Light sources 12/02/17
Primary light sources – stars
Energy striking the retina in our eyeball as well as the sensing element in digital cameras enables us to see things around us and far away. This energy is in packets, called photons, which constitutes light. Modern theory explains the emission of light by matter in terms of electronic energy levels. On the atomic level, an electron of relatively high energy may jump to a condition of lower energy, giving off the energy difference as electromagnetic radiation. Light beams have specific values of frequency and hence, energy which determines color. Visible light ranges from red, the lowest energy, to violet which is the highest, as seen in the rainbow. (Encyclopedia Britannica, Online, 31 May 2013).
Much of the light associated with astronomical sources arises from reactions at the atomic level where electrons move from one energy level to another and photons are emitted in this process. Stars (including our sun) are constantly emitting light as a result of nuclear fusion where the hydrogen gas is fused into helium and energy is released, i.e. light. Nuclear fission, found in typical nuclear reactors, also emits light when in the decay process the particles released move to a more tightly bound energy level and the difference on energy is released as light. (Seeds and Backman, 11th edition 2010). The photo below shows the glow in the water pool of a nuclear fission reactor where the light is emitted in the control rods.
All of the mass, all of the energy, and all of the laws of science and laws of life in today’s dynamic cosmos come from the chaos of these events. Order in this created universe is seen in the shape and movement of the nebulae, stars, planets and galaxies and other matter.
Galaxies, dark matter, quasars and black holes.
Stars can be formed in nebulae which are the most densely compressed parts of the molecular cloud. Nuclear reactions between the helium and the hydrogen generate the light and heat of the Sun. The three kinds of nebulae are emission, reflection and dark types. In the emission type a high energy action such as a shock wave further drives the nuclear reactions generating the light and heat which excite the atoms to an ionized state. . Reflection nebulae, on he other hand, do not generate heat or light on their own, they reflect the light os nearby emission nebulae.Reflection nebula may be the same type field of gas and dust, the difference being in the star providing illumination. For the reflection nebula the star is not of sufficient energy to ionize the surrounding gas which provides the secondary illumination. Instead, the star light is simply scattered and reflected by the gas and dust. These nebula are typically bluish in color. Dark nebulae are dense clouds of gas and dust outlined against the lighted background.The dense nebulae regions are the birthing places for stars,
Stars also are formed in the arms of spiral galaxies where gravitational waves passing trough the galaxy excite the region and cause star formation. Gravitational waves originate from impulse events in the cosmos such as nova and supernova explosions.
The three primary stars shown in the Orion belt below, Alnitak, Mintak and Alnilam are giant or massive stars many times larger than our Sun.
Stars drawn toward central black holes can be the driving force for spiral galaxies such as M51, M81 and our own Milky Way galaxy, seen in the Photo Gallery.
Orion Belt and Sword with Giant Stars Alnitak, Mintak and Alnilam aligned vertically from the bottom in the belt. Click image for enlarged view.
Nebulae made up of this gas and dust are easily visible in telescopes. They are excited by very hot nearby stars and they typically appear as a pinkish color resulting from an emission of red, blue and violet colors. The Orion Nebulae (M42) shown below is typical of this complex star birthing field of gas and dust. Here, the Trapezium (indicated) contains four hot stars which ionize the surrounding gas generating the pinkish color. The Trapezium stars can be individually seen in a different exposure in the Nebula gallery. Also, a longer exposure shows that the nebulosity is really quite a large field.
Orion Nebula M42
The planetary nebula is a unique emission nebula where the energizing star is at the center of an expanding gas field. The Ring Nebula in the gallery is an example of a planetary nebula. The association of this type of nebula with planets was a mistake of early astronomers, due to its shape, since it has no relationship to a planet. Additional detail on the Orion Nebula is in the Appendix.
We need to address the present work on “finding the Higgs boson” and its meaning on understanding the origin. Where the helium and deuterium are based on atomic structure. the Higgs boson discussion goes into the subatomic, quantum area of physics. Wilczek (2008) gives an understandable argument on quantum physics and the role that this recent research has on understanding the behavior of our universe.
Note that these photos are made with basic point and shoot and web cam type cameras which produce “not spectacular quality photos;” but they are of sufficient quality to demonstrate the point. In a couple of places I have supplemented the collection with photos from the Slooh telescopes in the Canary Islands. In most cases, the photo are best viewed in Full Screen (FS at the lower right).
Names such as Leo the Lion, Orion the Hunter, Pices the Fish, Libra the Scales, and Sagittarius the Archer were used by early observers of the heavens to try to understand the meaning of the what they saw. From the very first observers through the Chinese, Babylonians, Egyptians, Jews, Greeks and Romans and later the Europeans, the order of the heavens was apparent, but the depth of what they were seeing was not obvious. One of the early physical examples of the human understanding of the heavens was the Farnese Atlas in the Naples Museum, a Greek era sculpture showing Atlas holding the round Earth on his shoulder. On the surface of the Earth were various figures representing the constellations, as mentioned above.
Early man perceived the structure of the earth to be the firmament (ground) and the heavens, which they visualized to be a bowl of atmosphere hovering above the Earth. It was in this bowl that they perceived the constellations to be situated, and they noted the orderly movement of the constellations with the seasons. Interestingly, they were looking at the very same heavens that we see today, the difference being in the clarity of the skies and the absence of light pollution that they enjoyed. History shows that these early observers were able to identify and record features in the heavens, which in light polluted skies of today cannot easily without the aid of instruments. These early observers in fact were able to see to the ends of the Milky Way galaxy and beyond, even though they thought that what they were seeing was right above their head. Star atlases such as Kanas (2007) give good historical background on the constellations.
An example of the depth of the universe that was observable by these early sky watchers is in the constellation Sagittarius, which appears low in the Southern sky in the summer.
The link below is to the constellation Bootes in Arcturus. This a large file, so after clicking the link below allow time for large images to load. This image was made with a small camera (Canon S2IS) and the image is not very bright but the salient features of the constellation are clear.
Bootes with Arcturus