Search Publications
High-redshift galaxies in the Hubble Deep Field: colour selection and star formation history to z~4
Ferguson, Henry C.; Giavalisco, Mauro; Dickinson, Mark E. +3 more
The Lyman decrement associated with the cumulative effect of HI in QSO absorption systems along the line of sight provides a distinctive feature for identifying galaxies at z>~2.5. Colour criteria, which are sensitive to the presence of a Lyman continuum break superposed on an otherwise flat UV spectrum, have been shown, through Keck spectrosco…
Interstellar Abundances from Absorption-Line Observations with the Hubble Space Telescope
Sembach, Kenneth R.; Savage, Blair D.
The Goddard High-Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope (HST) has yielded precision abundance results for a range of interstellar environments, including gas in the local medium, in the warm neutral medium, in cold diffuse clouds, and in distant halo clouds. Through GHRS studies, investigators have determined the abundanc…
The Hubble Deep Field: Observations, Data Reduction, and Galaxy Photometry
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +14 more
The Hubble Deep Field (HDF) is a Director's Discretionary program on HST in Cycle 5 to image an undistinguished field at high Galactic latitude in four passbands as deeply as reasonably possible. These images provide the most detailed view to date of distant field galaxies and are likely to be important for a wide range of studies in galaxy evolut…
O-star mass-loss and wind momentum rates in the Galaxy and the Magellanic Clouds Observations and theoretical predictions.
Lennon, D. J.; Herrero, A.; Pauldrach, A. W. A. +8 more
A new, very fast approximate method is presented to determine mass-loss rates of O-stars from Halpha_ line profiles. The method uses H and HeII departure coefficients from unified model atmospheres parametrized in a simple way as function of wind velocity together with photospheric NLTE line profiles as the inner boundary condition for …
Galaxy morphology to I=25 mag in the Hubble Deep Field
Santiago, B. X.; Glazebrook, K.; Abraham, R. G. +3 more
The morphological properties of galaxies in the range 21<<e1>I<</e1>25 mag in the Hubble Deep Field are investigated using a quantitative classification system based on measurements of the central concentration and asymmetry of galaxian light. The class distribution of objects in the Hubble Deep Field is strongly skewed towards h…
Spectroscopy of Lyman Break Galaxies in the Hubble Deep Field
Dickinson, Mark; Giavalisco, Mauro; Steidel, Charles C. +1 more
We report on the initial results of a spectroscopic investigation of galaxies in the Hubble Deep Field which exhibit spectral discontinuities between the F450W and F300W passbands, indicative of the presence of the Lyman continuum break in the redshift range 2.4 <~ z <~ 3.4. We have employed color selection criteria similar to those we have …
Hubble Space Telescope Observations of the Lensing Cluster Abell 2218
Smail, I.; Kneib, J. -P.; Ellis, R. S. +2 more
We present a striking new Hubble Space Telescope (HST) observation of the rich cluster Abell 2218 taken with the Wide Field Planetary Camera 2. HST's restored image quality reveals a sizable number of gravitationally lensed features in this cluster, significantly more than bad been identified by using ground-based telescopes. The brightest arcs ar…
Hubble Space Telescope Observations of the Disk and Jet of HH 30
Ballester, Gilda E.; Krist, John E.; Crisp, David +13 more
HH 30 in Taurus has been imaged with the Hubble Space Telescope WFPC2. The images show in reflected light a flared disk with a radius of about 250 AU that obscures the protostar. The disk resembles detailed accretion disk models that constrain its density distribution and show that its inclination is less than 100. There are bipolar emission-line …
On the Automatic Determination of Light-Curve Parameters for Cepheid Variables
Stetson, Peter B.
A computerized algorithm for the automatic detection of Cepheid variables and for the estimation of their periods, amplitudes, and mean magnitudes from sparse data sets is presented. It is intended to be suitable for use in such programs as the measurement of Cepheid distances to external galaxies, for example with the Hubble Space Telescope. The …
The Morphologies of Distant Galaxies. II. Classifications from the Hubble Space Telescope Medium Deep Survey
Glazebrook, Karl; Ellis, Richard S.; Abraham, Roberto G. +4 more
The morphological properties of high-redshift galaxies are investigated using a sample of 507 objects (I < 22.0 mag) from the Hubble Space Telescope (HST) Medium Deep Survey. Independent visual morphological classifications for each galaxy are used to quantify the statistical uncertainties in the galaxy classifications. Visual classifications a…