Search Publications
Age and Structure Parameters of the Remote M31 Globular Cluster B514 Based on HST, 2MASS, GALEX, and BATC Observations
Fan, Zhou; Zhou, Xu; Ma, Jun +6 more
B514 is a remote M31 globular cluster (GC) which is located at a projected distance of Rp ~= 55 kpc. Deep observations with the Advanced Camera for Surveys on the Hubble Space Telescope are used to provide accurate integrated light and star counts of B514. By coupling the analysis of the distribution of the integrated light with star co…
Direct imaging of a massive dust cloud around R Coronae Borealis
Waters, L. B. F. M.; Jeffers, S. V.; Min, M. +5 more
We present recent polarimetric images of the highly variable star R CrB using ExPo and archival WFPC2 images from the HST. We observed R CrB during its current dramatic minimum where it decreased more than 9 mag due to the formation of an obscuring dust cloud. Since the dust cloud is only in the line-of-sight, it mimics a coronograph allowing the …
Adaptive Optics Observations of 3 µm Water Ice in Silhouette Disks in the Orion Nebula Cluster and M43
Tokunaga, Alan T.; Terada, Hiroshi; Pyo, Tae-Soo +9 more
We present the near-infrared images and spectra of four silhouette disks in the Orion Nebula Cluster (M42) and M43 using the Subaru Adaptive Optics system. While d053-717 and d141-1952 show no water ice feature at 3.1 µm, a moderately deep (τice ~ 0.7) water ice absorption is detected toward d132-1832 and d216-0939. Taking into ac…
Isolated starless cores in infrared dark clouds in the Hi-GAL survey
Peretto, N.; Elia, D.; Griffin, M. J. +15 more
In a previous paper, we identified cores within infrared dark clouds. We regarded those without embedded sources as the least evolved and labelled them starless. Here we identify the most isolated starless cores and model them using a three-dimensional multiwavelength Monte Carlo radiative transfer code. We derive the cores' physical parameters an…
Solar-cycle Variation of Sound Speed near the Solar Surface
Rabello-Soares, M. C.
We present evidence that the sound-speed variation with solar activity has a two-layer configuration, similar to the one observed below an active region, which consists of a negative layer near the solar surface and a positive one in the layer immediately below the first one. Frequency differences between the activity minimum and maximum of solar …
Processing of Polycyclic Aromatic Hydrocarbons in Molecular-Loop Regions near the Galactic Center Revealed by AKARI
Oyabu, Shinki; Onaka, Takashi; Yamagishi, Mitsuyoshi +7 more
We present an AKARI mid-infrared diffuse map of an area of about 4° × 3° near the Galactic center in the 9 µm band. The band intensity is mostly attributed to aromatic hydrocarbon infrared emissions of carbonaceous grains at wavelengths of 6.2, 7,7, 8.6, and 11.3 µm. We detected 9 µm emission structures extending from the Galacti…
Flux transfer events: Motion and signatures
Omidi, N.; Sibeck, D. G.
We present results from a 2.5 dimensional hybrid code simulation for the evolution of flux transfer events (FTEs) during intervals of due southward interplanetary magnetic field (IMF) orientation. The structures invariably form between pairs of reconnection lines, often remaining nearly stationary on the subsolar magnetopause before their motion b…
Axial symmetry breaking of Saturn's thermosphere
Achilleos, N.; Smith, C. G. A.
The source of the various planetary-period signals in Saturn's magnetosphere is at present unknown. We investigate the possibility that the source of these signals is an axially asymmetric wind system in the thermosphere. We describe a feedback mechanism that has the potential to drive such axially asymmetric wind systems. The proposed mechanism r…
Hunting for Young Dispersing Star Clusters in IC 2574
Pellerin, Anne; Harris, Jason; Meyer, Martin M. +1 more
Dissolving stellar groups are very difficult to detect using traditional surface photometry techniques. We have developed a method to find and characterize non-compact stellar systems in galaxies where the young stellar population can be spatially resolved. By carrying out photometry on individual stars, we are able to separate the luminous blue s…
Velocity Characteristics of Rotating Sunspots
Alexander, D.; Zhu, C.; Tian, L.
A statistical study is carried out to investigate the detailed relationship between rotating sunspots and the emergence of magnetic flux tubes. This paper presents the velocity characteristics of 132 sunspots in 95 solar active regions. The rotational characteristics of the sunspots are calculated from successive SOHO/MDI magnetograms by applying …