Search Publications
EUV Wave Reflection from a Coronal Hole
Temmer, M.; Howard, R. A.; Gopalswamy, N. +7 more
We report on the detection of EUV wave reflection from a coronal hole, as observed by the Solar Terrestrial Relations Observatory mission. The EUV wave was associated with a coronal mass ejection (CME) erupting near the disk center. It was possible to measure the kinematics of the reflected waves for the first time. The reflected waves were genera…
Every BCG with a Strong Radio Agn has an X-Ray Cool Core: Is the Cool Core-Noncool Core Dichotomy Too Simple?
Sun, M.
The radio active galactic nucleus (AGN) feedback in X-ray cool cores has been proposed as a crucial ingredient in the evolution of baryonic structures. However, it has long been known that strong radio AGNs also exist in "noncool core" clusters, which brings up the question whether an X-ray cool core is always required for the radio feedback. In t…
The 2008 Luminous Optical Transient in the Nearby Galaxy NGC 300
Walter, Frederick M.; Bond, Howard E.; Humphreys, Roberta M. +4 more
A luminous optical transient (OT) that appeared in NGC 300 in early 2008 had a maximum brightness, MV sime -12 to -13, intermediate between classical novae and supernovae. We present ground-based photometric and spectroscopic monitoring and adaptive-optics imaging of the OT, as well as pre- and postoutburst space-based imaging with the …
Physical Conditions in the Interstellar Medium of Intensely Star-Forming Galaxies at Redshift~2
Bournaud, F.; Chemin, L.; Lehnert, M. D. +5 more
We analyze the physical conditions in the interstellar gas of 11 actively star-forming galaxies at z~2, based on integral-field spectroscopy from the ESO-VLT and Hubble Space Telescope/Near Infrared Camera and Multi-Object Spectrometer imaging. We concentrate on the high Hα surface brightnesses, large line widths, line ratios, and the clumpy natur…
Emergence of Small-scale Magnetic Loops Through the Quiet Solar Atmosphere
Bellot Rubio, L. R.; Martínez González, M. J.
We investigate the emergence of magnetic flux in the quiet Sun at very small spatial scales, focusing on the magnetic connection between the photosphere and chromosphere. The observational data consist of spectropolarimetric measurements and filtergrams taken with the Hinode satellite and the Dutch Open Telescope. We find that a significant fracti…
The Environments of Starburst and Post-Starburst Galaxies at z = 0.4-0.8
Aragón-Salamanca, Alfonso; Milvang-Jensen, Bo; Zaritsky, Dennis +16 more
Post-starburst (E+A or k+a) spectra, characterized by their exceptionally strong Balmer lines in absorption and the lack of emission lines, belong to galaxies in which the star formation (SF) activity ended abruptly sometime during the past Gyr. We perform a spectral analysis of galaxies in clusters, groups, poor groups, and the field at z = 0.4-0…
Morphological Composition of z ~ 0.4 Groups: The Site of S0 Formation
Wilman, D. J.; Mulchaey, J. S.; Balogh, M. L. +3 more
The low-redshift universe (z <~ 0.5) is not a dull place. Processes leading to the suppression of star formation and morphological transformation are prevalent: this is particularly evident in the dramatic upturn in the fraction of S0-type galaxies in clusters. However, until now, the process and environment of formation remained unidentified. …
The Infrared Spectra of Very Large Irregular Polycyclic Aromatic Hydrocarbons (PAHs): Observational Probes of Astronomical PAH Geometry, Size, and Charge
Peeters, Els; Bauschlicher, Charles W., Jr.; Allamandola, Louis J.
The mid-infrared (IR) spectra of six large, irregular polycyclic aromatic hydrocarbons (PAHs) with formulae (C84H24-C120H36) have been computed using density functional theory (DFT). Trends in the dominant band positions and intensities are compared to those of large, compact PAHs as a function of geomet…
A Power-Law Distribution of Solar Magnetic Fields Over More Than Five Decades in Flux
Lamb, D. A.; DeForest, C. E.; Hagenaar, H. J. +3 more
Solar flares, coronal mass ejections, and indeed phenomena on all scales observed on the Sun, are inextricably linked with the Sun's magnetic field. The solar surface is covered with magnetic features observed on many spatial scales, which evolve on differing timescales: the largest features, sunspots, follow an 11-year cycle; the smallest seem to…
Variable Partial Covering and A Relativistic Iron Line in NGC 1365
Zezas, A.; Bianchi, S.; Elvis, M. +9 more
We present a complete analysis of the hard X-ray (2-10 keV) properties of the Seyfert galaxy NGC 1365, based on a 60 ks XMM-Newton observation performed in 2004 January. The two main results are as follows. (1) We detect an obscuring cloud with NH ~ 3.5 × 1023 cm-2 crossing the line of sight in ~25 ks. This implies…