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Primeval Structure Telescope
The Primeval Structure Telescope (PaST), also called 21 Centimetre Array (21CMA), is a Chinese radio telescope array designed to detect the earliest luminous objects in the universe, including the first stars, supernova explosions, and black holes, in the range of 100 to 1 billion years ago. All of these objects were strong sources of ultraviolet radiation, so they ionised the material surrounding them. The structure of this reionisation reflects the overall density structure at the redshift of luminous-object formation. Location The telescope is built on the high plateau of Ulasitai () in Xinjiang, close to the southern entrance of the Tianshan Shengli tunnel. This is a remote area away from most television and radios signals that may interfere the weak 21 cm background signals. It is also close to the existing Urumqi VLBI station (Nanshan Observatory) in Gangou township. Overview PaST consists of an array of some ten-thousand log-periodic antennas spread over several squar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultraviolet
Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs, Cherenkov radiation, and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. The photons of ultraviolet have greater energy than those of visible light, from about 3.1 to 12 electron volts, around the minimum energy required to ionize atoms. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack sufficient energy, it can induce chemical reactions and cause many substances to glow or fluoresce. Many practical applications, including chemical and biological effects, are derived from the way that UV radiation can interact with organic molecules. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reionisation
In the fields of Big Bang theory and cosmology, reionization is the process that caused electrically neutral atoms in the primordial universe to reionize after the lapse of the " dark ages". Detecting and studying the reionization process is challenging but multiple avenues have been pursued. This reionization was driven by the formation of the first stars and galaxies. Concept Reionization refers to a change in the intergalactic medium from neutral hydrogen to ions. The neutral hydrogen had been ions at an earlier stage in the history of the universe, thus the conversion back into ions is termed a ''re''ionization. The reionization was driven by energetic photons emitted by the first stars and galaxies. In the timeline of the universe, neutral hydrogen gas was originally formed when primordial hydrogen nuclei (protons) combined with electrons. Light with sufficient energy will ionize neutral hydrogen gas. At early times, light was so dense and energetic that hydrogen at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xinjiang
Xinjiang,; , SASM/GNC romanization, SASM/GNC: Chinese postal romanization, previously romanized as Sinkiang, officially the Xinjiang Uygur Autonomous Region (XUAR), is an Autonomous regions of China, autonomous region of the China, People's Republic of China (PRC), located in the Northwest China, northwest of the country at the crossroads of Central Asia and East Asia. Being the List of Chinese administrative divisions by area, largest province-level division of China by area and the List of the largest country subdivisions by area, 8th-largest country subdivision in the world, Xinjiang spans over and has about 25 million inhabitants. Xinjiang Borders of China, borders the countries of Afghanistan, India, Kazakhstan, Kyrgyzstan, Mongolia, Pakistan, Russia, and Tajikistan. The rugged Karakoram, Kunlun Mountains, Kunlun and Tian Shan mountain ranges occupy much of Xinjiang's borders, as well as its western and southern regions. The Aksai Chin and Trans-Karakoram Tract regions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tianshan Shengli Tunnel
The Tian Shan, also known as the Tengri Tagh or Tengir-Too, meaning the "Mountains of God/Heaven", is a large system of mountain ranges in Central Asia. The highest peak is Jengish Chokusu at high and located in Kyrgyzstan. Its lowest point is at the Turpan Depression, which is below sea level. The Tian Shan is sacred in Tengrism. Its second-highest peak is known as Khan Tengri, which can be translated as "Lord of the Spirits". At the 2013 Conference on World Heritage, the eastern portion of Tian Shan in western China's Xinjiang Region was listed as a World Heritage Site. The western portion in Kyrgyzstan, Kazakhstan, and Uzbekistan was then listed in 2016. Geography Tian Shan with the ancient Silk Road The Tian Shan range is located north and west of the Taklamakan Desert and directly north of the Tarim Basin. It straddles the border regions of Kazakhstan, Kyrgyzstan, Uzbekistan and Xinjiang in Northwest China. To the south, it connects with the Pamir Mountains, while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Line
The hydrogen line, 21 centimeter line, or H I line is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms. It is produced by a spin-flip transition, which means the direction of the electron's spin is reversed relative to the spin of the proton. This is a quantum state change between the two hyperfine levels of the hydrogen 1 s ground state. The electromagnetic radiation producing this line has a frequency of (1.42 GHz), which is equivalent to a wavelength of in a vacuum. According to the Planck–Einstein relation , the photon emitted by this transition has an energy of []. The constant of proportionality, , is known as the Planck constant. The hydrogen line frequency lies in the L band, which is located in the lower end of the microwave region of the electromagnetic spectrum. It is frequently observed in radio astronomy because those radio waves can penetrate the large clouds of interstellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Very-long-baseline Interferometry
Very-long-baseline interferometry (VLBI) is a type of astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telescopes on Earth or in space. The distance between the radio telescopes is then calculated using the time difference between the arrivals of the radio signal at different telescopes. This allows observations of an object that are made simultaneously by many radio telescopes to be combined, emulating a telescope with a size equal to the maximum separation between the telescopes. Data received at each antenna in the array include arrival times from a local atomic clock, such as a hydrogen maser. At a later time, the data are correlated with data from other antennas that recorded the same radio signal, to produce the resulting image. The resolution achievable using interferometry is proportional to the observing frequency. The VLBI technique enables the distance between t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gangou Township, Xinjiang
Gangou ( zh, s=甘沟话, p=Gāngōuhuà) is a variety of Mandarin Chinese that has been strongly influenced by Monguor (Mongol) and Amdo (Tibetan). It is representative of Chinese varieties spoken in rural Qinghai that have been influenced by neighboring minority languages.Feng Lide and Kevin Stuart, "Interethnic cultural contact on the Inner Asian frontier: The Gangou people of Minhe County, Qinghai." ''Sino-Platonic Papers'' 33 (1992), pp 4–/ref> Gangou Mandarin is spoken in Minhe Hui and Tu Autonomous County, at the very eastern tip of Qinghai, an area of the Gansu–Qinghai Sprachbund with a large minority population, and where even today Han Chinese were a minority in close contact with their neighbors. Many of the local Han may actually have little Chinese ancestry. The dialect has a number of common words borrowed from Monguor, as well as kinship terms from Monguor and Tibetan. Some syntactic structures, such as an SOV word order and direct objects marked by a pos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Line
The hydrogen line, 21 centimeter line, or H I line is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms. It is produced by a spin-flip transition, which means the direction of the electron's spin is reversed relative to the spin of the proton. This is a quantum state change between the two hyperfine levels of the hydrogen 1 s ground state. The electromagnetic radiation producing this line has a frequency of (1.42 GHz), which is equivalent to a wavelength of in a vacuum. According to the Planck–Einstein relation , the photon emitted by this transition has an energy of []. The constant of proportionality, , is known as the Planck constant. The hydrogen line frequency lies in the L band, which is located in the lower end of the microwave region of the electromagnetic spectrum. It is frequently observed in radio astronomy because those radio waves can penetrate the large clouds of interstellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interferometry
Interferometry is a technique which uses the ''interference (wave propagation), interference'' of Superposition principle, superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, Optical fiber, fiber optics, engineering metrology, optical metrology, oceanography, seismology, spectroscopy (and its applications to chemistry), quantum mechanics, Nuclear physics, nuclear and particle physics, plasma physics, interactome, biomolecular interactions, surface profiling, microfluidics, mechanical stress/strain measurement, velocimetry, optometry, and making holograms. Interferometers are devices that extract information from interference. They are widely used in science and industry for the measurement of microscopic displacements, refractive index changes and surface irregularities. In the case with most interferometers, light from a single source is split into two beams that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Radio Telescopes
This is a list of radio telescopes – over one hundred – that are or have been used for radio astronomy. The list includes both single dishes and interferometric arrays. The list is sorted by region, then by name; unnamed telescopes are in reverse size order at the end of the list. The first radio telescope was invented in 1932, when Karl Jansky at Bell Telephone Laboratories observed radiation coming from the Milky Way. Africa Antarctica Asia Australia Europe North America South America Arctic Ocean Atlantic Ocean Indian Ocean Pacific Ocean Space-based Under construction or planned construction Proposed telescopes Gallery of big dishes File:FAST Radio Telescope (captured from video).jpg, alt=Five-hundred-meter Aperture Spherical Telescope seen from above in 2020, The 500 meter Five-hundred-meter Aperture Spherical Telescope (FAST), China (2016) File:GBT.png, alt=Green Bank Telescope, The 100 meter Green Bank Teles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Five-hundred-meter Aperture Spherical Telescope
The Five-hundred-meter Aperture Spherical Telescope (FAST; ), nicknamed Tianyan (, lit. "Sky's/Heaven's Eye"), is a radio telescope located in the Dawodang depression (), a natural basin in Pingtang County, Guizhou, southwestern China. FAST has a diameter dish constructed in a natural depression in the landscape. It is the world's largest single-dish telescope. It has a novel design, using an active surface made of 4,500 metal panels which form a moving parabola shape in real time. The cabin containing the feed antenna, suspended on cables above the dish, can move automatically by using winches to steer the instrument to receive signals from different directions. It observes at wavelengths of 10 cm to 4.3 m. Construction of FAST began in 2011. It observed first light in September 2016. After three years of testing and commissioning, it was declared fully operational on 11 January 2020. The telescope made its first discovery, of two new pulsars, in August 2017. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
