Characteristics of Stars.pptx

Characteristics of Stars for Philippine Grade 9 students

1. Characteristics of Stars

2. Objectives 2 3 1 recall what a star is; recall that the sun is a star and that it is essential to Earth’s processes; understand what makes stars different from one another; describe the different characteristics of stars classify stars according to its characteristics and properties

3. Stars & Nuclear Fusion 01

4. Stars are….. …..massive balls of gas and plasma that emit heat, light, ultraviolet rays, x-rays, and other forms of radiation throughout the entire universe. Stars are composed mostly of hydrogen and some helium.

5. What is nuclear fusion? Stars produce energy primarily through nuclear fusion. Nuclear fusion refers to the process where two or more atomic nuclei combine to form new and heavier atomic nuclei (thus, a new element). It releases a great amount of energy, resulting in stars that are relatively hot and bright.

6. —Nuclear Physics This energy is released to account for the loss in mass when the two hydrogen atoms undergo nuclear fusion.

7. A star’s mass…. …..determines the elements produced during nuclear reactions. For example, small to medium-sized stars produce energy by fusing two hydrogen atoms to form an atom of helium.

8. For large mass stars, their cores are able to fuse elements until iron. This results in an “onion model” where successive elements are fused after the other. After the elements are fused and their fuel burned out, the “skin” is “peeled” to make way for the next fusion of elements.

9. Color and Temperature 02

10. Stars emit colors of different wavelengths. The color indicates the surface temperature of the star.

11. Stars having higher temperatures are bluer in color. Stars having lower temperatures are redder in color Stars in the middle range temperatures, like the sun, are white or yellow.

12. …..is based on their spectral types. Spectral types are also temperature measurements, but it is based on the elements that they absorb. It uses the principle that each element has its own unique set of spectral lines. Spectral types utilize the appearance of specific absorption lines from a star which is only observed at a certain temperature range. A more accurate classification of stars ….

13. Scientists discovered that when a hot solid object is heated at very high temperatures such that it glows, it produces a complete spectrum of light with no dark lines. It is called a continuous spectrum.

14. A hot solid object heated at very high temperature produces a (a) continuous spectrum. Hot gases generate a unique set of (b) emission lines. When a cooler gas is placed near the hot glowing object, it produces a spectrum with dark (c) absorption lines.

15. In order of decreasing temperatures …. ......the seven main types of stars are O, B, A, F, G, K, and M. Each stellar type is also divided into subclasses (from 0 to 9) depending on its position within the scale. For example, a G star can be classified as G1, G2, G3 up to G9.

16. Size 03

17. The size of the stars…… ……is measured by astronomers based on the radius of the sun. The sun is considered as a medium-sized star with a radius of 695 508 kilometers. Therefore, a star measuring one solar radius has the same size as the sun.

18. Stars that are much larger than the sun are referred to as giant and supergiant stars. Most stars such as the black and white dwarf stars are much smaller than the sun. They are approximately about the size of Earth.

19. ……are referred to as giant and supergiant stars. Stars that are much larger than the sun…… …..such as the black and white dwarf stars are much smaller than the sun. They are approximately about the size of Earth. Most stars…..

20. Mass 04

21. …..the mass of stars is also measured based on the mass of the sun. A star with a solar mass of 1 has the same size as the sun which is equivalent to 1.989×10^30 kilograms. Just like its size….

22. For example, Sirius B has approximately the same mass as the sun at 1.00 ± 0.02 solar mass. Rigel has 17 times the mass of the sun. Because of this, it also produces 66 000 times the energy produced by the sun.

23. Brightness 04

24. The brightness of a star….. ….…is dependent on its size and temperature. The two ways to describe the brightness of a star includes apparent brightness and absolute brightness.

25. The apparent brightness …… ….or apparent magnitude (m) of a star is the star’s brightness as seen from Earth. It depends on the location of the observer. Therefore, different observers may measure different degrees of brightness based on their location and distance from the star.

26. The apparent brightness of the object is measured…… ….such that the lower the value, the brighter the object. Negative values indicate extreme apparent brightness. For example, the sun has an apparent magnitude of –26.8 while Betelgeuse has +0.50. It means that the sun appears brighter than Betelgeuse as seen from Earth.

27. To measure the true brightness of a star, a convention was established where the difference in location was factored out. It was done through the use of the absolute brightness of a star.

28. …..or absolute magnitude (M) is the brightness a star would have if all stars were located at a standard distance of 32.6 light-years or 10 parsecs from Earth. It does not consider the distance of a star from Earth. This allows astronomers to compare the brightness of stars. The absolute brightness ….

29. —Astrophysics The unit used in measuring the distance between stars is called the light-year. A light year refers to the distance traveled by light in one year. A light year is equivalent to 9.5 x 1012 kilometers.

30. Absolute brightness is related to the star’s luminosity. Luminosity is the total amount of energy radiated by the star per second. A star is luminous when it is hot, large, or both. This means that a small, hot star can have the same luminosity as a large, cool star.

31. The star’s luminosity can be deceptive. It is because stars do not only radiate energy as visible light.

32. ….is the best way to compare the brightness of the star today, it also has limitations. First, astronomers should indicate which wavelength they are using to calculate the absolute brightness of the star. Remember that stars emit radiation in several forms such as infrared, visible light, or X-rays. Stars can be bright in some of these wavelengths while appearing dim in others. Lastly, the sensitivity of the instruments being used such as telescopes should also be considered . Even though absolute brightness ….

33. Key Points Stars are defined and classified based on their physical characteristics. It includes color and temperature, size, mass, and brightness. Stars observed are described by its different characteristics One of the notable ways to describe a star is by analyzing its spectral signature: through this, one can analyze and obtain its composition and characteristics.

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