Search Publications

What Is the Neon Abundance of the Sun?

Basu, Sarbani; Bahcall, John N.; Serenelli, Aldo M.

We have evolved a series of 13 complete solar models that utilize different assumed heavy-element compositions. Models that are based upon the heavy-element abundances recently determined by Asplund and coworkers are inconsistent with helioseismological measurements. However, models in which the neon abundance is increased by 0.4-0.5 dex to logN(N…

Quasi-parallel Shock Structure and Processes

Balogh, A.; Thomsen, M. F.; Lembège, B. +11 more

Observational Evidence of the Kink Instability in Solar Filament Eruptions and Sigmoids

Rust, D. M.; LaBonte, B. J.

Two lines of observational evidence are used to infer that the MHD helical kink instability is associated with solar eruptions. The senses of twist and writhe are determined in images of seven erupting filaments obtained at 10830, 1600, 195, and 171 Å. In every case the sense of twist is the same as the sense of writhe, as required for a kink. Fro…

Probing the Environment in Gamma-Ray Bursts: The Case of an X-Ray Precursor, Afterglow Late Onset, and Wind Versus Constant Density Profile in GRB 011121 and GRB 011211

Piro, L.; Frontera, F.; Costa, E. +9 more

In this paper we present BeppoSAX and XMM-Newton observations of two long gamma-ray bursts (GRBs), the X-ray-rich event of 2001 December 11 (GRB 011211) and the hard and very bright event of 2001 November 21 (GRB 011121). In both events we find evidence of a late X-ray burst taking place several minutes after the prompt emission. In the November b…

Gamma-ray continuum emission from the inner Galactic region as observed with INTEGRAL/SPI

Strong, A. W.; Bouchet, L.; Terrier, R. +5 more

The diffuse continuum emission from the Galactic plane in the energy range 18-1000 keV has been studied using 16 Ms of data from the SPI instrument on INTEGRAL. With such an exposure we can exploit the imaging properties of SPI to achieve a good separation of point sources from the various diffuse components. Using a candidate-source catalogue der…

Flow discharge and sediment transport models for estimating a minimum timescale of hydrological activity and channel and delta formation on Mars

Kleinhans, M. G.

This paper summarizes state-of-the-art models for water flow and sediment transport and suggests implications for the sediment grain size distribution, transport process, and delta formation. The flow velocity in Martian outflow channels is commonly calculated from the Manning equation, which is dimensionally incorrect and masks the large uncertai…

The Evolution of Early-Type Red Galaxies with the GEMS Survey: Luminosity-Size and Stellar Mass-Size Relations Since z=1

Bell, Eric F.; Somerville, Rachel S.; Wisotzki, Lutz +14 more

We combine imaging from the Hubble Space Telescope Advanced Camera for Surveys, as part of the GEMS (Galaxy Evolution from Morphologies and SEDs) survey, with redshifts and rest-frame quantities from COMBO-17 to study the evolution of morphologically early-type galaxies with red colors since z=1. From 0.5d×0.5d imaging, we draw a large sample of 7…

Hubble Space Telescope Advanced Camera for Surveys Coronagraphic Imaging of the AU Microscopii Debris Disk

Ford, H. C.; Demarco, R.; Infante, L. +38 more

We present Hubble Space Telescope Advanced Camera for Surveys multicolor coronagraphic images of the recently discovered edge-on debris disk around the nearby (~10 pc) M dwarf AU Microscopii. The disk is seen between r=0.75" and 15" (7.5-150 AU) from the star. It has a thin midplane with a projected FWHM thickness of 2.5-3.5 AU within r<50 AU o…

Evolution and rotation of large-scale photospheric magnetic fields of the Sun during cycles 21-23. Periodicities, north-south asymmetries and r-mode signatures

Stenflo, J. O.; Berdyugina, S. V.; Knaack, R.

We present the results of an extensive time series analysis of longitudinally-averaged synoptic maps, recorded at the National Solar Observatory (NSO/Kitt Peak) from 1975 to 2003, and provide evidence for a multitude of quasi-periodic oscillations in the photospheric magnetic field of the Sun. In the low frequency range, we have located the source…

A study of the Type II-P supernova 2003gd in M74

Smartt, S. J.; Peletier, R. F.; Kotak, R. +18 more

We present photometric and spectroscopic data of the Type II-P supernova (SN II-P) 2003gd, which was discovered in M74 close to the end of its plateau phase. SN 2003gd is the first Type II supernova (SN) to have a directly confirmed red supergiant (RSG) progenitor. We compare SN 2003gd to SN 1999em, a similar SN II-P, and estimate an explosion dat…