stayTotal solar eclipseSolararoundIt is inlaid with a red ring, on which a bright red flame tongue is beating. This flame tongue like object is called a prominence. The prominence is in the sunChromosphere A very strongsolar activityIs one of the signs of solar activity[1]。
Prominences usually occur in the chromosphere, like "earrings" on the solar surface.The large prominence is hundreds of thousands of kilometers higher than the solar surface, and there are numerous small high-temperature plasma prominences called spicules. The spicules are more than 9000 kilometers high, about 1000 kilometers wide, and have an average life of 5 minutes.
Chinese name
Prominence
Foreign name
Prominences
Properties
A solar activity occurring in the solar chromosphere
A huge cloud of gas in the sun's atmosphere, thicker and cooler than its surroundings, is usually visible with a spectroscope.They protrude like flames on the edge of the sun.In structure, they show great differences.The stationary prominence can last for several months at the high latitude of the sun, typically up to 40000 km high and 200000 km long.The active prominence has a relatively short time and can change its shape in a few minutes.[2]
alias
Announce
edit
Prominence is a kind of solar halo.Generally, it refers to a small arc outside the complete solar halo.
Alias
Coronal prominenceThe Rites of the Zhou Dynasty, the Spring Official, and the Ear: "The four names of the supervisor", Zheng Xuan of the Han Dynasty, notes: "The supervisor's crown is also prominent." Jia Gongyan of the Tang Dynasty said: "The cloud 'supervisor's crown is also prominent.' It means that there is red cloud gas near the sun like a crown ear. Ear is also ear, and today's people still call it a solar prominence." In the Book of Jin Astronomy, "The crown is backed by the ear, and the overlapping order lies next to the sun."
royal crownTang · Han Xuan's poem "Climbing the South Shenguang Temple Pagoda Yard": "The purple air in the Rigong gives birth to a crown, trying to look at the Fusang disease."[3]
Research History
Announce
edit
Prominence
During a total solar eclipse, the fiery red prominence can be seen with the naked eye.The observation of the total solar eclipse on July 8, 1842 left the earliest and clear observation record of solar prominence.A photo of a solar prominence was taken during the total solar eclipse on July 18, 1860.During the total solar eclipse on August 18, 1868, the spectrum of the prominence was taken, and it was determined that the main component of the prominence was hydrogen.In addition, there are still solar prominencesspectrumA 5876 angstrom wavelengthYellow lineHowever, this spectral line was never seen in the laboratory at that time, so the substance emitting this spectral line was named Helium（helium）, this word comes from the Greek Helios (sun), which means the sun element.In 1895, helium was refined in the laboratory.Since the early 20th century, astronomers have conducted a lot of research on the spectrum, state, structure, movement, formation and evolution of solar prominences with spectrometer and other instruments.nowadaysSpace explorationRise inEarth's atmosphereThe solar prominence can be seen from the outer layerultraviolet raysandX-rayspectrum[1]。In addition, the prominence was alsoradio observations 。
features
Announce
edit
Prominence
Prominence is the chromospheric layer protruding from the edge of the solar surface[4]One ofPlanting the sunActivity phenomenon.They are much weaker than the circular surface of the sun, and are generally affected by the solar halo (i.eEarth's atmosphereScatteredsunlight）It is submerged and cannot be seen directly.Therefore, it is necessary to use instruments such as solar spectrometer and monochromatic observation mirror, or observe during a total solar eclipse.The atmosphericChromosphereIt is similar to the burning grassland. The rose tongue like gas rises like fire, with various shapes, some like floating clouds, some likeArch Bridge, some likefountainSome look like clumps of grass, some are as beautiful as festival fireworks, and their overall shape looks like earrings attached to the edge of the sun, hence the name "prominence"[5]。
The eruption of the prominence is the most spectacular. Before the eruption, there was a dense "cold air mass" with a temperature of only 7000 ℃, suspended at 1 million ℃CoronaMedium.Prominences differ greatly in size, shape and movement, and there are two main types of active prominences and quiet prominences.The active prominence erupts rapidly, lasting for several minutes to several hours.Active prominence andSunspot groupThey are related to each other, and like sunspot groups, they are the same in quantity and activitySolar cycleClosely related.The quiet prominence erupts slowly and declines more slowly, which can last for several months[1]。
Causes
Announce
edit
The problem of prominence formation has not yet been solved.The hardest thing to explain is that most prominences are much thinnerCoronaIt often appears suddenly in the almost empty corona.The calculation shows that all the matter in the corona is not enough to condense into several large prominences, so the matter in the prominences is basically fromChromosphere 。The popular theory of prominence formation today believes that the prominence appears in the coronaMagnetic line of forceThe saddle shaped depression of (Fig. 2).If, for some reason, the coronal magnetic field line has a local depression, thenmagnetic fieldFrozenChromosphereWhen the matter moves along the magnetic field line, part of it will be left in such a "magnetic pit", thus forming a solar prominence.From the side view, due to the gravity of the prominence materialLorentz forceJust in balance, the magnetic lines of force can support the prominence.
classification
Announce
edit
According to the movement, prominence can be divided into three types: explosive, quiet and active.If subdivided, it can be divided into dozens of categories.The quiet prominence seems to be stationary during observation time, while the active prominence is always changing.They shot out of the sun's surface, followed an arc, and slowly fell back to the sun's surface.But some prominences spew very fast and high, and their substances did not fall back to the solar surface, butEjectionInto space,Eruptive prominenceIts height can reach hundreds of thousands of kilometers.One of the largest solar prominences erupted in 1938 rose to 1.57 million kilometers in an instant, while the diameter of the earth was only 13000 kilometers[1]。
There are two main types of prominence:
First
Prominences photographed during the total solar eclipse in 1999
Classification According to the characteristics of morphology and movement, prominence can be divided into several types.Several different methods of prominence classification have been proposed, and the more popular method is to divide the prominence into six categories:
③ Sunspot prominence (appearing inSunspot groupOverhead),
④ Tornado prominence (elephanttornadoSame, with a twisted shape),
⑤ Quiet prominence, ⑥Coronal prominence(FromCoronaStreamlike prominences from space).Each category is divided into several sub categories.The boundary of classification is not absolute. For example, some quiet prominences can suddenly change into active prominences orEruptive prominence。
Second
Prominences can be divided into three categories: quiet, active and explosive.As the name implies, compared with the other two types of prominence, the quiet prominence is obviously not active enough and changes slowly. It can generally survive in the sun for a few days, so it can often be seen.Sometimes the quiet prominence can even exist in the corona for several months without any change in shape, which is simply incredible.The material density of prominences is thousands or even thousands of times higher than that of the corona. They are indeedChromosphere The substance in.The temperature of the corona is as high as 1 million to 2 million K. What is the reason why the prominence with a temperature of about 7000 K can exist in such a high temperature state for a long time?How did they come into being?Now this is still an unsolved problem.Many astronomers believe thatSolar magnetic fieldAnd prominence magnetic field, leading to the emergence and existence of prominence.However, the specific details need further discussion.
The active prominence is much more active than the quiet prominence and always changes constantly.They are likefountainSimilarly, the jet from the sun surface is very high, and then slowly falls back to the sun surface along the arc path.Some prominences blow up quickly and high, and their matter no longer falls back to the solar surface, but is thrown into space.
The most spectacularEruptive prominence。When an eruptive prominence occurs, it ejects matter toCoronaIn the middle, the height reaches hundreds of thousands or even millions of kilometers, which is spectacular.The largest eruptive prominence observed by astronomers has a rising height of 1.57 million kilometers. The diameter of the sun is 1.39 million kilometers, higher than the diameter of the sun.
Prominence movement
Announce
edit
Prominence
The movement of prominence is very complicated and has many characteristics.For example, in the prominence, it keeps risingEjectionOr when falling, the motion tracks of several nodes are often consistent;When the prominence moves away from the sun, the speed will increase continuously, and this acceleration is sudden, and the speed will remain unchanged between two accelerations;When the prominence node suddenly accelerates, the brightness will also increase.There is no satisfactory explanation for these phenomena.The main problem is that the density of prominences is far greater thanCoronaBut the quiet prominence can exist in the corona for a long time, neither falling nor collapsing.What forces support and maintain it?Active prominence andEruptive prominenceThe speed of can reach hundreds of kilometers per second. Where does the power come from?The prominence movement often accelerates suddenly, and even the quiet prominence will suddenly become an active prominence. What is the reason?These problems need further study.It is generally believed that in addition to gravity and gas pressure, electromagnetic force is an important factor in the movement of prominence.The mutation of prominence movement may be related tomagnetic fieldRelated to[1]。
distribution
Prominences photographed during the 1992 total solar eclipse
Prominences may appear at different latitudes in the southern and northern hemispheres of the sun, but they are mainly concentrated in two latitudes in each hemisphere, with low latitudes as the main regions.The distribution of prominences in the low latitude region is similar to that of sunspotsSolar cycleDrift constantly.At the beginning of the activity cycle, the prominence occurs in the range of 30 °~40 °, and then gradually moves to the equator. At the end of the activity cycle, the average latitude is about 17 °.This is always about 10 ° higher than the average latitude of the sunspot region.As for the high latitude region, the prominence did not appear until about three years after the sunspot maximum period, until the sunspot minimum period.Prominences in high latitudes do not drift, and they are all within the range of 45 °~50 °.The boundary between the above two regions is about 40 ° latitude.
The number and area of prominences are the same as those of 11 yearsSolar cycleWithSunspot phase logarithmAnd change.But the range of variation is not as large as the relative number of sunspots.
The rising height of the prominence is about tens of thousands of kilometers. The large prominence can be hundreds of thousands of kilometers higher than the solar surface, generally about 200000 kilometers long, and some can reach 1.5 million kilometers.The prominence is brighter than the sunphotosphereIt is much weaker, so it cannot be observed with the naked eye at ordinary times. It can only be seen directly during the total solar eclipse.
Prominences are very peculiarsolar activityThe temperature is between 5000 and 8000K, and most of the prominence materials slowly fall to the solar surface after rising to a certain height, but some of the prominence materials float on the solar surface with a temperature of up to 2 million KCoronaAt the lower level, there is neither attachment nor disintegration. It is as strange as there is a piece of ice that does not melt in a steel furnace with a blazing fire. Moreover, the density of the prominence material is 1000 to 10000 times higher than that of the corona. It is puzzling that the two can coexist for several months.
spectrum
Through spectral analysis, the physical parameters and chemical components of the prominence can be measured, and the excitation andionizationState, establish the structural model of prominence, and studysolar radiation(especiallyCoronaUV and X-ray) on solar prominences.The spectrum of a prominence includes many emission lines and weak continuous spectrum.In the visible area, the main emission line is hydrogenBalmer line(Up to 40 lines have been seen from H α). In addition, there are helium, calcium, iron, magnesium, titaniumstrontiumIsometallicSpectral line。Using the spectral line width of different elements, the temperature of the prominence is about 7000K, and the turbulence speed is about 4km/s.From the analysis of the number of Balmer lines and the spectral line contour, it can be concluded that the electron density of the prominence is about 1011 per cubic centimeter, and the material density of the prominence is similar to this.
The main reason for the spectral line broadening of prominence emission line isDoppler broadeningandRadiation damping；Stark effectIt has little effect.The first few Balmer lines and the H, K and other strong lines of calcium are significantly affected by self absorption.The continuous spectrum of the prominence is mainly the Balmer continuous region extending from 3646 A to the short wave direction.The temperature and density of solar prominences can also be calculated from the distribution of energy of continuous spectrum with wavelength.
The Skylab, launched in May 1973, used a special instrument to take a large number of prominence and filament spectra at 280~1350 angstroms.Many streamers in this bandradial, some (e.g. hydrogenLymanThe low temperature (about 10-4K) core from the prominence, and some (such as C Ⅱ λ 1336 A and C Ⅲ λ 977 A) from the prominence andCoronaIntermediate layer between (temperature about 1.05 million K).In addition to light waves, the prominence also emits radio waves, which have been observed and recorded in the millimeter wave band.
magnetic field
It indicates that solar prominence hasmagnetic fieldThe fact is:
① The motion track of the active prominence is very similar to the annular prominence itselfMagnetic line of force；
② The prominence is a mass of low temperature (about 7000K)Plasma, but can be used at high temperature (about 1.06 million K)CoronaIt is likely that the thermal insulation magnetic field lines closely surround the prominence;
③ The material density of the prominence is 1000~10000 times higher than that of the corona, and it can suspend in the corona for a long time without falling and dispersion, which is likely to be supported and maintained by the magnetic field.Since 1960, astronomersSolar magnetic imagerMeasure the magnetic field of the prominence.
The results show that themagnetic field intensityAbout 10GaussianAnd the active prominence can reach 200 gauss.Quiet prominenceThe magnetic line of force in the active prominence is mainly along the horizontal directionmagnetic fieldThe structure is relatively complex,Eruptive prominenceThe magnetic lines of force are probably helical.
observation
Announce
edit
Those lucky enough to have seen the total solar eclipse must still remember the short and magnificent scenery.The sun was completely hidden by the moon, and "night" suddenly came.There is a red halo around the "black sun", which is extremely beautiful. This is the sun'sChromosphere 。Astronomers describe the solar chromosphere as "a burning prairie", or "an ocean of fire", where many small flames are constantly beating. From time to time, there are also bundles of fire pillars rising high. These high fire pillars are called "solar prominences"[5]。
Prominence is a regular and very beautiful phenomenon on the solar chromosphere.It is rare to see a total solar eclipse. How can we observe it in ordinary timesChromosphereWhat about studying prominences?Astronomers took advantage of the total solar eclipse to observe the flash spectrum of the solar chromosphere, and found that the solar chromosphere has several unique strong radiation.The strongest radiation ishydrogen atomThe emitted red light with a wavelength of 656.28 nm is called H α spectrum of chromosphere for shortLinear radiation。Then there is the dark purple light emitted by ionized calcium with a wavelength of 393.37nm, referred to as K spectral line for short, and the dark purple light with a wavelength of 396.85nmH-lineEtc.And the sunphotosphereTemperature ratio of layerChromosphere Low, the radiation of the photosphere at these wavelengths is almost zero.Astronomers use this feature of the chromosphere to create a chromosphere telescope.They will only allow 656.28 nm wavelength through the filter (also known as H αFilter）Installed onSolar telescopeIn this way, you can see the red sun in the eyepiece of the telescopeChromosphereIt looks like a big flaming fireball, with bright red flame tongues jumping on it, which is very beautiful and spectacular.Therefore, the solar chromosphere is also called H α chromosphere orHydrogen chromosphere。
YesChromosphere telescopeAstronomers can observe and take photos of the solar chromosphere and prominence at any time.The prominence is graceful and varied, some like floating clouds, some likefountainSome are like fences, others like rings, rainbowsArch Bridge, etc.Prominences are different in size, generally tens of thousands of kilometers high;Much more thanChromosphere Therefore, prominence mainly exists inCoronal layeramong.Through the analysis and research of prominence spectra, it is known that their temperature is about 7000K[5]。
Those who have observed prominences may find that they all appear on the edge of the solar surface.But it is not just the prominence that appears on the edge of the solar surface.The prominences in the middle of the solar surface are the same color as the background, so we cannot see their existence.However, we can see that their projections on the solar surface are dark strips calledBlack stripe。When these filaments reach the edge of the solar surface as the sun rotates, we can see these prominences.
2013
In 2013,NASAThe Solar Dynamics Observatory observed the huge solar prominences on the sun's surface, and the detector photographed the scene of the solar prominences. Under the action of the solar magnetic field line, such powerful eruptions can "hover" on the sun's surface for days or even weeks.
2015
Prominences photographed in 2015[6]
On February 9, the longest filament of the sun appeared on record, with a length of more than 1 million kilometers, which is longer than the solar radius.
This filament is actually a hot gas suspended in the solar magnetic field. If the filament appears on the side of the sun, it will become a towering prominence.The filament usually lasts for several hours to several days, and still exists as of February 13, 2015.
After the emergence of prominence, scientists are tracking this unusual structure, and some filaments may collapse or explode at any time, which will have an impact on the Earth.
When a solar storm occurs, it will output three kinds of effects to the surrounding space: electromagnetic radiation directly affects the earth's atmosphere and ionosphere toward the sun, causing interference to short wave communication;A large amount ofHigh-energy particle, will endangerSpacecraftSafety of astronauts and instruments inside;Coronal mass ejection, will cause strong magnetic field changes on the earth, and then the surface power grid may overheat, air transportation may be interrupted, and satellite navigation may lose its function[6]。
2022
On December 13, 2022, the National Space Science Center of the Chinese Academy of Sciences announced the first batch of scientific images of China's comprehensive solar exploration satellite "Kuafu I", one of the three sub loads of the Lehmann Alpha Solar Telescope, and the solar heliograph achieved the first international acquisition of the Lehmann Alpha band full heliograph on the satellite platform,The evolution image of prominence is clear and complete.[7]
