Search Publications
The Demography of Massive Dark Objects in Galaxy Centers
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +9 more
We construct dynamical models for a sample of 36 nearby galaxies with Hubble Space Telescope (HST) photometry and ground-based kinematics. The models assume that each galaxy is axisymmetric, with a two-integral distribution function, arbitrary inclination angle, a position-independent stellar mass-to-light ratio Upsilon, and a central massive dark…
Evolutionary models for solar metallicity low-mass stars: mass-magnitude relationships and color-magnitude diagrams
Hauschildt, P. H.; Allard, F.; Baraffe, I. +1 more
We present evolutionary models for low mass stars from 0.075 to 1 M_sun for solar-type metallicities [M/H]= 0 and -0.5. The calculations include the most recent interior physics and the latest generation of non-grey atmosphere models. We provide mass-age-color-magnitude relationships for both metallicities. The mass-M_V and mass-M_K relations are …
Discovery of a supernova explosion at half the age of the Universe
Panagia, N.; Lidman, C.; Aldering, G. +19 more
The ultimate fate of the Universe, infinite expansion or a big crunch, can be determined by using the redshifts and distances of very distant supernovae to monitor changes in the expansion rate. We can now find large numbers of these distant supernovae, and measure their redshifts and apparent brightnesses; moreover, recent studies of nearby type …
An unusual supernova in the error box of the γ-ray burst of 25 April 1998
Piro, L.; Pian, E.; Palazzi, E. +46 more
The discovery of afterglows associated with γ-ray bursts at X-ray, optical and radio wavelengths and the measurement of the redshifts of some of these events, has established that γ-ray bursts lie at extreme distances, making them the most powerful photon-emitters known in the Universe. Here we report the discovery of transient optical emission in…
Rotating Nuclear Rings and Extreme Starbursts in Ultraluminous Galaxies
Downes, D.; Solomon, P. M.
New CO interferometer data show that the molecular gas in infrared ultraluminous galaxies is in rotating nuclear disks or rings. The CO maps yield disk radii, kinematic major axes, rotation speeds, enclosed dynamical masses, and gas masses. The CO brightness temperatures, the double-peaked CO line profiles, the limits on thermal continuum flux fro…
What Powers Ultraluminous IRAS Galaxies?
Lutz, D.; Genzel, R.; Sturm, E. +9 more
We present an ISO SWS and ISOPHOT-S, mid-infrared spectroscopic survey of 15 ultraluminous IRAS galaxies (LIR >= 1012 L⊙). We combine the survey results with a detailed case study, based on arcsecond resolution, near-IR, and millimeter imaging spectroscopy, of one of the sample galaxies (UGC 5101). We compare th…
Are Gamma-Ray Bursts in Star-Forming Regions?
Paczyński, Bohdan
The optical afterglow of the gamma-ray burst GRB 970508 (z=0.835) was a few hundred times more luminous than any supernova. Therefore, the name ``hypernova'' is proposed for the whole GRB/afterglow event.
There is tentative evidence that the GRBs 970228, 970508, and 970828 were close to star-forming regions. If this case is strengthened with …Local stellar kinematics from HIPPARCOS data
Dehnen, Walter; Binney, James J.
From the parallaxes and proper motions of a kinematically unbiased subsample of the Hipparcos Catalogue, we have re-determined as a function of colour the kinematics of main-sequence stars. Whereas the radial and vertical components of the mean heliocentric velocity of stars show no trend with colour, the component in the direction of Galactic rot…
Helioseismic Studies of Differential Rotation in the Solar Envelope by the Solar Oscillations Investigation Using the Michelson Doppler Imager
Kosovichev, A. G.; Hoeksema, J. T.; Scherrer, P. H. +21 more
The splitting of the frequencies of the global resonant acoustic modes of the Sun by large-scale flows and rotation permits study of the variation of angular velocity Ω with both radius and latitude within the turbulent convection zone and the deeper radiative interior. The nearly uninterrupted Doppler imaging observations, provided by the Solar O…
Supernova Limits on the Cosmic Equation of State
Filippenko, Alexei V.; Riess, Adam G.; Tonry, John +18 more
We use Type Ia supernovae studied by the High-z Supernova Search Team to constrain the properties of an energy component that may have contributed to accelerating the cosmic expansion. We find that for a flat geometry the equation-of-state parameter for the unknown component, αx = Px/ρx, must be less than -0.55 (95…