1. [ 실습 ] Hubble’s Law 2009. 05. 27.

2. Hubble’s Law Edwin Hubble (1889 ~ 1953) * Period – Luminosity Relation of Cepheid Variable (Henrietta Leavitt, 1912) * ‘Shapley-Curtis debate’ in 1920 * Cepheid Variable of M31 using Mount Wilson 100-inch telescope => Andromeda Galaxy(not Nebula), ‘Island Universe!’ * Elliptical Galaxies – E0 ~ E7 * Spiral Galaxies – Sa ~ Sc / SBa ~ SBc * Lenticular Galaxies – S0 * Irregular Galaxies...

3. Hubble’s Law * A Relation Between Distance and Radial Velocity Among Extra-Galactic Nebulae (1929, Edwin Hubble) * V = H * d ( V : radial velocity, d : distance of galaxy) (H : Hubble Constant) Edwin Hubble (1889 ~ 1953) 745km/s for a distnace of 1.4Mpc => ~500km/s/Mpc Expanding Universe

4. Hubble’s Law Edwin Hubble (1889 ~ 1953) * Universe Age using Hubble Constant (H) => About 2/3 of the calculated result, in this case 13 billion years... * Universe Size using Hubble Constant (H)  Assuming H=50, this givea size of 19.5 billion light years.  Gravity reduction factor of about 2/3 is sometimes applied as it is for age, 13 billion light years...

5. Hubble’s Law =>Using “Doppler Effect”

6. Hubble’s Law =>Assume that “All galaxies of the same type are the same physical size”

7. Hubble’s Law

8. Hubble’s Law http://www.astro.washington.edu/courses/labs/clearinghouse/labs/HubbleLaw/hubbles_law_preselected.html Galaxy List : http://www.astro.washington.edu/courses/labs/clearinghouse/labs/HubbleLaw/galaxies.htmlhttp://www.astro.washington.edu/courses/labs/clearinghouse/labs/HubbleLaw/galaxies.html Ppt : http://www.astro.washington.edu/courses/labs/clearinghouse/labs/HubbleLaw/hubbleslaw_spreadsheet.xlshttp://www.astro.washington.edu/courses/labs/clearinghouse/labs/HubbleLaw/hubbleslaw_spreadsheet.xls 1.What are your values for the Hubble constant, maximum age of the Universe, and the age considering deceleration due to gravity? 2. Identify the galaxy with the highest redshift and state its recessional velocity. What fraction of the speed of light is that galaxy receding from us? 3. Why does the best-fit line to your data need to go through the origin of your graph? 4. Quantitatively compare your maximum age for the Universe to the age of the Sun (5 billion years), and to the age of the oldest stars in the Milky Way (approximately 12.5 billion years). 5. What is the currently accepted value for the Hubble constant? How does your value compare?