Search Publications
Changes of Magnetic Structure in Three Dimensions Associated with the X3.4 Flare of 2006 December 13
Jing, Ju; Wang, Haimin; Kubo, Masahito +2 more
Recent observations demonstrated that sunspot structure can change rapidly and irreversibly after flares. One of the most puzzling results is the increase in magnetic shear around the flaring magnetic polarity inversion line after flares. However, all these observations were made at the photosphere level. In this Letter, we study the altitude vari…
Comparing Suzaku and XMM-Newton Observations of the Soft X-Ray Background: Evidence for Solar Wind Charge Exchange Emission
Henley, David B.; Shelton, Robin L.
We present an analysis of a pair of Suzaku spectra of the soft X-ray background (SXRB), obtained from pointings on and off a nearby shadowing filament in the southern Galactic hemisphere. Because of the different Galactic column densities in the two pointing directions, the observed emission from the Galactic halo has a different shape in the two …
Multiple and Precessing Collimated Outflows in the Planetary Nebula IC 4634
Guerrero, Martín A.; Chu, You-Hua; Miranda, Luis F. +6 more
With its remarkable double-S shape, IC 4634 is an archetype of point-symmetric planetary nebulae (PNe). In this paper, we present a detailed study of this PN using archival HST WFPC2 and ground-based narrowband images to investigate its morphology, and long-slit spectroscopic observations to determine its kinematics and to derive its physical cond…
Angular Diameters of the G Subdwarf µ Cassiopeiae A and the K Dwarfs σ Draconis and HR 511 from Interferometric Measurements with the CHARA Array
Gies, Douglas R.; Henry, Todd; Jao, Wei-Chun +13 more
Using the longest baselines of the CHARA Array, we have measured the angular diameter of the G5 V subdwarf µ Cas A, the first such determination for a halo population star. We compare this result to new diameters for the higher metallicity K0 V stars, σ Dra and HR 511, and find that the metal-poor star, µ Cas A, has an effective temper…
Sequestration of Ethane in the Cryovolcanic Subsurface of Titan
Mousis, Olivier; Schmitt, Bernard
Saturn's largest satellite, Titan, has a thick atmosphere dominated by nitrogen and methane. The dense orange-brown smog hiding the satellite's surface is produced by photochemical reactions of methane, nitrogen, and their dissociation products with solar ultraviolet, which lead primarily to the formation of ethane and heavier hydrocarbons. In the…
Interferometric Detections of GOODS 850-5 at 1 mm and 1.4 GHz
Morrison, G.; Walter, F.; Dannerbauer, H.
We have obtained a position (at subarcsecond accuracy) of the submillimeter bright source GOODS 850-5 (also known as GN 10) in the GOODS-North field using the IRAM Plateau de Bure interferometer at 1.25 mm wavelengths (MM J123633+6214.1; flux density: S1.25 mm = 5.0 +/- 1.0 mJy). This source has no optical counterpart in deep ACS imagin…
The Accuracy of Morphological Decomposition of Active Galactic Nucleus Host Galaxies
Urry, C. M.; Simmons, B. D.
In order to assess the accuracy with which we can determine the morphologies of AGN host galaxies, we have simulated more than 50,000 ACS images of galaxies with z < 1.25, using image and noise properties appropriate for the GOODS survey. We test the effect of central point-source brightness on host galaxy parameter recovery with a set of simul…
Frequent Occurrence of High-Speed Local Mass Downflows on the Solar Surface
Kubo, M.; Lites, B. W.; Ichimoto, K. +7 more
We report on new spectropolarimetric measurements with simultaneous filter imaging observation, revealing the frequent appearance of polarization signals indicating high-speed, probably supersonic, downflows that are associated with at least three different configurations of magnetic fields in the solar photosphere. The observations were carried o…
Chandra Observation of PSR B1823-13 and Its Pulsar Wind Nebula
Pavlov, G. G.; Kargaltsev, O.; Brisken, W. F.
An observation of the Vela-like pulsar B1823-13 and its synchrotron nebula with the Chandra X-Ray Observatory allowed us to resolve the pulsar and the fine structure of the nebula. The pulsar's spectrum fits a power-law model with a photon index ΓPSR ≈ 2.4 for the plausible hydrogen column density nH = 1 × 1022 cm<…
Gemini Imaging of Mid-Infrared Emission from the Nuclear Region of Centaurus A
Levenson, N. A.; Perlman, Eric; De Buizer, James M. +7 more
We present high spatial resolution mid-IR images of the nuclear region of NGC 5128 (Centaurus A). Images were obtained at 8.8 µm, N band (10.4 µm), and 18.3 µm using the mid-IR imager/spectrometer T-ReCS on Gemini South. These images show a bright unresolved core surrounded by low-level extended emission. We place an upper limit …