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Solar spectra and line Doppler shift

 Solar spectra and line Doppler shift


Solar and star spectra are very important for the astronomy. The topic is considered already a closed subject but as it will be shown bellow we are not able to explain the spectra and the so called ,,Doppler effect” for our Sun. How can we pretend that we are able to understand what happen at hundred or even millions of light years?


Solar Spectra


Background and actual explanation

When sunlight is split by a prism, at first glance it appears to produce a continuous spectrum. However, closer scrutiny shows that the solar spectrum is interrupted by a large number of narrow dark lines.

First dark line in solar spectrum were reported by William Wollaston arround 1802. Fraunhofer not only confirmed Wollaston's results, but also found that there were far more dark lines in the spectrum than Wollaston had suspected. Fraunhofer mapped out about 600 lines that he observed in the sun's spectrum. Eight of the most prominent lines were labeled A to G. Today, these lines are known as the Fraunhofer lines as in fig 1.

At around the time solar absorption lines were discovered, scientists found that absorption lines could also be produced in the laboratory by passing a beam of light through a cool gas. They observed a connection between emission and absorption lines: The absorption lines associated with a given gas occur at precisely the same wavelengths as the emission lines produced when the gas is heated.

Many scientists worked in the field, but Gustav Kirchhoff was able to make the definitive discovery on the relationship between the emission (bright-line) spectrum and the absorption (dark-line) spectrum and these are known today as Kirchhoff’s laws and may be summarized as follows:

  1. A luminous solid or liquid, or a sufficiently dense gas, emits light of all wavelengths and so produces a continuous spectrum of radiation.

  2. A low-density hot gas emits light whose spectrum consists of a series of bright emission lines. These lines are characteristic of the chemical composition of the gas.

  3. A low-density cool gas absorbs certain wavelengths from a continuous spectrum, leaving dark absorption lines in their place, superimposed on the continuous spectrum. These lines are characteristic of the composition of the intervening gas. They occur at precisely the same wavelengths as the emission lines produced by the gas at higher temperatures.

Table 1 -- "Known" Lines


Wavelength (nm)




terrestrial oxygen



terrestrial oxygen



hydrogen (Hα)



neutral sodium (Na I)



neutral sodium (Na I)



neutral iron (Fe I)



hydrogen (Hβ)



ionized calcium (Ca II)



ionized calcium (Ca II)

solar spectra 01


Based on these concepts the actual interpretation for sun and star spectra seem straightforward. Sun or any other star, as a hot dense objects emit a continuous spectrum of light, regardless of their particular elemental composition given by blackbody radiation distribution.

When the visible light from below the Sun's surface passes through the layers above it (the photosphere and chromosphere), some of the light at particular wavelengths is absorbed by atoms and ions and so is missing in the spectrum we see on Earth.

On the other hand, for the discussion it is important to point out that, according to NASA latest information there is no temperature lower than 3700 K( ),  in the external layers of Sun.

IRIS will focus its investigation on the Chromosphere and Transition Region. More detail on the outer layers follows:
Photosphere- The photosphere is the deepest layer of the Sun that we can observe directly. It reaches from the surface visible at the center of the solar disk to about 250 miles (400 km) above that. The temperature in the photosphere varies between about 6500 K at the bottom and 4000 K at the top (6200 and 3700 degrees C). Most of the photosphere is covered by granulation.
Chromosphere- The chromosphere is a layer in the Sun between about 250 miles (400 km) and 1300 miles (2100 km) above the solar surface (the photosphere). The temperature in the chromosphere varies between about 4000 K at the bottom (the so-called temperature minimum) and 8000 K at the top (3700 and 7700 degrees C), so in this layer (and higher layers) it actually gets hotter if you go further away from the Sun, unlike in the lower layers, where it gets hotter if you go closer to the center of the Sun.
Transition Region- The transition region is a very narrow (60 miles / 100 km) layer between the chromosphere and the corona where the temperature rises abruptly from about 8000 to about 500,000 K (7700 to 500,000 degrees C).
Corona- The corona is the outermost layer of the Sun, starting at about 1300 miles (2100 km) above the solar surface (the photosphere). The temperature in the corona is 500,000 K (900,000 degrees F, 500,000 degrees C) or more, up to a few million K. The corona cannot be seen with the naked eye except during a total solar eclipse, or with the use of a coronagraph. The corona does not have an upper limit. Credit: National Solar Observatory

Last Updated:July 31, 2015



Why the actual explanation for solar spectra is absurd.....

Let us analyze the line spectra coming from Sun listed in Tab1 and observed at Earth level. Most of them are coming from neutral matter (hydrogen, sodium, iron) and 2 lines from ionised calcium.

This means somewhere in the path of photons emitted by Sun there must be a layer of neutral matter, able to absorb these lines as in fig. 1

The main problem regards the position of this layer of neutral matter. This cannot be in photosphere, this cannot be in chromosphere, this cannot be in corona.

Although in photosphere the temperature ,,is considered” much lower than chromosphere and corona, i.e. 3700 K, no neutral matter can exist in these conditions.

In consequence ,,there are some absorbtion line” coming from somewhat which cannot exist there. Maybe actual theoreticians feel a trace of dark matter there?


Solar spectra 02

Figure 1. Neutral matter layer around Sun.

Of course we can admit that absorption takes place due to the presence of these elements somewhere in the space between Earth and Sun, but this idea leads to such absurdities that it is no worth to loose the time describing them here....

The absorption measured on Earth should be proportional with the concentration of absorbing species... and when this is estimated, we will have another ,,invisible matter” in our Solar system.



,,Dopler effect “ and Sun rotation


Background and actual explanation

Like sound, light is Doppler-shifted depending on whether the object is moving towards or away from the viewer or listener. Approaching sound rises in pitch or frequency when it approaches the listener and drops in pitch when it moves away. The same thing happens to light. Approaching objects shift in color towards blue and receding objects shift towards red.

Measuring the Sun rotation with this effect is a piece of cake even for amateur astronomer like me.

The Sun being in rotation, the Eastern limb moves towards us while the Western limb moves away from us. By taking successively a spectrum with the western limb and another with the eastern limb, a slight difference (shifting) of an absorption line is observed in the spectroscope.

Solar spectra 03



Figure 2. Sun rotation measurements

Knowing the solar radius, the rotational period can be calculated.As far the sun rotates in 25 days at the equator, and a point of its equator makes approx. 4.4 million km during this time, the speed to be measured is about 2 km/s. This speed must induce a Doppler shifting about 589*2/300000 = 0.0039 nm for the yellow line of Sodium. This represents a variation of 0.0078 nm between the spectra east (shifted towards blue) and west (shifted towards red). A similar variation is observed when other dark lines in solar spectra are taken as reference.



Why the actual explanation is absurd?

For the beginning it is a common sense to admit that the same results are obtained when these measurements are performed with Earth in position A, B, C or D on its orbit (fig2). And we came back to the interpretation of the results. If the absorption species, in this case sodium atoms, are present in solar atmosphere, than we have measured the speed of rotation for solar atmosphere. This is because Sun as a blackbody emits a continuum spectra and we cannot make any correlation between atmosphere motion and the motion of sun layers under this atmosphere. For Earth, I cannot imagine that an extraterrestrial observer will ever deduce the speed of planet rotation measuring the Doppler effect in clouds. Why should someone believe that in case of Sun, considered as a gasball, different layers rotates with the same angular velocity like a rigid body? So we have to admit that Doppler shift according to actual science has not a consistent explanation in case of our Sun. Any extrapolation to far away universe is useless....


If astronomers from last century had been a bit more mindful with some simple data, by sure the gas model of a sun wouldn't have been accepted.

There were so many star spectra collected and, although astronomers are not chemists, someone should have looked a bit more careful at these data. Accepting that absorption lines in star spectra are coming from some elements in the star atmosphere, this does not mean that star atmosphere motion is identical with the star motion.

More than that, if atomic sodium is like a gas in star atmosphere, due to the proper motion of sodium atoms, there should be no separation of 589.6 nm from 589.0nm. Accepting by absurd that sodium atom could resist as neutral atom in star atmosphere, the thermal agitation of such species is so great that only a broad line between 588 and 590 should have been detected.

On the other hand, we know from analytical chemistry that absorption is proportional with the amount of absorbing species in the path of photons; and therefore beside lines of sodium, even the line of neutral hydrogen or other lines coming from neutral species in the solar spectra cannot be explained or should be broadened. There should be a correspondence between broadening of a line and the mass of the absorbing species. I cannot imagine that ,,hypothetical neutral’’ hydrogen atoms move with the same average speed as iron atoms in the solar atmosphere; this would contradicts blatantly the kinetic molecular theory. I haven’t seen a paper or I haven’t heard about astronomers who have looked for a cloud of neutral matter (hydrogen, sodium, iron) between Sun and Earth. Are these elements in the same cloud or in different clouds? Maybe with so many telescopes around, someone will make a bit time in order to clarify this problem …

In order to proper characterize the Sun, a new state of matter has to be postulated. It has not a name yet, but it is not a real fluid, although the equations of motion for fluids adapt quite well to this new state of matter. I do not have a name for this state of matter therefore until the book is published it will be called solar matter.

This solar matter although it has a temperature of 6000 K or even more (I am not sure about the real temperature of the Sun) and has a composition made from atomic species. It means hydrogen, helium, sodium, magnesium, iron, etc are present in the atomic state. Each electron for each atom orbits its own nucleus. For hydrogen an electron orbit around its nucleus, for helium there are two electrons on orbit and so on... for the Iron of course there are 26 electrons around nucleus.

In this new model,Sun has a clear border between atmosphere and solar matter. Solar matter has a proper motion and emission spectra of sun is dependent on the motion of solar matter.

How the solar spectra appears for an Earth observer will be presented in detail in the book...