Physics 320: Astronomy and Astrophysics – Lecture X

1. Physics 320: Astronomy and Astrophysics – Lecture X Carsten Denker Physics Department Center for Solar–Terrestrial Research

2. Problem 9.9 NJIT Center for Solar-Terrestrial Research

3. Problem 9.12 At wavelength where the opacity is greatest, the value of s is smallest. If the temperature of the star’s atmosphere increases outward, than a smaller value of s corresponds to looking at a higher temperature and a brighter gas. At wavelength where the opacity is greatest, you would therefore emission lines. NJIT Center for Solar-Terrestrial Research

4. Problem 9.13 A large hollow spherical shell of hot gas will look like a ring if you can see straight through the middle of the shell. That is, the shell must be optically thin, and an optically thin hot gas produces emission lines. Near the edges of the shell, where your line of sight passes through more gas, the shell appears brighter and you see in a ring. In 1992 a tremendous explosion occurred in the constellation of Cygnus. Dubbed Nova Cygni 1992. Astronomers hypothesize that this system's white dwarf had so much gas dumped onto it's surface that conditions became ripe for nuclear fusion. The resulting thermonuclear detonation blasted much of the surrounding gas into an expanding shell. NJIT Center for Solar-Terrestrial Research

5. Ian Journey to the Center of our/your Universe Voyage to the Center of our Solar System The Sun: More than a Reason to Skip Class Our Sun: What can it do for you? Brick City Sun The Key to Live on Earth: The Sun Our Sun: The Orb of Life The Giant Nuclear Reactor: The Sun John The Sun: Our Closest Star The Sun: A Look inside our Closest Star Gerardo, Matthew, & Mike Sunbelievable Solar Sciene Exhibition Title Contest NJIT Center for Solar-Terrestrial Research

6. The Sun • The Solar Interior • Mass • Luminosity • Radius • Effective Temperature • Surface Composition • The Solar Atmosphere • The Solar Cycle NJIT Center for Solar-Terrestrial Research

7. Mass (kg) 1.989e+30 Mass (Earth = 1) 332,830 Equatorial radius (km) 695,000 Equatorial radius (Earth = 1) 108.97 Mean density (gm/cm3) 1.410 Rotational period (days) 25-36 Escape velocity (km/sec) 618.02 Luminosity (ergs/sec) 3.827e33 Magnitude (Vo) -26.8 Mean surface temperature 6,000°C Age (billion years) 4.5 Principal chemistry Hydrogen Helium Oxygen Carbon Nitrogen Neon Iron Silicon Magnesium All others 92.1%7.8%0.061%0.030%0.0084%0.0076%0.0037%0.0031%0.0024%0.0030% Sun – Overview NJIT Center for Solar-Terrestrial Research

8. Evolution of the Sun and its Interior Standard Solar Model: X: 0.71  0.34 Y: 0.27  0.64 Sun–Earth Connection? NJIT Center for Solar-Terrestrial Research

9. pp–Chain Solar Neutrino Problem! NJIT Center for Solar-Terrestrial Research

10. Interior Structure NJIT Center for Solar-Terrestrial Research

11. Convection Condition The Sun is purely radiative below r/R = 0.71 and becomes convective above that point. Physically this occurs because the opacity in the outer layers of the Sun becomes large enough to inhibit the transport of energy. NJIT Center for Solar-Terrestrial Research

12. Differential Rotation and Magnetic Fields NJIT Center for Solar-Terrestrial Research

13. Helioseismology NJIT Center for Solar-Terrestrial Research

14. Photosphere NJIT Center for Solar-Terrestrial Research

15. Sunspots – Umbra and Penumbra NJIT Center for Solar-Terrestrial Research

16. Active Regions Active region 9169 was the host of the largest sunspot group observed so far during the current solar cycle. On 20 September 2000, the sunspot area within the group spanned 2,140 millionths of the visible solar surface, an area a dozen times larger than the entire surface of the Earth! NJIT Center for Solar-Terrestrial Research

17. Spectrum of Granulation “Wiggly” spectral lines in the solar photosphere inside and outside a region of activity, reflecting rising and sinking motions in granulation. Over the central one third of the spectrogram height, the slit crossed a magnetically active region. Here, the velocity amplitudes are much reduced, demonstrating how convection is disturbed in magnetic areas.  NJIT Center for Solar-Terrestrial Research

18. Model of Convection 3D animation of convection. The animation shows temperature fluctuations in a layer of unstable, turbulent gas. (Courtesy of Andrea Malagoli, University of Chicago) NJIT Center for Solar-Terrestrial Research

19. Supergranulation NJIT Center for Solar-Terrestrial Research

20. Photospheric Magnetic Fields NJIT Center for Solar-Terrestrial Research

21. Sunspots – Pores & Filigree NJIT Center for Solar-Terrestrial Research

22. Thin Flux Tube Model NJIT Center for Solar-Terrestrial Research

23. Magnetic Carpet NJIT Center for Solar-Terrestrial Research

24. Chromosphere NJIT Center for Solar-Terrestrial Research

25. Mercury Transit November 15th, 1999 The images were taken 20 seconds apart from 21:11 (first contact) to 22:10 UT (last contact). The image were captured with a Kodak MegaPlus 4.2 CCD camera. The spatial resolution is about 1 per pixel. Here, we show only a small portion of the full disk images near the solar north pole. The field of view is approximately 470 170 or 340,000 km  125,000 km on the Sun. NJIT Center for Solar-Terrestrial Research

26. Prominences The SoHO EIT full sun image, taken on 14 September 1999 in the He II line at 304 Å shows the upper chromosphere/lower transition region at a temperature of about 60,000 K. The bright features are called active regions. A huge erupting prominence escaping the Sun can be seen in the upper right part of the image. Prominences are “cool” 60,000 K plasma embedded in the much hotter surrounding corona, which is typically at temperatures above 1 million K. NJIT Center for Solar-Terrestrial Research

27. Filament Evolution Temporal evolution in Ha center line of a sigmoidal filament in active region NOAA 8668 during August 2000. (a) Videomagnetogram , (b) CaI line wing filtergram, (c) Ha – 0.6 Å filtergram, and (d) Ha center line filtergram. NJIT Center for Solar-Terrestrial Research

28. Filament Eruption NJIT Center for Solar-Terrestrial Research

29. Sympathetic Flare NJIT Center for Solar-Terrestrial Research

30. Transition Region & Corona NJIT Center for Solar-Terrestrial Research

31. Corona – EIT 304 Å NJIT Center for Solar-Terrestrial Research

32. Corona – EIT 171 Å NJIT Center for Solar-Terrestrial Research

33. Corona – LASCO C2 NJIT Center for Solar-Terrestrial Research

34. Corona – LASCO C3 NJIT Center for Solar-Terrestrial Research

35. Corona and Planets NJIT Center for Solar-Terrestrial Research

36. Coronal Mass Ejection– LASCO NJIT Center for Solar-Terrestrial Research

37. Coronal Mass Ejection & Comet NJIT Center for Solar-Terrestrial Research

38. Coronal Mass Ejection – TRACE NJIT Center for Solar-Terrestrial Research

39. Space Weather NJIT Center for Solar-Terrestrial Research

40. Space Weather – Sun Earth Connection NJIT Center for Solar-Terrestrial Research

41. Space Weather – Bow Shock NJIT Center for Solar-Terrestrial Research

42. Space Weather Effects on Earth NJIT Center for Solar-Terrestrial Research

43. Solar Cycle – Butterfly Diagram NJIT Center for Solar-Terrestrial Research

44. Solar Cycle NJIT Center for Solar-Terrestrial Research

45. Solar Cycle – Synoptic Map NJIT Center for Solar-Terrestrial Research

46. Big Bear Solar Observatory NJIT Center for Solar-Terrestrial Research

47. Telescopes and Control Room NJIT Center for Solar-Terrestrial Research

48. BBSO – Instruments NJIT Center for Solar-Terrestrial Research

49. Optical Lab and Parallel Computer NJIT Center for Solar-Terrestrial Research

50. Homework Class Project • Continue improving the PPT presentation. • Use the abstract from the previous assignment as a starting point for a PowerPoint presentation. • The PPT presentation should have between 5 and 10 slides. • Bring a print-out of the draft version to the next class as a discussion template for group work • Homework is due Wednesday November 12th, 2003 at the beginning of the lecture! • Exhibition name competition! NJIT Center for Solar-Terrestrial Research