Local BubbleThe Local Bubble, or Local Cavity, is a relative cavity in the interstellar medium (ISM) of the Orion Arm in the Milky Way. It contains the nearest stars and brown dwarfs and, among others, the Local Interstellar Cloud (which contains the Solar System), the neighboring G-Cloud, the Ursa Major moving group (List of nearby stellar associations and moving groups stellar moving group), and the Hyades (the nearest open cluster).
SupernovaAstrophysical phenomenonSN 1994D (bright spot on the lower left), a Type Ia supernova within its host galaxy, NGC 4526A supernova (pl.: supernovae) is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed to form a diffuse nebula.
Stellar classificationClassification of stars based on spectral properties In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element.
Interstellar mediumThe interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic medium. The energy that occupies the same volume, in the form of electromagnetic radiation, is the interstellar radiation field.
Solar SystemPlanetary system consisting of the Sun and objects orbiting itThe Solar System is the gravitationally bound system of the Sun and the masses that orbit it, most prominently its eight planets, of which Earth is one. The Solar System is an isolated single-star planetary system (not part of a larger star system) within the Milky Way Galaxy.Erg (unit)The erg is a unit of energy equal to 10joules (100nJ). It is not an SI unit, instead originating from the older centimetre–gram–second system of units (CGS). Its name is derived from ergon (ἔργον), a Greek word meaning 'work' or 'task'. An erg is the amount of work done by a force of one dyne exerted for a distance of one centimetre. In the CGS base units, it is equal to one gram centimetre-squared per second-squared (g⋅cm/s).
JouleThe joule ( , or ; symbol: J) is the unit of energy in the International System of Units (SI). In terms of SI base units, one joule corresponds to one kilogram-metre squared per second squared(1 J = 1 kg⋅m⋅s). One joule is equal to the amount of work done when a force of one newton displaces a body through a distance of one metre in the direction of that force.
Cosmic dustCosmic dust – also called extraterrestrial dust, space dust, or star dust – is dust that occurs in outer space or has fallen onto Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 μm), such as micrometeoroids (<30 μm) and meteoroids (>30 μm).
Stellar Wind"Stellar Wind" (or "Stellarwind") was the code name of a warrantless surveillance program begun under the George W. Bush administration's President's Surveillance Program (PSP). The National Security Agency (NSA) program was approved by President Bush shortly after the September 11, 2001 attacks and was revealed by Thomas Tamm to The New York Times in 2004.
Extinction (astronomy)In astronomy, extinction is the absorption and scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observer. Interstellar extinction was first documented as such in 1930 by Robert Julius Trumpler.
AstronomyAstronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation.
KelvinThe kelvin (symbol: K) is the base unit for temperature in the International System of Units (SI).
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