Search Publications
LBT Discovery of a Yellow Supergiant Eclipsing Binary in the Dwarf Galaxy Holmberg IX
Burwitz, V.; Garnavich, P. M.; Kochanek, C. S. +14 more
In a variability survey of M81 using the Large Binocular Telescope we have discovered a peculiar eclipsing binary (MV ~ - 7.1) in the field of the dwarf galaxy Holmberg IX. It has a period of 271 days, and the light curve is well fit by an overcontact model in which both stars are overflowing their Roche lobes. It is composed of two yel…
Comparisons between Isothermal and NFW Mass Profiles for Strong-Lensing Galaxy Clusters
Huang, J. -S.; Mellier, Yannick; Bartelmann, Matthias +3 more
While both isothermal and NFW-based mass models for galaxy clusters are widely adopted in strong-lensing studies, they cannot easily be distinguished based solely on observed positions of arcs and arclets. We compare the magnifications predicted for giant arcs obtained from isothermal and NFW profiles, taking axially symmetric and asymmetric mass …
Probing the Central Regions of Nearby Compact Elliptical Galaxies
Davidge, T. J.; Beck, Tracy L.; McGregor, Peter J.
K-band spectroscopic observations recorded with NIFS+ALTAIR on Gemini North are used to probe the central arcsecond of the compact elliptical galaxies NGC 4486B, NGC 5846A, and M32. The angular resolution of these data is ~0.1'' FWHM; this corresponds to a spatial scale of 12 pc in NGC 5846A, which is the most distant galaxy in the samp…
A Cryogenic Liquid-Mirror Telescope on the Moon to Study the Early Universe
Eisenstein, Daniel J.; Sivanandam, Suresh; Foing, Bernard +9 more
We have studied the feasibility and scientific potential of zenith observing liquid-mirror telescopes having 20-100 m diameters located on the Moon. They would carry out deep infrared surveys to study the distant universe and follow up discoveries made with the 6 m James Webb Space Telescope (JWST), with more detailed images and spectroscopic stud…
A Celestial Gamma-Ray Foreground Due to the Albedo of Small Solar System Bodies and a Remote Probe of the Interstellar Cosmic-Ray Spectrum
Porter, Troy A.; Digel, Seth W.; Moskalenko, Igor V. +2 more
We calculate the γ-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids (MBAs), Jovian and Neptunian Trojan asteroids, and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the γ-ray albedo for the Main Belt, Trojans, and Kuiper Belt strongly depends on the small-body size distrib…
Complex Organic Materials in the HR 4796A Disk?
Li, Aigen; Mann, I.; Köhler, M.
The red spectral shape of the visible to near-infrared reflectance spectrum of the sharply edged ringlike disk around the young main-sequence star HR 4796A was recently interpreted as the presence of tholin-like complex organic materials which are seen in the atmosphere and surface of Titan and the surfaces of icy bodies in the solar system. Howev…
Validation of Two MHD Models of the Solar Corona with Rotational Tomography
Sokolov, Igor V.; Hayashi, Keiji; Frazin, Richard A. +4 more
We demonstrate a validation of two 3D MHD models of the corona by comparing density values from solar rotational tomography (SRT) to densities and morphological properties of the two MHD solutions for CR 2029 (2005 April 21-May 18). The two MHD models are given by the Stanford and Michigan models, and both use the same synoptic magnetogram from MD…
Black Hole Accretion in Low-Mass Galaxies since z ~ 1
Rieke, George; Shi, Yong; Willmer, Christopher +3 more
We have selected a sample of X-ray-emitting active galactic nuclei (AGNs) in low-mass host galaxies (~5 × 109-2 × 1010 M⊙) out to z ~ 1. By comparing to AGNs in more massive hosts, we have found that the AGN spatial number density and the fraction of galaxies hosting AGNs depends strongly on the host mass, with the…
The Origin of Polar Streamers in the Solar Corona
Llebaria, A.; Zhukov, A. N.; Lamy, P. +2 more
We investigate the large-scale three-dimensional (3D) structure of the solar corona near the maximum of the 23rd solar cycle in an attempt to determine the origin of polar streamers. We use a model that allows us to simulate the quasi-stationary configuration of the large-scale coronal density distribution. The coronal neutral line, as given by th…
The Signature of Evolving Turbulence in Quiet Solar Wind as Seen by Ulysses
Chapman, S. C.; Nicol, R. M.; Dendy, R. O.
Solar wind fluctuations, such as magnetic field or velocity, show power-law power spectra suggestive both of an inertial range of intermittent turbulence (with ~-5/3 exponent), and at lower frequencies, of fluctuations of coronal origin (with ~-1 exponent). The Ulysses spacecraft spent many months in the quiet fast solar wind above the Sun's polar…