Search Publications
Spatiotemporal Organization of Energy Release Events in the Quiet Solar Corona
Davila, Joseph M.; Uritsky, Vadim M.
Using data from the STEREO and SOHO spacecraft, we show that temporal organization of energy release events in the quiet solar corona is close to random, in contrast to the clustered behavior of flaring times in solar active regions. The locations of the quiet-Sun events follow the meso- and supergranulation pattern of the underling photosphere. T…
How dusty is α Centauri?. Excess or non-excess over the infrared photospheres of main-sequence stars
Olofsson, G.; Krivov, A. V.; Eiroa, C. +19 more
Context. Debris discs around main-sequence stars indicate the presence of larger rocky bodies. The components of the nearby, solar-type binary α Centauri have metallicities that are higher than solar, which is thought to promote giant planet formation.
Aims: We aim to determine the level of emission from debris around the stars in the α Cen s…
An empirical model for the plasma environment along Titan's orbit based on Cassini plasma observations
Rymer, Abigail M.; Smith, H. Todd
Prior to Cassini's arrival at Saturn, the nitrogen-rich dense atmosphere of Titan was considered as a significant, if not dominant, source of heavy ions in Saturn's magnetosphere. While nitrogen was detected in Saturn's magnetosphere based on Cassini observations, Enceladus instead of Titan appears to be the primary source. However, it is difficul…
Comparison of Prestellar Core Elongations and Large-scale Molecular Cloud Structures in the Lupus I Region
Ward-Thompson, Derek; Fissel, Laura M.; Savini, Giorgio +28 more
Turbulence and magnetic fields are expected to be important for regulating molecular cloud formation and evolution. However, their effects on sub-parsec to 100 parsec scales, leading to the formation of starless cores, are not well understood. We investigate the prestellar core structure morphologies obtained from analysis of the Herschel-SPIRE 35…
Observational tests of backreaction with recent data
Maino, Davide; Chiesa, Matteo; Majerotto, Elisabetta
We explore the backreaction model based on the template metric proposed in Larena et al. [1] constraining the matter density parameter ΩmD0 and the Dark Energy parameter w with recent data. We provide constraints based on Supernovae Ia from the SNLS and the Union2.1 catalogs, confirming that the backreacted Univers…
The Closest M-dwarf Quadruple System to the Sun
White, R. J.; Quinn, S. N.; Riedel, A. R. +8 more
We report new infrared radial velocity measurements obtained with CSHELL at NASA's Infrared Telescope Facility that reveal the M3.5 dwarf GJ 867B to be a single-lined spectroscopic binary with a period of 1.795 ± 0.017 days. Its velocity semi-amplitude of 21.4 ± 0.5 km s-1 corresponds to a minimum mass of 61 ± 7 M JUP; the ne…
Numerical simulation of the effects of meteoroid ablation and solar EUV/X-ray radiation in the dayside ionosphere of Mars: MGS/MEX observations
Haider, S. A.; Pandya, B. M.
We have developed a model which produces three plasma layers simultaneously due to the impact of the meteoroids, solar X-ray (0.5-9 nm), and EUV (9-102.6 nm) radiation at altitude range 75-85 km, 100-115 km, and 135-140 km, respectively, in the dayside ionosphere of Mars. The calculated results are compared with the radio occultation measurements …
Detection of distinct power spectra in soft and hard X-ray bands in the hard state of GRS 1915+105
Stiele, H.; Yu, W.
The well-known black hole X-ray binary GRS 1915+105 is a unique source in the sense that it cannot be classified within the standard picture of black hole binary states. In this work, we study archival XMM-Newton observations taken between 2003 and 2004 of the χ variability class of GRS 1915+105, which corresponds to the hard state in the standard…
A survey of low-velocity collisional features in Saturn's F ring
Murray, Carl D.; Cooper, Nicholas J.; Williams, Gareth A. +1 more
Small (∼50 km scale), irregular features seen in Cassini images to be emanating from Saturn's F ring have been termed mini-jets by Attree et al. (2012). One particular mini-jet was tracked over half an orbital period, revealing its evolution with time and suggesting a collision with a local moonlet as its origin. In addition to these data we prese…
Evolutionary tracks of massive stars during formation
Smith, Michael D.
A model for massive stars is constructed by piecing together evolutionary algorithms for the protostellar structure, the environment, the inflow and the radiation feedback. We investigate specified accretion histories of constant, decelerating and accelerating forms and consider both hot and cold accretion, identified with spherical free-fall and …