During the first day of my first astronomy class the professor asked the class a question,
“when you look up at night what do you see?” Some said “stars, planets, moons”, and some idiot
that will not be named (me),”quasars”. “No, we see light” he responded. All the information we
get from a star is in its light. From the light of the star we get it’s temperature, what is made of,
the concentration of what is made of, and the mass.
What is light?
Light acts like a particle with no mass and also a wave. There is one experiment that can
demonstrate this and that is the Young double slit experiment. To set up this experiment you a card with
two slits in it, a light source shining through it and a screen opposite the light source. When
you run the experiment emitting one particle at a time over many times the pattern the many dots
make is the same interference as if a wave was going through the slits. At
Hitachi. These experiments both showed the wave-particle duality of the electrons. Light is also
the particle that conveys electromagnetic energy.
How is light generated?
Light can be generated by several different processes. One is nuclear reactions such as fission and
fusion, in either one of process happens a small portion of the mass converted to energy we
detect this energy in the form of light. Another way is when an electron which is orbiting around
the nucleus and then is excited by a photon (particle of light) and goes to higher orbit or leaves
the atom but the atom actually wants to be in lowest energy state so the electron will go back to
the lower energy level and admit a photon. When atoms are excited by thermal means, that
means the atoms move faster and faster, the atoms collide and electrons can be excited and as
before they want to be in the lowest energy level and the energy lost is seen as light.
What is the spectrum and how is created?
Take a prism and hold it to the sun get a rainbow coming out. The reason for this is that the
light from the sun is composed of all these colours and as they go through the prism they travel at
different speeds. We can only see a small part of the spectrum, there are X-rays, gamma rays and
UV light which have shorter wavelengths and are higher energy then we see, at the other end we
have infrared , microwaves and radio waves which are longer wavelength and lower energy.
There three different types of spectrum each dependent on what you are viewing. A
continuous spectrum has no lines and caused by a hot opaque, dense gas. An emission spectrum
is series of bright lines against a dark back ground and caused by a hot transparent gas. An
absorption spectrum is a series of dark lines against a background pf a continuous spectrum is
caused by the light from a source of a continuous passing through a cool transparent gas.
spectrum also come in a form of the intensity vs the wavelength.
How Do Astronomer’s use the Spectrum ?
There is gold in there light. First can determine what temperature an object is, this is
done by plotting the intensity (how strong) vs the wavelength. The plot you get for example for
the sun will have peak at 550 nm, this with a little math gives a temp of 5780 K. If you have an
emission or adsorption nebula you can determine what the object is composed. The orbits of
electrons around each type of element is slightly different so the energy needed to excite each
electron in different types of atoms or molecules is different. So if you know what the spectrum
for the various atoms or molecules you can figure out what the object is made of, some stars
show a spectrum of molecules and molecules break apart a fairly cool temperatures so these stars
must be cool, some stars show no molecules but show ionized atoms these stars are hotter
because the molecules have been broken apart.
Mass can be determined by the interaction of the object with other objects. When an
object moves away from the observer the light is shifted to the red end of the spectrum and when
the object moves closer the light is shifted towards the blue end. If there is a star where the
spectrum is shifted from the red and then to blue and does this one a regular period you can
determine the mass of the objects. This is also how most planets are found around other stars.
One claim by the electric universe proponents is that there is no connection to the mass and the colour of a star. Also all the light is generated on the surface of the star.
First most stars have an absorption spectrum and if the light was produced on the surface they would have an emission spectrum. There are some stars that have an emission spectrum but these are extremely hot stars and therefore the atmospheres are hot enough to ionizethe atoms. Second most stars in our galaxy are two or more stars that orbit around each other so there are plenty of stars of different types to see if there is correlation between mass and colour. Also smaller stars tend be cooler and more massive stars are hotter, so the less massive stars should have molecules
in there spectrum and larger stars shouldn’t have molecules in the spectrum. So scientists have found low mass stars that emit most of the light in the red part of the spectrum and have molecules in there spectrum while high mass stars emit most of there light in the blue part of the spectrum and have ionized atoms in the spectrum.
Light is a particle and a wave and conveys electromagnetic light. There is a lot of
information that can be found in the light that a star emits such as mass, temperature and
composition. We can show that there is correlation between mass, colour and temperature of a star.
Kauffman(1995),Universe,4th edition, pages 79,81,115
Bradley W. Carroll and Dale A. Ostlie(1996), An introduction to Modern Astrophysics,pages63-82,223-250