Search Publications
Luminous and Dark Matter Profiles from Galaxies to Clusters: Bridging the Gap with Group-scale Lenses
Treu, Tommaso; Ellis, Richard S.; Newman, Andrew B.
Observations of strong gravitational lensing, stellar kinematics, and larger-scale tracers enable accurate measures of the distribution of dark matter (DM) and baryons in massive early-type galaxies (ETGs). While such techniques have been applied to galaxy-scale and cluster-scale lenses, the paucity of intermediate-mass systems with high-quality d…
Revisiting Ulysses Observations of Interstellar Helium
Wood, Brian E.; Müller, Hans-Reinhard; Witte, Manfred
We report the results of a comprehensive reanalysis of Ulysses observations of interstellar He atoms flowing through the solar system, the goal being to reassess the interstellar He flow vector and to search for evidence of variability in this vector. We find no evidence that the He beam seen by Ulysses changes at all from 1994-2007. The direction…
The Multiplicity of Massive Stars: a High Angular Resolution Survey With the Guidance Sensor
Maíz Apellániz, J.; Norris, R. P.; Gies, D. R. +11 more
We present the results of an all-sky survey made with the Fine Guidance Sensor on the Hubble Space Telescope to search for angularly resolved binary systems among massive stars. The sample of 224 stars is comprised mainly of Galactic O- and B-type stars and luminous blue variables, plus a few luminous stars in the Large Magellanic Cloud. The FGS T…
Hubble Frontier Fields: the geometry and dynamics of the massive galaxy cluster merger MACSJ0416.1-2403
Richard, Johan; Massey, Richard; Kneib, Jean-Paul +13 more
We use a joint optical/X-ray analysis to constrain the geometry and history of the ongoing merging event in the massive galaxy cluster MACSJ0416.1-2403 (z = 0.397). Our investigation of cluster substructure rests primarily on a combined strong- and weak-lensing mass reconstruction based on the deep, high-resolution images obtained for the Hubble F…
The bubble-like interior of the core-collapse supernova remnant Cassiopeia A
Milisavljevic, Dan; Fesen, Robert A.
The death of massive stars is believed to involve aspheric explosions initiated by the collapse of an iron core. The specifics of these catastrophic explosions remain uncertain, due partly to limited observational constraints on asymmetries deep inside the star. Here we present near-infrared observations of the young supernova remnant Cassiopeia A…
Seasonal variations in Titan's middle atmosphere during the northern spring derived from Cassini/CIRS observations
Bézard, Bruno; Vinatier, Sandrine; Achterberg, Richard K. +8 more
We analyzed spectra acquired at the limb of Titan in the 2006-2013 period by the Cassini/Composite Infrared Spectrometer (CIRS) in order to monitor the seasonal evolution of the thermal, gas composition and aerosol spatial distributions. We are primarily interested here in the seasonal changes after the northern spring equinox and interpret our re…
KMOS view of the Galactic centre. I. Young stars are centrally concentrated
Kuntschner, H.; Hilker, M.; Walcher, C. J. +7 more
Context. The Galactic centre hosts a crowded, dense nuclear star cluster with a half-light radius of 4 pc. Most of the stars in the Galactic centre are cool late-type stars, but there are also ≳100 hot early-type stars in the central parsec of the Milky Way. These stars are only 3-8 Myr old.
Aims: Our knowledge of the number and distribution …
Heating Signatures in the Disk Counterparts of Solar Spicules in Interface Region Imaging Spectrograph Observations
De Pontieu, B.; Rouppe van der Voort, L.; Carlsson, M. +2 more
We use coordinated observations with the Interface Region Imaging Spectrograph (IRIS) and the Swedish 1 m Solar Telescope to identify the disk counterpart of type II spicules in upper-chromospheric and transition region (TR) diagnostics. These disk counterparts were earlier identified through short-lived asymmetries in chromospheric spectral lines…
Interplanetary Propagation Behavior of the Fast Coronal Mass Ejection on 23 July 2012
Temmer, M.; Nitta, N. V.
The fast coronal mass ejection (CME) on 23 July 2012 caused attention because of its extremely short transit time from the Sun to 1 AU, which was shorter than 21 h. In situ data from STEREO-A revealed the arrival of a fast forward shock with a speed of more than 2200 km s−1 followed by a magnetic structure moving with almost 1900 km s
The Influence of Spatial resolution on Nonlinear Force-free Modeling
Sun, X.; Schrijver, C. J.; Canou, A. +11 more
The nonlinear force-free field (NLFFF) model is often used to describe the solar coronal magnetic field, however a series of earlier studies revealed difficulties in the numerical solution of the model in application to photospheric boundary data. We investigate the sensitivity of the modeling to the spatial resolution of the boundary data, by app…