1 / 45

Physics 306 (Basic Astronomy) Fall 2006 Instructor: Dr. Alexey Belyanin

Physics 306 (Basic Astronomy) Fall 2006 Instructor: Dr. Alexey Belyanin (979) 845-7785, Room ENPH 509 Email: belyanin@tamu.edu http://faculty.physics.tamu.edu/belyanin/phys306.html Office Hours -- 12:45-14:45 TTR, or by appointment

hayfa-holland
Download Presentation

Physics 306 (Basic Astronomy) Fall 2006 Instructor: Dr. Alexey Belyanin

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Physics 306 (Basic Astronomy) Fall 2006 Instructor: Dr. Alexey Belyanin (979) 845-7785, Room ENPH 509 Email: belyanin@tamu.edu http://faculty.physics.tamu.edu/belyanin/phys306.html Office Hours -- 12:45-14:45 TTR, or by appointment The textbook is Foundations of Astronomy, Ninth Edition, by Michael Seeds (Thomson Brooks/Cole, 2007).

  2. Homework: 10% of the grade Use WebAssign to receive and submit assignments: http://www.webassign.net/

  3. Evaluation 3 mid-term exams: 20% of the final grade each Final exam: 30% of the final grade Homework: 10% of the grade Use WebAssign to receive and submit assignments: http://www.webassign.net/ If you have an excused absence for a mid-term exam, the grade for one exam can be dropped in calculating the final average. You are allowed to bring one 8.5" x 11" page with formulas (on one side) for every exam. You can bring three such pages for the final. With this “cheat sheet” you don’t have to memorize all formulas. However, you need to understand them!

  4. Level of math used: You will use simple algebra and some elementary functions, such as logarithms and exponents. Powers of 10 will occur all the time, so the ability to work with scientific notation is important. I will provide you with necessary math background; however, some of you might need extra practice to refresh your middle school math.

  5. We will use metric units. See Appendix A for definitions, tables, and other important info. Mars Climate Orbiter 1999 Remember and check UNITS for all terms in the formulas!!! Indicate units on your formula sheet Express all terms in correct units before plugging in the formula Check your answer for right unit

  6. Attendance is important. We will drop/add and rearrange some material as compared to the textbook Advantages of taking classes over self-study • Fighting intrinsic laziness • Maintaining a proper speed • Distinguishing important topics from less important ones • Learning supplementary materials as well • Someone is ready to answer questions

  7. From the Fall 2005

  8. Why astronomy is fun to study and to teach • In every lecture, we reach the frontier of human knowledge • Crossroads of physics, chemistry, biology, philosophy, … • Breakthrough discoveries occur every year • All scales from elementary particles (10-15 m) to the • Hubble radius (1026 m) are involved; all timescales from • 10-43 s to 1010 years • No need in sophisticated tools to do observations and make • discoveries

  9. Structure of the course • Scale and structure of the Universe • The night sky • History of astronomy • Celestial mechanics • Astronomical tools • The Sun • Birth, life, and death of stars • Galaxies • Cosmology • The Solar System • Life in the Universe

  10. Chapter 1: setting the stage Our place in the Universe Scales and distances

  11. Milky Way Galaxy 25,000 light years, Or ~ 8 kpc, or 2.5x1017 km 200 billion stars Galactic year = 225 million yr Our sun is 4.6 billion yr old

  12. “Milky Way” – a milky patch of stars that rings the Earth Galactos = milk in Greek

  13. Galileo found that the Milky Way is made up of stars

  14. Hubble Deep Field 10 day exposure photo! Over 1500 galaxies in a spot 1/30 the diameter of the Moon 1011 galaxies in the observable universe Farthest and oldest objects are 12-13 billion ly away! Space observations as a time machine

  15. 107 m Earth radius = 6378.164 km

  16. 102 109 m Radius of Moon’s orbit = 384000 km

  17. 102 1011 m 1 Astronomical Unit = 1.51011 m

  18. 102 1013 m Mean radius of Pluto’s orbit = 40 AU Pluto demoted to a dwarf planet on August 24, 2006!

  19. The Kuiper Belt – home for short-period comets and dwarf planets Starting in 1992, astronomers have become aware of a vast population of small bodies orbiting the sun beyond Neptune. There are at least 70,000 "trans-Neptunians" with diameters larger than 100 km in the radial zone extending outwards from the orbit of Neptune (at 30 AU) to 50 AU.

  20. 1-day motion of Varuna

  21. 2003 UB313 “Xena”: the largest dwarf planet so far R = 2400 +- 100 km – larger than Pluto! Pluto: R = 1185 km

  22. HST image of Xena

  23. Voyagers 1 and 2 Launched in 1977, Voyager 1 is now 100 AU from the Sun! (12 light-hours, or 15 billion km) The most distant human-made object in the Universe

  24. The Oort Cloud – source of long-period comets The comets that are more likely to be easily visible are much rarer, and are thought to come from a great spherical cloud of cometary material surrounding the Solar System called the Oort Cloud. This sphere is a light year (50,000 A. U.) in radius, but the total mass of cometary material in this cloud is probably less than that of the Earth. Occasionally a comet in this cloud is disturbed gravitationally, for example by a passing star, and started on a long elliptical or parabolic orbit toward the Sun. These long-period comets are primarily responsible for the brighter comets observed historically.

  25. 102 1017 m

  26. Proxima Centauri (Alpha Centauri C) Distance to  Cen C = 4.2 ly = 1.3 pc = 41016 m

  27. Need to introduce new units of distance 1 light-year (ly)  1016 m 1 ly = c1 year (the distance the light travels in 1 year) Velocity of light in vacuum c = 3 108 m/s 1 year  3.1  107 s 1 parsec (pc)  3.26 ly  3 1016 m 1 kpc = 1000 pc; 1 Mpc = 1 million pc; 1 Gpc = 1 billion pc

  28. Huge isolation of stars: Distance between stars = 107 Star diameter The time needed to reach Proxima with modern spacecrafts: Looking through space = travel in time!

  29. 102 1019 m

  30. Local Bubble Density ~ 0.05 atoms/cm3 Temperature ~ 105 K Remnant of supernova explosion?

  31. Milky Way Galaxy 102 1021 m 10kpc 100 billion stars

  32. 102 1023 m Neighboring galaxies: Mpc scale

  33. Groups clusters superclusters

  34. 102 1025 m 500 Mpc scale

  35. 1017 m = 3 pc distance between stars 107 m planets 109 m Sun 1011 m = 1 AU Solar System 1021 m = 10 kpc galaxy 1025 m = 100 Mpc Largest structure 1026 m = Gpc Hubble radius Distance scale Looking through space = travel in time!

  36. Contents of the Universe • 97% of all ordinary (baryonic) matter is in stars • Only 3-5% of matter in the Universe is baryonic! • 27% is cold dark matter • 70% is dark energy

  37. Dark matter as a gravitational lens

  38. Remaining 70% is “dark energy”

More Related