Search Publications
Cme Associated with Transequatorial Loops and a Bald Patch Flare
Aulanier, G.; Delannée, C.
We study a flare which occurred on 3 November 1997 at 10:31 UT in the vicinity of a parasitic polarity of AR 8100. Using SOHO/EIT 195 Å observations, we identify the brightening of thin transequatorial loops connecting AR 8100 and AR 8102, and dimmings located between the two active regions. Difference images highlight the presence of a loop-like …
Mass-loss rates and luminosity functions of dust-enshrouded AGB stars and red supergiants in the LMC
Waters, L. B. F. M.; van Loon, J. Th.; Loup, C. +5 more
A radiative transfer code is used to model the spectral energy distributions of 57 mass-losing Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud (LMC) for which ISO spectroscopic and photometric data are available. As a result we derive mass-loss rates and bolometric luminosities. A gap in the luminosity …
On the Origin of Impulsive Electron Events Observed at 1 AU
Krucker, Säm; Thompson, Barbara J.; Lin, Robert P. +1 more
A statistical survey of 12 impulsive electron events detected at energies down below 1 keV and 58 events detected above 25 keV observed at 1 AU by the 3-D Plasma and Energetic Particles experiment on the Wind spacecraft is presented. Timing analysis of the velocity dispersion reveals two different kinds of electron events: (1) events released from…
R-Process Abundances and Chronometers in Metal-poor Stars
Beers, Timothy C.; Burles, Scott; Tytler, David +5 more
Rapid neutron-capture (i.e., r-process) nucleosynthesis calculations, employing internally consistent and physically realistic nuclear physics input (quasi-particle random-phase approximation [QRPA] β-decay properties and the recent extended Thomas-Fermi with Strutinsky integral and quenching (ETFSI-Q) nuclear mass model), have been performed. The…
LASCO and EIT Observations of Helical Structure in Coronal Mass Ejections
Michels, D. J.; Howard, R. A.; Dere, K. P. +2 more
Observations of coronal mass ejections (CMEs) by the Large Angle Spectrometric Coronagraph (LASCO) on the Solar and Heliospheric Observatory (SOHO) show a significant fraction with circular intensity patterns. In the past, these would have been called ``disconnection'' events, but we suggest that these are evidence of CMEs containing helical magne…
Hubble Space Telescope and Palomar Imaging of GRB 990123: Implications for the Nature of Gamma-Ray Bursts and Their Hosts
Fruchter, Andrew S.; Hogg, David W.; Livio, Mario +13 more
We report on Hubble Space Telescope and Palomar optical images of the field of GRB 990123, obtained in 1999 February 8 and 9. We find that the optical transient (OT) associated with GRB 990123 is located on an irregular galaxy, with a magnitude of V=24.20+/-0.15. The strong metal absorption lines seen in the spectrum of the OT, along with the low …
Hot Horizontal-Branch Stars: The Ubiquitous Nature of the ``Jump'' in Strömgren u, Low Gravities, and the Role of Radiative Levitation of Metals
Grundahl, F.; Stetson, P. B.; Catelan, M. +2 more
A ``jump'' in the blue horizontal-branch (HB) distribution in the (V, u-y) color-magnitude diagram has recently been detected in the globular cluster (GC) M13 (NGC 6205) by Grundahl and coworkers. Such an effect is morphologically best characterized as a discontinuity in the (u, u-y) locus, with stars in the range 11,500 K<~Teff<~…
A Test of Pre-Main-Sequence Evolutionary Models across the Stellar/Substellar Boundary Based on Spectra of the Young Quadruple GG Tauri
Ghez, A. M.; Reid, I. Neill; White, Russel J. +1 more
We present spatially separated optical spectra of the components of the young hierarchical quadruple GG Tau. Spectra of GG Tau Aa and Ab (separation 0.25"~35 AU) were obtained with the Faint Object Spectrograph on board the Hubble Space Telescope. Spectra of GG Tau Ba and Bb (separation 1.48"~207 AU) were obtained with both the HIRES and the LRIS …
Silicate Mineralogy of the Dust in the Inner Coma of Comet C/1995 01 (Hale-Bopp) Pre- and Postperihelion
Woodward, Charles E.; Koike, Chiyoe; Witteborn, Fred C. +4 more
We present 7.5-13.4 µm infrared (IR) spectrophotometry (R~=180-360) of the 10 µm silicate emission from dust in the inner coma (i.e., within a diameter of 3") of comet C/1995 O1 (Hale-Bopp) at four temporal epochs from 1996 October through 1997 June during Hale-Bopp's approach to, arrival at, and recession from perihelion. Hale-Bopp's …
The Circumstellar Disk of HD 141569 Imaged with NICMOS
Zuckerman, B.; Schneider, G.; Silverstone, M. D. +5 more
Coronagraphic imaging with the Near-Infrared Camera and Multiobject Spectrometer on the Hubble Space Telescope reveals a large, ~400 AU (4") radius, circumstellar disk around the Herbig Ae/Be star HD 141569. A reflected light image at 1.1 µm shows the disk oriented at a position angle of 356deg+/-5deg and inclined to ou…