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Ultraviolet astronomy is the observation of electromagnetic radiation at ultraviolet wavelengths between approximately 10 and 320 nanometres; shorter wavelengths—higher energy photons—are studied by X-ray astronomy and gamma-ray astronomy. [1] Ultraviolet light is not visible to the human eye. [2]
The telescope made observations in ultraviolet wavelengths to measure the history of star formation in the universe 80% of the way back to the Big Bang. Since scientists have evidence that the Universe to be about 13.8 billion years old, the mission studied galaxies and stars across about 10 billion years of cosmic history. [8]
A star is a massive luminous spheroid astronomical object made of plasma that is held together by its own gravity.Stars exhibit great diversity in their properties (such as mass, volume, velocity, stage in stellar evolution, and distance from Earth) and some of the outliers are so disproportionate in comparison with the general population that they are considered extreme.
The first star in the list, Godzilla [1] — an LBV in the distant Sunburst galaxy — is probably the brightest star ever observed, although it is believed to be undergoing a temporary episode of increased luminosity that has lasted at least seven years, in a similar manner to the Great Eruption of Eta Carinae that was witnessed in the 19th ...
Marginal cases are allowed; for example, a star may be either a supergiant or a bright giant, or may be in between the subgiant and main-sequence classifications. In these cases, two special symbols are used: A slash (/) means that a star is either one class or the other. A dash (-) means that the star is in between the two classes.
International Ultraviolet Explorer (IUE or Explorer 57, formerly SAS-D), [2] was the first space observatory primarily designed to take ultraviolet (UV) electromagnetic spectrum. The satellite was a collaborative project between NASA , the United Kingdom 's Science and Engineering Research Council (SERC, formerly UKSRC) and the European Space ...
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars.
The Sun, the star in the center of the Solar System to which the Earth is gravitationally bound, is an example of a G-type main-sequence star (G2V type). Each second, the Sun fuses approximately 600 million tons of hydrogen into helium in a process known as the proton–proton chain (4 hydrogens form 1 helium), converting about 4 million tons ...