Search Publications
Speckle Interferometry and Orbits of "Fast" Visual Binaries
Tokovinin, Andrei
Results of speckle observations at the 4.1 m SOAR telescope in 2012 (158 measures of 121 systems, 27 non-resolutions) are reported. The aim is to follow fast orbital motion of recently discovered or neglected close binaries and sub-systems. Here, eight previously known orbits are defined better, two more are completely revised, and five orbits are…
Ion distributions in the vicinity of Mars: Signatures of heating and acceleration processes
Fedorov, A.; Barabash, S.; Lundin, R. +5 more
More than three years of data from the ASPERA-3 instrument on-board Mars Express has been used to compile average distribution functions of ions in and around the Mars induced magnetosphere. We present samples of average distribution functions, as well as average flux patterns based on the average distribution functions, all suitable for detailed …
Nonlinear spatiotemporal evolution of whistler mode chorus waves in Earth's inner magnetosphere
Omura, Yoshiharu; Summers, Danny; Lee, Dong-Hun +1 more
We analyze the nonlinear evolution of whistler mode chorus waves propagating along a magnetic field line from their equatorial source. We solve wave evolution equations off the equator for the wave magnetic field amplitude and wave frequency, subject to boundary conditions at the equator comprising model “chorus equations” that describe the genera…
C and N abundances of main sequence and subgiant branch stars in NGC 1851
Rejkuba, M.; Milone, A. P.; Marino, A. F. +6 more
We present the first chemical analysis of stars on the double subgiant branch (SGB) of the globular cluster NGC 1851. We obtained 48 Magellan IMACS spectra of subgiants and fainter stars covering the spectral region between 3650-6750 Å to derive C and N abundances from the spectral features at 4300 Å (G-band) and at ~3883 Å (CN). We added to our s…
Germanium, Arsenic, and Selenium Abundances in Metal-poor Stars
Roederer, Ian U.
The elements germanium (Ge, Z = 32), arsenic (As, Z = 33), and selenium (Se, Z = 34) span the transition from charged-particle or explosive synthesis of the iron-group elements to neutron-capture synthesis of heavier elements. Among these three elements, only the chemical evolution of germanium has been studied previously. Here we use archive obse…
From X-Ray Dips to Eclipse: Witnessing Disk Reformation in the Recurrent Nova U Sco
Talavera, A.; Ness, J. -U.; Hernanz, M. +9 more
The tenth recorded outburst of the recurrent eclipsing nova U Sco was observed simultaneously in X-ray, UV, and optical by XMM-Newton on days 22.9 and 34.9 after the outburst. Two full passages of the companion in front of the nova ejecta were observed, as was the reformation of the accretion disk. On day 22.9, we observed smooth eclipses in UV an…
Trajectories and Distribution of Interstellar Dust Grains in the Heliosphere
Slavin, Jonathan D.; Reach, William T.; Müller, Hans-Reinhard +4 more
The solar wind carves a bubble in the surrounding interstellar medium (ISM) known as the heliosphere. Charged interstellar dust grains (ISDG) encountering the heliosphere may be diverted around the heliopause or penetrate it depending on their charge-to-mass ratio. We present new calculations of trajectories of ISDG in the heliosphere, and the dus…
Constraints on mantle plumes on Venus: Implications for volatile history
Sotin, Christophe; Smrekar, Suzanne E.
The analysis of Venus' gravity field and topography suggests the presence of a small number of deep mantle plumes (∼9). This study predicts the number of plumes formed at the core-mantle boundary, their characteristics, and the production of partial melt from adiabatic decompression. Numerical simulations are performed using a 3D spherical code th…
Determination of binary asteroid orbits with a genetic-based algorithm
Berthier, J.; Marchis, F.; Vachier, F.
Aims: Over the past decade, discoveries of multiple and binary asteroid systems have played a significant role in our general understanding of small solar system bodies. Direct observations of satellites of asteroids are rare and difficult since they require the use of already over-subscribed facilities such as adaptive optics (AO) on large 8…
The dark GRB 080207 in an extremely red host and the implications for gamma-ray bursts in highly obscured environments
Cenko, S. B.; Bloom, J. S.; Watson, D. +9 more
We present comprehensive X-ray, optical, near- and mid-infrared and submm observations of GRB 080207 and its host galaxy. The afterglow was undetected in the optical and near-infrared (nIR) implying an X-ray-to-optical spectral slope less than 0.3, identifying GRB 080207 as a dark burst. Swift X-ray observations show extreme absorption in the host…