Search Publications
The True Durations of Starbursts: Hubble Space Telescope Observations of Three Nearby Dwarf Starburst Galaxies
McQuinn, Kristen B. W.; Cannon, John M.; Skillman, Evan D. +4 more
The duration of a starburst is a fundamental parameter affecting the evolution of galaxies yet, to date, observational constraints on the durations of starbursts are not well established. Here we study the recent star formation histories of three nearby dwarf galaxies to rigorously quantify the duration of their starburst events using a uniform an…
Keck Laser Guide Star Adaptive Optics Monitoring of the M8+L7 Binary LHS 2397aAB: First Dynamical Mass Benchmark at the L/T Transition
Dupuy, Trent J.; Ireland, Michael J.; Liu, Michael C.
We present Keck laser guide star adaptive optics imaging and aperture masking observations of the M8+L7 binary LHS 2397aAB. Together with archival Hubble Space Telescope, Gemini-North, and Very Large Telescope data, our observations span 11.8 years of the binary's 14.2 year orbital period. We determine a total dynamical mass of 0.146+0.015
On the Structure and Evolution of Complexity in Sigmoids: A Flux Emergence Model
Golub, L.; Hood, A. W.; Savcheva, A. +2 more
Sigmoids are structures with a forward or inverse S-shape, generally observed in the solar corona in soft X-ray emission. It is believed that the appearance of a sigmoid in an active region is an important factor in eruptive activity. The association of sigmoids with dynamic phenomena such as flares and coronal mass ejections (CMEs) make the study…
Three-dimensional MHD modeling of the solar wind structures associated with 13 December 2006 coronal mass ejection
Kataoka, R.; Ebisuzaki, T.; Kusano, K. +4 more
A 3-D magnetohydrodynamic (MHD) simulation is performed to reconstruct the interplanetary propagation of a coronal mass ejection (CME) that occurred on 13 December 2006. A spheromak-type magnetic field is superposed on a realistic ambient solar wind to reproduce the large-scale interplanetary magnetic field (IMF) associated with the CME. Here we s…
Theoretical analysis of secondary cratering on Mars and an image-based study on the Cerberus Plains
Neukum, Gerhard; Werner, Stephanie C.; Ivanov, Boris A.
The issue of crater retention age estimates on planetary surfaces is discussed with an attempt to quantify the effect of overlapping primary and secondary impact crater populations in restricted crater diameter ranges. The approach to this problem is illustrated with a simple model production function where the secondary crater input is artificial…
The Color-Magnitude Relation for Metal-Poor Globular Clusters in M87: Confirmation from Deep HST/ACS Imaging
Meurer, Gerhardt R.; Jordán, Andrés; Mieske, Steffen +6 more
Metal-poor globular clusters (GCs) are our local link to the earliest epochs of star formation and galaxy building. Studies of extragalactic GC systems using deep, high-quality imaging have revealed a small but significant slope to the color-magnitude relation for metal-poor GCs in a number of galaxies. We present a study of the M87 GC system usin…
Observation of waves near lower hybrid frequency in the reconnection region with thin current sheet
Lucek, E.; Vaivads, A.; Rème, H. +8 more
The role of waves and turbulence in the process of magnetic reconnection has been the subject of a great deal of studies and debates in the theoretical literature. Here we report the Cluster observations of electrostatic and electromagnetic waves near the lower hybrid frequency in the reconnection region with a thin current sheet. During the cross…
Titan solar occultation observed by Cassini/VIMS: Gas absorption and constraints on aerosol composition
Baines, K. H.; Nicholson, P. D.; Drossart, P. +5 more
A solar occultation by Titan's atmosphere has been observed through the solar port of the Cassini/VIMS instrument on January 15th, 2006. Transmission spectra acquired during solar egress probe the atmosphere in the altitude range 70 to 900 km at the latitude of 71° S. Several molecular absorption bands of CH 4 and CO are visible in thes…
Cosmic star-formation history from a non-parametric inversion of infrared galaxy counts
Elbaz, D.; Pichon, C.; Le Borgne, D. +1 more
Aims: This paper aims at providing new conservative constraints on the cosmic star-formation (SF) history from the empirical modeling of recent observations in the mid and far infrared.
Methods: We present a new empirical method based on a non-parametric inversion technique. It primarily uses multi-wavelength galaxy counts in the infrared and …
Mid-infrared spectroscopy of infrared-luminous galaxies at z ~ 0.5-3
Pérez-Fournon, I.; Pozzi, F.; Valtchanov, I. +19 more
We present results on low-resolution mid-infrared (MIR) spectra of 70 IR-luminous galaxies obtained with the infrared spectrograph (IRS) onboard Spitzer. We selected sources from the European Large Area Infrared Survey with S15 > 0.8 mJy and photometric or spectroscopic z > 1. About half of the samples are quasi-stellar objects (Q…