Search Publications
Missions
Journals
Publication Years
Birth and early evolution of a planetary nebula
Bobrowsky, Matthew; Sahu, Kailash C.; Parthasarathy, M. +1 more
The final expulsion of gas by a star as it forms a planetary nebula - the ionized shell of gas often observed surrounding a young white dwarf - is one of the most poorly understood stages of stellar evolution,. Such nebulae form extremely rapidly (about 100 years for the ionization) and so the formation process is inherently difficult to observe. …
Ejected Nebulae as Probes of the Evolution of Massive Stars in the Large Magellanic Cloud
Smith, Linda J.; Leitherer, Claus; Clampin, Mark +3 more
We present new Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) and ground-based long-slit spectroscopic observations of the nebulae around the two LMC luminous blue variables (LBVs) R127 (=HDE 269858) and R143 (=HDE 269929) and the Ofpe/WN9 star S119 (=HDE 269687). We have used the ground-based long-slit spectra to investigate the kin…
New Constraints on the Luminosity Evolution of Spheroidal Galaxies in Distant Clusters
Smail, I.; Poggianti, B. M.; Aragón-Salamanca, A. +6 more
We investigate various probes of luminosity evolution in the rich cluster environment, concentrating in particular on the spheroidal (E/S0) galaxies, using a newly constructed catalog of morphologically classified Hubble Space Telescope (HST) images of galaxies observed in the cores of 13 clusters with redshifts 0.17 <= z <= 0.56. An importa…
Nonparametric Reconstruction of Abell 2218 from Combined Weak and Strong Lensing
Saha, Prasenjit; Williams, Liliya L. R.; Abdelsalam, Hanadi M.
We apply a new nonparametric technique to reconstruct, with uncertainties, the projected mass distribution of the inner region of Abell 2218 using combined strong and weak lensing constraints from multiple-image systems and arclets with known redshifts. The reconstructed mass map broadly resembles previous, less detailed parametric models, but whe…
Solar wind measurements with SOHO: The CELIAS/MTOF proton monitor
Hsieh, K. C.; Wurz, P.; Bochsler, P. +26 more
The proton monitor, a small subsensor in the Charge, Element, and Isotope Analysis System/Mass Time-of-Flight (CELIAS/MTOF) experiment on the SOHO spacecraft, was designed to assist in the interpretation of measurements from the high mass resolution main MTOF sensor. In this paper we demonstrate that the proton monitor data may be used to generate…
Nuclear stellar discs in early-type galaxies - II. Photometric properties
van den Bosch, Frank C.; Scorza, Cecilia
Hubble Space Telescope images of two early-type galaxies harbouring both nuclear and outer stellar discs are studied in detail. By means of a photometric decomposition, the images of NGC 4342 and 4570 are analysed and the photometric properties of the nuclear discs investigated. We find a continuity of properties in the parameter space defined by …
The EC 14026 stars - VII. PG 1605+072, a star with many pulsation modes
O'Donoghue, D.; Kilkenny, D.; Lynas-Gray, A. E. +3 more
We report the discovery of large-amplitude (~0.25 mag) pulsations in the bright (V=12.8) sdB star, PG 1605+072. The dominant period is 480s, but more than 20 periods were present on at least three separate occasions. Frequency analysis of the complete data set yields more than 30 periods. A few of these are harmonics or linear combinations of the …
Spiral Galaxies with WFPC2. III. Nuclear Cusp Slopes
Carollo, C. M.; Stiavelli, M.
In this paper, the third of a series dedicated to the investigation of the nuclear properties of spiral galaxies, we (1) model the Wide Field Planetary Camera 2 F606W nuclear surface brightness profiles of 41 spiral galaxies presented in Papers I and II with the analytic law introduced by Lauer et al. and (2) deconvolve these surface brightness pr…
The Extragalactic Distance Scale Key Project. V. Photometry of the Brightest Stars in M100 and the Calibration of WFPC2
Illingworth, Garth D.; Madore, Barry F.; Freedman, Wendy L. +18 more
We present multiepoch VI observations of the brightest stars in the Virgo spiral galaxy M100 obtained with the WFPC2 aboard the Hubble Space Telescope. Particular attention has been given to the WFPC2 calibration process, and a new calibration is presented here. We find that a calibration based on short exposure (t <= 60 sec) observations of th…
Detection of methyl radicals (CH_3) on Saturn
Encrenaz, T.; Feuchtgruber, H.; Moses, J. I. +1 more
We report the first detection of methyl radicals (CH_3) in the upper atmosphere of