Hertzsprung Russell Diagram

This problem wasn't solved until the 1920s, when Edwin Hubble devised the first method of extragalactic distance measurement. His technique relied on stars known as Cepheid variables, whose luminosities can be easily determined by measuring their rates of pulsation. Comparing this luminosity with the stars' observed brightness allowed Hubble to estimate the distance to Cepheid stars in such galaxies, affirming their extragalactic location.

The order in which the greatest blue shift to the red shift of the five distant stars is E, D, B, C, A. The arrows in the diagram represent the speed of movement of the star, the longer the arrow the faster the movement of the star and vice versa. Furthermore, the motion of the source of light is said to be blueshifted if it is moving towards the observer, but if the source is moving away from the observer it is called redshifted (Prather p75). As a result, the star that is moving faster toward the observer will have the greatest blueshift while the star that is moving away from an observer will have the greatest redshift.

Both high- and low-mass stars respond to the depletion of hydrogen fuel in a similar manner. In order to supply the heat to oppose its own self-gravity, the star 's core again responds by shrinking. In a sort of reflex reaction, the outer regions of the star expand, causing a great increase of its radiating surface area. Although the total energy output of the star increases during this phase, the greatly enhanced surface area results in a cooling of the surface and the star takes on a redder appearance. The size and color change lead to the name of red giant for these stars. If the star is very massive, it may become what is called a red supergiant.

The area on the H-R diagram where “normal” stars can be found is known as the _________.

The discovery of the heliocentric model

2) Why are there different brightness of stars and how do we describe their brightness as compared to one another?

It’s called the HR diagram because it tells about the life cycles of stars. By observing and looking at the life cycles of many other stars we can evaluate the date that will tell us all different stages of evolution and growth. While discovering luminosities this helped measure how much energy a star gives off as well as it’s colour that makes categorizing pretty spot on. Because of that a Danish astronomer research combied with russells research based on their spectral types this helped figure out there life cycle of the stars. Even though two women was behind it and it should be named after them but you know how it goes.

14. Why do stars have different levels of brightness, and how does one describe their brightness as compared to one another?

R* is the average rate of formation for suitable stars. A suitable star must have an appropriate temperature (i.e. not too hot or cold). It is possible to use the average rate for the galaxy. This can get a bit hazy, as the

5. On what kind of diagram are stars plotted according to their surface temperature and luminosity?

Retrieved from http://spiff.rit.edu/classes/phys230/lectures/planneb/planneb.html 6. Smith, Gene. (1995, April 16) Stellar Evolution I-Solar Type Stars.

Red giants are dying stars that are in their last part of stellar evolution. Every star will eventually turn into a red giant over some point in time. Stars turn into red giants when there is no more hydrogen fuel for the star. Inside of a star, hydrogen goes through a process called nuclear fusion where hydrogen is getting converted into helium. Nuclear fusion helps create energy for the star so that the force of gravity isn’t crushing the star together. This is also the reason why stars are bright. When the star runs out of hydrogen to convert into helium, the energy that kept the star from collapsing is now gone. Gravity then takes over and compresses the star. From this point, the helium atoms are able to combine

I can tell many things about the star B-Centauri by looking at this H-R diagram. First of all I can see that it has a temperature of almost 30,000 K, that means it is almost five times hotter than our sun. Next, B-Centauri's luminosity is 10, 000 Lu which means it produces ten thousand times the energy of our sun. I know that B-Centauri is a spectral type O by reading the H-R diagram. During the Vlab we found that Naos was a spectral type O. All stars that are spectral type O are blue, meaning they are the hottest type of stars. Stars of the same spectral type have the same composition. Since Naos has hydrogen, helium, and helium ions so does B-Centauri. The mass of B-Centauri is twenty times the mass of our sun. The radius of B-Centauri

     Stars are a marvelous wonder to many people, that is why some people spend most of their lives wondering what is “above the world so high” (Gardner 98). These people study and map the little twinkling stars in order to get a better meaning of them; they are astronomers. Great astronomers like Edwin Hubble, Immanuel Kant, and William Huggins, never stopped valuing the beauty of the stars. While they developed great astronomical principals. One astronomer who fits this mold most is, Edwin Powell Hubble. Wondering about what was

Main sequence stars like our own sun enduring in a state of nuclear fusion during which they will produce energy for billions of years by replacing hydrogen to helium. Stars change over billions of years. When their main sequence phase ends they pass through other states of existence according to their size and other characteristics. The larger a star's mass, the shorter its lifespan is. As stars move toward the end of their lives, much of their hydrogen will be converted to helium. Helium sinks to the star's core and raises the star's temperature—causing its outer shell to expand. These large, puffy stars are known as Red Giants. The red giant phase is actually a prelude to a star shedding its outer layers and becoming a small, dense body called a White Dwarf. White dwarfs cool down for billions and billions of years, until they finally go dark and produce no energy at all. Once this happens, scientists have yet to observe, such stars become known as Black Dwarfs. A few stars avoid this evolutionary path and instead go out with a bang, exploding as Supernovae. These violent explosions leave behind a small core that will then turn into something called a Neutron Star or even, if the remainder is large enough, it is then turned into something called a Black Hole.