Search Publications
A mass-velocity anisotropy relation in galactic stellar disks
Chemin, Laurent
The ellipsoid of stellar random motions is a fundamental ingredient of galaxy dynamics. Yet it has long been difficult to constrain this component in disks others than the Milky Way. This article presents the modeling of the azimuthal-to-radial axis ratio of the velocity ellipsoid of galactic disks from stellar dispersion maps using integral field…
The Physical Characteristics of Interstellar Medium in NGC 3665 with Herschel Observations
Gu, Qiu-Sheng; Shi, Yong; Zhao, Yinghe +1 more
We present the analysis of the physical properties of the interstellar medium in the nearby early-type galaxy NGC 3665, based on the far-infrared photometric and spectroscopic data as observed by the Herschel Space Observatory. The fit to the spectral energy distribution reveals a high dust content in the galaxy, with a dust-to-stellar mass ratio …
Proper Motion of the Faint Star near KIC 8462852 (Boyajian's Star)—Not a Binary System
Wright, J. T.; Montgomery, J.; Clemens, Dan P. +4 more
A faint star located 2 arcsec from KIC 8462852 was discovered in Keck 10 m adaptive optics imaging in the JHK near-infrared (NIR) in 2014 by Boyajian et al. (2016). The closeness of the star to KIC 8462852 suggested that the two could constitute a binary, which might have implications for the cause of the brightness dips seen by Kepler and in grou…
Speckle observations with PISCO in Merate (Italy): XVI. Astrometric measurements of visual binaries in 2015, and new orbits for DUN 5, ADS 5958, 6276, 7294, 8211, and 13169
Scardia, M.; Prieur, J. -L.; Pansecchi, L. +3 more
We present relative astrometric measurements of visual binaries, made in 2015, with the speckle camera PISCO of the 102-cm Zeiss telescope of Brera Astronomical Observatory, Merate, Italy. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 196 new measurements of 173 visual binary stars, wi…
Proper Motions of Sunspots’ Umbral Dots at High Temporal and Spatial Resolution
Koutchmy, Serge; Goodarzi, Hadis; Adjabshirizadeh, Ali
To deepen the analysis of the photometric properties of the umbra of a sunspot, we study proper motions of small features such as umbral dots (UDs) inside a single sunspot observed by the Solar Optical Telescope of Hinode close to the disk center. We consider horizontal flows with high precision and details to study the transient motion behavior o…
Nonlinear evolutions of large amplitude oblique whistler waves
Yoon, Peter H.; Hwang, Kyoung-Joo; Min, Kyoung-Wook +3 more
This paper investigates nonlinear evolutions of large amplitude oblique whistler waves (LOWWs) and the interaction with electrons using one-dimensional electromagnetic kinetic simulations. The present research is motivated by recent studies about the nonlinear phenomena of LOWWs. When the propagation angle is not close to the resonance cone angle,…
Finite-Larmor-radius equilibrium and currents of the Earth's flank magnetopause
Cerri, S. S.
We consider the one-dimensional equilibrium problem of a shear-flow boundary layer within an `extended-fluid model' of a plasma that includes the Hall and the electron pressure terms in Ohm's law, as well as dynamic equations for anisotropic pressure for each species and first-order finite-Larmor-radius (FLR) corrections to the ion dynamics. We pr…
Dawn-dusk asymmetry induced by the Parker spiral angle in the plasma dynamics around comet 67P/Churyumov-Gerasimenko
Behar, E.; Nilsson, H.; Tabone, B.
The solar wind and the ionized atmosphere of a comet, exchange energy and momentum on interacting. Our aim is to understand the influence of the average Parker spiral configuration of the solar wind magnetic field on this interaction. We compare the theoretical expectations of an analytical generalized gyromotion with Rosetta observations at comet…
Galactic cartography with SkyMapper - I. Population substructure and the stellar number density of the inner halo
Lewis, Geraint F.; Sharma, Sanjib; Ibata, Rodrigo A. +3 more
The stars within our Galactic halo presents a snapshot of its ongoing growth and evolution, probing galaxy formation directly. Here, we present our first analysis of the stellar halo from detailed maps of Blue Horizontal Branch (BHB) stars drawn from the SkyMapper Southern Sky Survey. To isolate candidate BHB stars from the overall population, we …
First Extended Catalogue of Galactic bubble infrared fluxes from WISE and Herschel surveys
Umana, G.; Riggi, S.; Trigilio, C. +8 more
In this paper, we present the first extended catalogue of far-infrared fluxes of Galactic bubbles. Fluxes were estimated for 1814 bubbles, defined here as the 'golden sample', and were selected from the Milky Way Project First Data Release (Simpson et al.) The golden sample was comprised of bubbles identified within the Wide-field Infrared Survey …