Search Publications
Non-neutralized Electric Current Patterns in Solar Active Regions: Origin of the Shear-generating Lorentz Force
Mikić, Zoran; Georgoulis, Manolis K.; Titov, Viacheslav S.
Using solar vector magnetograms of the highest available spatial resolution and signal-to-noise ratio, we perform a detailed study of electric current patterns in two solar active regions (ARs): a flaring/eruptive and a flare-quiet one. We aim to determine whether ARs inject non-neutralized (net) electric currents in the solar atmosphere, respondi…
Distance and Kinematics of the Red Hypergiant VY CMa: Very Long Baseline Array and Very Large Array Astrometry
Menten, K. M.; Zhang, B.; Reid, M. J. +1 more
We report astrometric results of phase-referencing very long baseline interferometry observations of 43 GHz SiO maser emission toward the red hypergiant VY Canis Majoris (VY CMa) using the Very Long Baseline Array (VLBA). We measured a trigonometric parallax of 0.83 ± 0.08 mas, corresponding to a distance of 1.20+0.13 -0.10 k…
Optical constants of Titan tholins at mid-infrared wavelengths (2.5-25 µm) and the possible chemical nature of Titan’s haze particles
Khare, Bishun N.; McKay, Christopher P.; Cruikshank, Dale P. +1 more
Complex organic materials may exist as haze layers in the atmosphere of Titan and as dark coloring agents on icy satellite surfaces. Laboratory measurements of optical constants of plausible complex organic materials are necessary for quantitative evaluation from remote sensing observations, and to document the existence of complex organic materia…
Photoevaporating Proplyd-like Objects in Cygnus OB2
Drake, Jeremy J.; Gutermuth, Robert A.; Wright, Nicholas J. +4 more
We report the discovery of 10 proplyd-like objects in the vicinity of the massive OB association Cygnus OB2. They were discovered in IPHAS Hα images and are clearly resolved in broadband Hubble Space Telescope/Advanced Camera for Surveys, near-IR, and Spitzer mid-IR images. All exhibit the familiar tadpole shape seen in photoevaporating objects su…
The calculation of Afρ and mass loss rate for comets
Rubin, Martin; Fink, Uwe
Ab initio calculations of Afρ are presented using Mie scattering theory and a Direct Simulation Monte Carlo (DSMC) dust outflow model in support of the Rosetta mission and its target 67P/Churyumov-Gerasimenko (CG). These calculations are performed for particle sizes ranging from 0.010 µm to 1.0 cm. The present status of our knowledge of vari…
Coplanar circumbinary debris discs
Wyatt, M. C.; Matthews, B. C.; Kennedy, G. M. +3 more
We present resolved Herschel images of circumbinary debris discs in the α CrB (HD 139006) and β Tri (HD13161) systems. By modelling their structure, we find that both discs are consistent with being aligned with the binary orbital planes. Though secular perturbations from the binary can bring the disc into alignment, in both cases the alignment ti…
The Earliest Phases of Star formation (EPoS) observed with Herschel: the dust temperature and density distributions of B68
Henning, Th.; Krause, O.; Balog, Z. +13 more
Context. Isolated starless cores within molecular clouds can be used as a testbed to investigate the conditions prior to the onset of fragmentation and gravitational proto-stellar collapse.
Aims: We aim to determine the distribution of the dust temperature and the density of the starless core B68.
Methods: In the framework of the Hersche…
A Detection of Weak-lensing Magnification Using Galaxy Sizes and Magnitudes
Koekemoer, Anton M.; Leauthaud, Alexie; Massey, Richard +5 more
Weak lensing is commonly measured using shear through galaxy ellipticities or using the effect of magnification bias on galaxy number densities. Here, we report on the first detection of weak-lensing magnification with a new, independent technique using the distribution of galaxy sizes and magnitudes. These data come for free in galaxy surveys des…
Dust coagulation processes as constrained by far-infrared observations
Abergel, A.; Bernard, J. -P.; Ristorcelli, I. +4 more
Aims: We develop a simple model of coagulated dust particles of two sizes (3.5 and 60 nm radius) to understand the nature and the effects of coagulation, which could explain the evolution of the far-infrared (FIR) dust opacity observed in the transition between the diffuse and the dense interstellar medium (ISM) (nH > 103
PHAT Stellar Cluster Survey. I. Year 1 Catalog and Integrated Photometry
Monachesi, Antonela; Gouliermis, Dimitrios A.; Dolphin, Andrew E. +21 more
The Panchromatic Hubble Andromeda Treasury (PHAT) survey is an ongoing Hubble Space Telescope (HST) multi-cycle program to obtain high spatial resolution imaging of one-third of the M31 disk at ultraviolet through near-infrared wavelengths. In this paper, we present the first installment of the PHAT stellar cluster catalog. When completed, the PHA…