-based, data-driven approach to compute …
Study of the thermal and nonthermal emission components in M 31: the Sardinia Radio Telescope view at 6.6 GHz
de Bernardis, P.; Masi, S.; Paladini, R. +21 more
Context. The Andromeda galaxy is the best-known large galaxy besides our own Milky Way. Several images and studies exist at all wavelengths from radio to hard X-ray. Nevertheless, only a few observations are available in the microwave range where its average radio emission reaches the minimum.
Aims: In this paper, we want to study the radio m…
Flow directions of low-energy ions in and around the diamagnetic cavity of comet 67P
Nilsson, Hans; Stenberg Wieser, Gabriella; Wieser, Martin +5 more
The flow direction of low-energy ions around comet 67P/Churyumov-Gerasimenko has previously been difficult to constrain due to the influence of the spacecraft potential. The Ion Composition Analyzer of the Rosetta Plasma Consortium (RPC-ICA) on Rosetta measured the distribution function of positive ions with energies down to just a few eV/q throug…
Forward Modeling Helioseismic Signatures of One- and Two-cell Meridional Circulation
Kosovichev, Alexander G.; Pipin, Valery V.; Stejko, Andrey M.
Using a 3D global solver of the linearized Euler equations, we model acoustic oscillations over background velocity flow fields of single-cell meridional circulation with deep and shallow return flows as well as double-cell meridional circulation with strong and weak reversals. The velocities are generated using a mean-field hydrodynamic and dynam…
UV and X-ray observations of the neutron star LMXB EXO 0748-676 in its quiescent state
Degenaar, N.; Wijnands, R.; Costantini, E. +5 more
The accretion behaviour in low-mass X-ray binaries (LMXBs) at low luminosities, especially at <1034 erg s-1, is not well known. This is an important regime to study to obtain a complete understanding of the accretion process in LMXBs, and to determine if systems that host neutron stars with accretion-heated crusts can be u…
Jet‑triggered star formation in young radio galaxies
Baum, Stefi; Morganti, Raffaella; Tremblay, Grant +7 more
Emission in the ultraviolet continuum is a salient signature of the hot, massive and consequently short-lived, stellar population that traces recent or ongoing star formation. With the aim of mapping star forming regions and morphologically separating the generic star formation from that associated with the galaxy-scale jet activity, we obtained h…
K-band GRAVITY/VLTI interferometry of "extreme" Herbig Be stars. The size-luminosity relation revisited
Montesinos, B.; Mendigutía, I.; Vioque, M. +7 more
Context. It has been hypothesized that the location of Herbig Ae/Be stars (HAeBes) within the empirical relation between the inner disk radius (rin), inferred from K-band interferometry, and the stellar luminosity (L*), is related to the presence of the innermost gas, the disk-to-star accretion mechanism, the dust disk proper…
Multi-Instrument Investigation of the Impact of the Space Weather Events of 6-10 September 2017
Simi, K. G.; Amaechi, Paul O.; Akala, Andrew O. +3 more
We analyzed the space weather events of 6-10 September 2017 using the multi-instrument approach. We focused on the four X-class flares which emanated from the Active Region AR 12673 and the Ground Induced Currents hazard associated with the geomagnetic storm of 7-8 September 2017. The flare effect on the equatorial electrojet (EEJ) recorded on boa…
HERMES spectroscopy of normal A and Am stars
Joshi, Santosh; De Cat, Peter; Lampens, Patricia +2 more
The nominal Kepler mission provided very high precision photometric data. Using these data, interesting phenomena such as spots, and 'hump and spike' features were observed in the light curves of some normal A and metallic lined A stars (Am stars). However, the connection between such phenomena and the chemical peculiarity of the Am stars is still…
Observation and calibration strategies for large-scale multi-beam velocity-resolved mapping of the [CII] emission in the Orion molecular cloud
Teyssier, D.; Goicoechea, J. R.; Stutzki, J. +15 more
Context. The [CII] 158 µm far-infrared fine-structure line is one of the dominant cooling lines of the star-forming interstellar medium. Hence [CII] emission originates in and thus can be used to trace a range of ISM processes. Velocity-resolved large-scale mapping of [CII] in star-forming regions provides a unique perspective of the kinemat…