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46-412: Radio Star may refer to: Radio star , in astronomy Radio Star (film) , a 2006 South Korean film Radio Star (TV series) , a 2007 South Korean TV series Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Radio Star . If an internal link led you here, you may wish to change

92-440: A magnetic crochet . The latter term derives from the french word crochet meaning hook reflecting the hook-like disturbances in magnetic field strength observed by ground-based magnetometers . These disturbances are on the order of a few nanoteslas and last for a few minutes, which is relatively minor compared to those induced during geomagnetic storms. For astronauts in low Earth orbit , an expected radiation dose from

138-401: A class is noted by a numerical suffix ranging from 1 up to, but excluding, 10, which is also the factor for that event within the class. Hence, an X2 flare is twice the strength of an X1 flare, an X3 flare is three times as powerful as an X1. M-class flares are a tenth the size of X-class flares with the same numeric suffix. An X2 is four times more powerful than an M5 flare. X-class flares with

184-482: A helix of magnetic field unconnected to the rest of the arcade. The sudden release of energy in this reconnection is the origin of the particle acceleration. The unconnected magnetic helical field and the material that it contains may violently expand outwards forming a coronal mass ejection. This also explains why solar flares typically erupt from active regions on the Sun where magnetic fields are much stronger. Although there

230-587: A lesser extent, that of Venus . The impacts on other planets in the Solar System are little studied in comparison. As of 2024, research on their effects on Mercury have been limited to modeling of the response of ions in the planet's magnetosphere , and their impact on Jupiter and Saturn have only been studied in the context of X-ray radiation back scattering off of the planets' upper atmospheres. Enhanced XUV irradiance during solar flares can result in increased ionization , dissociation , and heating in

276-555: A peak flux that exceeds 10 W/m may be noted with a numerical suffix equal to or greater than 10. This system was originally devised in 1970 and included only the letters C, M, and X. These letters were chosen to avoid confusion with other optical classification systems. The A and B classes were added in the 1990s as instruments became more sensitive to weaker flares. Around the same time, the backronym moderate for M-class flares and extreme for X-class flares began to be used. An earlier classification system, sometimes referred to as

322-755: A series of intense, coherent radio bursts" from the nearest star to the Sun. They state that it constitutes the "most compelling detection of a solar-like radio burst from another star to date" and strongly indicates a causal relationship between these emissions. Like BLC1, the signal was recorded in April and May 2019. Despite this, their finding has not been put in direct relation to the BLC1 signal by scientists or media outlets as of January 2021 but implies that planets around Proxima Centauri and other red dwarfs are likely to be rather uninhabitable for humans and other currently known organisms. Stellar flare A solar flare

368-484: Is a general agreement on the source of a flare's energy, the mechanisms involved are not well understood. It is not clear how the magnetic energy is transformed into the kinetic energy of the particles, nor is it known how some particles can be accelerated to the GeV range (10 electron volt ) and beyond. There are also some inconsistencies regarding the total number of accelerated particles, which sometimes seems to be greater than

414-455: Is a relatively intense, localized emission of electromagnetic radiation in the Sun 's atmosphere . Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections , solar particle events , and other eruptive solar phenomena . The occurrence of solar flares varies with the 11-year solar cycle . Solar flares are thought to occur when stored magnetic energy in

460-545: Is also characterized by radio emissions: the rotating radio transient (RRAT). As suggested by the name, the radio emission is erratic. Quasars (quasi-stellar radio sources) are not radio stars. They also emit radio frequencies, but from the effects of supermassive black holes at the centre of galaxies . Although they appear to be stars, they are not stars, but the hyperactive heart of a galaxy. Some late-type stars can produce astrophysical masers from their atmospheres and beam out coherent bursts of microwaves. The Sun ,

506-425: Is heated to >10 kelvin , while electrons , protons , and heavier ions are accelerated to near the speed of light . Flares emit electromagnetic radiation across the electromagnetic spectrum , from radio waves to gamma rays . Flares occur in active regions , often around sunspots , where intense magnetic fields penetrate the photosphere to link the corona to the solar interior. Flares are powered by

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552-413: Is then classified taking S or a number that represents its size and a letter that represents its peak intensity, v.g.: Sn is a normal sunflare. A common measure of flare duration is the full width at half maximum (FWHM) time of flux in the soft X-ray bands 0.05 to 0.4 and 0.1 to 0.8 nm measured by GOES. The FWHM time spans from when a flare's flux first reaches halfway between its maximum flux and

598-550: Is thought to be continued by prolonged heating present after the eruption and during the flare's decay stage. In sufficiently powerful flares, typically of C-class or higher, the loops may combine to form an elongated arch-like structure known as a post-eruption arcade . These structures may last anywhere from multiple hours to multiple days after the initial flare. In some cases, dark sunward-traveling plasma voids known as supra-arcade downflows may form above these arcades. The frequency of occurrence of solar flares varies with

644-469: The FIRST and NVSS surveys, but estimated that 108 ± 13 of the samples are from "contamination" from background sources. They estimate that less than 1.2 in 1 million stars between an apparent magnitude of 15 and 19.1 emit more than 1.25 mJy in the 21-centimeter band. Fast radio bursts (FRB) are hypothesized to originate from extra-galactic sources. These bright, brief emissions of ~1 GHz radio occur at

690-406: The flare importance , was based on H-alpha spectral observations. The scheme uses both the intensity and emitting surface. The classification in intensity is qualitative, referring to the flares as: faint (f), normal (n), or brilliant (b). The emitting surface is measured in terms of millionths of the hemisphere and is described below. (The total hemisphere area A H = 15.5 × 10 km .) A flare

736-528: The ionospheres of Earth and Earth-like planets. On Earth, these changes to the upper atmosphere, collectively referred to as sudden ionospheric disturbances , can interfere with short-wave radio communication and global navigation satellite systems (GNSS) such as GPS , and subsequent expansion of the upper atmosphere can increase drag on satellites in low Earth orbit leading to orbital decay over time. Flare-associated XUV photons interact with and ionize neutral constituents of planetary atmospheres via

782-399: The plasma medium. Evidence suggests that the phenomenon of magnetic reconnection leads to this extreme acceleration of charged particles. On the Sun, magnetic reconnection may happen on solar arcades – a type of prominence consisting of a series of closely occurring loops following magnetic lines of force. These lines of force quickly reconnect into a lower arcade of loops leaving

828-466: The 11-year solar cycle . It can typically range from several per day during solar maxima to less than one every week during solar minima . Additionally, more powerful flares are less frequent than weaker ones. For example, X10-class (severe) flares occur on average about eight times per cycle, whereas M1-class (minor) flares occur on average about 2000 times per cycle. Erich Rieger discovered with coworkers in 1984, an approximately 154 day period in

874-543: The Sun with wavelengths shorter than 300 nm, space-based telescopes allowed for the observation of solar flares in previously unobserved high-energy spectral lines. Since the 1970s, the GOES series of satellites have been continuously observing the Sun in soft X-rays, and their observations have become the standard measure of flares, diminishing the importance of the H-alpha classification. Additionally, space-based telescopes allow for

920-415: The Sun's atmosphere accelerates charged particles in the surrounding plasma . This results in the emission of electromagnetic radiation across the electromagnetic spectrum . The extreme ultraviolet and X-ray radiation from solar flares is absorbed by the daylight side of Earth's upper atmosphere, in particular the ionosphere , and does not reach the surface. This absorption can temporarily increase

966-553: The Sun, are thought to occur and have been observed on other Sun-like stars . Flares produce radiation across the electromagnetic spectrum, although with different intensity. They are not very intense in visible light, but they can be very bright at particular spectral lines . They normally produce bremsstrahlung in X-rays and synchrotron radiation in radio. Solar flares were first observed by Richard Carrington and Richard Hodgson independently on 1 September 1859 by projecting

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1012-605: The ambient electrons and neutral species and via secondary ionization due to collisions with the latter, or so-called photoelectron impact ionization . In the process of thermalization, photoelectrons transfer energy to neutral species, resulting in heating and expansion of the neutral atmosphere. The greatest increases in ionization occur in the lower ionosphere where wavelengths with the greatest relative increase in irradiance—the highly penetrative X-ray wavelengths—are absorbed, corresponding to Earth's E and D layers and Mars's M 1 layer. The temporary increase in ionization of

1058-447: The background flux and when it again reaches this value as the flare decays. Using this measure, the duration of a flare ranges from approximately tens of seconds to several hours with a median duration of approximately 6 and 11 minutes in the 0.05 to 0.4 and 0.1 to 0.8 nm bands, respectively. Flares can also be classified based on their duration as either impulsive or long duration events ( LDE ). The time threshold separating

1104-424: The daylight side of Earth's atmosphere, in particular the D layer of the ionosphere , can interfere with short-wave radio communications that rely on its level of ionization for skywave propagation. Skywave, or skip, refers to the propagation of radio waves reflected or refracted off of the ionized ionosphere. When ionization is higher than normal, radio waves get degraded or completely absorbed by losing energy from

1150-404: The distance from its source region . The excess ionizing radiation , namely X-ray and extreme ultraviolet (XUV) radiation, is known to affect planetary atmospheres and is of relevance to human space exploration and the search for extraterrestrial life. Solar flares also affect other objects in the Solar System. Research into these effects has primarily focused on the atmosphere of Mars and, to

1196-674: The electromagnetic radiation emitted during a solar flare is about 0.05 gray , which is not immediately lethal on its own. Of much more concern for astronauts is the particle radiation associated with solar particle events. The impacts of solar flare radiation on Mars are relevant to exploration and the search for life on the planet . Models of its atmosphere indicate that the most energetic solar flares previously recorded may have provided acute doses of radiation that would have been almost harmful or lethal to mammals and other higher organisms on Mars's surface. Furthermore, flares energetic enough to provide lethal doses, while not yet observed on

1242-422: The event. Using these magnetometer readings, its soft X-ray class has been estimated to be greater than X10 and around X45 (±5). In modern times, the largest solar flare measured with instruments occurred on 4 November 2003 . This event saturated the GOES detectors, and because of this, its classification is only approximate. Initially, extrapolating the GOES curve, it was estimated to be X28. Later analysis of

1288-457: The image of the solar disk produced by an optical telescope through a broad-band filter. It was an extraordinarily intense white light flare , a flare emitting a high amount of light in the visual spectrum . Since flares produce copious amounts of radiation at H-alpha , adding a narrow (≈1 Å) passband filter centered at this wavelength to the optical telescope allows the observation of not very bright flares with small telescopes. For years Hα

1334-444: The ionization of the ionosphere which may interfere with short-wave radio communication. The prediction of solar flares is an active area of research. Flares also occur on other stars, where the term stellar flare applies. Solar flares are eruptions of electromagnetic radiation originating in the Sun's atmosphere. They affect all layers of the solar atmosphere ( photosphere , chromosphere , and corona ). The plasma medium

1380-417: The ionosphere's dayside E layer inducing small-amplitude diurnal variations in the geomagnetic field. These ionospheric currents can be strengthened during large solar flares due to increases in electrical conductivity associated with enhanced ionization of the E and D layers. The subsequent increase in the induced geomagnetic field variation is referred to as a solar flare effect ( sfe ) or historically as

1426-525: The ionospheric effects suggested increasing this estimate to X45. This event produced the first clear evidence of a new spectral component above 100 GHz. Current methods of flare prediction are problematic, and there is no certain indication that an active region on the Sun will produce a flare. However, many properties of active regions and their sunspots correlate with flaring. For example, magnetically complex regions (based on line-of-sight magnetic field) referred to as delta spots frequently produce

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1472-494: The largest flares. A simple scheme of sunspot classification based on the McIntosh system for sunspot groups, or related to a region's fractal complexity is commonly used as a starting point for flare prediction. Predictions are usually stated in terms of probabilities for occurrence of flares above M- or X-class within 24 or 48 hours. The U.S. National Oceanic and Atmospheric Administration (NOAA) issues forecasts of this kind. MAG4

1518-466: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Radio_Star&oldid=763361763 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Radio star Pulsars , a type of neutron star , are examples of radio stars. Rotation-powered pulsars are, as

1564-536: The more frequent collisions with free electrons. The level of ionization of the atmosphere correlates with the strength of the associated solar flare in soft X-ray radiation. The Space Weather Prediction Center , a part of the United States National Oceanic and Atmospheric Administration , classifies radio blackouts by the peak soft X-ray intensity of the associated flare. During non-flaring or solar quiet conditions, electric currents flow through

1610-498: The name suggests, powered by the slow-down of their rotation. The rotation powers a magnetic field, which generates the radio emissions. Not all rotation-powered pulsars generate their pulses in the radio spectrum. Some of them, from the millisecond pulsars , generate X-rays instead. Aside from radio pulsars and X-ray pulsars , there are also gamma ray pulsars , which are mostly magnetars . Some radio pulsars are also optical pulsars . Aside from pulsars, another type of neutron star

1656-415: The nearest star to Earth , is known to emit radio waves, though it is virtually the only regular star that has been detected in the radio spectrum, because it is so close. It is not considered a radio star because it is not a strong radio source. Some studies have found that main-sequence stars may extremely rarely emit radio waves. A 2009 survey found a maximum of 112 candidate radio stars cross-matching

1702-429: The observation of extremely long wavelengths—as long as a few kilometres—which cannot propagate through the ionosphere. The most powerful flare ever observed is thought to be the flare associated with the 1859 Carrington Event. While no soft X-ray measurements were made at the time, the magnetic crochet associated with the flare was recorded by ground-based magnetometers allowing the flare's strength to be estimated after

1748-513: The occurrence of gamma-ray emitting solar flares at least since the solar cycle 19 . The period has since been confirmed in most heliophysics data and the interplanetary magnetic field and is commonly known as the Rieger period . The period's resonance harmonics also have been reported from most data types in the heliosphere . The frequency distributions of various flare phenomena can be characterized by power-law distributions . For example,

1794-522: The peak fluxes of radio, extreme ultraviolet, and hard and soft X-ray emissions; total energies; and flare durations (see § Duration ) have been found to follow power-law distributions. The modern classification system for solar flares uses the letters A, B, C, M, or X, according to the peak flux in watts per square metre (W/m ) of soft X-rays with wavelengths 0.1 to 0.8 nanometres (1 to 8 ångströms ), as measured by GOES satellites in geosynchronous orbit . The strength of an event within

1840-456: The process of photoionization . The electrons that are freed in this process, referred to as photoelectrons to distinguish them from the ambient ionospheric electrons, are left with kinetic energies equal to the photon energy in excess of the ionization threshold . In the lower ionosphere where flare impacts are greatest and transport phenomena are less important, the newly liberated photoelectrons lose energy primarily via thermalization with

1886-503: The rate of 10 per day across the sky, and no emission counterparts have been found in other bands. An alternative scenario is that FRBs are emitted as the result of flare activity on nearby stars within a kiloparsec of the Sun. This would make it easier to explain the luminosity of these events. In 2020, 10 days before reports about BLC1 – reported to be an apparent possible radio signal from Proxima Centauri , astronomers reported "a bright, long-duration optical flare, accompanied by

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1932-516: The sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona. The same energy releases may also produce coronal mass ejections (CMEs), although the relationship between CMEs and flares is not well understood. Associated with solar flares are flare sprays. They involve faster ejections of material than eruptive prominences , and reach velocities of 20 to 2000 kilometers per second. Flares occur when accelerated charged particles, mainly electrons, interact with

1978-425: The total number in the coronal loop. After the eruption of a solar flare, post-eruption loops made of hot plasma begin to form across the neutral line separating regions of opposite magnetic polarity near the flare's source. These loops extend from the photosphere up into the corona and form along the neutral line at increasingly greater distances from the source as time progresses. The existence of these hot loops

2024-406: The two is not well defined. The SWPC regards events requiring 30 minutes or more to decay to half maximum as LDEs, whereas Belgium's Solar-Terrestrial Centre of Excellence regards events with duration greater than 60 minutes as LDEs. The electromagnetic radiation emitted during a solar flare propagates away from the Sun at the speed of light with intensity inversely proportional to the square of

2070-454: Was the first to report radioastronomical observations of the Sun at 160 MHz. The fast development of radioastronomy revealed new peculiarities of the solar activity like storms and bursts related to the flares. Today, ground-based radiotelescopes observe the Sun from c. 15 MHz up to 400 GHz. Because the Earth's atmosphere absorbs much of the electromagnetic radiation emitted by

2116-467: Was the main, if not the only, source of information about solar flares. Other passband filters are also used. During World War II , on February 25 and 26, 1942, British radar operators observed radiation that Stanley Hey interpreted as solar emission. Their discovery did not go public until the end of the conflict. The same year, Southworth also observed the Sun in radio, but as with Hey, his observations were only known after 1945. In 1943, Grote Reber

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