scholarly journals A Spectropolarimetric Atlas of 61 Bright Northern Be Stars

2000 ◽  
Vol 175 ◽  
pp. 48-50 ◽  
Author(s):  
Karen S. Bjorkman ◽  
Marilyn R. Meade ◽  
Brian L. Babler
Keyword(s):  
Wavelength Range ◽  
Spectral Resolution ◽  
Wavelength Dependence ◽  
Be Stars ◽  
University Of Wisconsin ◽  
Time Period ◽  
Ccd Detector ◽  
Ccd Observations ◽  
Full Analysis ◽  
The University

AbstractWe are developing an atlas of spectropolarimetric observations of 61 bright northern Be stars obtained from 1989-94 using the halfwave polarimeter (HPOL) at the 0.9m telescope of the University of Wisconsin Pine Bluff Observatory (PBO). The data cover the wavelength range from about 3400-7600Å, with a spectral resolution of about 25Å. This atlas will contain all data (297 observations total) obtained as part of a survey program with HPOL during the time when the detector in use was a dual Reticon array; the survey observations with HPOL continue, using a new CCD detector which extends the spectral coverage out to 1.05μm and improves the spectral resolution to about 12Å. The CCD observations will be presented later in a second volume of the atlas.Only a brief summary of the findings of the survey from the first 5 years of the project is presented here. A full analysis of the data will be included in a paper to be published elsewhere. The general wavelength dependence of polarization for classical Be stars can be considered on the basis of these observations, and results on polarimetric variability are available. In particular, we find that 56% (20 of 36) of the Be stars observed 3 or more times from 1989-94 show significantly variable polarization at the level of 0.1% changes (inclusion of preliminary results from the continuing CCD survey indicates that the percentage is even higher). The timescales for these changes range from as short as night-to-night to as long as several months. Several of the stars showed evidence for polarimetric “outbursts” during the time period covered by the observations.

scholarly journals Spectral Energy Distribution of Be Stars

1987 ◽  
Vol 92 ◽  
pp. 206-207
Author(s):  
Dieter Kaiser ◽  
Reinhard W. Hanuschik
Keyword(s):  
Energy Distribution ◽  
Wavelength Range ◽  
Spectral Resolution ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Be Stars ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
The University

During two observation periods in Nov./Dec. 1981 and April/ May 1985, absolute spectral energy distributions of 41 southern and equatorial Be stars were photometrically measured at 10 Å spectral resolution in the wavelength range between 3200 Å and 8500 Å, using the scanning spectrophotometer attached to the 61 cm telescope of the University of Bochum at La Silla/Chile. Spectral fluxes of the program stars have been determined with an error of 0m.03 or less.

scholarly journals Spectroscopic and Polarimetric Observations of AC Her and UU Her

1989 ◽  
Vol 106 ◽  
pp. 296-296
Author(s):  
M.A. Nook ◽  
J.A. Cardelli ◽  
K.H. Nordsieck
Keyword(s):  
Wavelength Range ◽  
Spectral Resolution ◽  
Preliminary Results ◽  
Cassegrain Telescope ◽  
The University

We present preliminary results obtained between March and August of 1987 of a two-year spectropolarimetric study of 10 RV Tauri stars. The observations were made at the University of Wisconsin's Pine Bluff Observatory using the 36 inch cassegrain telescope with a Lyot polarimeter. The spectral resolution of the instrument was 6 A and covered the range between 4350 A and 7500 A. The polarimetry covered the same wavelength range but is binned in four broad bands at 4828 A, 5361 A, 6025 A, and 6877 A.

scholarly journals Dispersion of Interstellar Polarization

1965 ◽  
Vol 7 ◽  
pp. 57-64
Author(s):  
Thomas Gehrels
Keyword(s):  
Data Processing ◽  
High Altitude ◽  
Wavelength Range ◽  
Wavelength Dependence ◽  
Probable Error ◽  
Percentage Polarization ◽  
University Of Arizona ◽  
The University ◽  
Observing Techniques

The Wavelength Dependence of Polarization as observed in 32 stars, for which the Henry Draper numbers are given, is shown in figure 1. Details of some of these observations are presented in reference 1.The equipment is now being used with the new 154-cm Catalina reflector of the Lunar and Planetary Laboratory at the University of Arizona. The instrumental polarizations are nearly zero. The data processing and observing techniques have been further improved; the precision is mainly determined by statistics such that the internal probable error in the percentage polarization is ±0.03 percent (±0.0006 magnitude) for a half-hour observation per filter on objects brighter than about 7 magnitudes. The wavelength λ ranges from 0.33 to 0.95 μ covered by seven filters of bandwidth of about 0.05 μ. The wavelength range is being extended to 1.2, 1.6, and 2.2 μ and, with high-altitude ballooning, to 0.28 and 0.22 μ.

scholarly journals High spectral resolution lidar at the university of wisconsin-madison

2018 ◽  
Vol 176 ◽  
pp. 01024
Author(s):  
Ilya I. Razenkov ◽  
Edwin W. Eloranta
Keyword(s):  
Spectral Resolution ◽  
Atmospheric Temperature ◽  
High Spectral Resolution ◽  
Science And Engineering ◽  
Extinction Cross Section ◽  
University Of Wisconsin ◽  
Atmospheric Temperature Profile ◽  
Field Campaigns ◽  
The University ◽  
High Spectral Resolution Lidar

This paper describes the modifications done on the University of Wisconsin-Madison High Spectral Resolution Lidar (HSRL) that improved the instrument’s performance. The University of Wisconsin HSRL lidars designed by our group at the Space Science and Engineering Center were deployed in numerous field campaigns in various locations around the world. Over the years the instruments have undergone multiple modifications that improved the performance and added new measurement capabilities such as atmospheric temperature profile and extinction cross-section measurements.

Some Biological Applications of High Voltage Electron Microscopy

1974 ◽  
Vol 32 ◽  
pp. 298-299
Author(s):  
Hans Ris
Keyword(s):  
High Voltage ◽  
Chromosome Structure ◽  
Nerve Fibers ◽  
Good Resolution ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
University Of Wisconsin ◽  
High Voltage Electron ◽  
One Year ◽  
The University

The High Voltage Electron Microscope Laboratory at the University of Wisconsin has been in operation a little over one year. I would like to give a progress report about our experience with this new technique. The achievement of good resolution with thick specimens has been mainly exploited so far. A cold stage which will allow us to look at frozen specimens and a hydration stage are now being installed in our microscope. This will soon make it possible to study undehydrated specimens, a particularly exciting application of the high voltage microscope.Some of the problems studied at the Madison facility are: Structure of kinetoplast and flagella in trypanosomes (J. Paulin, U. of Georgia); growth cones of nerve fibers (R. Hannah, U. of Georgia Medical School); spiny dendrites in cerebellum of mouse (Scott and Guillery, Anatomy, U. of Wis.); spindle of baker's yeast (Joan Peterson, Madison) spindle of Haemanthus (A. Bajer, U. of Oregon, Eugene) chromosome structure (Hans Ris, U. of Wisconsin, Madison). Dr. Paulin and Dr. Hanna are reporting their work separately at this meeting and I shall therefore not discuss it here.

Ultrastructural characteristics of sporidia of Ustilago

1989 ◽  
Vol 47 ◽  
pp. 786-787
Author(s):  
Patricia N. Hackney
Keyword(s):  
Electron Microscope ◽  
Type System ◽  
Tube Formation ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
University Of Wisconsin ◽  
Transmission Electron ◽  
Ustilago Hordei ◽  
Silene Alba ◽  
The University

Ustilago hordei and Ustilago violacea are yeast-like basidiomycete pathogens ofHordeum vulgare and Silene alba respectively. The mating type system in both species of Ustilago is bipolar, with alleles, A,a, (U.hordei) and a1, a2 (U.violacea) at a single locus. Haploid sporidia maintain the asexual phase by budding, while the sexual phase is initiated by conjugation tube formation between the mating types during budding and conjugation.For observation of budding, sporidia were prepared by culturing the four types on YEG (yeast extract glucose) broth for 24 hours. After centrifugation at 5000g cells were either left unmated or mated in a1/a2,A/a combinations. The sporidia were then mixed 1:1 with 4% agar and the resulting 1mm cubes fixed in 8% gluteraldehyde and post fixed in osmium tetroxide. After dehydration and embedding cubes were thin sectioned with a LKB ultratome and photographed in a Zeiss 9s transmission electron microscope or in an AE1 electron microscope of MK11 1MEV at the High Voltage Electron Microscopy Center of the University of Wisconsin-Madison.

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