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Cellinoid shape model for Hipparcos data

Ip, Wing-Huen; Cellino, Alberto; Hestroffer, Daniel +1 more

Being intermediate between a regular triaxial ellipsoid shape and a more complex convex shape, the so-called "cellinoid" shape model consists of eight octants of eight ellipsoids with the constraint that neighbouring octants share two common axes. The resulting variety of possible shapes, obtained at the cost of only three extra parameters to be a…

Where and when does reconnection occur in the tail?

McPherron, Robert L.

We comment on the question of when and where reconnection begins in the tail and how it is related to the onset of auroral expansion. This question was addressed in a workshop dedicated to Unsolved Problems in Magnetospheric Physics held in Scarborough, UK, in September 2015. The answer is that it typically occurs first in the midtail a little bey…

Herschel observations of the nebula M1-67 around the Wolf-Rayet star WR 124

Barlow, M. J.; Groenewegen, M. A. T.; Waelkens, C. +3 more

Infrared Herschel imaging and spectroscopic observations of the nebula M1-67 around the Wolf-Rayet star WR 124 have been obtained along with optical imaging observations. The infrared images reveal a clumpy dusty nebula that extends up to 1 pc. The comparison with the optical images shows that the ionized gas nebula coincides with the dust nebula,…

Of Genes and Machines: Application of a Combination of Machine Learning Tools to Astronomy Data Sets

Kumar, S.; Chambers, K. C.; Flewelling, H. +8 more

We apply a combination of genetic algorithm (GA) and support vector machine (SVM) machine learning algorithms to solve two important problems faced by the astronomical community: star-galaxy separation and photometric redshift estimation of galaxies in survey catalogs. We use the GA to select the relevant features in the first step, followed by op…

The circumstellar disc of FS Tau B - a self-consistent model based on observations in the mid-infrared with NACO

Kirchschlager, Florian; Wolf, Sebastian; Madlener, David

Protoplanetary discs are a byproduct of the star formation process. In the dense mid-plane of these discs, planetesimals and planets are expected to form. The first step in planet formation is the growth of dust particles from submicrometre-sized grains to macroscopic mm-sized aggregates. The grain growth is accompanied by radial drift and vertica…

A photochemical model of the dust-loaded ionosphere of Mars

Montmessin, F.; O'Brien, K.; Michael, M. +5 more

The ionization of the lower Martian atmosphere and the presence of charged species are fundamental in the understanding of atmospheric electricity phenomena, such as electric discharges, large-scale electric currents, and Schumann resonances. The present photochemical model of the lower ionosphere of Mars (0-70 km) is developed to compute the conc…

Panchromatic Imaging of a Transitional Disk: The Disk of GM Aur in Optical and FUV Scattered Light

Apai, D.; Hamaguchi, K.; Henning, Th. +18 more

We have imaged GM Aurigae with the Hubble Space Telescope, detected its disk in scattered light at 1400 and 1650 Å, and compared these with observations at 3300 Å, 5550 Å, 1.1 µm, and 1.6 µm. The scattered light increases at shorter wavelengths. The radial surface brightness profile at 3300 Å shows no evidence of the 24 au radius cavit…

Kinetic models of magnetic flux ropes observed in the Earth magnetosphere

Petrukovich, A. A.; Zelenyi, L. M.; Artemyev, A. V. +3 more

Magnetic flux ropes (MFR) are universal magnetoplasma structures (similar to cylindrical screw pinches) formed in reconnecting current sheets. In particular, MFR with scales from about the ion inertial length to MHD range are widely observed in the Earth magnetosphere. Typical MFR have force-free configuration with the axial magnetic field peaking…

MATISSE: A novel tool to access, visualize and analyse data from planetary exploration missions

Antonelli, L. A.; Giommi, P.; Capria, M. T. +2 more

The increasing number and complexity of planetary exploration space missions require new tools to access, visualize and analyse data to improve their scientific return.

ASI Science Data Center (ASDC) addresses this request with the web-tool MATISSE (Multi-purpose Advanced Tool for the Instruments of the Solar System Exploration), allowing the…

The Time Evolution of HH 1 from Four Epochs of HST Images

Bally, J.; Raga, A. C.; Esquivel, A. +1 more

We present an analysis of four epochs of Hα and [S II] λλ 6716/6731 Hubble Space Telescope (HST) images of HH 1. For determining proper motions, we explore a new method based on the analysis of spatially degraded images obtained convolving the images with wavelet functions of chosen widths. With this procedure, we are able to generate maps of prop…