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T Dwarf
An object with the spectral type T (also called T dwarf or methane brown dwarf) is either a brown dwarf or young free-floating planetary-mass object. A directly imaged exoplanet with a young age can also be a T-dwarf. T dwarfs are colder than L dwarfs, but warmer than Y dwarfs. Prototype Gliese 229B The first T-dwarf discovered was Gliese 229B, which was discovered in 1995. This object had a temperature below 1000 K and showed methane (CH4), water vapor (H2O) and carbon monoxide (CO) in its spectrum. In the upper atmosphere CO is converted into CH4 and H2O, while the opposite is true for the hotter lower atmosphere. It also showed absorption due to caesium (Cs), but absorption features commonly found in M-dwarfs ( CaH, FeH, TiO, and VO) were missing. Ammonia (NH3) was included in the analysis of the spectrum. Sodium (Na) and potassium (K) are also detected in this T-dwarf. Later work found a dynamical mass of 70 ± 5 for Gliese 229B, which is much higher than the cooli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Dwarf
Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main sequence, main-sequence stars. Their mass is approximately 13 to 80 Jupiter mass, times that of Jupiter ()not big enough to sustain nuclear fusion of hydrogen into helium in their cores, but massive enough to emit some light and heat from the deuterium fusion, fusion of deuterium (deuterium, 2H). The most massive ones (> ) can lithium burning, fuse lithium (lithium-7, 7Li). Astronomers classify self-luminous objects by Stellar classification#Spectral types, spectral type, a distinction intimately tied to the surface temperature, and brown dwarfs occupy types M (2100–3500 Kelvin, K), L (1300–2100 Kelvin, K), T (600–1300 Kelvin, K), and Y ( 80 ''M''J), which have spectral classes L2 to L6. Spectral class T As GD 165B is the prototype of the L dwarfs, Gliese 229B is the prototype of a second ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium
Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the periodic table. Its only stable isotope is 23Na. The free metal does not occur in nature and must be prepared from compounds. Sodium is the Abundance of elements in Earth's crust, sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars, sodalite, and halite (NaCl). Many salts of sodium are highly water-soluble: sodium ions have been Leaching (chemistry), leached by the action of water from the Earth, Earth's minerals over eons, and thus sodium and chlorine are the most common dissolved elements by weight in the oceans. Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful sodium compounds, sodium hydroxide (lye) is used in Soap, soap manufac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H Band (infrared)
In infrared astronomy, the H band refers to an atmospheric transmission window centred on 1.65 micrometres with a Full width at half maximum of 0.35 micrometresIan McClean, Electronic Imaging in Astronomy, Second Edition, Springer, 2008. (in the near-infrared). Save for a limited amount of absorption by water vapor, Earth's atmosphere is highly translucent at the wavelengths covered by the H band. The window is also notably less likely to be contaminated by infrared excess than other bands. The band is useful for a range of infrared observations including the imaging of sunspots, spectroscopic investigation of late-type stars, and imaging planetary phenomena such as extraterrestrial vortices or volcanic activity in the Solar System. In addition stellar atmospheres are highly transparent in the H band and stellar light in the window originates from deeper in the stellar atmosphere than any other band. It also includes within it access to several sets of spectral lines including f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
K Band (infrared)
In infrared astronomy, the K band is an atmospheric transmission window centered on 2.2 μm (in the near-infrared 136 THz range). HgCdTe-based detectors are typically preferred for observing in this band. Photometric system In astronomy, a photometric system is a set of well-defined passbands (or optical filters), with a known sensitivity to incident radiation. The sensitivity usually depends on the optical system, detectors and filters used. For each photometric s ...s used in astronomy are sets of filters or detectors that have well-defined windows of absorption, based around a central peak detection frequency and where the edges of the detection window are typically reported where sensitivity drops below 50% of peak. Various organizations have defined systems with various peak frequencies and cutoffs in the K band, including , and KS, and Kdark. Table 1., Filter sets used at Mauna Kea and the South Pole. See also * Absolute magnitude References Electromagn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sloan Digital Sky Survey
The Sloan Digital Sky Survey or SDSS is a major multi-spectral imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project began in 2000 and was named after the Alfred P. Sloan Foundation, which contributed significant funding. A consortium of the University of Washington and Princeton University was established to conduct a redshift survey. The Astrophysical Research Consortium (ARC) was established in 1984 with the additional participation of New Mexico State University and Washington State University to manage activities at Apache Point. In 1991, the Sloan Foundation granted the ARC funding for survey efforts and the construction of equipment to carry out the work. Background At the time of its design, the SDSS was a pioneering combination of novel instrumentation as well as data reduction and storage techniques that drove major advances in astronomical observations, dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SDSS 1021 , a school in Delta, British Columbia, Canada
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SDSS may refer to: * Sloan Digital Sky Survey, a major multi-filter imaging and spectroscopic redshift survey * Social Democratic Party of Slovakia * Spatial Decision Support System, a GIS based decision aiding system * Independent Democratic Serb Party, a political party of Croatian Serbs (''Samostalna demokratska srpska stranka'' in Serbo-Croatian) * South Delta Secondary School South Delta Secondary (SDSS) is a public high school in Tsawwassen, British Columbia, Canada. There are approximately 1,500 students enrolled in each grade 8 through 12 (as of 2019/2020). Graduation rates in the years 2005 to 2010 vary between 9 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SDSS 1624+00
SDSS 1624+00 (also known as SDSSp J162414.371+002915.6) is the first T dwarf discovered in the field, meaning it does free-float in space and does not belong to a group of stars. The object was discovered after Gliese 229B and at around the same time Gliese 570D was discovered. SDSS 1624+00 was discovered in 1999 with preliminary data of the Sloan Digital Sky Survey. It was selected because of its extreme red color (i-z=3.77 ±0.21 mag). Optical spectroscopy was obtained with the Apache Point 3.5 m telescope and near-infrared photometry and spectroscopy with the United Kingdom Infrared Telescope. The spectrum showed absorption due to water vapor, methane and caesium and the spectrum was similar to Gliese 229B, but with SDSS 1624+00 showing a stronger potassium line. It is 1.2 mag fainter than Gliese 229B, which helped to constrain the distance to around 10 parsec. A red spectrum was obtained with the Keck Observatory. The researchers found that SDSS 1624+00 is likely w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliese 570
Gliese 570 (or 33 G. Librae) is a quaternary star system approximately 19 light-years away. The primary star is an orange dwarf star (much dimmer and smaller than the Sun). The other secondary stars are themselves a binary system, two red dwarfs that orbit the primary star. A brown dwarf has been confirmed to be orbiting in the system. In 1998, an extrasolar planet was thought to orbit the primary star, but it was discounted in 2000. Distance and visibility In the night sky, the Gliese 570 system lies in the southwestern part of Libra. The system is southwest of Alpha Librae and northwest of Sigma Librae. In the early 1990s, the European Hipparcos mission measured the parallax of components B and C, suggesting that the system was at a distance of 24.4 light-years from the Sun. This, however, was a relatively large error as Earth-based parallax and orbit observations suggest that the two stars are actually part of a system with Gliese 570 A, and must actually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectral Sequence With The Coolest T-dwarfs And The Two Ammonia-bearing Brown Dwarfs (geminiann08011a)
''Spectral'' is a 2016 Hungarian-American military science fiction action film co-written and directed by Nic Mathieu. Written with Ian Fried (screenwriter), Ian Fried & George Nolfi, the film stars James Badge Dale as DARPA research scientist Mark Clyne, with Max Martini, Emily Mortimer, Clayne Crawford, and Bruce Greenwood in supporting roles. The film is set in a civil war-ridden Moldova as invisible entities slaughter any living being caught in their path. The film was released worldwide on December 9, 2016 on Netflix. On February 1, 2017, Netflix released a prequel graphic novel of the film called ''Spectral: Ghosts of War'' which was made available digitally through the website ComiXology. Plot DARPA researcher Mark Clyne is sent to a United States, US United States Armed Forces, military Air base, airbase on the outskirts of Chișinău, to consult his created line of hyperspectral imaging goggles issued to United States Army, US Army United States Army Special Forces, S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
