Search Publications
Dynamics of solar active region loops
Ichimoto, K.; Hara, H.; Matthews, S. A. +1 more
It has been frequently observed that in solar active regions the measured line widths are larger than those based on thermal equilibrium widths. This excess width (characterised as non-thermal velocity, Vnt) has been proposed as a signature of the heating mechanism. The behaviour of the Vnt at coronal temperatures has not pro…
The Integrated Spectra of M32 and of 47 Tucanae: A Comparative Study in the Mid-Ultraviolet With IUE
Rose, James A.; Deng, Shibing
Low-resolution mid-UV spectra of M32 and 47 Tuc have been extracted from the IUE archival database, along with spectra of 41 F and G dwarfs with well-determined atmospheric parameters and integrated spectra of 24 Galactic globular clusters. We have used five mid-UV spectral indices defined by Fanelli et al. to constrain the stellar content of M32 …
The Mid-IR view of interacting galaxies
Cesarsky, C.; Sauvage, M.; Vigroux, L. +5 more
In this paper, we present ISOCAM mid-IR broad band images and spectraof three well known interacting galaxies. These are the prototypicalultraluminous IR galaxy Arp 220, and NGC 6240, which are classifiedas major mergers resulting from a collision of two disk galaxies ofapproximately equal mass, and the prime example of collisional ringgalaxies, t…
The Resolved Outer Population of NGC 6822 with WFPC2
Bianchi, L.; Hutchings, J. B.; Cavanagh, B.
We present F336W (U), F439W (B), F555W (V), and F675W (R) Wide Field Planetary Camera 2 (WFPC2) photometry of two outer regions of the Local Group dwarf irregular galaxy NGC 6822. The northeast region is ~13' from the galaxy center, whereas the west region lies 10' out and within the wispy low surface brightness outer regions of the galaxy. The fi…
Proton and hydrogen temperatures at the base of the solar polar corona
Heinzel, P.; Wilhelm, K.; Tu, C. -Y. +2 more
The SUMER (Solar Ultraviolet Measurements of Emitted Radiation) Spectrometer on SOHO (Solar and Heliospheric Observatory) has been used to observe the lines of the Lyman series (up to quantum numbers larger than 20) of hydrogen emitted in the solar atmosphere. The line shapes and intensities versus height are obtained near the limb from about -10\…
Energetic particle abundances at CIR shocks
Fränz, M.; Keppler, E.; Mason, G. M. +3 more
The forward and reverse shocks that bound corotating interaction regions (CIRs) travel into different solar wind regimes. In order to test whether the energetic ions associated with the CIR shocks reflect the ambient solar wind, we investigate the elemental composition of 0.1-4.0 MeV/N ions in CIRs observed from 1 to 5 AU with instrumentation on b…
Pronounced enhancements of pickup hydrogen and helium in high-latitude compressional regions
Schwadron, N. A.; Zurbuchen, T. H.; Gloeckler, G. +1 more
Pickup hydrogen and helium distributions are measured in compressive corotating regions at high heliographic latitudes. The enhancements can be explained using a pickup ion transport model which includes compression but requires a long scattering mean free path. The long mean free path is generally observed for pickup ions at high latitudes, but i…
Modelling ISO galaxy counts with luminosity and merger rate evolution
Eales, Stephen A.; Roche, Nathan
We model galaxy evolution in the 6.75- and 15-µm passbands of the ISO satellite, by combining models of galaxy evolution at optical wavelengths (which are consistent with the optical galaxy counts) with observed spectral energy distributions in the infrared. Our model is consistent with the local 12-µm galaxy luminosity function (from …
ISOCAM 15 Micron Search for Distant Infrared Galaxies Lensed by Clusters
Helou, George; Antonucci, Robert; Barvainis, Richard
In a search for lensed infrared galaxies, ISOCAM images have been obtained toward the rich clusters Abell 2218 and Abell 2219 at 15 mum. Nine galaxies (four in Abell 2218 and five in Abell 2219) were detected with flux levels in the range 530-1100 muJy. Three of the galaxies detected in Abell 2218 have previously known redshifts; of these one is a…
The Rise and Fall of µ Velorum: A Remarkable Flare on a Yellow Giant Star Observed with the Extreme Ultraviolet Explorer
Ayres, Thomas R.; Brown, Alexander; Osten, Rachel A.
The close visual double µ Velorum (HD 93497; G6 III+dF) consists of a yellow giant and a fainter companion currently 2" apart. Recently µ Vel was the source of a large flare recorded by the Extreme Ultraviolet Explorer. The long 1.5 day decay phase was like the extremes seen on hyperactive RS CVn-type binaries. The primary, µ Vel…