A shining star is a variable star. Its brightness often changes unpredictably. Sometimes it changes more than a few stars in a few minutes, and then slowly recovers after a few minutes to a few hours. The reason for this brightness change is thatfixed starLarge scale on the surface chromospheresolar flareThe spectral range of changes caused by the explosion is very wide, ranging from radio waves to x-rays.Such flares can also be observed in the sun, but the energy scale is not so large.
Yaoxing is a special typeVariable star, the typical star is whale UV, so it is also calledWhale UV star。The main feature is that the brightness sometimes suddenly increases by a few tenths to a few stars in a few minutes or even seconds, some of which can reach 10, while the brightness decreases slightly slowly, and it returns to the normal state after several minutes to dozens of minutes.
The joint observation of optics, radio and X-ray shows that the time interval of X-ray brightness is the shortest, the radio brightness is the longest, and the radio band is the earliest and the X-ray band is the latest when the brightness starts.The brightness frequency is related to the brightness of the star, and the smaller the brightness, the more frequent the brightness.Yaoliang is youngfixed starThe unique phenomenon is similar to that of the sunsolar flareThere are similarities, but on a much larger scale.
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Shining stars, also known as whale UV stars, their brightness is basically unchanged at ordinary times. Sometimes, their brightness suddenly increases irregularly in a few minutes or even seconds. The brightness changes from a few tenths to several magnitudes, and some can reach more than 10 magnitudes. After several decades, they slowly recover. This phenomenon is called "Shining" or "Shining".
As early as 1924, the bright DH star at the bottom of the ship was found, but it did not attract enough attention at that time.Discovered in 1948UV star CetusThe luminosity ofUV type variable star of Cetus。
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The most observed stars are those near the sun. After years of international joint observation, many data have been accumulated in the visible, radio and X-ray bands.The main characteristics of the flare are that when it shines, radiation can be measured in a wide band from 1~7 kiloelectron volts of X-ray to about 196 MHz of radio waves, both continuous radiation and emission lines.
In the optical band, the ultraviolet amplitude is generally the largest, followed by blue light, and yellow light is the smallest.There is no correlation between the amplitudes of radiation in different bands, that is, several bands may not appear bright at the same time.There is also no correlation between different types of radiation (continuous spectrum or emission line).
The temporal distribution of brightness is similar to the Poisson distribution (the same is true for the Pleiades cluster stars).The light curve is composed of "fast" and "slow" parts."Fast" corresponds to continuous radiation, and "slow" corresponds to emission line.The emission lines mainly include hydrogen, ionized calcium, helium, etc. The variation range of the color index U-B and B-V may be large when the radiation is bright. The spectral index of radio radiation is also the same.The average energy emitted when shining is related to the luminosity of the star.
Photorefractive curveThe type is also photometric.The photoelectric spectral observation of the eclipsed binary Y Y Gemini (both of which are flares) shows that there is a local active region on the surface of the star.Shining occurs in the activity area, and multiple shinings can occur in the same activity area.The spectral observations of some flares for more than ten years show that the annual average intensity of their radiation changes slowly, and the change period is similar to that of the sun.The brightness of flares near the sun is similar to the activity of solar flares in nature, but its scale is much larger than that of solar flares.
At present, nearly 100 shining stars have been found near the sun, including the nearby Centauri star.After years of observation, shining stars have also been found in some star clusters or star associations.For example, more than 460 stars have been found in the Pleiades regionOrion nebula More than 300 have been found in the areaNorth America nebulaMore than 50 stars have been found in the region, and more than 30 stars have been found in the ghost cluster region. These stars can mainly be used to study the evolutionary relationship between them and other types of objects in star clusters of different ages.
In recent years, some so-called nonclassical flares have been found, that is, the phenomenon of brightness has been found in the eclipsed binary W Ursa Major, the close binary UX Ursa Major, the U-shaped star in Gemini, and the early stars.Due to the lack of systematic search, there is little information, and their nature is still unclear.
