Search Publications
The Boron Abundance of Procyon
Lambert, David L.; Edvardsson, Bengt; Lemke, Michael
The B I 2496.8 A resonance line and HST/GHRS echelle spectra are used with model atmospheres and synthetic spectra to derive the B abundance of the F dwarfs Procyon (alpha CMi), Theta UMa, and Iota Peg. The B abundance (log epsilon(B)~/=2.3) of Theta UMa and Iota Peg is similar to that derived by Boesgaard and Heacox from the B II resonance line i…
A General Bayesian Image Reconstruction Algorithm with Entropy Prior. Preliminary Application to HST Data
Nunez, Jorge; Llacer, Jorge
This paper describes a general Bayesian iterative algorithm with entropy prior for image reconstruction. It solves the cases of both pure Poisson data and Poisson data with Gaussian readout noise. The algorithm maintains positivity of the solution; it includes case-specific prior information (default map) and flatfield corrections; it removes back…
Periodic Low Amplitude Variations in the Brightness of Proxima Centauri
Benedict, G. F.; Franz, O. G.; Hemenway, P. D. +10 more
Using data acquired with Fine Guidance Sensor #3 on board the Hubble Space Telescope we find that the brightness of Proxima Centauri varies with an amplitude of 0.01 magnitude and a period P=41.6 +/- 0.6 days. We interpret this variation as rotational modulation of star spots or bright regions in the photosphere of Proxima Centauri. In a total of …
Imaging the Bipolar Nebula around HM Sagittae
Paresce, Francesco; Hack, Warren J.
Hubble Space Telescope Faint Object Camera UV images are presented for HM Sge showing a bipolar optical nebula similar to that in R Aquarii and RX Puppis. The nebula extends to a distance of 0.174" with a P.A. of 135 degrees inside a faint halo extending to a radius of 0.28". A kinematic distance to HM Sge based on positions of features in the neb…
Recent Results from the Hubble Space Telescope
Maran, Stephen P.; Kinney, Anne L.
A selection of recent findings from the Hubble Space Telescope (HST) are presented as a supplement to the earlier review by Kinney & Maran (1991). In stellar astrophysics, noteowrthy results include the first ultraviolet science from the High Speed Photometer, as well as spectroscopic studies of black hole and neutron star binaries and a flare…
Focus History of the Hubble Space Telescope - Launch to May 1993
Burrows, C. J.; Hasan, H.; Schroeder, D. J.
Since the launch of the Hubble Space Telescope (HST) the secondary mirror of the telescope has been moved several times in order to collimate the telescope and also to define a position of best focus. In addition to these moves the focus position changes over time because of water desorption by the graphite epoxy in the metering truss. We report h…
Resolved Structure in M33 Supernova Remnants
Blair, William P.; Davidsen, Arthur F.
We present WF/PC narrow band [S II] lambda-6725 images of two M33 supernova remnants obtained with the Wide Field/Planetary Camera on the Hubble Space Telescope. Comparison of these images with ground-based CCD data indicates that HST has resolved the nebular structures into shells or partial shells, permitting improved measurements of the diamete…
Hubble Space Telescope Observations of the Center of Globular Cluster M15
Yanny, Brian
Images of the dense center of globular cluster M15 (NGC 7078) have been obtained with the Hubble Space Telescope in the V and I filters. Accurate photometry is possible in the very densest part of the cluster center with rms errors of <0.3 magnitudes for stars down to the main sequence turnoff. Evidence for radial segregation between horizontal…