Electromagnetic field of the sun. Apparatuses behind the sun
Combining direct observations with computer modeling, NASA heliophysics created a plasma movement model in the crown of the Sun, which will better understand the nature of the magnetic field of the Sun
The surface of the sun continuously boils and dancing. The plasma jets removed from it are bent, wept the loops, tightened into cyclones and reach the upper layers of the solar atmosphere - the crown having a temperature of millions of degrees.
Modeling results. The magnetic field of the Sun in 2011 is much more focused near the poles. Spots little. (NASA Image "S Goddard Space Flight Center / Bridgman)
The magnetic field of the Sun in 2014 became more confusing and disorderly, creating conditions for outbreaks and emissions of coronal mass. (NASA Image "S Goddard Space Flight Center / Bridgman)
Sun surface (image http://www.nasa.gov)
This is an eternal movement that cannot be observed in the visible light, first noticed in the 1950s, and since then physics are trying to understand why it happens. It is already known that the substance from which the sun is, is moving in accordance with the laws of electromagnetism.
Studying the magnetic field of the Sun, it is possible to better understand the nature of the cosmos in the entire solar system: it affects both an interplanetary magnetic field and radiation, through which the spaceships have to move and on the outer weather on the ground (polar beams, magnetic storms, etc. depend on solar flares).
But, despite the many years of research, the final understanding of the nature of the magnetic field of the Sun is not yet. It is assumed that it arises from the movements of charged particles, which move through complex trajectories due to the rotation of the Sun (solar dynamo) and thermal convection, supported by heat from thermonuclear synthesis in the center of the Sun. However, all the details of the process are still not known. In particular, it is not known where the magnetic field is created: close to the solar surface, deep inside the sun, or in a wide range of depths.
How can you see an invisible magnetic field? On the movement of the solar plasma. And so, in order to learn more about the "magnetic life" of the Sun, NASA scientists decided to analyze the plasma movement through its crown, combining the results of computer modeling and the data obtained when observed in real time.
The magnetic field controls the movement of charged particles, electrons and ions, of which the plasma consists. The loops formed with this and other plasma structures are bright in the pictures made in the extreme ultraviolet range. In addition, their traces on the surface of the Sun, or the photoosphere, can be accurately measured with a tool called a radio tape recorder, which measures the force and direction of magnetic fields.
The results of observations, which describe the tension of the magnetic field and its direction, are then combined with a model of moving solar plasma in a magnetic field. Together they give a good idea of \u200b\u200bhow the magnetic field looks like in the crown of the Sun and how it hesitates there.
In periods of maximum solar activity, the magnetic field has a very complex form with a large number of small structures everywhere, which are active regions. In the minimum of solar activity, the field is weaker and concentrated on the poles. A very smooth structure without spots is formed.
According to NASA
There you can see the animation according to the results of modeling.
L. Shirshov, Researcher at the Institute of High Energy Physics.
The solar wind (flow of the particles) is streamlined by the Earth and interacts with its magnetic field, generating a shock wave on the distance of ten terrestrial radius from the planet.
The structure of the magnetic field of the Sun in the plane of the ecliptic. The field is divided into several sectors, which are directed either to the luminaries or from it.
Distribution of the magnetic field of the Sun in the outer space. The field covers the entire solar system by a giant "bubble"; His border is called Heliophasis. Due to the rotation of the Sun, the magnetic field takes the shape of the spiral of the archimedes. This curve describes the exact
The solar wind (flow of charged particles) is streamlined the ground and interacts with its magnetic field, generating a shock wave at a distance of ten terrestrial radii from the planet.
At the very beginning of the new century, our sun has changed the direction of its magnetic field to the opposite. The coup of magnetic poles (reverse) was registered by NASA (US National Office for Air Space and Space Research), leading to the behavior of the Sun. The article "The Sun produced a reverse", published on February 15, it was noted that his northern magnetic pole, which was in the northern hemisphere just a few months ago, is now in South.
Such an event - the phenomenon is far from unique. A complete 22-year-old magnetic cycle is associated with a 11-year-old solar activity cycle, and the coup of the poles occurs during its maximum passage. The magnetic poles of the Sun will now remain in new places until the next transition, which happens with the regularity of the clock mechanism. Mysterious causes and reverses, and the cyclical of solar activity. The geomagnetic field has also changed its direction repeatedly, but the last time it happened 740 thousand years ago. Some researchers believe that our planet has already crushed the moment of coup for magnetic poles, but no one can accurately predict when it happens.
Although the magnetic fields of the Sun and Earth behave differently, they have both shafts. During the minimum of solar activity, the magnetic field of the shone, as well as the geomagnetic field of our planet, is directed along the meridian, its power lines are concentrated in the poles and are raised in the equator area. This field is called dipole - the title reflects the presence of two poles. The tension of the magnetic field of the Sun is about 50 Gauss, and the magnetic field of the Earth is weaker than it 100 times.
When solar activity grows and increases the number of solar spots on the surface of the sun, the magnetic field of our star begins to change. In sunbursters, magnetic induction streams are closed, and the field value in these areas increases hundreds of times. As the Sun Physics Specialist in the center of Marshall's Space Flights, David Hathaway, "Meridianal flows on the sun surface capture and carry magnetic streams of solar spots from medium latitudes to poles, and the dipole field is resistant to weaken." Using data collected by astronomers of the US National Observatory in Peak Kit, it registers the average magnetic field of the Sun daily depending on the latitude and time since 1975 to the present. As a result, it turned out a kind of route card protonding the behavior of magnetic streams on the surface of the Sun.
In the "Sunny Dynamo" model (http://science.msfc.nasa.gov/ssl/pad/solar/dynamo.htm) it is assumed that our luminaire works as a direct current generator acting mainly in the convection zone. Magnetic fields are created by electric currents that occur when driving hot ionized gases. We observe a series of streams regarding the surface of the Sun, and they all can create high-intensity magnetic fields. The meridianoal flow on the surface of the Sun makes large masses from the equator to the poles (75% of the mass of the Sun is hydrogen, about 25% - helium, and the share of other elements accounts for less than 0.1%). On the poles, these streams go inside the luminaries and form an internal countercurrent substance. Due to such circulation of the charged plasma and the DC is a solar magnetic generator. On the surface of the Sun, the flow rate along the meridian is about 20 meters per second. In the depths of the sun, the density of matter is much higher, and therefore the rate of reverse counterpart is reduced to 1-2 meters per second. This slow flow carries material from the poles to the equator for about twenty years.
The theory of "Sunny Dynamo" is in development and requires new experimental data. Until now, researchers have never observed immediately the moment of magnetic reversing of the Sun. Today, the Ulysses Spaceship (Ulysses) may allow scientists to check theoretical models and get unique information.
"Ulysses" is the fruit of international cooperation of the European Space Agency and NASA. It was launched in 1990 to observe the solar system above the orbital plane planets. Moving the South Pole of the Sun, he is now returning to fall on his north pole and get new information. The ship flew over the poles of the Sun in 1994 and 1996, during reduced solar activity, and allowed to make several important discoveries regarding cosmic rays and solar winds. The final of the mission of this scout will be the study of the Sun during the maximum activity period, which will allow to obtain data on the full solar cycle. Information about the Sunny Spaceship "Ulysses" is provided at http://ulysses.jpl.nasa.gov.
Continuing changes are not limited to the area of \u200b\u200bspace near our star. The magnetic field of the Sun limits our solar system with a giant "bubble", forming the so-called heliospher. It extends from 50 to 100 astronomical units (1 AE \u003d 149,597,871 km, the average distance from the ground to the Sun) Next Pluto orbits. All that is within this sphere is considered a solar system, and then the interstellar space.
"The signal of the firing of the magnetic field of the Sun is transmitted through the solar wind of the solar wind, - explains Steve Sonsum (Steve Souss), another astrophysicist from the Marshall Space Flight Center. - It takes about a year to have this news from the sun to the outer borders of the heliosphere. As the sun rotates , Making one turn every 27 days, the magnetic fields outside the luminaries have the shape of the Spiral of Archimedes. Their complex form does not allow to evaluate in the details the effect of the magnetic field reverse on the behavior of the heliosphere.
The magnetosphere of the Earth protects the inhabitants of the planet from the solar wind. Outbreaks in the Sun are accompanied by magnetic Buryami and polar shining, which can be observed in Alaska, in Canada, Norway and the Northern Territories of our country. But there are other, less obvious links of solar activity with processes on the planet. In particular, it was noted that the seismicity of the Earth increases during the passage of the maximum activity of the Sun, and the connection of strong earthquakes with the characteristics of the solar wind has been established. Perhaps these circumstances also explains a series of catastrophic earthquakes that happened in India, Indonesia and Salvador after the new century.
Magnetic field modern ideas It is formed inside the Sun in its convective zone located directly under the solar surface (photosphere). The role of a magnetic field in the dynamics of processes occurring in the sun is huge. Apparently, it is the key to all active phenomena taking place in the solar atmosphere, including solar flashes. We can say that if the sun did not possess a magnetic field, it would be an extremely boring star.
Many objects observed in the sun are also required by their origin to the magnetic field. For example, solar stains are places where gigantic magnetic loops that pop up from the subsoil of the sun penetrate through the sun's surface. It is for this reason that the group of spots, as a rule, consist of two areas of various magnetic polarity - North and South. These two areas correspond to the opposite bases of the pop-up magnetic tube. The solar activity cycle is also the result of cyclic changes in the magnetic field occurring in solar departures. Protubereans, who, as it were, hovering in emptiness above the surface of the Sun, are actually supported by the magnetic field lines with which they are permeated. Finally, many objects observed in the crown, in particular the streamers and loops, simply repeat their shape to the topology of their surrounding magnetic fields.
Magnetic field measurements
The magnetic field affects the movement of charged particles entering it. For this reason, the electrons that are part of any atom rotating around the kernel in one direction, occupying the magnetic field will increase its energy, while electrons rotating in the other direction will reduce their energy. This effect (zeeman effect) leads to the splitting of an atom emission lines into several components. Measuring this splitting allows you to determine the magnitude and direction of the magnetic field on the objects remote from us are not available for direct research, such as the sun. Modern methods Measurements make it possible to determine the field on the surface of the Sun with high accuracy, but are often powerless when measuring the three-dimensional field in the solar crown. In this case, special mathematical methods are used to restore the total three-dimensional pattern of field measurements.
Space weather prediction
Understanding the nature of the solar magnetic field and its behavior will make more reliable space weather predictions. Currently, some indirect signs are known indicating that an outbreak can occur in an active area. However, more long-term predictions, such as the prediction of the duration of the future of the Solar Cycle, are still extremely inaccurate and are not based on strict physical models, but on the search for different types of empirical dependencies. Nevertheless, we hope that in the near future we will be able to understand the sun well enough to simulate his future activity and predict space weather just as the weather is predicted now.
Solar spots give us the most visual samples of nonstationary processes in the sun. First of all, these are their violent development. Sometimes there are enough two or three days so that a large spot or a large spat group has developed on the "clean" place of the photosphere. As a rule, however, the development of them is slower and large groups Reaches a maximum in 2-3 weeks. Small spots and groups appear and disappear within a week, while major exist for several months. One spot that existed for 1.5 years is known. When the stain occurs when his half day is still small, the same photospheric granulation (Ghanaian, Tissren) is visible in it, which further development takes a fibrous form; Fibers are much more rack than granules. When the rounded spot of the right form approaches the solar edge, it is observed by us in the projection and its diameter in the direction of the solar radius is strongly reduced (proportional; see Fig. 8). At the same time, the so-called Wilson effect is often observed, which consists in the fact that halftime spots from the edge side of the disk is visible good, and from the side facing the center of the disk, is strongly reduced. Such a phenomenon admits a geometric approach of the solar spot with a giant deepening with conienticating walls. But not all stains find it.
Typically, a group of spots is stretched along a helographic longitude (in exceptional cases - up to 20 ° and more). At the same time, often in the group there are two largest stains with separate seats, which have a slightly different movement on the surface of the sun. The eastern spot is called the leading, West - next. Often, such a tendency to form in pairs is observed in individual spots that do not form groups with a large number of small spatials.
Fig. 38. Vortex stain structure in a bipolar group. The directions of the vortices are opposite. (Spectrogram in the rays on)
Observations of radial velocities at different spectral lines in different places of stains and at different angles of view to it show the presence of a strong (up to 3 km / s) movements in the sevens of the spots - the spreading of the substance in the depths of its and the flow of the substance inside at high altitude. The latter is confirmed by the vortex structure, noticeable above the spots on spectrochelograms in the rays. The directions of these vortices are opposite in the southern and northern hemispheres of the Sun and indicate in single stains for the flow of a substance in accordance with how the Coriolis force must be rejected.
Usually, at the external edge of a half, systematic movements are no longer observed.
As mentioned above, solar spots have strong magnetic fields. Tension in 1000-2000 E is usual, and in the same group at the end of February 1942, the tension 5100 E. Detailed studies of the distribution of the direction and tension of the magnetic field inside the spots showed that in the center of the stain magnetic power lines go along the spots axis (up or down), and as it removed to the periphery of the stains, they are increasingly evading normal to the surface, almost up to 90 ° on the edge of the half. In this case, the tension of the magnetic field decreases from the maximum almost to zero.
Fig. 39. Changing the average latitude and magnetic polarity of solar spots in consecutive solar activity cycles
The larger the spot, as a rule, its magnetic field is stronger, but when a large spot, reaching the maximum size, begins to decrease, the intensity of its magnetic field remains unchanged, and the full magnetic flux decreases in proportion to the spot area. This can be interpreted as if the stain only contributes to the end of the magnetic field, existing for a long surface under the surface. The said is also confirmed by the fact that often the magnetic field does not disappear after the stain disappearance, but continues to exist there and is reinforced with the new appearance of stains in the same area. The presence of permanent torch fields here allows that there are sustainable active areas in these places.
In groups with two large stained stains, the drive and the following have opposite magnetic polarity (Fig. 38 and 39), which justifies the name of such groups - bipolar, as opposed to unipolar groups, which includes single spots. There are complex groups in which stains of the other polarity are randomly mixed. In each cycle of solar activity of the polarity of the presenter and the next spot in the northern and southern hemispheres are opposite to each other.
So, if in the northern hemisphere of the Sun, the polarity of the leading spot of the Northern (N), and the following - southern (s), then at the same time in the southern hemisphere the polarity of the leading spot - S, and the following - N. At those rare spots that intersect the equator , Polarity of the North and South Half is the opposite. But with the end of the solar cycle, when it passes its minimum, in each hemisphere, the distribution of magnetic polarity in the spots of the bipolar group changes to the one in the previous cycle on the opposite hemisphere. This important fact Halee was installed with employees in 1913
Although the local magnetic fields of the Sun are very strong, its overall magnetic field is very weak and only hardly stands out against the background of local fields only during the years of solar spots. In addition, it is changeable. In the years 1953-1957, his tension corresponded to the dipol with induction in 1 GC, the sign was opposite the sign of the magnetic field of the Earth, and the axis of the dipole coincided with the axis of rotation. In 1957, the field sign changed to the opposite in the southern polar areas of the Sun, and at the end of 1958 - and in the northern. The last change in the field sign was observed in 1970-1971.
The change of magnetic polarity of spots with the end of the solar activity cycle is not the only sign of the end of the cycle. Solar spots are rarely formed away from the equator. Their preferred zone is enclosed within half of 1-2 ° to 30 ° in both hemispheres. At the equator, the stains are rarely found, as well as on more than 30 ° latitudes. But this picture has a feature of its change in time: the first spots of the new cycle (after imaginary) appear far from the equator (for example, the spot was registered on March 15, 1914, from May 1943 and from October 1954), in The time the last stains of the outgoing cycle are still observed near the equator. During the heyday of the cycle near his high, the stains can be found on all helographic latitudes between - 45 ° and + 45 ° (a group of spots is known even with a latter + 50 °, observed in June 1957 during the maximum of solar activity), but mainly between 5 and 20 °. Thus, the average helicing latitude of spots as the 11-year-old solar activity cycle develops steadily decreases, and new spots appear closer and closer to the equator (Fig. 39). This pattern was established for the first time in 1858 by Karrington and is sometimes called the Spener's law (although the latter set it 10 years later).
Thus, if under a period to understand the period of time during which all properties change and return to the initial state, then the true period of solar activity is not 11 years old, and 22 years. Interestingly, some alternation of the maximum height through the cycle also confirms 22-year periodicity. The 80-year-old cycle of solar activity is planned. For some reason internal reasons Solar activity is changing widely with a characteristic time near a century.
So, between 1645 and 1715. There was almost no spots on the sun, and the group appeared only "once. This is the so-called minimum mounder. The other minimum, at least Sperera, was between 1410 and 1510. On the contrary, a medieval maximum between 1120 and 1280. It was very energetic, like us now. The variations described were accompanied by oscillations of the average annual temperature in England within 1 ° C.
Per last years The theory of the structure of the sun and phenomena on it strongly advanced. In particular, on the basis of laboratory experiments with plasma, they concluded that the magnetic fields in the sun play very big role In the phenomena observed on it.
Nuclear reactions occur in the Sun kernel, where the temperature is high enough - 16 million degrees. The radius of this zone where energy is produced under nuclear reactions is, it seems to be about 200,000 km. With the removal from the center of the Sun, the temperature drops quickly - by 20 ° per kilometer. In this area, the radiant radiation is transferred. Not reaching one tenth along the radius to the photosphere, the temperature drops slower, and convection in the form of a vertical lift of hot gases and lowering cold gases takes part in it. A stirring of a substance occurs, which, however, is unevenly in different directions.
In the photosphere, hydrogen atoms in the main mass are neutral, in a chromosphere, which is a transition layer, they are ionized and in the crown comes complete ionization. The thickness of the photosphere is only 200-300 km, i.e. about the V300 of the radius of the sun. Thus, the atmosphere of the Sun consists of plasma - mixtures of ions and free electrons. Chromosphere, hundreds of thousands of times less dense than the photosphere, goes into the crown. Due to the irradiation with the energy emitted by the photosphere, at its temperature in 6000 °, the thermometer in the chromosphere would show 5000 °, and in the crown even less. The particles of sparse gas chromosphere and the crown would fly to the thermometer so rarely, which could not heat it. However, the speed of movement of particles in the chromosphere and the crown is very large. It is known that the gas temperature can be measured by the kinetic energy of its particles. This is the so-called kinetic temperature. In the radiation temperature photosphere and kinetic correspond to each other, and in the chromosphere and the crown they differ sharply - in the chromosphere, the kinetic temperature is tens of thousands of degrees, and in the crown - about a million degrees.
The "heating" of the chromosphere takes effect the energy of the waves spreading in it generated by the movement of the granules in the photoosphere. In the crown that extends to a distance of up to 10 radii of the sun, the number of atoms in 1 cm 3 at 100 billion times less than the number of molecules in 1 cm 3 of the air at the surface of the Earth. With the same density as the air, the substances in the crown would have enough on the layer surrounding the sun with a thickness of just a few millimeters. It arises the main "Sun radio emission. With the same intensity as a crown, the heated body of the same size would radiate at a temperature of per million degrees, and such a kinetic temperature require how we saw, and the bright lines observed in the corona spectrum are repeatedly ionized metals.
The study of the interaction of the magnetic field and plasma has shown that the plasma in general, movement along the power lines of the magnetic field does not affect. When the electrically charged particles are moved across the field lines (i.e., during current), an additional magnetic field occurs. The addition of these magnetic fields causes curvature and pulling the power lines after the movement of the substance. Meanwhile, the magnetic power lines have tension, striving to straighten them. It creates magnetic pressure, and the field, laying the plasma to cross the power lines, it slows down and can even get carried away if the field is strong. If it is weak, then the plasma moves the power lines along with them. So, in all cases, we can say that the power lines are "enlarged" in the plasma.
This information, as well as regular measurements of the magnetic field voltage in different places in the sun, allowed to approach the explanation of many phenomena on it.
The total magnetic field of the Sun is very weak, but it apparently plays a big role. The rays of the crown, especially in the polar regions of the Sun, are located like the power lines emerging and incoming the poles of the magnetized ball. The change in the direction of the field in each hemisphere of the Sun from one solar activity cycle to the following is also very important. The reason for this change is not yet clear, but the stars with very powerful magnetic fields are known, in which the polarity of the field also changes periodically.
When the sun is rotated, the fastest (equatorial) layers carries the power lines of the weak general field of the Sun, which are "enclosed" in them. These lines are pulled under the photosphere and are wrapped around the Sun for three years, forming a tight spiral. If the power lines settled closely, then, it means that there is a common (and distorted here) the magnetic field of the Sun intensified.
Closer to the poles, the total fields of the common field come out of the photosphere, and therefore the field is not enhanced here. However, at the same equator, where the angular speed of rotation in some zone changes little, the field is also not amplified, and on the latitudes + 30 °, where the rotational speed changes faster, the increase in the field is maximum. So under the photosphere, the similarity of tubes from condensed power lines are formed. The gas pressure in them is folded with a magnetic field pressure perpendicular to its lines. Gas in the "tube" expands and becomes easier and can "float" up. In this place, where it approaches the surface, an increase in the magnetic field is observed in the sun, and then the appearance of a torch, and behind it the fields of torches. Their hot gases rise higher than the neighboring places of the photosphere, because the weak magnetic field around them quenurates small turbulent movements, seeking to slow down the stream of hot-out gas. Over the torches in the chromosphere, heating also occurs and hot floccula arises. Finally, the floccula in the crown begins a brighter glow. So develops an active area in the sun. Pop-up to the surface and crossing it, the tube with condensed power lines forms the local enhancement of the magnetic field and the solar spots occur. Them reduced temperature due to the fact that a very strong magnetic field in this area suppresses not only turbulence, but also strong convective movements. Therefore, here the inflow from the bottom of the hot gases is stopped, while around the spot, in the area of \u200b\u200btorches and floccul, convection with a weak magnetic field strengthened, as it suppresses a weak turbulence and there the inflow of hot gases is facilitated from below. It is clear that the intersection of the curved tube with this surface in two places determines the opposite magnetic polarities in two main spots. The output of the tube from the photosphere and the dispersion of its lines lead to crushing and disappearance of two main spots formed by the intersection of the power tube with the surface of the Sun. The output is the power lines of the tube into a rarefied chromosphere and the crown, where the gas pressure is less than the pressure of the magnetic field, leads to the fact that the lines are diverted, forming loops and arcs.
Gradually, the area of \u200b\u200bactivity with the generating magnetic tubes in the eastern part form stains with polarities opposite to the one at the beginning of the cycle of this pole of the sun. This causes the neutralization of the former general magnetic field first, and then, in three years to the end of the 11-year-old solar activity cycle, creates a common field of opposite polarity.
After 11 years, the previous picture of the polarities of the common field is restored.
So gets in the main features, apparently, the correct explanation (given by Babkok), the 22-year periodicity of solar activity.
Chromospheric flashes in the sun are formed near neutral points of magnetic fields in active areas, where, with the removal of these points, the field voltage increases rapidly. Here there is an extremely fast compression of the magnetic field along with the plasma, into which it is "enclosed", and the magnetic field energy passes to the radiation of the gas. The plasma is compressed into a thin cord and the temperature increases sharply - up to several tens of thousands of degrees. The chromosphere density increases here in a few minutes in hundreds of thousands of times.
In addition to a huge increase in temperature, and with it and radiation, especially ultraviolet and X-ray, chromospheric flash consists in the so-called burst of radio emission. On meter waves, the latter increases to tens of millions of times.
The source of this radio emission moves from the chromosphere to the crown at a speed of about 1000 km / s. It is likely that it arises as a result of the emission of cosmic rays generated by the outbreak, and the plasma bombardment with these rays, which causes plasma fluctuations that generate a splash of radio emission.
The rays observed in the crown apparently are generated by these fluxes of rapid, electrically charged particles, drawn by the power lines of the magnetic field. And this field, and the crown plasma inhibit particle flows, but part of them breaks out of the atmosphere of the Sun and, getting into the earth's atmosphere, produces polar shines. Changing the picture of the magnetic field of the Sun from the minimum of its activity to the maximum and determines changes in the shape of the crown, which we have already spoken.
Many protuberans, like the rays of the crown, are due to the movement of gas along the power lines, which is happening, for example, emissions of them on the arcuate trajectory and "rolling" them back to the surface of the Sun. Apparently, the protuberances are mainly in the areas of smooth changes in the magnetic field. The emergence of the glow of the protuberans is suddenly at the top, and then their movement is only downward due, apparently, processes similar to what chromospheric flashes give, but less sharp. The compression of the magnetic field leads to compression relative to cold gas, to the lifting of its density and to the luminescence.
Such are the main features of modern, mainly gas-magnetic, solar phenomena theory.