Search Publications
Measuring Sizes of Marginally Resolved Young Globular Clusters with the Hubble Space Telescope
Holtzman, Jon A.; Carlson, Matthew N.
We present a method for deriving sizes of marginally resolved star clusters from Hubble Space Telescope/WFPC2 observations by fitting King models to observations. We describe results both on simulated images and on observations of young compact clusters in NGC 3597 and NGC 1275. From the simulations, we find that we can measure King model concentr…
EUV Sprays: Jet-like eruptive activity on the solar limb
Harrison, R. A.; Bryans, P.; Bingham, R.
Jet-like eruptive events have been detected in the extreme ultraviolet (EUV) observations from the Solar and Heliospheric Observatory (SOHO) spacecraft. Some jet-like events are shown and for one event, that of January 22 2000, we provide a detailed analysis of the EUV observations. The January 22 observation was part of an on-going campaign to ob…
The Bismuth Abundance in the HGMN Stars χ Lupi and HR 7775 and Improved Atomic Data for Selected Transitions of BI I, BI II, and BI III
Leckrone, D. S.; Wahlgren, G. M.; Johansson, S. +6 more
High-resolution spectra of the chemically peculiar HgMn stars χ Lupi and HR 7775, obtained with the Hubble Space Telescope/Goddard High Resolution Spectrograph, are investigated for their abundance of bismuth by comparison with LTE synthetic spectrum modeling. HR 7775, previously known from International Ultraviolet Explorer spectra to display str…
Radio Frequency Fluctuation Spectra During the Solar Conjunctions of the Ulysses and Galileo Spacecraft
Plettemeier, D.; Bird, M. K.; Wohlmuth, R. +5 more
Temporal power spectra have been computed from recordings of the downlink frequency fluctuations of the Galileo and Ulysses radio signals during their solar conjunctions. Both the equatorial streamer belt and the polar coronal holes were investigated over a range of ray path solar offset distances from 4 to 80 R⊙. By combining gapless d…
A nanoflare heating model for the quiet solar corona
Benz, A. O.; Mitra-Kraev, U.
The energy input into the lower solar corona by flare evaporation events has been modeled according to the available observations for quiet regions. The question is addressed whether such heating events can provide the observed average level of the coronal emission measure and thus of the observed flux of extreme ultraviolet (EUV) and X-ray emissi…
Far Ultraviolet Spectroscopic Explorer observations of high-velocity gas associated with the Monoceros Loop SNR
Lallement, R.; Welsh, B. Y.; Sallmen, S. +1 more
We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of high-velocity gas (VLSR = +65 km s-1) seen towards the star HD 47240 which lies just behind the Monoceros Loop Supernova Remnant at a distance of ~ 1800 pc. This high-velocity absorption feature is detected in the far ultraviolet lines of O I, Ar I, N I,…
Cluster observations of the high-latitude magnetopause and cusp: initial results from the CIS ion instruments
Lundin, R.; Sauvaud, J. -A.; Escoubet, C. P. +22 more
Launched on an elliptical high inclination orbit (apogee: 19.6 RE) since January 2001 the Cluster satellites have been conducting the first detailed three-dimensional studies of the high-latitude dayside magnetosphere, including the exterior cusp, neighbouring boundary layers and magnetopause regions. Cluster satellites carry the CIS ion spectrome…
Hubble Space Telescope Ultraviolet and Ground-based Optical Spectropolarimetry of IRAS Quasi-stellar Objects: Dusty Scattering in Luminous Active Galactic Nuclei
Gordon, Karl D.; Hines, Dean C.; Sitko, Michael L. +4 more
We present UV and optical spectropolarimetry of two highly polarized IRAS-selected quasi-stellar objects (QSOs), IRAS 13349+2438 and the broad absorption line QSO (BALQSO) IRAS 14026+4341. The polarization in both objects rises rapidly toward the blue, peaks near 3000 Å in the rest frame and remains nearly constant for shorter wavelengths. The res…
Magnetic cloud evolution in a two-speed solar wind
Cargill, Peter J.; Schmidt, Joachim M.
The Ulysses spacecraft has observed interplanetary coronal mass ejections in pure high-speed solar wind, in the shear layer between high-speed and low-speed, and, in conjunction with other satellites, the same coronal mass ejection (CME) has been seen in both high- and low-speed wind. If CMEs originate in the equatorial streamer belt, they must be…
Gravitationally lensed high redshift galaxies in the field of 1E0657-56
Saglia, R. P.; Pauldrach, A. W. A.; Bender, R. +7 more
We present images and long-slit spectra obtained with FORS1 at UT1 of the VLT centered on the gravitational arc of the galaxy cluster 1E0657-56 (z = 0.296). The cluster is one of the hottest, most massive clusters known so far and acts as a powerful gravitational telescope, amplifying the flux of background sources by up to a factor of 20. We pres…