Medellín, December 11, 2008
stellar properties and the main sequence in the diagram Hertzprung Russell
Geo logos, with the help of physical and based on the information they provide on the one hand the volcanism and tectonics on the other, chemistry, mining, astrophysics, the litologíay the environment, have constructed mathematical models on the computer, enabling them to make inferences about the interior of our planet. Based on the resultados have created theories to explain satisfactorily the questions on the subject and at the same time allow predictions about the internal composition of our planet Earth.
Surprisingly, in the 50s, when, when the computational tools were emerging, astrophysicists at the time, based on the laws of physics, chemistry and astronomy, the stars also modeled, to the point, now has a better understanding of stellar interiors, which the interior of our planet, and not only that, but we know the stellar evolution which naturally draws the evolution & oacute n land, bearing in mind that this is only a tiny part of the solar system or just the Sun
This modeling of the 50s, what was forced to first give a definition of star, that meets the new knowledge of physics and chemistry, especially the theories of relativity and quantum. The modeling began with the Sun and then to many major stars in our galaxy.
The following definition was taken as a consensus, at that time:
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"A star is a very massive field of plasma, which emits light" (1)
The main star main materials are hydrogen, helium, oxygen oxygen and carbon. However, for much of the life of the star, the amount of hydrogen is much higher than other elements, even summing them.
is difficult to understand two things: How can a gaseous body can take a spherical shape and second, where does the energy that stars radiate Diaye night for thousands and millions of years.
The first question can understand, saying that each particle of the field stellar gas, act two opposing forces. On the one hand the gravity and the other pressure of the gas itself. Without the gravity, pressure all the gas would disperse in space. Without the pressure, gravity all the mass concentrated around its center. Under these conditions and taking into account homogeneity of space, form of this mass, this buoyancy should be that of a sphere.
The answer to the second question is a bit more complicated. The models computer in the 50s, concluded that the only way to maintain a sustained energy production and huge for so many millions of years is through the fusion of Hydra Helium and oxygen in helium into carbon and oxygen. To be in this nuclear autofusión, requires that both the core and the outer layers of stars with extremely high temperatures of tens of thousands of degrees Kelvin. A star, besides being a gaseous sphere, is a nuclear fusion machine that turns hydrogen into helium and helium into heavier materials. (1)
is important to note that there are only two sources to provide scientific data for the stellar model. The first is the astronomical observation and the second the analysis of light received, especially its spectrum.
The primary data are unavailable. Recall that the closest star to Earth is Alpha Centauri, which is at 4.2 light years to go to it would need about 1 million years, at a rate equal 50 times the cruising speed of oceanic aircraft.
The model computesCurly (2), yielded important data on the composition of the Sun and stars, as their properties and their evolution, since they cease to be a protostar, until they die, the become a nova or supernova.
One of the most important tools for the study of the stars: Their properties and stellar evolution is the chart called "Herztprung Russell" in which, in the y-axis lies the absolute magnitude of each star and its equivalent in brightness, compared with the corresponding Sun (Bright = Brightness) and the axis x, located both in temperature, as the classificationNo spectral light received from the stars. (2). Figure 1
Figure 1
The absolute magnitude of a star is inferred from its apparent magnitude and this, spectrometric analysis ; Trico of light received, both in the visible spectrum, as in the invisible to the naked eye. From Hipparcos know that if the magnitude of a first star is 1, and the second is 2, the first is brighter than the second and the relationship is that the brightness of the 1 st is 2.51 times higher than that of the 2 nd. If a third star has an absolute magnitude6, then the first star is 2.51 5 = 100 times brighter than the third.
As the absolute magnitude may be negative, a formula that makes us absolute magnitudes Suns luminosity is:
Luminosity (Suns) = 2.51 (4.8 -Mabs) ,
Given that the absolute magnitude of the Sun is 4.8.
Thus, a star that has an absolute magnitude of -1.27 (much brighter than the Sun), has a luminosity L (Soles) CHT MLXC
L (Soles) = 2.51 (4.8 - (-1.27)) = 267 Suns.
Figure 1 is also a direct relationship between the spectral classification and the temperature of the star, although it is not possible to obtain a formula as above.
is important to note that the spectral signatures O, B, A, F, G, K and M are helped with subdivisions between 0 and 9. Thus, the G2 star is hotter than the G3 and the G5 more than the G9.
However, with optical and electromagneticsophisticated ethical, together with advanced computational tools and modern very large observatories, it is possible, based on spectral analysis of the observed stars, stellar obtain the following properties: Absolute Magnitude, Spectral Type and temperature and therefore it is possible to locate each of them, Hertzprung Russell diagram.
Most of these data can be found on the Web, mostly in English Wikipedia, but also in the English version. Likewise, there are star catalogs on the Web, allowing us to find stellar properties, starsas specific.
an example:
| Star | Absolute Magnitude | Spectral Type | solar masses |
| Rigel | -7.0 | B8Ia | 17 Sun |
| Deneb | -7.2 | A2iA | Sol 20 to 25 |
|
| Betelgeuse-5.6
| M2Iab | 20 Sun |
| Sirius | 1.4 |
| A1V 2.20 Sun |
| Sun 1.0 |
| G2V | 1 Sol |
star property more difficult to obtain the mass, as the analysis spectrum is not always enough. To get an idea of the value of the mass of a star relies on astronomical measurements, combined with spectral results relating to the constituent elements and also its density and gravitational wobble.
STDrella of the table, like many others, have been located in the HR diagram, Figure No 1.
is important to note in Figure 1 HR diagram, which is a central area that winds from top left to bottom right, which is a good concentration of stars. The Sun and Sirius are in this age, while Rigel, Betelgeuse and Deneb are above it. That strip is called the main sequence and it is 90% of the known stars.
When a star is born, is still a protostar becomes a nuclear fusion machine, andis there when you start the fusion of hydrogen into helium. When stars are born are located on the main sequence HR diagram. The stars are many millions of years in the main sequence and mandatory, then they should leave it. The median Pequena mass stars consume their hydrogen more slowly than the mass and therefore its presence in the main sequence for longer and in many cases much higher.
is believed that a star is on the main sequence, from birth until the initial hydrogen is reduced by about 70%. (2)
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The model that gave us all this informacióny which allowed us to better understand the Sun, gave us information on when it formed. The sun is still in the main sequence band, for now a bit above the starting position. It is estimated that the Sun was born 4500 Millions of years ago and is now just above the center of the band. The model shows that in 4500 years, the sun will rise on the main sequence and begin their journey to become a red giant, before his death.
The modewhat we have been quoting a formula gave us very important and useful. The mass of main sequence stars can be determined based on its brightness. Figure 2
Figure 2
an interesting correlation exists between the mass of main sequence stars and their brightness. This is given, approximately, with the formula
Mass (Suns) = (Luminosity (Suns)) ^ 0.254
And with a little less precision & oacutee, n
m = L (fourth)
Let's see if both the graph, how the formula works.
Sirius: Main Sequence
Sirius absolute M = 1.4 Sirius
Brightness = 2.51 ^ (4,8-1,27) = 26 Soles
Sirius mass = 26 ^ (0.254) = 2.28 Soles
Rigel: Near the main sequence. Rigel
absolute M = - 7.0
Rigel Brightness = 2.51 ^ (4.8-(-7))= 52,000 Soles
Rigelmass = 52,000 ^ (0.254) = 15.77 Soles
In Figure 1 we see that Rigel is very close to the main sequence therefore gives us a value that may not apply, however, given its proximity, the formula gave us a close estimate. At Wikipedia we find that the mass of Rigel is 17 Soles.
Betelgeuse: Outside the main sequence. Betelgeuse
absolute M = - 7.2
Betelgeuse Brightness = 2.51 ^ (4.8 - (-5.6)) = 14,341 Soles
Betelgeusemass =14341 ^ (0.254) = 11 Soles very different from the mass accepted by the scientific community that is 20 Soles.
Vega: Main Sequence
absolute Vega M = 0.58
Vega Brightness = 2.51 ^ (4,8-0,65) = 45.5 Soles Vega
mass = 45.5 ^ 0,254 = 2.63 Soles
Note. The information found on the web about Vega is not consistent.
Altair, is on the main sequence. Altair
: Brightness = 10 Soles
high mass = 100.254 = 1.8 Soles
Conclusion.
The computer model of the Sun and stars, answered nearly every question that we can think and at the same time allows to make predictions. It is also widely accepted.
The mass determines luminosity for main sequence stars works well and is very helpful, given the difficulty of determining the mass of stars.
The complete model is highly regarded within the scientific community and has helped launch the contemporary theoriesof astrophysics. However, there are dissenting voices of respected scientists, who have doubts about these theories, which is why we should not be dogmatic and excommunicate those who do not share. In fact, the voices mentioned which are not entirely convinced of the theory of stellar evolution, nor are the current cosmic pattern, since the Big Bang, to relativistic physics and quantum.
(1) Power Point Presentation on properties and stellar evolution, professor of astronomy at the University of Antioquiaquia Dr. George Johnson.
(2) KIPPENHAN RUDOLF. A hundred billion suns. Salvat Editores Barcelona 1986.
Juan Fernando Sanin
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