Presentation is loading. Please wait.

Presentation is loading. Please wait.

Charles Hakes Fort Lewis College1. Charles Hakes Fort Lewis College2.

Similar presentations


Presentation on theme: "Charles Hakes Fort Lewis College1. Charles Hakes Fort Lewis College2."— Presentation transcript:

1 Charles Hakes Fort Lewis College1

2 Charles Hakes Fort Lewis College2

3 Charles Hakes Fort Lewis College3 Chapter 12 Stellar Evolution/ Supernovae

4 Charles Hakes Fort Lewis College4 Outline Test 3 Wednesday Death of Low-mass Stars Death of High-mass Stars

5 Charles Hakes Fort Lewis College5 Current Events http://apod.nasa.gov/apod/ap111109.html http://www.youtube.com/watch?feature=pla yer_embedded&v=vtEvuz_oQ5o http://www.youtube.com/watch?feature=pla yer_embedded&v=vtEvuz_oQ5o http://www.space.com/scienceastronomy/g reen-brown-dwarf-star-spotted- 101110.html http://www.space.com/scienceastronomy/g reen-brown-dwarf-star-spotted- 101110.html http://news.discovery.com/space/top-5- space-spirals.html http://news.discovery.com/space/top-5- space-spirals.html

6 Charles Hakes Fort Lewis College6 Figure 12.10 White Dwarf on H–R Diagram 12 - For 1 solar mass stars, that is all that will fuse. (need 600 million K for the next reactions to occur.) The outer shell gets “blown off” by the hot, dense, core. Result is a planetary nebula around a white dwarf (13).

7 Charles Hakes Fort Lewis College7 Figure 12.9 Planetary Nebulae

8 Charles Hakes Fort Lewis College8 Figure 12.12 Distant White Dwarfs - globular cluster M4

9 Charles Hakes Fort Lewis College9 Figure 12.11 Sirius Binary System - nearby example of a white dwarf

10 Charles Hakes Fort Lewis College10 Figure 12.14 Close Binary System

11 Charles Hakes Fort Lewis College11 Figure 12.13ab Nova A nova forms when the temperature in the accretion disk reaches 10 7 K (H fusion). Such a star might “go nova” dozens (if not hundreds) of times.

12 Charles Hakes Fort Lewis College12 Figure 12.13c Nova

13 Charles Hakes Fort Lewis College13 Figure 12.15 Nova Matter Ejection

14 Charles Hakes Fort Lewis College14 High Mass Stars

15 Charles Hakes Fort Lewis College15 Figure 12.16 High-Mass Evolutionary Tracks Intermediate mass (~4 M sun ) stars fuse carbon, but end up as white dwarfs. High mass (>10 M sun ) stars evolve rapidly. Helium (and other) fusion begins before the star ever gets to the Red Supergiant stage.

16 Charles Hakes Fort Lewis College16 Figure 12.16 High-Mass Evolutionary Tracks Wolf Rayet stars (are really big ones) have very strong winds. http://upload.wikimedia.org/wi kipedia/commons/4/49/Crescen thunter.jpghttp://upload.wikimedia.org/wi kipedia/commons/4/49/Crescen thunter.jpg

17 Charles Hakes Fort Lewis College17 When fusion is happening in the core of a star, the core is A) heating and shrinking B) heating and expanding C) cooling and expanding D) in equilibrium

18 Charles Hakes Fort Lewis College18 When fusion is happening in the core of a star, the core is A) heating and shrinking B) heating and expanding C) cooling and expanding D) in equilibrium

19 Charles Hakes Fort Lewis College19 When fusion stops in the core of a star, the core is A) heating and shrinking B) heating and expanding C) cooling and expanding D) in equilibrium

20 Charles Hakes Fort Lewis College20 When fusion stops in the core of a star, the core is A) heating and shrinking B) heating and expanding C) cooling and expanding D) in equilibrium

21 Charles Hakes Fort Lewis College21 Figure 12.17 Heavy Element Fusion Each stage is faster than the stage before. H - 10 million years He - 1 million years C - 1000 years O - 1 year Si - 1 week

22 Charles Hakes Fort Lewis College22 Figure 12.17 Heavy Element Fusion Fusion of iron does not produce energy!

23 Charles Hakes Fort Lewis College23 Core-Collapse The iron core shrinks and heats. Photons are energetic enough to photo- dissociate iron nuclei. Iron converted back to protons and neutrons. This uses up energy - reduces pressure Collapse accelerates!

24 Charles Hakes Fort Lewis College24 Core-Collapse Protons and electrons combine to form neutrons releasing neutrinos. Collapse continues until neutrons are in contact with each other. Core “rebounds” and a shock wave throws off the outer layers of the star (mostly H and He.)

25 Charles Hakes Fort Lewis College25 Core-Collapse Protons and electrons combine to form neutrons releasing neutrinos. Collapse continues until neutrons are in contact with each other. Core “rebounds” and a shock wave throws off the outer layers of the star (mostly H and He.) This collapse takes about 1 second!

26 Charles Hakes Fort Lewis College26 Figure 12.18 Supernova 1987A

27 Charles Hakes Fort Lewis College27 Recent Supernovae

28 Charles Hakes Fort Lewis College28 Recent Supernovae

29 Charles Hakes Fort Lewis College29 Figure 12.19 Supernova Light Curves

30 Charles Hakes Fort Lewis College30 Figure 12.20 Two Types of Supernova

31 Charles Hakes Fort Lewis College31 Carbon Detonation (Type I) Supernova Recall the accretion around a white dwarf star. When the star reaches 1.4 M sun, the density and temperature allow carbon to finally fuse. It fuses everywhere simultaneously. Almost no hydrogen observed in the spectrum of Type I supernova.

32 Charles Hakes Fort Lewis College32 Figure 12.21 Supernova Remnants

33 Charles Hakes Fort Lewis College33 Formation of Heavy Elements Elements heavier than iron require energy input for creation. Supernovae provide the energy source. The expanding cloud contains primarily H and He, but is enriched in heavy elements. The Sun was created from “enriched” interstellar gas and dust.

34 Charles Hakes Fort Lewis College34 More Precisely 12-1 The Cycle of Stellar Evolution

35 Charles Hakes Fort Lewis College35 Three Minute Paper Write 1-3 sentences. What was the most important thing you learned today? What questions do you still have about today’s topics?


Download ppt "Charles Hakes Fort Lewis College1. Charles Hakes Fort Lewis College2."

Similar presentations


Ads by Google