Search Publications
Solar Energetic Particle Event Associated with the 2012 July 23 Extreme Solar Storm
Wang, Rui; Yang, Zhongwei; Liu, Ying D. +3 more
We study the solar energetic particle (SEP) event associated with the 2012 July 23 extreme solar storm, for which Solar Terrestrial Relations Observatory (STEREO) and the spacecraft at L1 provide multi-point remote sensing and in situ observations. The extreme solar storm, with a superfast shock and extremely enhanced ejecta magnetic fields observ…
Multi-wavelength Study of a Delta-spot. I. A Region of Very Strong, Horizontal Magnetic Field
Jaeggli, S. A.
Active region NOAA 11035 appeared in 2009 December, early in the new solar activity cycle. This region achieved a delta sunspot (δ spot) configuration when parasitic flux emerged near the rotationally leading magnetic polarity and traveled through the penumbra of the largest sunspot in the group. Both visible and infrared imaging spectropolarimetr…
Investigating the Origin of Hot Gas Lines in Herbig Ae/Be Stars
Johns-Krull, Christopher M.; Cauley, P. Wilson
We analyze high-resolution UV spectra of a small sample of Herbig Ae/Be stars (HAEBESs) in order to explore the origin of the T ∼ 105 K gas in these stars. The C IV λ λ1548, 1550 line luminosities are compared to nonsimultaneous accretion rate estimates for the objects showing C IV emission. We show that the correlation between L C…
The Gini Coefficient as a Morphological Measurement of Strongly Lensed Galaxies in the Image Plane
Florian, Michael K.; Gladders, Michael D.; Li, Nan
Characterization of the morphology of strongly lensed galaxies is challenging because images of such galaxies are typically highly distorted. Lens modeling and source plane reconstruction is one approach that can provide reasonably undistorted images from which morphological measurements can be made, though at the expense of a highly spatially var…
Subsurface Characterization of 67P/Churyumov-Gerasimenko’s Abydos Site
Jorda, L.; Lamy, P.; Mousis, O. +12 more
On 2014 November 12, the ESA/Rosetta descent module Philae landed on the Abydos site of comet 67P/Churyumov-Gerasimenko. Aboard this module, the Ptolemy mass spectrometer measured a CO/CO2 ratio of 0.07 ± 0.04, which differs substantially from the value obtained in the coma by the Rosetta/ROSINA instrument, suggesting a heterogeneity in…
Relationship between Distribution of Magnetic Decay Index and Filament Eruptions
Liu, Y.; Li, H.; Elmhamdi, A. +1 more
The decay index n of a horizontal magnetic field is considered to be an important parameter in judging the stability of a flux rope. However, the spatial distribution of this parameter has not been extensively explored so far. In this paper, we present a delineative study of the three-dimensional maps of n for two eruptive events, in which filamen…
The Intermediate-mass Star-forming Region Lynds 1340. An Optical View
Moór, Attila; Kun, Mária; Reipurth, Bo +1 more
We have performed an optical spectroscopic and photometric search for young stellar objects associated with the molecular cloud Lynds 1340, and examined the structure of the cloud by constructing an extinction map, based on SDSS data. The new extinction map suggests a shallow, strongly fragmented cloud, having a mass of some 3700 M ⊙. L…
X-Ray Afterglow of Swift J1644+57: A Compton Echo?
Cheng, K. S.; Kong, Albert K. H.; Chernyshov, D. O. +2 more
Swift, Chandra, and XMM have found a weak but nearly constant X-ray component from Swift J1644+57 that appeared at ∼500 days and was visible at least until ∼1400 days after the stellar capture, which cannot be explained by standard tidal disruption theories. We suggest that this X-ray afterglow component may result from the Thomson scattering betw…
Galaxy Infall by Interacting with Its Environment: A Comprehensive Study of 340 Galaxy Clusters
Gandhi, Poshak; Makishima, Kazuo; Nakazawa, Kazuhiro +7 more
To study systematically the evolution of the angular extents of the galaxy, intracluster medium (ICM), and dark matter components in galaxy clusters, we compiled the optical and X-ray properties of a sample of 340 clusters with redshifts <0.5, based on all the available data from the Sloan Digital Sky Survey and Chandra/XMM-Newton. For each clu…
On the Absence of EUV Emission from Comet C/2012 S1 (ISON)
Pesnell, W. Dean; Bryans, Paul
When the sungrazing comet C/2012 S1 (ISON) made its perihelion passage within two solar radii of the Sun’s surface, it was expected to be a bright emitter at extreme ultraviolet (EUV) wavelengths. However, despite solar EUV telescopes repointing to track the orbit of the comet, no emission was detected. This “null result” is interesting in its own…