Search Publications
Integrated light chemical tagging analyses of seven M31 outer halo globular clusters from the Pan-Andromeda Archaeological Survey
Dotter, Aaron; Venn, Kim A.; Sakari, Charli M. +4 more
Detailed chemical abundances are presented for seven M31 outer halo globular clusters (with projected distances from M31 greater than 30 kpc), as derived from high-resolution integrated light spectra taken with the Hobby-Eberly Telescope. Five of these clusters were recently discovered in the Pan-Andromeda Archaeological Survey (PAndAS) - this pap…
Ionization of the venusian atmosphere from solar and galactic cosmic rays
Coates, A. J.; Jones, G. H.; Desorgher, L. +2 more
The atmospheres of the terrestrial planets are exposed to solar and galactic cosmic rays, the most energetic of which are capable of affecting deep atmospheric layers through extensive nuclear and electromagnetic particle cascades. In the venusian atmosphere, cosmic rays are expected to be the dominant ionization source below ∼100 km altitude. Whi…
Electrostatic solitary waves observed at Saturn by Cassini inside 10 Rs and near Enceladus
Gurnett, D. A.; Pickett, J. S.; Jones, G. H. +5 more
We have analyzed the Cassini Radio and Plasma Wave Science Wideband Receiver (WBR) data specifically looking for the presence of bipolar electrostatic solitary waves (ESWs). Typical examples of these ESWs are provided to show that when they are present, several of them may be detected over a few to several millisecond time span. We carried out an …
New constraints on the star formation history of the star cluster NGC 1856
Goudfrooij, Paul; Puzia, Thomas H.; Correnti, Matteo +1 more
We use the Wide Field Camera 3 onboard the Hubble Space Telescope to obtain deep, high-resolution photometry of the young (age ∼ 300 Myr) star cluster NGC 1856 in the Large Magellanic Cloud. We compare the observed colour-magnitude diagram (CMD), after having applied a correction for differential reddening, with Monte Carlo simulations of simple s…
Simultaneous spectral and reverberation modelling of relativistic reflection in Mrk 335
Chainakun, P.; Young, A. J.
We present an X-ray spectral and timing model to investigate the broad and variable iron line seen in the high flux state of Mrk 335. The model consists of a variable X-ray source positioned along the rotation axis of the black hole that illuminates the accretion disc producing a back-scattered, ionized reflection spectrum. We compute time lags in…
Ensemble forecasting of major solar flares: First results
Pulkkinen, A.; Guerra, J. A.; Uritsky, V. M.
We present the results from the first ensemble prediction model for major solar flares (M and X classes). The primary aim of this investigation is to explore the construction of an ensemble for an initial prototyping of this new concept. Using the probabilistic forecasts from three models hosted at the Community Coordinated Modeling Center (NASA-G…
Variations between Dust and Gas in the Diffuse Interstellar Medium
Heiles, Carl; Reach, William T.; Bernard, Jean-Philippe
Using the Planck far-infrared and Arecibo GALFA 21 cm line surveys, we identified a set of isolated interstellar clouds (approximately degree-sized on the sky and comprising 100 solar masses) and assessed the ratio of gas mass to dust mass. Significant variations of the gas/dust ratio are found both from cloud to cloud and within regions of indivi…
Electron impact ionization in the Martian atmosphere: Interplay between scattering and crustal magnetic field effects
Lillis, Robert J.; Fang, Xiaohua
Precipitating electrons are typically the dominant source of energy input into Mars' nighttime upper atmosphere, with consequences for atmospheric and ionospheric structure, composition, chemistry, and electrodynamics. Mars' spatially heterogeneous crustal magnetic fields affect the fluxes of precipitating electrons, via both the magnetic mirror f…
The Team Keck Redshift Survey 2: MOSFIRE Spectroscopy of the GOODS-North Field
Barro, Guillermo; Trump, Jonathan R.; Faber, S. M. +9 more
We present the Team Keck Redshift Survey 2 (TKRS2), a near-infrared spectral observing program targeting selected galaxies within the CANDELS subsection of the GOODS-North Field. The TKRS2 program exploits the unique capabilities of the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE), which entered service on the Keck I telescope in …
Seasonal evolution of Saturn's polar temperatures and composition
Fletcher, Leigh N.; Irwin, P. G. J.; Orton, G. S. +7 more
The seasonal evolution of Saturn's polar atmospheric temperatures and hydrocarbon composition is derived from a decade of Cassini Composite Infrared Spectrometer (CIRS) 7-16 µm thermal infrared spectroscopy. We construct a near-continuous record of atmospheric variability poleward of 60° from northern winter/southern summer (2004, Ls