相关论文: Variations on a classical theme: On the formal rel…
The visual brightness of the night sky is not a single-valued function of its brightness in other photometric bands, because the transformations between photometric systems depend on the spectral power distribution of the skyglow. We…
We present a geometrical model of the distribution of luminous matter in the universe, derived from a very simple reaction-diffusion model of turbulent phenomena. The apparent dimension of luminous matter, $D(l)$, depends linearly on the…
The relative brightnesses of standard candles have long been known to be potentially powerful probes of distance. The distance modulus, the difference between observed and absolute magnitudes, has been associated with the values of the…
The dependency of the Cepheid Period-Luminosity Relation on chemical composition at different wavelengths is assessed via direct detailed abundance analysis of Galactic and Magellanic Cepheids, as derived from high resolution, high…
Luminosity is a measure of the colliding frequency between beam and target and it is a crucial parameter for the measurement of absolute values, such as reaction cross sections. In this paper, we make use of experimental data from the ESR…
The relationship between the luminescence at 1.9 eV and the absorption bands at 2.0 eV and at 4.8 eV were investigated in a wide variety of synthetic silica samples exposed to different gamma- and beta-ray irradiation doses. We found that…
This paper deals with the effect of errors in the B and V magnitudes, or measurements in any other color system, on the width of the main sequence in a color-magnitude (Hertzsprung-Russell) diagram. The width is defined as the dispersion in…
Magnitude is a real-valued invariant of metric spaces, analogous to the Euler characteristic of topological spaces and the cardinality of sets. The definition of magnitude is a special case of a general categorical definition that clarifies…
Direct-view LED displays are widely adopted in large-format applications due to their high luminance and reliability. However, visual comfort and accurate performance evaluation remain challenging due to the complex interaction between…
The relationship between galaxy luminosities and rotation rates is studied with total luminosities in the K' band. Extinction problems are essentially eliminated at this band centered at 2.1 micron. A template luminosity-linewidth relation…
In this tutorial, the physical origins and mathematical analyses of laser linewidths are reviewed. The semi-classical model is based on an equation for the light-mode amplitude that includes random source terms, one term for each process…
The goal of this document is to illustrate that teaching the concepts of magnitudes is a needless complication in introductory astronomy courses, and that use of monochromatic luminosities, rather than arbitrarily defined magnitudes, leads…
We investigate the accuracy and reliability of the semiempirical period - blue amplitude - V-band luminosity relationship for ab-type RR Lyrae stars originally obtained by Castellani & De Santis (1994) and De Santis (1996). We infer that…
The Cepheid Leavitt Law (LL), also known as the Period-Luminosity relation, is a crucial tool for assembling the cosmic distance ladder. By combining data from the OGLE-IV catalogue with mid-infrared photometry from the Spitzer Space…
The primary challenge in silicon photonics is achieving efficient luminescence in the communication band, crucial for its large-scale application. Despite significant efforts, silicon light sources still suffer from low efficiency and…
The luminosity-angular distance relation for an expanding universe is given by $D_L=D_A(1+z)^2$. This relation is commonly proven by geometrical considerations from the source point of view assuming an expanding universe. In this note, the…
We prove a gravitational lensing theorem: the magnification of a source of uniform brightness by a foreground spherical lens is mu =1+pi(2R_E^2-R_L^2)/A, where A is the area of the source and R_E and R_L are the Einstein radius and size of…
TThe Period-Luminosity (PL) relation for Cepheid variable stars in the Large Magellanic Cloud (LMC) is crucial for distance measurements in astronomy. This study analyzes the impact of using the median rather than the mean on the PL…
The absorption length, $\lambda_{abs}$, of light with wavelengths between 0.95 and 1.30$~\mu$m in silicon irradiated with 24$~$GeV/c protons to 1$~$MeV neutron equivalent fluences between 0 and $8.6 \times 10^{15}~$cm$^{-2}$ has been…
We show that the Euclidean value of <V/Vmax> for gamma-ray bursts (GRB) selected on a timescale of 1024 ms is correlated with spectral hardness. The value of <V/Vmax> ranges from 0.42 for soft bursts to 0.26 for the hardest bursts. Given…