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Massive Star Formation and Evolution in Starburst Galaxies: Mid-infrared Spectroscopy with the ISO Short Wavelength Spectrometer
Förster Schreiber, Natascha M.; Lutz, Dieter; Spoon, Henrik W. W. +4 more
We present new Infrared Space Observatory Short Wavelength Spectrometer data for a sample of 27 starburst galaxies, and with these data we examine the issues of formation and evolution of the most massive stars in starburst galaxies. Using starburst models which incorporate time evolution, new stellar atmosphere models for massive stars, and a sta…
The European Large Area ISO Survey - I. Goals, definition and observations
Elbaz, D.; Genzel, R.; Omont, A. +67 more
We describe the European Large Area ISO Survey (ELAIS). ELAIS was the largest single Open Time project conducted by ISO, mapping an area of 12deg2 at 15µm with ISOCAM and at 90µm with ISOPHOT. Secondary surveys in other ISO bands were undertaken by the ELAIS team within the fields of the primary survey, with 6deg2…
Catalogue of the 1997 SOHO-EIT coronal transient waves and associated type II radio burst spectra
Thompson, B. J.; Mann, G.; Aurass, H. +1 more
We compare the coronal transient wave phenomenon discovered by SOHO extreme ultraviolet observations (``EIT waves'') with the associated radio signature of a coronal shock wave (type II burst). 90% of the type II bursts are associated with an EIT wave. On average, the speed derived from the radio burst is about three times larger than the EIT wave…
K-Band Calibration of the Red Clump Luminosity
Alves, David R.
The average near-infrared (K-band) luminosity of 238 Hipparcos red clump giants is derived and then used to measure the distance to the Galactic center. These Hipparcos red clump giants have been previously employed as I-band standard candles. The advantage of the K-band is a decreased sensitivity to reddening and perhaps a reduced systematic depe…
The MACHO Project: Microlensing Optical Depth toward the Galactic Bulge from Difference Image Analysis
Alcock, C.; Allsman, R. A.; Alves, D. R. +22 more
We present the microlensing optical depth toward the Galactic bulge based on the detection of 99 events found in our Difference Image Analysis (DIA) survey. This analysis encompasses 3 yr of data, covering ~17 million stars in ~4 deg2, to a source-star baseline magnitude limit of V=23. The DIA technique improves the quality of photometr…
X-Ray and Optical Variability in NGC 4051 and the Nature of Narrow-Line Seyfert 1 Galaxies
Vestergaard, M.; Papadakis, I.; Peterson, B. M. +14 more
We report on the results of a three-year program of coordinated X-ray and optical monitoring of the narrow-line Seyfert 1 galaxy NGC 4051. The rapid continuum variations observed in the X-ray spectra are not detected in the optical, although the time-averaged X-ray and optical continuum fluxes are well correlated. Variations in the flux of the bro…
Space Telescope Imaging Spectrograph Coronagraphic Observations of β Pictoris
Hubeny, Ivan; Woodgate, Bruce; Heap, Sara R. +4 more
We present new coronagraphic images of β Pictoris obtained with the Space Telescope Imaging Spectrograph (STIS) in 1997 September. The high-resolution images (0.1") clearly detect the circumstellar disk as close to the star as 0.75", corresponding to a projected radius of 15 AU. The images define the warp in the disk with greater precision and at …
Hubble Space Telescope Weak-Lensing Study of the z=0.83 Cluster MS 1054-03
Hoekstra, H.; Franx, M.; Kuijken, K.
We have measured the weak gravitational lensing of faint, distant background galaxies by MS 1054-03, a rich and X-ray luminous cluster of galaxies at a redshift of z=0.83, using a two-color mosaic of deep WFPC2 images. The small corrections for the size of the point-spread function and the high number density of background galaxies obtained in the…
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…