Search Publications
A Markov Stochastic Process Theory of Cosmic-Ray Modulation
Zhang, Ming
This paper introduces the use of Markov stochastic process theory to study heliospheric modulation of cosmic rays. The basic cosmic-ray transport equation is reformulated with a set of stochastic differential equations that describe the guiding center and momentum of individual charged particles randomly walking in the heliospheric magnetic field.…
The discovery of ERO counterparts to faint submillimetre galaxies
Kneib, J. -P.; Ivison, R. J.; Morrison, G. +5 more
We have used deep ground-based imaging in the near-infrared (near-IR) to search for counterparts to the luminous submillimetre (submm) sources in the catalogue of Smail et al. For the majority of the submm sources the near-IR imaging supports the counterparts originally selected from deep optical images. However, in two cases (10per cent of the sa…
Hubble Space Telescope Snapshot Survey of 3CR Radio Source Counterparts. III. Radio Galaxies with z<0.1
Baum, Stefi A.; McCarthy, Patrick J.; Sparks, William B. +7 more
We present and describe optical counterparts to 46 3CR radio galaxies of redshifts less than 0.1 that were imaged with the Hubble Space Telescope's (HST) WFPC2 camera through the broadband F702W filter as part of the 3CR Snapshot Survey. This is the fifth and last such paper describing the 252 radio galaxies of this R-band survey. At the 0.1" reso…
Accretion of low-metallicity gas by the Milky Way
Savage, B. D.; Wakker, B. P.; Peletier, R. F. +7 more
Models of the chemical evolution of the Milky Way suggest that the observed abundances of elements heavier than helium (`metals') require a continuous infall of gas with metallicity (metal abundance) about 0.1 times the solar value. An infall rate integrated over the entire disk of the Milky Way of ~1 solar mass per year can solve the `G-dwarf pro…
SOHO EIT Observations of Extreme-Ultraviolet ``Dimming'' Associated with a Halo Coronal Mass Ejection
Sterling, Alphonse C.; Nitta, Nariaki; Thompson, Barbara J. +2 more
A solar flare was observed on 1997 April 7 with the Soft X-ray Telescope (SXT) on Yohkoh. The flare was associated with a ``halo'' coronal mass ejection (CME). The flaring region showed areas of reduced soft X-ray (SXR) brightness--``dimmings''--that developed prior to the CME observed in white light and persisted for several hours following the C…
The Optical Mass-Luminosity Relation at the End of the Main Sequence (0.08-0.20 Msolar)
Henry, Todd J.; Kirkpatrick, J. Davy; Wasserman, Lawrence H. +5 more
The empirical mass-luminosity relation at MV is presented for stars with masses 0.08-0.20 Msolar based upon new observations made with Fine Guidance Sensor 3 on the Hubble Space Telescope. The targets are nearby, red dwarf multiple systems in which the magnitude differences are typically measured to +/-0.1 mag or better. The …
Effects of Tidal Shocks on the Evolution of Globular Clusters
Ostriker, Jeremiah P.; Lee, Hyung Mok; Gnedin, Oleg Y.
We present new Fokker-Planck models of the evolution of globular clusters, including gravitational tidal shocks. We extend our calculations beyond the core collapse by adopting three-body binary heating. Effects of the shocks are included by adding the tidal shock diffusion coefficients to the ordinary Fokker-Planck equation: the first-order heati…
Simultaneous Multicolor Detection of Faint Galaxies in the Hubble Deep Field
Szokoly, Gyula P.; Szalay, Alexander S.; Connolly, Andrew J.
We present a novel way to detect objects when multiband images are available. Typically, object detection is performed in one of the available bands or on a somewhat arbitrarily co-added image. Our technique provides an almost optimal way to use all the color information available. We build up a composite image of the N passbands where each pixel …
The η Chamaeleontis Cluster: A Remarkable New Nearby Young Open Cluster
Feigelson, Eric D.; Mamajek, Eric E.; Lawson, Warrick A.
A cluster of young, X-ray-emitting stars is found in the vicinity of η Chamaeleontis from a deep ROSAT high-resolution imager observation. The 12 X-ray sources have prominent (R=5-14) stellar counterparts, including two early-type stars (η Cha and RS Cha) and 10 Li-rich, Hα emission-line, late-type stars (K3-M5). Hipparcos astrometry reveals that …
Dust in the Local Interstellar Wind
Zank, Gary P.; Slavin, Jonathan D.; Geiss, Johannes +13 more
The gas-to-dust mass ratios found for interstellar dust within the solar system, versus values determined astronomically for the cloud around the solar system, suggest that large and small interstellar grains have separate histories and that large interstellar grains preferentially detected by spacecraft are not formed exclusively by mass exchange…