Search results
Results From The WOW.Com Content Network
The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength. The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high frequency these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and ...
Energy band gaps can be classified using the wavevectors of the states surrounding the band gap: Direct band gap: the lowest-energy state above the band gap has the same k as the highest-energy state beneath the band gap. Indirect band gap: the closest states above and beneath the band gap do not have the same k value.
Photometric system. In astronomy, a photometric system is a set of well-defined passbands (or optical filters ), with a known sensitivity to incident radiation. The sensitivity usually depends on the optical system, detectors and filters used. For each photometric system a set of primary standard stars is provided.
Absolute magnitude is defined as the apparent magnitude that a star or object would have if it were observed from a distance of 10 parsecs (33 light-years; 3.1 × 10 14 kilometres; 1.9 × 10 14 miles). Therefore, it is of greater use in stellar astrophysics since it refers to a property of a star regardless of how close it is to Earth.
The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The spectral class of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature.
Quantum dots are theoretically described as a point-like, or zero dimensional (0D) entity. Most of their properties depend on the dimensions, shape, and materials of which QDs are made. Generally, QDs present different thermodynamic properties from their bulk materials. One of these effects is melting-point depression.
Models. A stellar evolutionary model is a mathematical model that can be used to compute the evolutionary phases of a star from its formation until it becomes a remnant. The mass and chemical composition of the star are used as the inputs, and the luminosity and surface temperature are the only constraints.
In some materials, for example, in graphene and zigzag graphene quantum dot, there exists the energy states having energy eigenvalues exactly equal to zero (E=0) besides the conduction and valence bands. These states are called edge states which modifies the electronic and optical properties of the materials significantly. [3] [4] [5] [6]