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] Most of the light at these wavelengths is absorbed by the Earth's atmosphere, so observations at these wavelengths must be performed from the upper atmosphere or from space.[1]
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How do astronomers use ultraviolet light to make discoveries?
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This Is Not What Space Looks Like
Transcription
Swirling spiral arms of galaxy M33 can be seen in visible light, but the true extent of these spiral arms are revealed in ultraviolet light. Just as a dog can hear a whistle just outside the range of human hearing, bugs can see light just outside the range our eyes can see. A bug zapper emits this ultraviolet light to attract insects. Johann Ritter conducted an experiment in 1801 to find out what, if any, electromagnetic waves are beyond violet. Ritter knew that photographic paper would turn black more rapidly in blue light than in red light. So he tried exposing the paper beyond the violet end of the visible spectrum. Sure enough, the paper turned black proving the existence of light beyond violet, ultraviolet rays These ultraviolet rays, or UV radiation, vary in wavelength from 400 nanometers to 10 nanometers and can be subdivided into 3 regions: UV-A, UV-B and UV-C. Visible light from the Sun passes through the atmosphere and reaches the Earth's surface. UV-A, long wave ultraviolet, is the closest to visible light. Most UV-A also reaches the surface. But shorter wavelengths, called UV-B, are the harmful rays that cause sunburn. Fortunately, about 95% of these harmful UV-B rays are absorbed by ozone in the Earth's atmosphere. UV-C rays are the shortest and most harmful and are almost completely absorbed by our atmosphere. The Ozone Monitoring Instrument aboard NASA's Aura satellite detects ultraviolet radiation to help scientists study and monitor the chemistry of our atmosphere, including UV absorbing ozone. While atmospheric protection from harmful UV radiation is good for humans... it complicates the study of naturally produced UV rays in the Universe, by scientists here on the Earth's surface. Young hot stars shine most of their light beyond the visible light spectrum at ultraviolet wavelengths. Scientists need telescopes in orbit above the Earth's UV absorbing atmosphere to find and study these UV-bright regions of star formations in distant galaxies. New young stars in the spiral arms of galaxy M81 can be seen in this Galaxy Evolution Explorer, GALEX, image from NASA. Chemical substances, both atoms and molecules, interact with UV light making this region particularly interesting to scientists. An ultraviolet instrument aboard Cassini has detected hydrogen, oxygen, water ice, and methane in the Saturn system. UV data have also revealed details of Saturn's aurorae. Scientists also use UV waves shining from distant stars to view permanently shadowed regions of lunar craters. The Lyman-Alpha Mapping Project, or LAMP, instrument aboard NASA's Lunar Reconnaissance Orbiter can use this faint star-shine to look for possible water ice on the moon. Ultraviolet rays may be harmful to humans, but they are essential to studying the health of our planet's protective atmosphere and give us valuable clues to the formation and composition of distant celestial objects.
Overview
Ultraviolet line spectrum measurements (spectroscopy) are used to discern the chemical composition, densities, and temperatures of the interstellar medium, and the temperature and composition of hot young stars. UV observations can also provide essential information about the evolution of galaxies. They can be used to discern the presence of a hot white dwarf or main sequence companion in orbit around a cooler star.[3][4]
The ultraviolet universe looks quite different from the familiar stars and galaxies seen in visible light. Most stars are actually relatively cool objects emitting much of their electromagnetic radiation in the visible or near-infrared part of the spectrum. Ultraviolet radiation is the signature of hotter objects, typically in the early and late stages of their evolution. In the Earth's sky seen in ultraviolet light, most stars would fade in prominence. Some very young massive stars and some very old stars and galaxies, growing hotter and producing higher-energy radiation near their birth or death, would be visible. Clouds of gas and dust would block the vision in many directions along the Milky Way.
Space-based solar observatories such as SDO and SOHO use ultraviolet telescopes (called AIA and EIT, respectively) to view activity on the Sun and its corona. Weather satellites such as the GOES-R series also carry telescopes for observing the Sun in ultraviolet.
The Hubble Space Telescope and FUSE have been the most recent major space telescopes to view the near and far UV spectrum of the sky, though other UV instruments have flown on smaller observatories such as GALEX, as well as sounding rockets and the Space Shuttle.
Pioneers in ultraviolet astronomy include George Robert Carruthers, Robert Wilson, and Charles Stuart Bowyer.
Ultraviolet space telescopes
- Far Ultraviolet Camera/Spectrograph on Apollo 16 (April 1972)- + ESRO - TD-1A (135-286 nm; 1972–1974)
- - Orbiting Astronomical Observatory (#2:1968-73. #3:1972-1981)
- Orion 1 and Orion 2 Space Observatories (#1: 200-380 nm, 1971; #2: 200-300 nm, 1973)- +
- Astronomical Netherlands Satellite (150-330 nm, 1974–1976) - +
- International Ultraviolet Explorer (115-320 nm, 1978–1996) - - Astron-1 (150-350 nm, 1983–1989)
- - Glazar 1 and 2 on Mir (in Kvant-1, 1987–2001)
- - FAUST (140-180 nm, in ATLAS-1 Spacelab aboard STS-45 mission, March 1992)[5]
- - EUVE (7-76 nm, 1992–2001)
- - FUSE (90.5-119.5 nm, 1999–2007)
- + - Extreme ultraviolet Imaging Telescope (on SOHO imaging Sun at 17.1, 19.5, 28.4, and 30.4 nm)
- + - Hubble Space Telescope (various 115-800 nm,1990-1997-) (STIS 115–1030 nm, 1997–) (WFC3 200-1700 nm, 2009–)
- - Swift Gamma-Ray Burst Mission (170–650 nm, 2004- )
- - Hopkins Ultraviolet Telescope (flew in 1990 and 1995)
- ROSAT XUV[6] (17-210eV) (30-6 nm, 1990–1999)- - Far Ultraviolet Spectroscopic Explorer (90.5-119.5 nm, 1999–2007)
- - Galaxy Evolution Explorer (135–280 nm, 2003–2012)
- Hisaki (130-530 nm, 2013 - 2023)
- Lunar-based ultraviolet telescope (LUT) (on Chang'e 3 lunar lander, 245-340 nm, 2013 -)
- Astrosat (130-530 nm, 2015 -)- - Colorado Ultraviolet Transit Experiment (CUTE) - (255-330 nm spectrograph, 2021- )
- - Public Telescope (PST)[7] (100-180 nm, Proposed 2015, EU funded study )
- - Viewpoint-1 SpaceFab.US (200-950 nm, Launch planned 2022)[8]
See also List of ultraviolet space telescopes
Ultraviolet instruments on planetary spacecraft
- - UVIS (Cassini) - 1997 (at Saturn from 2004 to 2017)
- - MASCS (MESSENGER) - 2004 (at Mercury from 2011 to 2015)
- - Alice (New Horizons) - 2006 (Pluto flyby in 2015)
- - UVS (Juno) - 2011 (at Jupiter since 2016)
- - IUVS (MAVEN) - 2013 (at Mars since 2014)
See also
- Markarian galaxies – Galaxy with a nucleus emitting exceptionally large amounts of ultraviolet
- Pea galaxy – Possible type of luminous blue compact galaxy
References
- ^ a b A. N. Cox, ed. (2000). Allen's Astrophysical Quantities. New York: Springer-Verlag. ISBN 0-387-98746-0.
- ^ "Ultraviolet Light". Archived from the original on 2017-02-13. Retrieved 2017-02-12.
- ^ Reimers, D. (July 1984). "Discovery of a white dwarf companion of the "hybrid" K giant HD 81817". Astronomy and Astrophysics. 136: L5–L6. Bibcode:1984A&A...136L...5R.
- ^ Ortiz, Roberto; Guerrero, Martín A. (September 2016). "Ultraviolet emission from main-sequence companions of AGB stars". Monthly Notices of the Royal Astronomical Society. 461 (3): 3036–3046. arXiv:1606.09086. Bibcode:2016MNRAS.461.3036O. doi:10.1093/mnras/stw1547.
- ^ Lampton, M., Sasseen, T. P., Wu, X., & Bowyer, S. (1993). "A study of the impact of the space shuttle environment on faint far-UV geophysical and astronomical phenomena". Geophysical Research Letters. 20 (6): 539–542. Bibcode:1993GeoRL..20..539L. doi:10.1029/93GL00093.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ R. Staubert, H. Brunner,1 H.-C. Kreysing - The German ROSAT XUV Data Center and a ROSAT XUV Pointed Phase Source Catalogue (1996)
- ^ Ein privates Weltraumteleskope für Amateure und Profis Spektrum DE. June 2015
- ^ "Space Telescopes".
External links
Media related to Ultraviolet astronomy at Wikimedia Commons
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This page was last edited on 2 April 2024, at 14:37