scholarly journals Ultraviolet Photometry from the S2/68 Observations in the TD1 Satellite

1977 ◽  
Vol 35 ◽  
pp. 85-91
Author(s):  
K. Nandy
Keyword(s):  
Spectral Type ◽  
Photometric System ◽  
Sky Survey ◽  
Free Parameters

SummaryAn ultraviolet photometric system based on observations obtained from the ultraviolet Sky Survey Telescope in the TD1 satellite is described. The system considered here consists of ultraviolet magnitudes at λ1 = 2740A, λ2 = 2190A and λ3 = 1490A. The extinction free parameters derived from the observed ultraviolet colours enable determination of interstellar reddening, spectral type and luminosity. This photometric system has been evaluated by comparing these parameters with other classification parameters.

scholarly journals The Integrated Photometry of Globular Clusters in the Vilnius Photometric System

1980 ◽  
Vol 85 ◽  
pp. 483-484
Author(s):  
K. Zdanavičius ◽  
V. Straižys
Keyword(s):  
Globular Clusters ◽  
Color Index ◽  
Photometric System ◽  
Intrinsic Values ◽  
Average Color ◽  
Color Excess ◽  
Free Parameters ◽  
Range Of Variation

Thirty-three globular clusters of our Galaxy were observed with the filters of the Vilnius photometric system UPXYZVS with 3450, 3740, 4050, 4660, 5160, 5440, 6550 å filters (Straižys 1977). For the classification of clusters in metallicities the reddening-free parameters QUYV QPYV and QXYV can be used. In Figure 1 these Q parameters, having a range of variation of the order of 0.4, are plotted against metallicity values from Kukarkin (1974). The parameter QPYZ has an even larger range of variation (of the order of 0.6). For determination of color excesses of clusters every color index can be used if its intrinsic values for a given metallicity defined by quantities Q are known (Figure 2). Average color excesses determined from the diagrams QUYV, (Y-V)o; QPYV, (Y-V)o and QXYV (Y-V)o and transformed to EB-V in Figure 3 are compared with color excesses from Kukarkin (1974). To summarize, the Vilnius system presents a number of metallicity sensitive, reddening-free parameters which can be used for [Fe/H] and color-excess determinations of globular clusters.

scholarly journals Observed Relations Between Physical Properties and MK Classification as Functions of Metal Abundance for F5-K4 Stars

1976 ◽  
Vol 72 ◽  
pp. 75-78
Author(s):  
M. Grenon
Keyword(s):  
Physical Properties ◽  
Spectral Range ◽  
Spectral Type ◽  
Photometric System ◽  
Luminosity Class ◽  
Empirical Relations ◽  
Metal Abundance ◽  
Systematic Effects ◽  
The Absolute ◽  
Absolute Magnitudes

The Geneva photometric system has been calibrated in terms of [M/H], θeff, Mv in the spectral range F5 to K4. As the spectral type is a datum generally available, we derive empirical relations showing the coupling of θeff and [M/H] at given spectral type and luminosity class. Similar relations are offered for the absolute magnitudes and provide a more accurate means for deriving spectroscopic parallaxes. Systematic effects on the estimation of the luminosity class are also shown.

scholarly journals Predicted properties of RR Lyrae stars in the Sloan Digital Sky Survey photometric system

2006 ◽  
Vol 371 (3) ◽  
pp. 1503-1512 ◽  
Author(s):  
M. Marconi ◽  
M. Cignoni ◽  
M. Di Criscienzo ◽  
V. Ripepi ◽  
F. Castelli ◽  
...  
Keyword(s):  
Sloan Digital Sky Survey ◽  
Photometric System ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Sky Survey ◽  
Lyrae Stars

On the Measurement of Atmospheric Extinction by Rufener’s Method

1979 ◽  
Vol 3 (5) ◽  
pp. 326-327
Author(s):  
Z. KviZ
Keyword(s):  
Adverse Effect ◽  
Photometric System ◽  
Photoelectric Photometry ◽  
Atmospheric Extinction ◽  
Air Mass

The coefficient of atmospheric extinction may change during the night and in fact it often does. This has an adverse effect on the determination of atmospheric extinction by simple Bouguer plot of magnitude against air mass. This effect was studied by Rufener (1964), who introduced for the purpose of accurate photoelectric photometry in the Geneva photometric system the method of two ‘extinction stars’. His method consists of the measurement of two stars of the same colour — one starting at high air mass 2 - 3, the M-star (for French montante = rising) and the second starting simultaneously in the meridian at low air mass, the D—star (for descending).

Determination of hyperon properties through the variational method considering the hyperfine interaction

2019 ◽  
Vol 28 (10) ◽  
pp. 1950087 ◽  
Author(s):  
S. M. Moosavi Nejad ◽  
A. Armat
Keyword(s):  
Experimental Data ◽  
Wave Function ◽  
Ground State ◽  
Radiative Decay ◽  
Magnetic Moments ◽  
Wave Functions ◽  
Decay Widths ◽  
Free Parameters ◽  
Theoretical Results

Performing a fit procedure on the hyperon masses, we first determine the free parameters in the Cornell-like hypercentral potential between the constituent quarks of hyperons in their ground state. To this end, using the variational principle, we apply the hyperspherical Hamiltonian including the Cornell-like hypercentral potential and the perturbation potentials due to the spin–spin, spin–isospin and isospin–isospin interactions between constituent quarks. In the following, we compute the hyperon magnetic moments as well as radiative decay widths of spin-3/2 hyperons using the spin-flavor wave function of hyperons. Our analysis shows acceptable consistencies between theoretical results and available experimental data. This leads to reliable wave functions for hyperons at their ground state.

scholarly journals The number of Be stars compared with the number of B stars, taking into account the specific physical characteristics of Be stars

1994 ◽  
Vol 162 ◽  
pp. 356-357
Author(s):  
D. Briot ◽  
J. Zorec
Keyword(s):  
Spectral Type ◽  
Bright Star ◽  
Physical Parameters ◽  
Emission Characteristics ◽  
Be Stars ◽  
Constant Mass ◽  
B Stars ◽  
The Past ◽  
Star Catalogue

It is very important for the understanding of the Be phenomenon, and particularly for locating a possible Be phase in the evolutionary track of B stars, to accurately determine the proportion of Be stars among all B stars. This type of study was already made several times in the past. Results obtained generally show a maximum Be frequency around spectral type B2 then a decrease towards late spectral types. Actually Be stars do not have the same characteristics as “normal” B stars and we have to take this into account in the determination of the ratio : number of Be stars / number of B stars. We use the Bright Star Catalogue (Hoffleit & Jaschek 1982) and the Supplement to the Bright Star Catalogue (Hoffleit, Saladyga & Wlasuk 1983) containing stars V= 7.10 and brighter. This study needed to be made separately for the different spectral types because:- Physical parameters of B stars are very different from B0 to B9;- Emission characteristics of Be stars vary very much, with a decrease from B0e to B9e.We successively consider three effects which can influence the frequency of Be stars:- The over-luminosity of Be stars as compared with B stars;- Spectral type changes during constant mass evolution;- Spectral type changes due to the fast rotation of Be stars.

Dwarfs Cooler than “M”: The Definition of Spectral Type “L” Using Discoveries from the 2 Micron All‐Sky Survey (2MASS)

1999 ◽  
Vol 519 (2) ◽  
pp. 802-833 ◽  
Author(s):  
J. Davy Kirkpatrick ◽  
I. Neill Reid ◽  
James Liebert ◽  
Roc M. Cutri ◽  
Brant Nelson ◽  
...  
Keyword(s):  
Spectral Type ◽  
Sky Survey ◽  
Definition Of
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