# degeneracy

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**Supernova**— This article is about the astronomical event. For other uses, see Supernova (disambiguation). Multiwavelength X ray, infrared, and optical compilation image of Kepler s supernova remnant, SN 1604. A supernova is a stellar explosion that is more… …82

**Quantum harmonic oscillator**— The quantum harmonic oscillator is the quantum mechanical analogue of the classical harmonic oscillator. It is one of the most important model systems in quantum mechanics because an arbitrary potential can be approximated as a harmonic potential …83

**Compact star**— In astronomy, the term compact star (sometimes compact object) is used to refer collectively to white dwarfs, neutron stars, other exotic dense stars, and black holes. These objects are all small for their mass. The term compact star is often… …84

**Partition function (statistical mechanics)**— For other uses, see Partition function (disambiguation). Partition function describe the statistical properties of a system in thermodynamic equilibrium. It is a function of temperature and other parameters, such as the volume enclosing a gas.… …85

**Helium flash**— A helium flash is the runaway fusion of helium in the core of low mass stars of less than about 2.25 solar masses and greater than about 0.5 solar mass, or on the surface of an accreting white dwarf star. They may also occur in the outer layers… …86

**Immirzi parameter**— The Immirzi parameter (also known as the Barbero Immirzi parameter) is a numerical coefficient appearing in loop quantum gravity, a nonperturbative theory of quantum gravity. The Immirzi parameter measures the size of the quantum of area in… …87

**Bose gas**— An ideal Bose gas is a quantum mechanical version of a classical ideal gas. It is composed of bosons, which have an integer value of spin, and obey Bose Einstein statistics. The statistical mechanics of bosons were developed by Satyendra Nath… …88

**LGBT history**— Gay Liberation monument in New York City LGBT history refers to the history of lesbian, gay, bisexual, and transgender (LGBT) peoples and cultures around the world, dating back to the first recorded instances of same sex love and sexuality of… …89

**Arboricity**— The arboricity of an undirected graph is the minimum number of forests into which its edges can be partitioned. Equivalently it is the minimum number of spanning trees needed to cover all the edges of the graph.ExampleThe figure shows the… …90

**Nearly-free electron model**— Electronic structure methods Tight binding Nearly free electron model Hartree–Fock method Modern valence bond Generalized valence bond Møller–Plesset perturbat …