photosphere

Technical Term

Collection

zero Useful+1

zero

The photosphere is the lowest layer of the solar atmosphere, that is, the solar surface observed with white light, with a thickness of about 500 kilometers. The solar energy we receive is basically from the photosphere. Therefore, the spectrum of the sun is actually the spectrum of the photosphere.

Chinese name: photosphere
Foreign name: photosphere
Alias: photosphere
Properties: sunlight atmosphere Bottom atmosphere
Discipline: Astronomy , Sun

Location: The lowest layer of the solar atmosphere
Thickness: About 500 km
Features: The earth receives most of the energy from the sun
Border characteristics: Temperature drops to the lowest value
Temperature characteristics: From the inside out, the temperature gradually decreases

catalog

nine Photosphere activity

Overview of photosphere

Announce

edit

The sun's atmosphere has three layers, namely, the photosphere, the chromosphere and the corona, but there is no clear boundary between the three layers. The solar photosphere is the circular surface of the sun that we usually see Solar radius It also refers to the radius of the photosphere. The photosphere layer is located at troposphere In addition, it belongs to the lowest or innermost layer of the solar atmosphere. The surface of the photosphere is gaseous, and its average density is only a few hundred million times that of water. But because its thickness is 500 kilometers, the photosphere is Opaque Of. There are intense activities in the atmosphere of the photosphere. With a telescope, you can see many densely dotted structures on the surface of the photosphere, much like rice grains, which are called rice grains. They are extremely unstable, generally lasting only 5~10 minutes, and their temperature is 300~400 ℃ higher than the average temperature of the photosphere. At present, scientists believe that this rice grain structure is caused by the violent convection of gas under the photosphere.^[1]

Physical state

Announce

edit

Although the photosphere is bright as a whole, the brightness of each part is uneven. The non disturbing light sphere is full of rice grain tissue, with an estimated total of 4 million. In the activity area of the photosphere, there are Sunspot , flares, and occasionally white flares. Their brightness, physical state and structure are very different. Every square centimetre The radiation flow emitted per second is 6.3X10 ergs, from which the Effective temperature It is 5500 degrees.

photosphere

This radiation flow is the sum of radiation intensity of each band. The temperature of the photosphere varies with the height, and gradually decreases from the inside out. Photosphere and Chromosphere At the junction of the solar corona, the temperature dropped to the lowest value, only more than 4000 degrees, but then rose inversely, reaching millions of degrees in the corona. The material density of the photosphere is about 10 grams per cubic centimeter, and the gas pressure is roughly equal to 10 dynes/cm.

chemical composition

Announce

edit

Through the sun Spectral line Can qualitatively know what is on the sun chemical element However, the content of various elements on the sun should also be measured quantitatively.

quantitative study The classic method of growth curve Law. This curve represents the Spectral line The equivalent width of Atomic number Relationship between. If the growth curve is known, the corresponding atomic number can be obtained by calculating the equivalent width from the observed spectral line contour. A series of corresponding atomic numbers can be obtained from several spectral lines of the same element, and then the total number of atoms of the element can be obtained by summation. By doing this for a series of elements, we can determine the chemical composition of the sun.

A new method is spectrum synthesis Its main content is to use a series of physical parameters including chemical content to calculate Wavelength range All within Spectral line And compare with the observation. If it does not conform to the observation, adjust the chemical content or other parameters until it conforms to the observation.

The following table lists the common logarithms of the relative content A of various elements in the photosphere. The content of helium is not listed in the table because there is no helium line in the photosphere spectrum. But through Chromosphere And solar prominences Content ratio 63:1000. The layers of the solar atmosphere are often motion state The chemical composition should be basically the same. Therefore, this figure can also represent the helium content of the photosphere.

Chemical composition of the solar photosphere:

Atomic number	element	lgA	Atomic number	element	lgA
one	H	zero	forty-one	Nb	-9.70
three	Li	-11.40	forty-two	Mo	-10.10
four	Be	-10.94	forty-four	Ru	-10.43
five	B	-9.20	forty-five	Rh	-10.45
six	C	-3.43	forty-six	Pd	-10.43
seven	N	-3.94	forty-seven	Ag	-11.33
eight	O	-3.17	forty-eight	Cd	-10.03
nine	F	-7.44	forty-nine	In	-10.29
ten	Ne	-4.55	fifty	Sn	-10.29
eleven	Na	-5.76	fifty-one	Sb	-11.25
twelve	Mg	-4.46	fifty-five	Cs	-10.21
thirteen	Al	-5.60	fifty-six	Ba	-10.20
fourteen	Si	-4.45	fifty-seven	La	-10.19
fifteen	P	-6.57	fifty-eight	Ce	-10.36
sixteen	S	-4.79	fifty-nine	Pr	-10.37
seventeen	Cl	-6.35	sixty	Nd	-10.18
eighteen	Ar	-5.27	sixty-two	Sm	-10.34
nineteen	K	-6.95	sixty-three	Eu	-11.51
twenty	Ca	-5.67	sixty-four	Gd	-10.88
twenty-one	Sc	-8.93	sixty-six	Dy	-10.89
twenty-two	Ti	-7.26	sixty-eight	Er	-11.24
twenty-three	V	-7.90	sixty-nine	Tm	-11.57
twenty-four	Cr	-6.30	seventy	Yb	-11.19
twenty-five	Mn	-6.80	seventy-one	Lu	-11.16
twenty-six	Fe	-4.60	seventy-four	W	-9.43
twenty-seven	Co	-7.50	seventy-six	Os	-11.25
twenty-eight	Ni	-5.72	seventy-seven	Ir	-9.79
twenty-nine	Cu	-7.55	seventy-nine	Au	-11.68
thirty	Zn	-7.58	eighty	Hg	-9.00
thirty-one	Ga	-9.16	eighty-one	Tl	-11.80
thirty-two	Ge	-8.68	eighty-two	Pb	-10.13
thirty-seven	Rb	-9.37	eighty-three	Bi	-11.20
thirty-eight	Sr	-9.18	ninety	Th	-11.18
thirty-nine	Y	-10.38	ninety-two	U	-11.40

Structural model

Announce

edit

The temperature, pressure, density and other physical parameters of the photosphere are not equal everywhere, so it presents a certain structure. Due to the complexity of the actual situation, the photosphere can only be established under a series of simplified assumptions Structural model 。 Common assumptions are:

The photosphere is a parallel plane layer, that is, at the same level, all physical parameters have the same value. In other words, each parameter is just a function of height.

The photosphere is in hydrostatic equilibrium, that is, there is no large-scale material flow; Rice grain tissue sunspot 、 facula etc. Uneven The structure can be ignored; There is local thermal dynamic balance, so common Laws of physics [Planck's law, Boltzmann distribution, Saha formula, etc.] can be applied; The influence of magnetic field is not considered.

After long-term research, astronomers have established many models of photosphere structure. The following table is one of them. It lists the temperature T gas pressure Pg 、 Electronic pressure Pe Particle number density N、 Number of electrons The distribution of parameters such as density Ne and material density ρ with the optical depth τ and geometric depth z of the continuous spectrum at 5000 angstroms.

Structural model of solar photosphere

Z [km]	τ	T	LgPg	LgPe	LgN	LgNe	lgρ
three hundred and twenty	zero point zero zero five	four thousand five hundred and sixty	three point nine three	-0.24	sixteen point one three	eleven point nine six	-7.51
two hundred and seventy-eight	zero point zero one	four thousand six hundred and forty	four point one zero	-0.07	sixteen point two nine	twelve point one two	-7.35
two hundred and thirty-five	zero point zero two	four thousand seven hundred and sixty	four point two seven	zero point one zero	sixteen point four five	twelve point two eight	-7.19
one hundred and seventy-eight	zero point zero five	four thousand nine hundred and fifty	four point four nine	zero point three five	sixteen point six six	twelve point five two	-6.98
one hundred and thirty-six	zero point one	five thousand one hundred and forty	four point six seven	zero point five six	sixteen point eight two	twelve point seven one	-6.82
ninety-one	zero point two	five thousand four hundred and ten	four point eight three	zero point eight one	sixteen point nine six	twelve point nine four	-6.68
thirty-six	zero point five	five thousand nine hundred and twenty	five point zero one	one point two eight	seventeen point one zero	thirteen point three seven	-6.54
zero	one	six thousand four hundred and thirty	five point one three	one point seven six	seventeen point one eight	thirteen point eight one	-6.46
-27	two	seven thousand one hundred and twenty	five point one eight	two point three two	seventeen point one nine	fourteen point three three	-6.45
-56	five	eight thousand and one hundred	five point two six	two point nine nine	seventeen point two one	fourteen point nine four	-6.43
-72	ten	eight thousand six hundred and fifty	five point three zero	three point three eight	seventeen point two two	fifteen point three zero	-6.42
-88	twenty	nine thousand and two hundred	five point three two	three point six four	seventeen point two two	fifteen point five four	-6.42

Edge dim

Announce

edit

photosphere

If not considered Activity area With rice grain tissue, it is easy to see that the brightness of each part of the photosphere is different: the central area of the solar surface is the brightest, and the closer to the edge, the darker. This phenomenon is called edge dimming. By observing the edge darkening phenomenon, we can deduce the temperature distribution 。 To a point on the surface of the sun normal And Observer Direction of sight If the included angle of is θ, the intensity of the outgoing radiation is given by the formal solution of the radiation transfer equation, namely:

I（θ，0）=∫S exp(-tsecθ)secθd t [ 1 ]

Assume that the distribution of source function S with depth is given by the following formula:

S=a+bt [ 2 ]

Substituting [2] formula into [1] formula, it is easy to find:

I（θ，0）= a+bcosθ [ 3 ]

The coefficients a and b are measured from the edge darkening view at a certain frequency and substituted into the formula [2] to obtain the distribution of the source function with depth. Furthermore, the source function is mainly a function of temperature. For example, under the assumption of local thermal dynamic balance, the source function is Planck function, which can be combined with formula [2] to obtain the temperature distribution with depth.

Continuous spectrum

Announce

edit

In terms of visible light and some ultraviolet and infrared bands, the solar spectrum is basically the spectrum of the photosphere. It is a bright Continuous spectrum A large number of absorption lines "namely, Francois Feuerbach lines" are superimposed on it. Continuous spectra and absorption lines are formed in the photosphere, but the central part of some strong lines, such as Ha of hydrogen and H of calcium, is formed in the chromosphere. This is because there absorption coefficient Very large, photosphere radiation cannot be emitted directly. As for ultraviolet, far ultraviolet X-ray And far-infrared and radio band radiation Corona Generated.

The continuous spectrum of the sun is mainly composed of Negative hydrogen ion Generated. stay free electron cover hydrogen atom During adsorption, excess energy is released. This energy release is continuous, so continuous spectrum is generated. The energy of continuous spectrum is mainly transmitted by radiation process in the photosphere.

Francois fee line

Announce

edit

Solar spectrum There are many Franco Fey lines in China, with more than 26000 lines in the range from 2935 to 13495. They are caused by the absorption or scattering of atoms of various elements. Absorption line The temperature, density, pressure chemical composition , magnetic field Velocity field And other information. The absorption lines are all atoms that go down after absorbing the radiation of the photosphere Energy state Produced by an upward transition.

Average density

Announce

edit

photosphere

The average density of gas in the photosphere is only a few hundred million times that of water. The photosphere gas is so thin that it should be very transparent, but actually it is not. Although a thin layer of gas a few centimeters thick is as transparent as a piece of gauze, the gas hundreds of kilometers thick is like thousands of layers of gauze overlapping, and its effect is like a wall, becoming opaque. Therefore, it is difficult for people to see solar radiation 。

If you put Astronomical telescope Aim at the sun (never look directly with your eyes! It will burn your eyes and may lead to blindness!), and use the sun in the telescope filter After reducing the brightness, you can see the surface of the photosphere. At this time, the middle part of the sun circle is brighter than the edge. This is the so-called "edge darkening" phenomenon of the sun. This is because the light emitted from the middle part of the sun's circular surface is emitted from the deeper part of the sun, while the light emitted from the edge of the sun's circular surface is emitted from the shallower and cooler atmosphere of the sun. From the observation of this phenomenon, the temperature distribution of the photosphere can also be deduced. The temperature of the upper layer of the photosphere is only more than 4500 centigrade The lower the temperature is, the higher the temperature will be. At the bottom of the photosphere, it will reach more than 6000 degrees Celsius.

The light ball is densely covered with Granular "Rice grain tissue". If you use a high-speed camera to shoot a film for these rice grains, you can see their various "dances" on the screen. They change very quickly. A few minutes later, they are replaced by new "rice grains", just like rolling up and down Rice porridge , very spectacular! Can you imagine how big these "rice grains" are? The big "rice grains" are more than 1400 kilometers long, and the small ones are more than 300 kilometers long. Astronomers estimate that the total number of rice grains on the solar surface is about several million.

The rice grain tissue is brighter than its surroundings, its temperature is about 200~300 ℃ higher than its surroundings, and it moves upward at a speed of 0.5 kilometers per second. Some people think that rice grains move irregularly on the surface of the sun, with a speed of about 4 kilometers per second. The rapid movement of the rice grain indicates that the rice grain structure is the air flow rising from the photosphere layer, indicating that the photosphere is actually below it and boiling Solar troposphere Top of.

Photosphere activity

Announce

edit

photosphere

The photosphere is the actually seen circular surface of the sun, which has a relatively clear circumferential boundary. The surface of the photosphere is gaseous, and its average density is only a few hundred million times that of water. The photosphere is 500 kilometers thick and extremely opaque. The photosphere is densely dotted with extremely unstable spots, known as "rice grain tissue". The rice grain structure may be the phenomenon of gas convection under the photosphere. In addition, there is super rice grain structure, whose diameter and life span are much larger. In the photosphere Sunspot And flares, occasionally white flares will appear. These activities have different brightness, physical state and structure.

The so-called sunspot is the dark area on the photosphere, its temperature is about 4500K, and the temperature of the rest of the photosphere is about 6000K. It looks very dark against the bright light ball. Completely developed sunspots are composed of darker nuclei（ Umbra ）And the lighter part around it（ Penumbra ）It is shaped like a shallow dish.

Sunspots are one of the most obvious signs of solar activity. The prominent feature of sunspots is their strong magnetic fields, ranging from 500 gauss for small sunspots to 4000 gauss for large sunspots. The year with the most sunspots solar activity The year of maximum and minimum solar activity is called the year of minimum solar activity. The average activity cycle of sunspots is 11.2 years. There are also some areas on the photosphere that are brighter than the surrounding areas, called light spots. It is often accompanied by sunspots.

Novice on the road

Growth task Getting Started with Editing Edit Rule Edit by myself

I have questions

Content query Online Service Official post bar Feedback

Complaints and suggestions

Report bad information Failed to appeal through entries Complaint of infringement information Blocking query and unblocking

Jinggong Network Anbei No. 1100000200001