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Cone model for halo CMEs: Application to space weather forecasting
Xie, Hong; Ofman, Leon; Lawrence, Gareth
In this study, we present an innovative analytical method to determine the angular width and propagation orientation of halo Coronal Mass Ejections (CMEs). The relation of CME actual speed with apparent speed and its components measured at different position angle has been investigated. The present work is based on the cone model proposed by [2002…
Constraining Solar Abundances Using Helioseismology
Basu, Sarbani; Antia, H. M.
Recent analyses of solar photospheric abundances suggest that the oxygen abundance in the solar atmosphere needs to be revised downward. In this study, we investigate the consequence of this revision on helioseismic analyses of the depth of the solar convection zone and the helium abundance in the solar envelope and find no significant effect. We …
Star formation history and dust content of galaxies drawn from ultraviolet surveys
Kong, X.; Brinchmann, J.; Charlot, S. +1 more
We compile a new sample of 115 nearby, non-Seyfert galaxies spanning a wide range of star formation activities, from starburst to nearly dormant, based on ultraviolet observations with various satellites. We combine these observations with infrared observations to study the relation between ratio of total far-infrared to ultraviolet luminosity and…
High-Redshift Supernova Rates
Ferguson, Henry C.; Giavalisco, Mauro; Fruchter, Andrew S. +10 more
We use a sample of 42 supernovae detected with the Advanced Camera for Surveys on board the Hubble Space Telescope as part of the Great Observatories Origins Deep Survey to measure the rate of core-collapse supernovae to z~0.7 and Type Ia supernovae to z~1.6. This significantly increases the redshift range at which supernova rates have been estima…
ISO Spectroscopy of Gas and Dust: From Molecular Clouds to Protoplanetary Disks
van Dishoeck, Ewine F.
Observations of interstellar gas-phase and solid-state species in the 2.4 200 m range obtained with the spectrometers on board the Infrared Space Observatory (ISO) are reviewed. Lines and bands caused by ices, polycyclic aromatic hydrocarbons, silicates, and gas-phase atoms and molecules (in particular H2, CO, H2O, OH, and CO…
Intensity variation of large solar energetic particle events associated with coronal mass ejections
Krucker, S.; Howard, R. A.; Gopalswamy, N. +2 more
We studied the coronal mass ejections (CMEs) and flares associated with large solar energetic particle (SEP) events of solar cycle 23 (1996-2002) in order to determine what property of the solar eruptions might order the SEP intensity. The SEP events were divided into three groups: (1) events in which the primary CME was preceded by one or more wi…
Observations and Modeling of a Filament on the Sun
van Ballegooijen, A. A.
Hα observations of a filament were obtained at the Swedish Vacuum Solar Telescope in 1998 June. The U-shaped filament has a prominent barb that exhibits interesting fine structure and internal motions. A three-dimensional magnetic model of the filament is presented. The model is based on a National Solar Observatory (Kitt Peak) magnetogram and is …
Color-selected Galaxies at z ~ 6 in the Great Observatories Origins Deep Survey
Stern, D.; Dickinson, M.; Ferguson, H. C. +15 more
We report early results on galaxies at z~6 selected from Hubble Space Telescope imaging for the Great Observatories Origins Deep Survey. Spectroscopy of one object with the Advanced Camera for Surveys grism and from the Keck and Very Large Telescope observatories shows a strong continuum break and asymmetric line emission, identified as Lyα at z=5…
The Profiles of the 3-12 Micron Polycyclic Aromatic Hydrocarbon Features
Hony, S.; Tielens, A. G. G. M.; Allamandola, L. J. +4 more
We present spectra of the 3.3 µm and 11.2 µm polycyclic aromatic hydrocarbon (PAH) features of a large number of stellar sources, planetary nebulae, reflection nebulae, H II regions, and galaxies, obtained with Infrared Space Observatory Short Wavelength Spectrometer. Clear variations are present in the profiles of these features. Most…
Polycyclic Aromatic Hydrocarbon Contribution to the Infrared Output Energy of the Universe at z ~= 2
Le Floc'h, E.; Dole, H.; Lagache, G. +10 more
We present an updated phenomenological galaxy evolution model to fit the Spitzer 24, 70, and 160 µm number counts, as well as all the previous mid- and far-infrared observations. Only a minor change of the comoving luminosity density distribution in the previous model (Lagache, Dole, & Puget), combined with a slight modification of the s…