Search Publications
The Local Lyα Forest. I. Observations with the GHRS/G160M on the Hubble Space Telescope
Shull, J. Michael; Stocke, John T.; Penton, Steven V.
We present the target selection, observations, and data reduction and analysis process for a program aimed at discovering numerous, weak (equivalent width <=100 mÅ) Lyα absorption lines in the local universe (0.003<=z<=0.069). The purpose of this program is to study the physical conditions of the local intergalactic medium, including abso…
A Spectroscopic Redshift for the Cl 0024+16 Multiple Arc System: Implications for the Central Mass Distribution
Ellis, Richard; Broadhurst, Tom; Frye, Brenda +1 more
We present a spectroscopic redshift of z=1.675 for the well-known multiply lensed system of arcs seen in the z=0.39 cluster Cl 0024+16. In contrast to earlier work, we find that the lensed images are accurately reproduced by a projected mass distribution which traces the locations of the brightest cluster elliptical galaxies, suggesting that the m…
Mid-infrared imaging and spectrophotometry of N 66 in the SMC with ISOCAM
Boulanger, F.; Sauvage, M.; Contursi, A. +8 more
We present observations with the mid-infrared camera ISOCAM on board the Infrared Space Observatory of the major star-forming region N 66 in the Small Magellanic Cloud (SMC) and of its surroundings. These observations were performed with broad filters and Circular Variable Filters giving a spectral resolution of about 40. In addition, CO(2-1) data…
Spatially Resolved Spectroscopy of Io's Pele Plume and SO 2 Atmosphere
McGrath, Melissa A.; Spencer, John R.; Belton, Michael J. S. +1 more
We report on the first successful, spatially resolved spectroscopic observations of Io's SO 2 atmosphere. Observations made with the Hubble Space Telescope Faint Object Spectrograph on 1 August 1996 using the 0.26 '' aperture have provided detections of SO 2 gas in absorption in three locations on the Io disk: the …
The 2.4- 45 µm spectrum of Mars observed with the infrared space observatory
Lellouch, E.; Encrenaz, T.; de Graauw, T. +6 more
The spectrum of Mars at 2.4- 45 µm has been observed on July 31, 1997 ( Ls=157°) by the short-wavelength spectrometer of the Infrared Space Observatory. The data consist of a high signal to noise, complete grating spectrum (resolving power R∼1500-2500) and portions of the 20- 40 µm spectrum observed in Fabry-Perot mode ( R∼3…
ISO deep far-infrared survey in the ``Lockman Hole". II. Power spectrum analysis: evidence of a strong evolution in number counts
Sanders, D. B.; Kawara, K.; Taniguchi, Y. +8 more
We investigate the characteristics of FIR brightness fluctuations at 90 mu m and 170 mu m in the Lockman Hole, which were surveyed with ISOPHOT aboard the Infrared Space Observatory (ISO). We first calculated the angular correlation function of each field and then its Fourier transform (the angular Power Spectral Density: PSD) over the spatial fre…
Oscillations in the Magnetic Field of the Solar Corona in Response to Flares near the Photosphere
Schrijver, Carolus J.; Brown, Daniel S.
The magnetic field in the outer solar atmosphere is frequently distorted by flares. In some cases, a fraction of the field exhibits a rapidly damped oscillation (Schrijver et al.; Aschwanden et al.). If this is a resonating wave trapped in the field, then the rapid damping requires a viscosity or resistivity that is at least 108 times l…
Chandra X-Ray Observatory Detection of Extended X-Ray Emission from the Planetary Nebula BD +30°3639
Soker, Noam; Kastner, Joel H.; Vrtilek, Saeqa D. +1 more
We report the detection of well-resolved, extended X-ray emission from the young planetary nebula BD +30°3639 using the Advanced CCD Imaging Spectrometer (ACIS) aboard the Chandra X-ray Observatory. The X-ray emission from BD +30°3639 appears to lie within, but is concentrated to one side of, the interior of the shell of ionized gas seen in high-r…
Heliospheric modulation of cosmic ray protons: Role of enhanced perpendicular diffusion during periods of minimum solar modulation
Potgieter, Marius S.
The effect of enhanced perpendicular diffusion in the polar regions of a simulated heliosphere seems required in drift models for the modulation of galactic cosmic rays in order to find a latitude dependence of cosmic ray protons in the inner heliosphere that is compatible with Ulysses observations. This effect was studied in detail to establish h…
Drive Mechanisms of Erupting Solar Magnetic Flux Ropes
Chen, J.; Krall, J.; Santoro, R.
The dynamics of magnetic flux ropes near the Sun and in interplanetary space are studied using a magnetohydrodynamic model of erupting magnetic flux ropes. In this model, the magnetic structure of a coronal mass ejection (CME) corresponds to a flux rope with footpoints that remain anchored below the photosphere. The model flux rope eruption can be…