Search Publications
Rheologies and ages of lava flows on Elysium Mons, Mars
Reiss, Dennis; Hiesinger, Harald; Pasckert, Jan Hendrik
We present results of our study of the rheologies and ages of lava flows in the Elysium Mons region of Mars. Previous studies have shown that the geometric dimensions of lava flows reflect rheological properties such as yield strength, effusion rate and viscosity. In this study the rheological properties of lava flows in the Elysium Mons region we…
Revisiting the Chlorine Abundance in Diffuse Interstellar Clouds from Measurements with the Copernicus Satellite
Federman, S. R.; Sheffer, Y.; Moomey, Daniel
We reanalyzed interstellar Cl I and Cl II spectra acquired with the Copernicus satellite. The directions for this study come from those of Crenny & Federman and sample the transition from atomic to molecular-rich clouds where the unique chemistry leading to molecules containing chlorine is initiated. Our profile syntheses relied on up-to-date …
A Lighthouse Effect in Eta Carinae
Madura, Thomas I.; Groh, Jose H.
We present a new model for the behavior of scattered time-dependent, asymmetric near-UV emission from the nearby ejecta of η Car. Using a three-dimensional (3D) hydrodynamical simulation of η Car's binary colliding winds, we show that the 3D binary orientation derived by Madura et al. in 2012 is capable of explaining the asymmetric near-UV variabi…
AGN Activity and the Misaligned Hot ISM in the Compact Radio Elliptical NGC 4278
Trinchieri, Ginevra; Zezas, Andreas; Gallagher, John S. +5 more
The analysis of a deep (579 ks) Chandra ACIS pointing of the elliptical galaxy NGC 4278, which hosts a low-luminosity active galactic nucleus (AGN) and compact radio emission, allowed us to detect extended emission from hot gas out to a radius of ~5 kpc, with 0.5-8 keV luminosity of 2.4 × 1039 erg s-1. The emission is elongat…
Production of neutral species in Titan's ionosphere through dissociative recombination of ions
Carrasco, Nathalie; Plessis, Sylvain; Dobrijevic, Michel +1 more
The production rates of neutral species by dissociative recombination (DR) of molecular ions with electrons in the ionosphere of Titan are quantified by a new model, including, for the first time, all the available kinetic data on this process. The calculation is based on the ion densities measured by the INMS instrument on Cassini orbiter during …
Measuring Sizes of Ultra-faint Dwarf Galaxies
Geha, Marla; Padmanabhan, Nikhil; Muñoz, Ricardo R.
The discovery of ultra-faint dwarf (UFD) galaxies in the halo of the Milky Way extends the faint end of the galaxy luminosity function to a few hundred solar luminosities. This extremely low luminosity regime poses a significant challenge for the photometric characterization of these systems. We present a suite of simulations aimed at understandin…
Lagrangian coherent structures in photospheric flows and their implications for coronal magnetic structure
Yeates, A. R.; Welsch, B. T.; Hornig, G.
Aims: We show how the build-up of magnetic gradients in the Sun's corona may be inferred directly from photospheric velocity data. This enables computation of magnetic connectivity measures such as the squashing factor without recourse to magnetic field extrapolation.
Methods: Assuming an ideal evolution in the corona, and an initially u…
Galactic annihilation emission from nucleosynthesis positrons
Strong, A. W.; Diehl, R.; Jean, P. +2 more
Context. The Galaxy hosts a widespread population of low-energy positrons revealed by successive generations of gamma-ray telescopes through a bright annihilation emission from the bulge region, with a fainter contribution from the inner disk. The exact origin of these particles remains currently unknown.
Aims: We estimate the contribution to…
Solar migrating atmospheric tides in the winds of the polar region of Venus
Hueso, R.; Sánchez-Lavega, A.; Drossart, P. +5 more
We study the effects of migrating solar tides on the winds at the cloud tops of the polar region of Venus. The winds were measured using cloud tracking on images obtained at wavelengths of 3.9 and 5.0 µm by the instrument VIRTIS-M onboard Venus Express. These wavelengths probe about the same altitude close to the cloud tops, allowing for the…
Detection of multiple modes in a new double-mode RR Lyrae star
Chadid, M.
Context. We present the first long-time coverage of high precision and uninterrupted light curve of a new double-mode RR Lyrae star allowing the determination of accurate Fourier components and the estimatation of fundamental parameters.
Aims: We used high-precision space data of a new star CoRoT ID 0101368812, obtained by the satellite CoRoT…