1 / 33

LIFECYCLES OF STARS

LIFECYCLES OF STARS. Option 2601. Stellar Physics. Unit 1 - Observational properties of stars Unit 2 - Stellar Spectra Unit 3 - The Sun Unit 4 - Stellar Structure Unit 5 - Stellar Evolution Unit 6 - Stars of particular interest. Unit 6. Particularly Interesting Stars.

akio
Download Presentation

LIFECYCLES OF STARS

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. LIFECYCLES OF STARS Option 2601

  2. Stellar Physics • Unit 1 - Observational properties of stars • Unit 2 - Stellar Spectra • Unit 3 - The Sun • Unit 4 - Stellar Structure • Unit 5 - Stellar Evolution • Unit 6 - Stars of particular interest

  3. Unit 6 Particularly Interesting Stars

  4. Particularly Interesting Stars • Binaries – visual, spectroscopic, eclipsing • Variable stars • Active/interacting binaries (Novae) • Stellar pulsations • Cepheid variables and the distance scale

  5. Types of binary system

  6. Spectroscopic Binaries

  7. Eclipsing Binaries

  8. Eclipsing Binaries

  9. Information from Binary Systems • Masses of components • Dimensions of components (particularly in eclipsing systems) • Physical characteristics of systems

  10. (Other) Variable Stars • Intrinsic variables… i.e. pulsating stars • Geometric (extrinsic) variables… i.e. eclipsing systems • Naming variables… constellation & letters beginning with R • R…. To Z, then RR…. To ZZ (i.e. R CrB) • Then Vijk constellation (i.e. V471 Tau)

  11. Accretion in Binaries

  12. Novae

  13. Novae • Brightness increases by 10 magnitudes during outburst • Rise time 2-3 days • Gradual decline over months (fast novae) or years (slow novae) • Material ejected with velocities up to ~2000km s-1 • Explosions can repeat (recurrent novae)

  14. Nova Cassiopeiae 1993 light curve (first 3 months)

  15. Nova Cassiopeiae 1993 light curve (first 2½ years)

  16. Nova Cassiopeiae 1995 light curve

  17. Pulsating Stars • Pulsating stars are not in hydrostatic equilibrium • Star is partially ionized at some critical depth • Degree of ionization sensitive to small temperature changes • Small perturbation can be “amplified”

  18. MAX. COMPRESSION Pressure driving Max. opacity & ionisation, min. photon flux COMPRESSION EXPANSION Max. compression rate Max. expansion rate Gravity (restoring force) Min. opacity & ionisation, max. photon flux MAX. EXPANSION Cycle of a pulsating star Phase

  19. H-R diagram for pulsating stars

  20. Cepheid Variables Typical Cepheid light curve

  21. Cepheid Variables

  22. Cepheid Variables

  23. The period-luminosity relation for Cepheids

  24. Redshift • Edwin Hubble discovers galaxies are receding from us (c. 1930) • Hubbles Law - speed increases with distance • Expansion of the Universe - Big Bang theory

  25. Cepheids in M100

  26. Beyond M100

  27. Unit 6 Particularly Interesting Stars

  28. Particularly Interesting Stars • Binaries – visual, spectroscopic, eclipsing • Variable stars • Active/interacting binaries • Stellar pulsations • Cepheid variables and the distance scale

  29. Stellar Physics • Unit 1 - Observational properties of stars • Unit 2 - Stellar Spectra • Unit 3 - The Sun • Unit 4 - Stellar Structure • Unit 5 - Stellar Evolution • Unit 6 - Stars of particular interest

  30. LIFECYCLES OF STARS Option 2601

More Related