The Hertzsprung-Russell Diagram or, the H-R Diagram for short, is a graph which plots stars according to their temperature and absolute magnitude. This graph reveals a pattern, which in fact is quite interesting. The H-R Diagram is named for the two astronomers, Ejnar Hertzsprung and Henry Russell, who discovered this pattern of stars. These two astronomers independently discovered that comparing magnitudes and spectral class (color) of stars yielded a lot of information about them. One key purpose of the H-R diagram is to show the relationship between temperature and absolute magnitude of stars. The type of temperature measurement used is Kelvin, where the zero point is equal to -273.16 C.
On the H-R Diagram, the temperature of degrees Kelvin ranges from 3,000 to 30,000. The absolute magnitude of stars on the H-R Diagram ranges from +15 to -10. Absolute magnitude is how bright stars would appear if they were positioned at 32.6 light years away from earth. On this scale, the lower the number, the brighter the star. Thus, a start with an absolute magnitude of -10 would be much brighter than a star with an absolute magnitude of +15.
The two astronomers found many patterns after developing their graph. They found that 90% of stars graphed fell within a band that ran through the middle of the graph. These stars range from cool, dim, red stars at the lower right of the H-R Diagram to hot, bright, blue stars at the upper left corner of the H-R Diagram. The stars that fall into to this band are known as main-sequence stars. Stars such as the sun, and almost every start visible in the night sky fall within this band of main sequence stars. There is another group of stars which are cool and bright that appear near the upper right corner of the H-R Diagram.
These stars are very large and therefore have very big surface areas. These large surface areas give off large amounts of light and this makes the stars bright. Most of these stars are known as red giants. Some are so large however that they are referred to as supergiants. Red giants have a temperature of about 3,500 degrees Kelvin and an absolute magnitude of around 0. Supergiants have a temperature of around 3,000 degrees Kelvin and an absolute magnitude of about -7.
Another group of stars, which are rather small, is found near the bottom left of the H-R Diagram.
But this does not justify it. Whether there is a star after the other, the assumption of uniform distribution (at that time there was no reason to think of a more privileged, more full of stars elsewhere) allows the existence of stars "next". This formal language, the stars are "dense" in the celestial sphere.
It’s a white giant and has a temperature of 7700 Kelvin. It’s a type A star that is 8.5 times brighter than the sun. It is most likely to be in the last stage of ordinary star-type life. Scientists are saying the sun’s older twin is found in the middle of Capricorn. Studying this star will help them see how the Earth’s sun will develop.
Alpha Centauri (α Cen) is our solar system closest star neighbor. There are three stars in the system: Alpha Centauri A, Alpha Centauri B, and Alpha Centauri C or Proxima Centauri. To the unaided eye, Alpha Centauri A, Alpha Centauri B look like one of the brightest stars in the night sky to help form the constellation Centaurus. This star system resides at 4.37 ly (1.34 pc) away from us. But
2, Alter Dinsmore, Cleminshaw H. Clarence, Philips G John. Pictorial Astronomy. United States: Sidney Feinberg, 1963.
The Orion Nebula is an emission nebula because of the O-type and B-type stars contained within it. These high-temperature stars emit ultraviolet (UV) light that ionizes the surrounding hydrogen atoms into protons (H+) and electrons (e-). When the protons and electrons recombine, the electrons enter a higher energy level (n=3). Then, when the electron drops from the n=3 level to the n=2 level, an Hphoton is emitted. 2 This photon has a wavelength of 6563 Å, and therefore corresponds to the red portion of the visible spectrum. It is these H photons which give the nebula the distinctive red color which we see.
is the Kelvin scale. On the Kelvin scale absolute zero has a value of zero
A star begins as nothing more than a very light distribution of interstellar gases and dust particles over a distance of a few dozen lightyears. Although there is extremely low pressure existing between stars, this distribution of gas exists instead of a true vacuum. If the density of gas becomes larger than .1 particles per cubic centimeter, the interstellar gas grows unstable. Any small deviation in density, and because it is impossible to have a perfectly even distribution in these clouds this is something that will naturally occur, and the area begins to contract. This happens because between about .1 and 1 particles per cubic centimeter, pressure gains an inverse relationship with density. This causes internal pressure to decrease with increasing density, which because of the higher external pressure, causes the density to continue to increase. This causes the gas in the interstellar medium to spontaneously collect into denser clouds. The denser clouds will contain molecular hydrogen (H2) and interstellar dust particles including carbon compounds, silicates, and small impure ice crystals. Also, within these clouds, there are 2 types of zones. There are H I zones, which contain neutral hydrogen and often have a temperature around 100 Kelvin (K), and there are H II zones, which contain ionized hydrogen and have a temperature around 10,000 K. The ionized hydrogen absorbs ultraviolet light from it’s environment and retransmits it as visible and infrared light. These clouds, visible to the human eye, have been named nebulae. The density in these nebulae is usually about 10 atoms per cubic centimeter. In brighter nebulae, there exists densities of up to several thousand atoms per cubic centimete...
The gas giants are a collection of planets in our solar system. As can be told from their name, they are mostly composed of differing mixtures of gases and ices. The gas and ice composition in question varies among the different planets. This mix of gases gives much of the planets an extremely thick atmosphere. At the very center of a gas giant is a core of liquid heavy metals. The gas giants are also called Jovian planets, taken from the largest planet in our solar system: Jupiter. Due to the fact the the majority of a gas giant planet is gas, the planet isn’t very dense and therefore, very large as a result. In fact, all of the gas giants are vastly larger than all of the terrestrial planets. Another common factor of the gas giants are their large amount of moons. The terrestrial planet, Mars, has the largest amount of moons, 2. The amount of moons of Mars is dwarfed in comparison to Saturn’s and Jupiter’s moo...
...ve different colors, colors tell about a star’s temperature, composition, age, size, and distance. Red stars are usually older; coolers stars have used up much of their hydrogen fuel. Blue stars are much younger and hotter. Most of Orion’s stars are blue except for the very red star, Betelgeuse. Orion is most easily seen from the months of November through February. The latitudes at which Orion can be best seen are 85 and -75 degrees. Its right ascension is 5 hours, and its declination is 5 degrees.
is hotter or colder, but never actually tell what the absolutes are. This is a
Supernovas are extremely powerful explosions of radiation. A supernova can give off as much energy as a Sun can within its whole life. A star will release most of its material when it undergoes this type of explosion. The explosion of a supernova can also help in creating new stars.
...nucleus; this type of AGN was discovered byHeckman (1980) is called Low-Ionization Nuclear Emission-line Region (LINER); examples include the Andromeda Galaxy (M31) andM65.
However, this is where the questions start to enter. How were the ancient Egyptians able to know the exact area or position of these stars in order to align each of the three pyramids to them?
From 1922 to 1925 Hubble devised a classification system for galaxies by grouping them according to their content, distance, shape, size, and brightness. The galaxy classification system had become the Hubble morphological (The study of form, structure and the like. ) sequence of galaxy types. Previous to this, no satisfactory system existed, thus Hubble's powerful, yet simple scheme was an incredibly important scientific achievement.