Search Publications
Helioseismic Holography of Simulated Solar Convection and Prospects for the Detection of Small-Scale Subsurface Flows
Birch, A. C.; Braun, D. C.; Nordlund, Å. +2 more
We perform helioseismic holography on realistic solar convection simulations and compare the observed travel-time perturbations with the expected travel times from the horizontal flows in the simulations computed from forward models under the assumption of the Born approximation. We demonstrate reasonable agreement between the observed and model t…
Chandra Observations of Candidate ``True'' Seyfert 2 Nuclei
Shields, Joseph C.; Pogge, Richard W.; Mathur, Smita +2 more
The unification model for AGNs posits that Seyfert 2 galaxies are intrinsically like Seyfert 1 galaxies, but that their broad-line regions (BLRs) are hidden from our view. A Seyfert 2 nucleus that truly lacked a BLR, instead of simply having it hidden, would be a so-called true Seyfert 2. No object has as yet been conclusively proven to be one. We…
Far-Infrared Characterization of an Ultraluminous Starburst Associated with a Massively Accreting Black Hole at z=1.15
Elbaz, D.; Le Floc'h, E.; Maiolino, R. +24 more
As part of the All-Wavelength Extended Groth Strip International Survey (AEGIS), we describe the panchromatic characterization of an X-ray-luminous active galactic nucleus (AGN) in a merging galaxy at z=1.15. This object is detected at infrared (8, 24, 70, and 160 µm), submillimeter (850 µm), and radio wavelengths, from which we derive…
Sizes of Confirmed Globular Clusters in NGC 5128: A Wide-Field High-Resolution Study
Woodley, Kristin A.; Gómez, Matías
Using Magellan/IMACS images covering a 1.2 × 1.2 deg2 field of view with seeing of 0.4"-0.6", we have applied convolution techniques to analyze the light distribution of 364 confirmed globular clusters in the field of NGC 5128 and to obtain their structural parameters. Combining these parameters with existing Washington photometry from …
Ion Temperatures in the Quiet Solar Corona
Landi, E.
We measure the upper and lower limits of the temperatures Ti for a number of ions observed in the quiescent solar corona from 1996 to 2000, in order to compare with the measured electron temperature Te and test the assumption Ti=Te commonly adopted to measure the plasma nonthermal velocity vnth
Time-Distance Helioseismology: Sensitivity of f-mode Travel Times to Flows
Birch, A. C.; Duvall, T. L., Jr.; Gizon, L. +1 more
Time-distance helioseismology has shown that f-mode travel times contain information about horizontal flows in the Sun. The purpose of this study is to provide a simple interpretation of these travel times. We study the interaction of surface gravity waves with horizontal flows in an incompressible, plane-parallel solar atmosphere. We show that fo…
Bulges and Disklike Components in the Host Galaxies of Low-Redshift 3CR Sources: A Near-Infrared View of Their Radial Brightness Profiles
Marchesini, Danilo; Chiaberge, Marco; Capetti, Alessandro +3 more
We analyze the near-infrared luminosity profiles and photometric parameters of the host galaxies of 3CR radio sources with z<0.3, to investigate their physical nature. Our sample includes 82 galaxies, of which 22 (27%) are FR Is and 60 (73%) are FR IIs. Using near-infrared data taken both with NICMOS on board the Hubble Space Telescope and from…
Magnetic Interaction: An Erupting Filament and a Remote Coronal Hole
Yang, Liheng; Shen, Yuandeng; Jiang, Yunchun +1 more
For the first time, we present a rare observation of direct magnetic interaction between an erupting filament and a coronal hole (CH). The small active region filament obliquely erupted toward the CH getting in the way, met and interacted with it, and then was deflected back. The erupting filament thus underwent a distinct to-and-fro motion in the…
A Quadrupolar Preplanetary Nebula: IRAS 19475+3119
Sahai, Raghvendra; Sánchez Contreras, Carmen; Morris, Mark +1 more
Our imaging of the preplanetary nebula IRAS 19475+3119 (hereafter I19475) at 0.43 and 0.6 µm with HST reveals a quadrupolar nebula of size about 10.5''×4.7'', with two bipolar elongated lobes emanating from the center of the nebula. One of the bipolar lobes shows detailed point-symmetric structure with respect to the ce…
Coronal and Chromospheric Dimmings during a Halo-Type CME Event
Yang, Liheng; Jiang, Yunchun; Li, Kejun +1 more
We present complementary solar observations of a filament eruption occurring in association with a halo-type coronal mass ejection (CME) on 2006 July 6 in AR 10898. This eruption was followed by an M2.5 flare and has led to the formation of a pair of dimmings, observed in Hα, over network patterns in regions of opposite magnetic polarities located…