V - THE SOLAR DUST IN THE ATMOSPHERE POLAR LIGHTS AND THE VARIATIONS OF TERRESTRIAL MAGNETISM, concluded …
Before we close this chapter we will briefly refer to the peculiar phenomenon known as the Zodiacal Light, which can be seen in the tropics almost any clear night for a few hours after or before sunset or sunrise.
In our latitudes the light is rarely visible, and is best seen about the periods of the vernal and autumnal equinoxes.
The phenomenon is generally described as a luminous cone whose basis lies on the horizon, and whose middle line coincides with the zodiac.
Hence the name.
According to Wright and Liais, its spectrum is continuous.
It is stated that the Zodiacal Light is as strong in the tropics as that of the Milky Way.
There can be no doubt that this glow is due to dust particles illuminated by the sun.
It has therefore been assumed that this dust is floating about the sun in a ring, and that it represents the rest of that primeval nebula out of which the solar system has been condensed, according to the theory of Kant and Laplace (compare Chapter VII.).
Sometimes a fairly luminous band seems to shoot out from the apex of the cone of the Zodiacal Light and to cross the sky in the plane of the ecliptic.
In that part of the sky which is just opposite the sun this band expands to a larger, diffused, not well-defined spot of light covering about 12 of arc in latitude and 90 in longitude.
This luminescence is called the counter-glow (Gegenschein), and was first described by Pezenas in 1780.
The most probable view concerning the nature of this counter-glow is that it is caused by small particles of meteorites or dust which fall towards the sun.
Like the position of the corona of the aurora, the position of this counter-glow seems to be an effect of perspective; the orbits of the little particles are directed towards the sun, and they therefore appear to radiate from a point opposite to it.
We know very little about this phenomenon.
Even the position of the Zodiacal Light along the zodiac which has given rise to its name has been questioned, and it would appear from recent investigations that the glow is situated in the plane of the solar equator.
However that may be, the view is very generally held that the glow is due to particles which come from the sun or enter into it.
We have already adduced arguments to prove that the mass of solar dust cannot be unimportant; this dust may therefore be the cause of the phenomenon which we have just been discussing.
TO BE CONTINUED ...
ARRHENIUS, WORLDS IN THE MAKING
Re: ARRHENIUS, WORLDS IN THE MAKING
VI - END OF THE SUN ORIGIN OF NEBULA
WE have seen that the sun is dissipating and wasting almost inconceivable amounts of heat every year.
We have also obtained an idea as to how the enormous storage of heat energy in the sun may endure this loss for ages.
Finally, however, the time must come when the sun will cool down and when it will cover itself with a solid crust, as the earth and the other planets so far, probably, in a gaseous state have done long since or will do before long.
No living being will be able to watch this extinction of the sun despairingly from one of the wandering planets; for, in spite of all our inventions, all life will long before have ceased on the satellites of the sun for want of heat and light.
The further development of the cold sun will recall the actual progress of our earth, except in so far as the sun will have no life-spending, central source of light and heat near it.
In the beginning the thin, solid crust will again and again be burst by gases, and streams of lava will rush out from the interior of the sun.
After a while these powerful discharges will stop, the lava will freeze, and the fragments will close up more firmly than before.
Only on some of the old fissures volcanoes will rise and allow the gases to escape from the interior water vapor and, to a less extent, carbonic acid, liberated by the cooling.
Then water will be condensed.
Oceans will flood the sun, and for a short period it will resemble the earth in its present condition, though with the one important difference.
The extinct sun, unlike our earth, will not receive life-giving heat from the outside, excepting the small amount of radiation from universal space and the heat generated by the fall of meteorites.
The temperature fall will therefore be rapid, and the vanishing clouds of the attenuated atmosphere will not long check radiation.
The ocean will become covered with a crust of ice.
Then the carbonic acid will commence to condense, and will be precipitated as a light snow in the solar atmosphere.
Finally, at a temperature of about 200 Cent., the gases of the atmosphere will be condensed, and new oceans, now principally of nitrogen, will be produced.
Let the temperature sink another 20, and the energy of the in-rushing meteorites will just suffice to balance a further loss of heat by radiation.
The solar atmosphere will then consist essentially of helium and hydrogen - the two gases which are most difficult to condense and of some nitrogen.
TO BE CONTINUED ...
WE have seen that the sun is dissipating and wasting almost inconceivable amounts of heat every year.
We have also obtained an idea as to how the enormous storage of heat energy in the sun may endure this loss for ages.
Finally, however, the time must come when the sun will cool down and when it will cover itself with a solid crust, as the earth and the other planets so far, probably, in a gaseous state have done long since or will do before long.
No living being will be able to watch this extinction of the sun despairingly from one of the wandering planets; for, in spite of all our inventions, all life will long before have ceased on the satellites of the sun for want of heat and light.
The further development of the cold sun will recall the actual progress of our earth, except in so far as the sun will have no life-spending, central source of light and heat near it.
In the beginning the thin, solid crust will again and again be burst by gases, and streams of lava will rush out from the interior of the sun.
After a while these powerful discharges will stop, the lava will freeze, and the fragments will close up more firmly than before.
Only on some of the old fissures volcanoes will rise and allow the gases to escape from the interior water vapor and, to a less extent, carbonic acid, liberated by the cooling.
Then water will be condensed.
Oceans will flood the sun, and for a short period it will resemble the earth in its present condition, though with the one important difference.
The extinct sun, unlike our earth, will not receive life-giving heat from the outside, excepting the small amount of radiation from universal space and the heat generated by the fall of meteorites.
The temperature fall will therefore be rapid, and the vanishing clouds of the attenuated atmosphere will not long check radiation.
The ocean will become covered with a crust of ice.
Then the carbonic acid will commence to condense, and will be precipitated as a light snow in the solar atmosphere.
Finally, at a temperature of about 200 Cent., the gases of the atmosphere will be condensed, and new oceans, now principally of nitrogen, will be produced.
Let the temperature sink another 20, and the energy of the in-rushing meteorites will just suffice to balance a further loss of heat by radiation.
The solar atmosphere will then consist essentially of helium and hydrogen - the two gases which are most difficult to condense and of some nitrogen.
TO BE CONTINUED ...
Re: ARRHENIUS, WORLDS IN THE MAKING
VI - END OF THE SUN ORIGIN OF NEBULA, continued ...
In this stage the heat loss of the sun will be almost imperceptible.
Owing to the low thermal conductive power of the earth's crust, there escapes through each square mile of this crust scarcely one-thousand-millionth part of the heat which the sun is radiating from an equal area of its surface.
In future days, when the solar crust will have attained a thickness of 60 km. (40 miles), its loss of heat will be diminished to the same degree.
The temperature on the surface of the sun may then still be some 50 or 60 above absolute zero, and volcanic eruptions will raise the temperature only for short periods and over small areas.
Yet in the interior the temperature will still be at nearly the same actual intensity, something like several million degrees, and the compounds of infinite explosive energy will be stored up there as today.
Like an immense dynamite magazine, the dark sun will float about in universal space without wasting much of its energy in the course of billions of years.
Immutable, like a spore, it will retain its immense store of force until it is awakened by external forces into a new span of life similar to the old life.
A slow shrinkage of the surface, due to the progressive loss of heat of the core and to the consequent contraction, will in the meanwhile have covered the sun with the wrinkles of old age.
TO BE CONTINUED ...
In this stage the heat loss of the sun will be almost imperceptible.
Owing to the low thermal conductive power of the earth's crust, there escapes through each square mile of this crust scarcely one-thousand-millionth part of the heat which the sun is radiating from an equal area of its surface.
In future days, when the solar crust will have attained a thickness of 60 km. (40 miles), its loss of heat will be diminished to the same degree.
The temperature on the surface of the sun may then still be some 50 or 60 above absolute zero, and volcanic eruptions will raise the temperature only for short periods and over small areas.
Yet in the interior the temperature will still be at nearly the same actual intensity, something like several million degrees, and the compounds of infinite explosive energy will be stored up there as today.
Like an immense dynamite magazine, the dark sun will float about in universal space without wasting much of its energy in the course of billions of years.
Immutable, like a spore, it will retain its immense store of force until it is awakened by external forces into a new span of life similar to the old life.
A slow shrinkage of the surface, due to the progressive loss of heat of the core and to the consequent contraction, will in the meanwhile have covered the sun with the wrinkles of old age.
TO BE CONTINUED ...
Re: ARRHENIUS, WORLDS IN THE MAKING
VI - END OF THE SUN ORIGIN OF NEBULA, continued …
Let us suppose that the crusts of the sun and the earth have the same thermal conductivity namely, that of granite.
According to Homen, a slab of granite one centimetre in thickness, whose two surfaces are at a temperature difference of 1 Cent., will permit 0.582 calorie to pass per minute per square centimetre of surface.
By analogy, the earth's crust, with an increase of temperature of 30 per kilometre, as we penetrate inward, would allow 1.75x10~4 calorie to pass per minute and per square centimetre (this is a percentage of the mean heat supply of the earth, 0.625 calorie per minute per square centimetre); while the sun, with a crust of the same thickness as the earth, but with a diameter 108.6 times larger, would lose 3.3 times more heat per minute than the earth receives from it at the present time.
At present the sun loses 2260 million times more heat than the earth receives; consequently, the loss of heat would be reduced.
If the thickness of the solar crust amounted to the same fraction that the thickness of the earth's crust represents of the terrestrial radius the sun would in 74,500 million years not lose any more heat than it does now in a single year.
This number has to be diminished, on account of the colder surface which the sun would have by that time, to about 60,000 million years.
Considering that the mean temperature of the sun may be as high as 5 million degrees Celsius, the cooling down to the freezing-point of water might occupy 150,000 billion years, assuming that its mean specific heat is as great as that of water.
During this time the crust of the sun would increase in thickness and the cooling would, of course, proceed at a decreasing rate.
In any case, the total loss of energy during a period of a thousand billion years could, under these circumstances, only constitute a very small fraction of the total stored energy.
TO BE CONTINUED ...
Let us suppose that the crusts of the sun and the earth have the same thermal conductivity namely, that of granite.
According to Homen, a slab of granite one centimetre in thickness, whose two surfaces are at a temperature difference of 1 Cent., will permit 0.582 calorie to pass per minute per square centimetre of surface.
By analogy, the earth's crust, with an increase of temperature of 30 per kilometre, as we penetrate inward, would allow 1.75x10~4 calorie to pass per minute and per square centimetre (this is a percentage of the mean heat supply of the earth, 0.625 calorie per minute per square centimetre); while the sun, with a crust of the same thickness as the earth, but with a diameter 108.6 times larger, would lose 3.3 times more heat per minute than the earth receives from it at the present time.
At present the sun loses 2260 million times more heat than the earth receives; consequently, the loss of heat would be reduced.
If the thickness of the solar crust amounted to the same fraction that the thickness of the earth's crust represents of the terrestrial radius the sun would in 74,500 million years not lose any more heat than it does now in a single year.
This number has to be diminished, on account of the colder surface which the sun would have by that time, to about 60,000 million years.
Considering that the mean temperature of the sun may be as high as 5 million degrees Celsius, the cooling down to the freezing-point of water might occupy 150,000 billion years, assuming that its mean specific heat is as great as that of water.
During this time the crust of the sun would increase in thickness and the cooling would, of course, proceed at a decreasing rate.
In any case, the total loss of energy during a period of a thousand billion years could, under these circumstances, only constitute a very small fraction of the total stored energy.
TO BE CONTINUED ...
Re: ARRHENIUS, WORLDS IN THE MAKING
VI - END OF THE SUN ORIGIN OF NEBULA, continued …
When an extinct star moves forward through infinite spaces of time, it will ultimately meet another luminous or likewise extinct star.
The probability of such a collision is proportional to the angle under which the star appears which, though very small, is not of zero magnitude and to the velocity of the sun.
The probability is increased by the deflection which these celestial bodies will undergo in their orbits on approaching each other.
Our nearest neighbors in the stellar universe are so far removed from us that light, the light of our sun, requires, on an average, perhaps ten years to reach them.
In order that the sun, with its actual dimensions and its actual velocity in space 20 km. (13 miles) per second should collide with another star of similar kind, we should require something like a hundred thousand billion years.
Suppose that there are a hundred times more extinct than luminous stars - an assumption which is not unjustifiable - the probable interval up to the next collision may be something like a thousand billion years.
The time during which the sun would be luminous would represent perhaps one-hundredth of this that is to say, ten billion years.
This conclusion does not look unreasonable.
For life has only been existing on the earth for about a thousand million years, and this age represents only a small fraction of the time during which the sun has emitted light and will continue to emit light.
The probability of a collision between the sun and a nebula is, of course, much greater; for the nebulae extend over very large spaces.
In such a case, however, we need not apprehend any more serious consequences than result when a comet is passing through the corona of the sun.
Owing to the very small amount of matter in the corona, we have not perceived any noteworthy effects in these instances.
Nevertheless, the entrance of the sun into a nebula would increase the chance of a collision with another sun; for we shall see below that dark and luminous celestial bodies appear to be aggregated in the nebulae.
TO BE CONTINUED ...
When an extinct star moves forward through infinite spaces of time, it will ultimately meet another luminous or likewise extinct star.
The probability of such a collision is proportional to the angle under which the star appears which, though very small, is not of zero magnitude and to the velocity of the sun.
The probability is increased by the deflection which these celestial bodies will undergo in their orbits on approaching each other.
Our nearest neighbors in the stellar universe are so far removed from us that light, the light of our sun, requires, on an average, perhaps ten years to reach them.
In order that the sun, with its actual dimensions and its actual velocity in space 20 km. (13 miles) per second should collide with another star of similar kind, we should require something like a hundred thousand billion years.
Suppose that there are a hundred times more extinct than luminous stars - an assumption which is not unjustifiable - the probable interval up to the next collision may be something like a thousand billion years.
The time during which the sun would be luminous would represent perhaps one-hundredth of this that is to say, ten billion years.
This conclusion does not look unreasonable.
For life has only been existing on the earth for about a thousand million years, and this age represents only a small fraction of the time during which the sun has emitted light and will continue to emit light.
The probability of a collision between the sun and a nebula is, of course, much greater; for the nebulae extend over very large spaces.
In such a case, however, we need not apprehend any more serious consequences than result when a comet is passing through the corona of the sun.
Owing to the very small amount of matter in the corona, we have not perceived any noteworthy effects in these instances.
Nevertheless, the entrance of the sun into a nebula would increase the chance of a collision with another sun; for we shall see below that dark and luminous celestial bodies appear to be aggregated in the nebulae.
TO BE CONTINUED ...
Re: ARRHENIUS, WORLDS IN THE MAKING
VI - END OF THE SUN ORIGIN OF NEBULA, continued …
From time to time we see new stars suddenly flash up in the sky, rapidly decrease in splendor again, to become extinguished or, at any rate, to dwindle down to faint visibility once more.
The most remarkable of these exceedingly interesting events occurred in February, 1901, when a star of the first magnitude appeared in the constellation of Perseus.
This star was discovered by Anderson, a Scotchman, on the morning of February 22, 1901.
It was then a star of the third magnitude.
Note: Stars are classified in magnitude, the order being such that the
most luminous stars have the lowest numbers. A star of the first magnitude is 2.52 times brighter than a star of the second magnitude; this, again, 2.52 times brighter than a star of the third magnitude, and so on. All this from the point of view of an observer on the earth.
On a photograph which had been taken only twenty-eight hours previous to the discovery of this star, the star was not visible at all, although the plate marked stars down to the twelfth magnitude.
The light intensity of this new star would hence appear to have increased more than five-thousand-fold within that short space of time.
On February 23d the new star surpassed all other stars except Sirius in intensity.
By February 25th it was of the first magnitude, by February 27th of the second, by March 6th of the third, and by March 18th of the fourth magnitude.
Then its brightness began to fluctuate periodically up to June 22d, with a period first of three, then of five days, while the average light intensity decreased.
By June 23d it was of the sixth magnitude.
The light intensity diminished then more uniformly.
By October, 1901, it was a star of the seventh magnitude; by February, 1901, of the eighth magnitude; by July, 1902, of the ninth magnitude; by December, 1902, of the tenth magnitude; and since then it has gradually dwindled to the twelfth magnitude.
When this star was at its highest intensity it shone with a bluish-white light.
The shade then changed into yellow, and by the beginning of March, 1901, into reddish.
During its periodical fluctuations the hue was whitish yellow at its maximum and reddish at its minimum intensity.
Since then the color has gradually passed into pure white.
TO BE CONTINUED ...
From time to time we see new stars suddenly flash up in the sky, rapidly decrease in splendor again, to become extinguished or, at any rate, to dwindle down to faint visibility once more.
The most remarkable of these exceedingly interesting events occurred in February, 1901, when a star of the first magnitude appeared in the constellation of Perseus.
This star was discovered by Anderson, a Scotchman, on the morning of February 22, 1901.
It was then a star of the third magnitude.
Note: Stars are classified in magnitude, the order being such that the
most luminous stars have the lowest numbers. A star of the first magnitude is 2.52 times brighter than a star of the second magnitude; this, again, 2.52 times brighter than a star of the third magnitude, and so on. All this from the point of view of an observer on the earth.
On a photograph which had been taken only twenty-eight hours previous to the discovery of this star, the star was not visible at all, although the plate marked stars down to the twelfth magnitude.
The light intensity of this new star would hence appear to have increased more than five-thousand-fold within that short space of time.
On February 23d the new star surpassed all other stars except Sirius in intensity.
By February 25th it was of the first magnitude, by February 27th of the second, by March 6th of the third, and by March 18th of the fourth magnitude.
Then its brightness began to fluctuate periodically up to June 22d, with a period first of three, then of five days, while the average light intensity decreased.
By June 23d it was of the sixth magnitude.
The light intensity diminished then more uniformly.
By October, 1901, it was a star of the seventh magnitude; by February, 1901, of the eighth magnitude; by July, 1902, of the ninth magnitude; by December, 1902, of the tenth magnitude; and since then it has gradually dwindled to the twelfth magnitude.
When this star was at its highest intensity it shone with a bluish-white light.
The shade then changed into yellow, and by the beginning of March, 1901, into reddish.
During its periodical fluctuations the hue was whitish yellow at its maximum and reddish at its minimum intensity.
Since then the color has gradually passed into pure white.
TO BE CONTINUED ...
Re: ARRHENIUS, WORLDS IN THE MAKING
VI - END OF THE SUN ORIGIN OF NEBULA, continued …
The spectrum of this star shows the greatest similarity to that of the new star in the constellation Auriga (Nova Aurigae) of the year 1892 (Fig. 45).
On the whole, it is characteristic of new stars that the spectrum lines appear double dark on the violet and bright on the red side.
In the spectrum of Nova Aurigse this peculiarity is, among others, striking in the three hydrogen lines C, F, and H, in the sodium line, in the nebula lines, and also in the magnesium line.
In the spectrum of Nova Persei the displacement of the hydrogen lines towards the violet is so great that, according to Doppler's principle, the hydrogen gas which absorbed the light must have been moving towards us with a velocity of 700 or more kilometres (450 miles) per second.
Some calcium lines show a similar displacement, which is less noticeable in the case of the other metals.
This would appear to indicate that relatively cold masses of gas are issuing from the stars and streaming with enormous velocities towards the earth.
The luminous parts of the stars were either at a stand-still or they were moving away from us.
The simplest explanation of these phenomena would be that a star when flashing up by virtue of its high temperature and high pressure shows enhanced (widened) spectral lines, whose violet portion is absorbed by the strongly cooled masses of gas which are moving towards us and are cooled by their own strong expansion.
These gases stream, of course, in all directions from the star, but we only become aware of those gases which absorb the light of the stars that is to say, those situated between the star and the earth, and streaming in our direction.
TO BE CONTINUED ...
The spectrum of this star shows the greatest similarity to that of the new star in the constellation Auriga (Nova Aurigae) of the year 1892 (Fig. 45).
On the whole, it is characteristic of new stars that the spectrum lines appear double dark on the violet and bright on the red side.
In the spectrum of Nova Aurigse this peculiarity is, among others, striking in the three hydrogen lines C, F, and H, in the sodium line, in the nebula lines, and also in the magnesium line.
In the spectrum of Nova Persei the displacement of the hydrogen lines towards the violet is so great that, according to Doppler's principle, the hydrogen gas which absorbed the light must have been moving towards us with a velocity of 700 or more kilometres (450 miles) per second.
Some calcium lines show a similar displacement, which is less noticeable in the case of the other metals.
This would appear to indicate that relatively cold masses of gas are issuing from the stars and streaming with enormous velocities towards the earth.
The luminous parts of the stars were either at a stand-still or they were moving away from us.
The simplest explanation of these phenomena would be that a star when flashing up by virtue of its high temperature and high pressure shows enhanced (widened) spectral lines, whose violet portion is absorbed by the strongly cooled masses of gas which are moving towards us and are cooled by their own strong expansion.
These gases stream, of course, in all directions from the star, but we only become aware of those gases which absorb the light of the stars that is to say, those situated between the star and the earth, and streaming in our direction.
TO BE CONTINUED ...
Re: ARRHENIUS, WORLDS IN THE MAKING
VI - END OF THE SUN ORIGIN OF NEBULA, continued …
Gradually the light of the metallic lines and of the continuous spectrum on which they were superposed began to fade, first in the violet, while the hydrogen lines and nebular lines still remained distinct; like other new stars, this star showed, after a while, the nebular spectrum.
This interesting fact was first noticed by H. C. Vogel in the new star in the Swan (Nova Cygni, 1876).
The star P in the Swan, which flashed up in the year 1600, still offers us a spectrum which indicates the emission of hydrogen gas.
It is not impossible that this "new" star has not yet reached its equilibrium, and is still continuing to emit cold streams of gases.
Insignificant quantities of gas suffice for the formation of an absorption spectrum; thus the emission of gas might continue for long periods without exhausting the supply.
We have already mentioned (page 116) the peculiar clouds of light which were observed around Nova Persei.
Two annular clouds moved away from this star with velocities of 1.4 and 2.8 seconds of arc per day between March 29, 1901, and February, 1902.
If we calculate backward from these dates the time which must have elapsed since those gases left the star, we arrive at the date of the week February 8 to 16, 1901 in satisfactory agreement with the period of greatest luminosity of the star of February 23d.
It would, therefore, appear that these emanations came from the star and were ejected by the radiation pressure.
Their light did not mark any noticeable polarization, and could not be reflected light for this reason.
We may suppose that the dust particles discharged their electric charges, and that the gases became thereby luminous.
TO BE CONTINUED ...
Gradually the light of the metallic lines and of the continuous spectrum on which they were superposed began to fade, first in the violet, while the hydrogen lines and nebular lines still remained distinct; like other new stars, this star showed, after a while, the nebular spectrum.
This interesting fact was first noticed by H. C. Vogel in the new star in the Swan (Nova Cygni, 1876).
The star P in the Swan, which flashed up in the year 1600, still offers us a spectrum which indicates the emission of hydrogen gas.
It is not impossible that this "new" star has not yet reached its equilibrium, and is still continuing to emit cold streams of gases.
Insignificant quantities of gas suffice for the formation of an absorption spectrum; thus the emission of gas might continue for long periods without exhausting the supply.
We have already mentioned (page 116) the peculiar clouds of light which were observed around Nova Persei.
Two annular clouds moved away from this star with velocities of 1.4 and 2.8 seconds of arc per day between March 29, 1901, and February, 1902.
If we calculate backward from these dates the time which must have elapsed since those gases left the star, we arrive at the date of the week February 8 to 16, 1901 in satisfactory agreement with the period of greatest luminosity of the star of February 23d.
It would, therefore, appear that these emanations came from the star and were ejected by the radiation pressure.
Their light did not mark any noticeable polarization, and could not be reflected light for this reason.
We may suppose that the dust particles discharged their electric charges, and that the gases became thereby luminous.
TO BE CONTINUED ...
Re: ARRHENIUS, WORLDS IN THE MAKING
VI - END OF THE SUN ORIGIN OF NEBULA, continued …
In this case we were evidently witnesses of the grand finale of the independent existence of a celestial body by collision with some other body of equal kind.
The two colliding bodies were both dark, or they emitted so little light that their combined light intensities did not equal that of a star of the twelfth magnitude.
As, now, their splendor after the collision was greater than that of a star of the first magnitude, although their distance has been estimated to be at least 120 light years, their radiation intensity must have exceeded that of the sun several thousand times.
Under these circumstances the mechanical radiation pressure must also have been many times more powerful than on the surface of the sun, and the masses of dust which were ejected by the new star must have possessed a velocity very much greater than that of solar dust.
Yet this velocity must have been smaller than that of light, which, indeed, the effect of the radiation pressure can never equal.
It is not difficult to picture to ourselves the enormous violence with which this "collision" must have taken place.
A strange body for instance, a meteorite which rushes from the infinite universe into the sun has at its collision a velocity of 600 km. (400 miles) per second, and the velocity of the two colliding suns must have been of approximately that order.
The impact will in general be oblique, and, although part of the energy will of course be transformed into heat, the rest between two extinct suns, of the kinetic energy must have produced a rotational velocity of hundreds of kilometres per second.
By comparison with this number the actual circumferential speed of the sun, about 2 km. (1.3 miles) per second on the equator, would vanish altogether; and the difference is still more striking for the earth, with its 0.465 km. per second at the equator.
We shall, therefore, not commit an error of any consequence if we presume the two bodies to have been practically devoid of circumferential speeds before their collision.
TO BE CONTINUED ...
In this case we were evidently witnesses of the grand finale of the independent existence of a celestial body by collision with some other body of equal kind.
The two colliding bodies were both dark, or they emitted so little light that their combined light intensities did not equal that of a star of the twelfth magnitude.
As, now, their splendor after the collision was greater than that of a star of the first magnitude, although their distance has been estimated to be at least 120 light years, their radiation intensity must have exceeded that of the sun several thousand times.
Under these circumstances the mechanical radiation pressure must also have been many times more powerful than on the surface of the sun, and the masses of dust which were ejected by the new star must have possessed a velocity very much greater than that of solar dust.
Yet this velocity must have been smaller than that of light, which, indeed, the effect of the radiation pressure can never equal.
It is not difficult to picture to ourselves the enormous violence with which this "collision" must have taken place.
A strange body for instance, a meteorite which rushes from the infinite universe into the sun has at its collision a velocity of 600 km. (400 miles) per second, and the velocity of the two colliding suns must have been of approximately that order.
The impact will in general be oblique, and, although part of the energy will of course be transformed into heat, the rest between two extinct suns, of the kinetic energy must have produced a rotational velocity of hundreds of kilometres per second.
By comparison with this number the actual circumferential speed of the sun, about 2 km. (1.3 miles) per second on the equator, would vanish altogether; and the difference is still more striking for the earth, with its 0.465 km. per second at the equator.
We shall, therefore, not commit an error of any consequence if we presume the two bodies to have been practically devoid of circumferential speeds before their collision.
TO BE CONTINUED ...
Re: ARRHENIUS, WORLDS IN THE MAKING
VI - END OF THE SUN ORIGIN OF NEBULA, continued …
At the collision, matter will have been ejected from both these celestial bodies at right angles to the relative directions of their motion in two powerful torrents, which would be situated in the plane in which the two bodies were approaching each other (compare Fig. 46).
The rotational speed of the double star, which will be diminished by this ejection of matter, will have contributed to increase the energy of ejection.
We remember, now, that when matter is brought up from the interior to the surface of the sun it will behave like an explosive of enormous power.
The ejected gases will be hurled in terrific flight about the rapidly revolving central portions.
We obtain an idea (though a very imperfect one) of these features when we look at a revolving pinwheel in a fireworks display.
Two pinwheels have been attached to the ends of a diameter and belch forth fire in radial lines.
The farther removed from the wheel, the smaller will be the actual velocity and also the angular velocity of these torrents of fire.
Similarly with the star.
The streams are rapidly cooled, owing to the rapid expansion of the gas.
They will also contain fine dust, largely consisting of carbon, probably, which had been bound by the explosive materials.
The clouds of fine dust will obscure the new star more and more, and will gradually change its white brilliancy into yellow and reddish, because the fine dust weakens blue-and-green rays more than it does yellow-and-red rays.
At first the clouds were so near to the the star that they possessed a high angular velocity of their own; they then appeared to surround the star completely.
But after March 22, 1901, the outer particles of the streams attained greater distances and assumed longer periods of revolution (six days); the star then became more obscured when the extreme dust clouds of the streams covering it happened to get between us and the star.
As the streams of particles were moving farther away, their rotational periods increased gradually to ten days.
The star, therefore, became periodical with a slowly growing length of period, and its glow turned more reddish at its minimum than at its maximum of intensity.
At the same time, the absorptive power of the marginal particles decreased, partly owing to their increasing expansion, partly because the dust was slowly aggregating to coarser particles; possibly, also, because the finest particles were being driven away by the radiation pressure.
The sifting influence which the dust exercised upon the light, and owing to which the red-and-yellow rays were more readily transmitted than the blue-and-green, gradually became impaired; hence the color of the light burned more gray, and after a certain time the star appeared once more of a whitish hue.
This white color indicates that the star must still have a very high temperature.
TO BE CONTINUED ...
At the collision, matter will have been ejected from both these celestial bodies at right angles to the relative directions of their motion in two powerful torrents, which would be situated in the plane in which the two bodies were approaching each other (compare Fig. 46).
The rotational speed of the double star, which will be diminished by this ejection of matter, will have contributed to increase the energy of ejection.
We remember, now, that when matter is brought up from the interior to the surface of the sun it will behave like an explosive of enormous power.
The ejected gases will be hurled in terrific flight about the rapidly revolving central portions.
We obtain an idea (though a very imperfect one) of these features when we look at a revolving pinwheel in a fireworks display.
Two pinwheels have been attached to the ends of a diameter and belch forth fire in radial lines.
The farther removed from the wheel, the smaller will be the actual velocity and also the angular velocity of these torrents of fire.
Similarly with the star.
The streams are rapidly cooled, owing to the rapid expansion of the gas.
They will also contain fine dust, largely consisting of carbon, probably, which had been bound by the explosive materials.
The clouds of fine dust will obscure the new star more and more, and will gradually change its white brilliancy into yellow and reddish, because the fine dust weakens blue-and-green rays more than it does yellow-and-red rays.
At first the clouds were so near to the the star that they possessed a high angular velocity of their own; they then appeared to surround the star completely.
But after March 22, 1901, the outer particles of the streams attained greater distances and assumed longer periods of revolution (six days); the star then became more obscured when the extreme dust clouds of the streams covering it happened to get between us and the star.
As the streams of particles were moving farther away, their rotational periods increased gradually to ten days.
The star, therefore, became periodical with a slowly growing length of period, and its glow turned more reddish at its minimum than at its maximum of intensity.
At the same time, the absorptive power of the marginal particles decreased, partly owing to their increasing expansion, partly because the dust was slowly aggregating to coarser particles; possibly, also, because the finest particles were being driven away by the radiation pressure.
The sifting influence which the dust exercised upon the light, and owing to which the red-and-yellow rays were more readily transmitted than the blue-and-green, gradually became impaired; hence the color of the light burned more gray, and after a certain time the star appeared once more of a whitish hue.
This white color indicates that the star must still have a very high temperature.
TO BE CONTINUED ...