Search Publications
The Structure and Emission of the Accretion Shock in T Tauri Stars. II. The Ultraviolet-Continuum Emission
Hartmann, Lee; Calvet, Nuria; Muzerolle, James +1 more
We compare accretion-shock models with optical and ultraviolet spectra of pre-main-sequence stars to (1) make the first determinations of accretion rates in intermediate-mass T Tauri stars from continuum emission and (2) derive improved estimates of accretion rates and extinctions for continuum T Tauri stars. Our method extends the shock models de…
Hubble Space Telescope STIS Spectroscopy of the Optical Outflow from DG Tauri: Structure and Kinematics on Subarcsecond Scales
Bacciotti, Francesca; Eislöffel, Jochen; Mundt, Reinhard +3 more
We have carried out a spatio-kinematic study of the outflow from the classical T Tauri star DG Tau using the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope. A series of seven spatially offset long-slit spectra spaced by 0.07" were obtained along the axis of the outflow to build up a three-dimensional intensity-velo…
The Vienna-KPNO search for Doppler-imaging candidate stars. I. A catalog of stellar-activity indicators for 1058 late-type Hipparcos stars
Weber, M.; Granzer, Th.; Washuettl, A. +2 more
We present the results from a spectroscopic Ca ii H&K survey of 1058 late-type stars selected from a color-limited subsample of the Hipparcos catalog. Out of these 1058 stars, 371 stars were found to show significant H&K emission, most of them previously unknown; 23% with strong emission, 36% with moderate emission, and 41% with weak emiss…
Coronal dimmings and energetic CMEs in April-May 1998
Thompson, B. J.; Delaboudinière, J. -P.; Nitta, N. +2 more
We have analyzed the coronal dimmings for seven fast (> 600 km/s) coronal mass ejections (CMEs) occurring between 23 April and 9 May which were associated with flares from NOAA active region (AR) 8210. Each of these CMEs had at least one group of interplanetary radio bursts associated with them. These dimming regions were identified by their st…
The Fundamental Plane of Gravitational Lens Galaxies and The Evolution of Early-Type Galaxies in Low-Density Environments
Peng, C. Y.; Keeton, C. R.; Kochanek, C. S. +6 more
Most gravitational lenses are early-type galaxies in relatively low density environments-a ``field'' rather than a ``cluster'' population. Their average properties are the mass-averaged properties of all early-type galaxies. We show that field early-type galaxies with 0<z<1, as represented by the lens galaxies, lie on the same fundamental pl…
Protons in near earth orbit
Finelli, F.; Santos, D.; Usoskin, I. +212 more
The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380km. Above the geomagnetic cutoff the observed spectrum is parameterized by a power law. Below the geomagnetic cutoff a substantial second spectrum was observed concentrated at …
The origin and development of the May 1997 magnetic cloud
Plunkett, S. P.; Webb, D. F.; Burlaga, L. F. +5 more
A complete halo coronal mass ejection (CME) was observed by the SOHO Large-Angle and Spectrometric Coronagraph (LASCO) coronagraphs on May 12, 1997. It was associated with activity near Sun center, implying that it was aimed earthward. Three days later on May 15 an interplanetary shock and magnetic cloud/flux rope transient was detected at the Win…
A Database of Cepheid Distance Moduli and Tip of the Red Giant Branch, Globular Cluster Luminosity Function, Planetary Nebula Luminosity Function, and Surface Brightness Fluctuation Data Useful for Distance Determinations
Kelson, Daniel D.; Illingworth, Garth D.; Madore, Barry F. +14 more
We present a compilation of Cepheid distance moduli and data for four secondary distance indicators that employ stars in the old stellar populations: the planetary nebula luminosity function (PNLF), the globular cluster luminosity function (GCLF), the tip of the red giant branch (TRGB), and the surface brightness fluctuation (SBF) method. The data…
Infrared colours for Mira-like long-period variables found in the (M⊙<~10-7 Msolar yr-1) Hipparcos Catalogue
Feast, Michael; Whitelock, Patricia; Marang, Freddy
Near-infrared, JHKL, photometry is presented for 193 Mira and semi-regular variables that were observed by Hipparcos; periods, bolometric magnitudes and amplitudes are derived for 92 of them. Because of the way in which the Hipparcos targets were selected, this group of stars provides a useful data base of Miras with low mass-loss rates (M⊙
The age of the solar neighbourhood
Binney, James; Dehnen, Walter; Bertelli, Gianpaolo
High-quality Hipparcos data for a complete sample of nearly 12000 main-sequence and subgiant stars, together with Padua isochrones, are used to constrain the star formation history of the solar neigbourhood and the processes that stochastically accelerate disc stars. The velocity dispersion of a coeval group of stars is found to increase with time…