Eugenio E. Mendoza

MULTICOLOR PHOTOMETRY OF CARBON STARS

Abstract : Multicolor photometric observations, were made over the range of wavelength from 0.35 microns in the ultraviolet to nearly 10 microns in the infrared, were made on thirty-nine carbon stars and six late-type long period variable stars. The bolometric corrections and effective temperatures of these stars were computed and used to construct the absolute bolometric-magnitude---effectivetemperature diagram for carbon stars. The effective temperatures of the carbon stars range from 5500 degrees K downward to 2270K. The bolometric corrections range from almost zero to nearly 5 mag. The apparent angular diameters of some of the carbon stars are as large as 0.01 inches---large enough to be measurable by a Michelson interferometer with a 50-foot beam. (Author)

Simple enhancement techniques in digital image processing

Abstract Operators based upon partial derivatives are very useful in digital image processing. In this paper results using a gradient-like map and a three-parameter family of filters are presented. An important parameter of this family is the fraction of original data to be combined simultaneously with an enhanced image obtained through the use of a generalized Laplacian-like map. By superposing different sets of data new images are obtained with highly enhanced edges and contours, while still preserving the original texture. The results are illustrated by using Landsat images of Mexico.

Digital Spectral Analysis Of αCygni And εAurigae

This paper presents results on spectral line and profile variability, equivalent widths and line identification for α Cygni (A2 Ia) and ε Aurigae (A8 Ia). The results are based upon photometrically precise spectra obtained with a Michelson-Fourier spectrophotometer. The wavelength interval extends from 0.48 to 1.02 microns, approximately. The spectral resolution is 3.85 cm-1. The analysis has been carried out totally with computers using, both, automatic and interactive techniques. These are briefly discussed.

A PHOTOMETRIC STUDY OF EARLY-TYPE STARS.

Observation data in the alpha16, Lambda9 photometric system are presented for 228 early-type O4-B8 stars of all luminosity classes. Also included are data for Be stars, B-type stars with a shell, and Beta Canis Majoris stars. The comparison with R-alpha and beta indices suggests that the alpha16 photometry is of good quality. The photometry can be used in separating different kinds of stars; when combined with the 13-color photometry, it makes possible a finer classification. The alpha16 index also provides an indication of stellar mass-loss rates, especially for supergiant stars. Preliminary He I (5876 A) measurements suggest that this line is well correlated with MK types. Be stars observed over several years also exhibit H-alpha line-strength variability. It is found that the Lambda9 index separates supergiant stars later than B2.