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Main-sequence stars vary in surface temperature from approximately 2,000 to 50,000 K, whereas more-evolved stars – in particular, newly-formed white dwarfs – can have surface temperatures above 100,000 K. [3] Physically, the classes indicate the temperature of the star's atmosphere and are normally listed from hottest to coldest.
The internal structure of a main sequence star depends upon the mass of the star. In stars with masses of 0.3–1.5 solar masses (M ☉), including the Sun, hydrogen-to-helium fusion occurs primarily via proton–proton chains, which do not establish a steep temperature gradient. Thus, radiation dominates in the inner portion of solar mass stars.
Below there are lists the nearest stars separated by spectral type. The scope of the list is still restricted to the main sequence spectral types: M , K , F , G , A , B and O . It may be later expanded to other types, such as S , D or C .
A multiple star system consists of two or more stars that appear from Earth to be close to one another in the sky. [dubious – discuss] This may result from the stars actually being physically close and gravitationally bound to each other, in which case it is a physical multiple star, or this closeness may be merely apparent, in which case it is an optical multiple star [a] Physical multiple ...
The O-B stars in the association will have burned all their fuel within 10 million years. (Compare this to the current age of the Sun at about 5 billion years.) The Hipparcos satellite provided measurements that located a dozen OB associations within 650 parsecs of the Sun. [ 8 ] The nearest OB association is the Scorpius–Centaurus ...
In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is uniformly isotropic and homogeneous when viewed on a large enough scale, since the forces are expected to act equally throughout the universe on a large scale, and should, therefore, produce no observable inequalities in the large-scale structuring over the course ...
F-type main-sequence stars are main-sequence stars (luminosity class V) of spectral type F. Subcategories. This category has only the following subcategory. ...
The oldest stars observed thus far, [10] known as population II, have very low metallicities; [16] [6] as subsequent generations of stars were born, they became more metal-enriched, as the gaseous clouds from which they formed received the metal-rich dust manufactured by previous generations of stars from population III.