Eta CarinaeEta Carinae (η Carinae, abbreviated to η Car), formerly known as Eta Argus, is a stellar system containing at least two stars with a combined luminosity greater than five million times that of the Sun, located around distant in the constellation Carina. Previously a 4th-magnitude star, it brightened in 1837 to become brighter than Rigel, marking the start of its so-called "Great Eruption". It became the second-brightest star in the sky between 11 and 14 March 1843 before fading well below naked-eye visibility after 1856.
Plasma betaThe beta of a plasma, symbolized by β, is the ratio of the plasma pressure (p = n kB T) to the magnetic pressure (pmag = B2/2μ0). The term is commonly used in studies of the Sun and Earth's magnetic field, and in the field of fusion power designs. In the fusion power field, plasma is often confined using strong magnets. Since the temperature of the fuel scales with pressure, reactors attempt to reach the highest pressures possible. The costs of large magnets roughly scales like β1⁄2.
BoötesBoötes (boʊˈoʊtiːz ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from Boōtēs, which comes from Boṓtēs 'herdsman' or 'plowman' (literally, 'ox-driver'; from βοῦς boûs 'cow'). One of the 48 constellations described by the 2nd-century astronomer Ptolemy, Boötes is now one of the 88 modern constellations. It contains the fourth-brightest star in the night sky, the orange giant Arcturus.
HohlraumIn radiation thermodynamics, a hohlraum (a non-specific German word for a "hollow space" or "cavity") is a cavity whose walls are in radiative equilibrium with the radiant energy within the cavity. This idealized cavity can be approximated in practice by making a small perforation in the wall of a hollow container of any opaque material. The radiation escaping through such a perforation will be a good approximation to black-body radiation at the temperature of the interior of the container.
Jeans instabilityIn stellar physics, the Jeans instability causes the collapse of interstellar gas clouds and subsequent star formation, named after James Jeans. It occurs when the internal gas pressure is not strong enough to prevent gravitational collapse of a region filled with matter. For stability, the cloud must be in hydrostatic equilibrium, which in case of a spherical cloud translates to where is the enclosed mass, is the pressure, is the density of the gas (at radius ), is the gravitational constant, and is the radius.
Compton wavelengthThe Compton wavelength is a quantum mechanical property of a particle, defined as the wavelength of a photon whose energy is the same as the rest energy of that particle (see mass–energy equivalence). It was introduced by Arthur Compton in 1923 in his explanation of the scattering of photons by electrons (a process known as Compton scattering). The standard Compton wavelength λ of a particle is given by while its frequency f is given by where h is the Planck constant, m is the particle's proper mass, and c is the speed of light.
Beta PictorisBeta Pictoris (abbreviated β Pictoris or β Pic) is the second brightest star in the constellation Pictor. It is located from the Solar System, and is 1.75 times as massive and 8.7 times as luminous as the Sun. The Beta Pictoris system is very young, only 20 to 26 million years old, although it is already in the main sequence stage of its evolution. Beta Pictoris is the title member of the Beta Pictoris moving group, an association of young stars which share the same motion through space and have the same age.
Thirty Meter TelescopeThe Thirty Meter Telescope (TMT) is a planned extremely large telescope (ELT) that has become controversial due to its location on Mauna Kea, on the island of Hawaiʻi. The TMT would become the largest visible-light telescope on Mauna Kea. Scientists have been considering ELTs since the mid 1980s. In 2000, astronomers considered the possibility of a telescope with a light-gathering mirror larger than 20 meters (65') in diameter, using either small segments that create one large mirror, or a grouping of larger 8-meter (26') mirrors working as one unit.
Extremely large telescopeAn extremely large telescope (ELT) is an astronomical observatory featuring an optical telescope with an aperture for its primary mirror from 20 metres up to 100 metres across, when discussing reflecting telescopes of optical wavelengths including ultraviolet (UV), visible, and near infrared wavelengths. Among many planned capabilities, extremely large telescopes are planned to increase the chance of finding Earth-like planets around other stars.
Legendre transformationIn mathematics, the Legendre transformation (or Legendre transform), named after Adrien-Marie Legendre, is an involutive transformation on real-valued convex functions of one real variable. In physical problems, it is used to convert functions of one quantity (such as velocity, pressure, or temperature) into functions of the conjugate quantity (momentum, volume, and entropy, respectively).
