Beyond the Solar System

1. Beyond the Solar System

2. Terms • Quark • Subatomic particle • Makes up protons and neutrons • Degenerate matter • Compressed atoms • Electrons pushed close to nucleus

3. Terms • Interstellar • “Between the stars” • Any part of the universe not within a solar system • Parsec (pc): 3.26 light-years • Kiloparsec (Kpc): 1000 parsecs • Megaparsec (Mpc): 1 million parsecs

4. Terms • Magnitude • Brightness of a celestial object • Higher number = dimmer object

5. Beyond the Solar System PSCI 131: Beyond the Solar System • Introduction to the Universe • Interstellar Matter • Classifying Stars • Stellar Evolution • Stellar Remnants

6. Introduction to the Universe PSCI 131: Beyond the Solar System

7. How the Universe is Organized PSCI 131: Beyond the Solar System – Intro to the Universe • Galactic clusters • Galaxies • Stars/solar systems • Where are we? • Local Group galactic cluster • Milky Way galaxy • Our solar system Map of the Local Group. pc: parsec. Mpc: megaparsec.

8. Size of the Known Universe PSCI 131: Beyond the Solar System – Intro to the Universe • 100s of billions of galaxies • Nearest large galaxy: 2.5 million ly (light-yrs) • Furthest object observed: 13 billion ly From: nasa.gov Hubble Telescope “Deep Field” image. Most objects are distant galaxies.

9. History of the Universe PSCI 131: Beyond the Solar System – Intro to the Universe • Age: about 13.7 billion years From: tandempost.com The Big Bang and the evolution of the universe. Matter has cooled and “clumped” over time to form galaxies and stars.

10. Interstellar Matter PSCI 131: Beyond the Solar System

11. Interstellar Matter PSCI 131: Beyond the Solar System • Matter that occupies space between solar systems • Mostly dispersed hydrogen and helium atoms (99%) • Rest is atom-sized dust of other elements • Nebula: localized concentration of gas and dust into a cloud

12. Role of Nebulae PSCI 131: Beyond the Solar System: Interstellar Matter • Birth of stars and solar systems

13. Types of Nebulae PSCI 131: Beyond the Solar System: Interstellar Matter • Bright • Emission • Reflection • Planetary • Dark

14. Bright Nebulae: Emission PSCI 131: Beyond the Solar System: Interstellar Matter • Emit their own radiation • Glowing gases The Lagoon Nebula, 1,250 parsecs from Earth.

15. Bright Nebulae: Reflection PSCI 131: Beyond the Solar System: Interstellar Matter • Reflect radiation from other sources From: thinkquest.org The Merope Nebula, in the Pleiades star cluster.

16. Bright Nebulae: Planetary PSCI 131: Beyond the Solar System: Interstellar Matter • Envelope of gases ejected from a dying medium-mass star • Gases glow (emit their own radiation) From: thinkquest.org The Helix Nebula, remnant of a dead Sun-like star.

17. Dark Nebulae PSCI 131: Beyond the Solar System: Interstellar Matter • Not hot enough to glow • Not close enough to light sources to reflect The Horsehead Nebula. From: nasa.gov

18. Classifying Stars PSCI 131: Beyond the Solar System

19. Luminosity PSCI 131: Beyond the Solar System: Classifying Stars • Brightness relative to the Sun (Sun=1) • Expresses “true” brightness of an object • Distance from Earth is factored out

20. The Herzsprung-Russell Diagram PSCI 131: Beyond the Solar System: Classifying Stars Brightest Luminosity Dimmest Hottest Coolest Surface temperature

21. Stellar Evolution PSCI 131: Beyond the Solar System

22. Two Key Forces Within Stars PSCI 131: Beyond the Solar System: Stellar Evolution • Gravity • Promotes contraction • Gas pressure • Outward movement of gas and energy from star’s core • Promotes expansion • Stellar evolution is a balance between them

23. Steps in a Star’s Life Cycle PSCI 131: Beyond the Solar System: Stellar Evolution • Birth • Protostar • Main-sequence • Red Giant* • Death *Medium- and high-mass stars only Stellar evolution of a medium-mass star, plotted on the H-R diagram.

24. Stellar Birth PSCI 131: Beyond the Solar System: Stellar Evolution • Contraction and heating of nebular gases (mostly hydrogen)

25. Protostar PSCI 131: Beyond the Solar System: Stellar Evolution • Contracting nebula becomes hot enough to glow

26. Main Sequence PSCI 131: Beyond the Solar System: Stellar Evolution • Nuclear fusion begins • Gas pressure balances gravity • Star becomes stable • Longest part of cycle

27. Red Giant PSCI 131: Beyond the Solar System: Stellar Evolution • Hydrogen fuel in core runs out • Star expands, cools

28. Red Giant PSCI 131: Beyond the Solar System: Stellar Evolution • Core • Hydrogen fuel depleted, nuclear fusion stops • Core collapses and heats up • Heat radiates into outer shell

29. Red Giant PSCI 131: Beyond the Solar System: Stellar Evolution • Outer shell • Nuclear fusion continues • Accelerated by heat from core • More gas pressure, so outer shell expands and cools

30. Red Giant PSCI 131: Beyond the Solar System: Stellar Evolution • Outer shell • Gravity balances gas pressure • Expansion stops • Size of star becomes stable • Core • Still contracting and heating: 2 million degrees F • Starts to fuse helium, forming carbon

31. Stellar Death: Low-mass stars PSCI 131: Beyond the Solar System: Stellar Evolution • Stars with less than one-half of Sun’s mass • No red giant stage • Not enough heat from gravitational collapse • Contract into a white dwarf star when hydrogen depleted

32. Stellar Death: Medium-mass stars PSCI 131: Beyond the Solar System: Stellar Evolution • Stars one-half to eight times Sun’s mass • Core contracts into a white dwarf when helium gone • Outer shell ejected into space: planetary nebula

33. Stellar Death: High-mass stars PSCI 131: Beyond the Solar System: Stellar Evolution • Stars more than eight times Sun’s mass • Core collapses • Heat causes outer shell to explode in a supernova • Brightness increases by millions of times • Generates heavier elements (gold, lead, uranium, etc.) • Collapsed core becomes a neutron star or black hole, depending on star’s mass

34. Stellar Remnants PSCI 131: Beyond the Solar System

35. Types of Stellar Remnants PSCI 131: Beyond the Solar System • White dwarf • Low- and medium-mass stars • Neutron star • High-mass stars • Black hole

36. White Dwarf PSCI 131: Beyond the Solar System: Stellar Remnants • About Earth-sized, but mass is similar to Sun’s • Degenerate matter • Extremely dense • A handful would weigh many tons

37. Neutron Star PSCI 131: Beyond the Solar System: Stellar Remnants • Denser than white dwarf • Electrons pushed into nucleus • A handful would weigh millions of tons Hypothesized cross-section of a neutron star. Note mass and diameter.

38. Black Holes PSCI 131: Beyond the Solar System: Stellar Remnants • Densest known objects • Remnants of highest-mass stars (more than 25 times Sun’s mass) • Radiation (light) can’t escape gravity

39. Black Holes PSCI 131: Beyond the Solar System: Stellar Remnants Artist’s conception of a black hole. Matter being pulled in gives off energy as it is compressed, creating detectable signals from around the black hole itself. Inset shows jet of electrons from a black hole in galaxy M87 (bright area).

40. End of Chapter