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A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.
Awareness space includes activity space, and it enlarges as new locations are discovered and new information is gathered. [4] See also search space and mental map. axis 1. (coordinate system) Any of the reference lines of a Cartesian coordinate system, from which the signed distances to each coordinate are measured, e.g. the x-axis or the y ...
Since X-rays are absorbed by the Earth's atmosphere, all X-ray observations must be performed from high-altitude balloons, rockets, or X-ray astronomy satellites. Notable X-ray sources include X-ray binaries , pulsars , supernova remnants , elliptical galaxies , clusters of galaxies , and active galactic nuclei .
The features of a place related to the immediate environment in which the place is located (e.g. terrain, soil, subsurface, geology, groundwater, etc.). [5] situation The features of a place related to its location relative to other places (e.g., accessibility, hinterland quality). [5] skerry
"Fierce" may easily describe lions or other grand, wild animals, but nowadays, the term is given to someone confident and eye-catching. The term entered the mainstream in part thanks to Beyoncé's ...
Lists of galaxies. List of galaxies; List of largest galaxies; List of galaxies with richest globular cluster systems; List of nearest galaxies; List of galaxies named after people
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The branch of astronomy that deals with the physics of the Universe, especially with the compositional nature of celestial bodies rather than their positions or motions in space. attenuation coefficient The measure of how much the incident energy beam (e.g. ultrasound or x-rays) is weakened by the material it is passing through. [19] atom