• Publications
  • Influence
Differentiation of the asteroid Ceres as revealed by its shape
C Ceres has a shape and smoothness indicative of a gravitationally relaxed object that is significantly less flattened than that expected for a homogeneous object, but is consistent with a central mass concentration indicative of differentiation.
A New Spectral Classification System for the Earliest O Stars: Definition of Type O2
High-quality, blue-violet spectroscopic data are collected for 24 stars that have been classified as type O3 and that display the hallmark N IV and N V lines. A new member of the class is presented;
The Pluto system: Initial results from its exploration by New Horizons
The New Horizons encounter revealed that Pluto displays a surprisingly wide variety of geological landforms, including those resulting from glaciological and surface-atmosphere interactions as well as impact, tectonic, possible cryovolcanic, and mass-wasting processes.
SN 1991bg - A type Ia supernova with a difference
We present 13 spectra and 31 photometric observations covering the first 150 days of SN 1991bg in NGC 4374 (M 84). Although SN 1991bg was a type Ia supernova displaying the characteristic Si II
The stellar content of NGC 346: A plethora of O stars in the SMC
The stellar content of NGC 346, the largest and brightest H II region in the SMC, was investigated using the results of CCD UBV photometry and spectroscopy. Spectra of 42 blue stars were classified,
The stellar content of LH 9 and 10 (N11) in the LMC - A case for sequential star formation
The young OB associations Lucke-Hodge 9 and 10 are studied with UBV photometry that is independent of reddening to determine the IMF directly from star counts. The temperature and reddening of the
HST/FOS Spatially Resolved Spectral Classification of Compact OB Groups in the Large Magellanic Cloud*
Blue-violet spectrograms of individual components in four compact OB groups of the Large Magellanic Cloud, obtained with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS), are
The small satellites of Pluto as observed by New Horizons
The New Horizons results on Pluto’s small moons help to elucidate the conditions under which the Pluto system formed and evolved, and massively increase the understanding of the bodies in the outer solar system.
Ultraviolet Imaging Telescope Observations of the Magellanic Clouds
We present wide-field far-ultraviolet (FUV; 1300–1800 A) images of the Large and Small Magellanic Clouds (LMC, SMC). These data were obtained by the Ultraviolet Imaging Telescope (UIT) during the