Search Publications
Large-scale horizontal flows in the solar photosphere. III. Effects on filament destabilization
Bommier, V.; Schmieder, B.; Rondi, S. +7 more
Aims:We study the influence of large-scale photospheric motions on the destabilization of an eruptive filament, observed on October 6, 7, and 8, 2004, as part of an international observing campaign (JOP 178).
Methods: Large-scale horizontal flows were investigated from a series of MDI full-disc Dopplergrams and magnetograms. From the Dopplergr…
Suzaku X-Ray Spectroscopy of a Peculiar Hot Star in the Galactic Center Region
Nagata, Tetsuya; Tsujimoto, Masahiro; Koyama, Katsuji +5 more
We present the results of a Suzaku study of a bright point-like source in the 6.7keV intensity map of the Galactic center region. We detected an intense FeXXV 6.7keV line with an equivalent width of ∼1keV as well as emission lines of highly ionized Ar and Ca from a spectrum obtained by the X-ray Imaging Spectrometer. The overall spectrum is descri…
Keck spectroscopy of globular clusters in the spiral galaxy NGC 2683
Forbes, Duncan A.; Brodie, Jean P.; Strader, Jay +1 more
We analyse Keck spectra of 24 candidate globular clusters (GCs) associated with the spiral galaxy NGC 2683. We identify 19 bona fide GCs based on their recession velocities, of which 15 were suitable for stellar population analysis. Age and metallicity determinations reveal old ages in 14 out of 15 GCs. These old GCs exhibit age and metallicity di…
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…
Penumbral models in the light of Hinode spectropolarimetric observations
Bellot Rubio, L. R.; Jurčák, J.
Aims:The realism of current models of the penumbra is assessed by comparing their predictions with the plasma properties of penumbral filaments as retrieved from spectropolarimetric observations.
Methods: The spectropolarimeter onboard Hinode allows us, for the first time, to distinguish the fine structure of the penumbra. Therefore, we can us…
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…
Relationship between Powerful Flares and Dynamic Evolution of the Magnetic Field at the Solar Surface
Zhang, Hongqi; Liu, Jihong; Zhang, Yin
Powerful flares are closely related to the evolution of the complex magnetic field configuration at the solar surface. The strength of the magnetic field and speed of its evolution are two vital parameters in the study of the change of magnetic field in the solar atmosphere. We propose a dynamic and quantitative depiction of the changes in complex…
The changing accretion states of the intermediate polar MU Camelopardalis
Krumpe, M.; Schwope, A. D.; Schwarz, R. +3 more
Aims: We study the timing and spectral properties of the intermediate polar MU Camelopardalis (1RXS J062518.2+733433) to determine the accretion modes and the accretion geometry from multi-wavelength, multi-epoch observational data.
Methods: Light curves in different observed energy ranges (optical, UV, X-ray) are extracted. The timescales of …
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…