1 / 17

Stellar Corpses and Other Space Oddities

Stellar Corpses and Other Space Oddities. Black Holes, Neutron Stars, Nova and other creatures in the stellar zoo. End of a Massive Star. Core contracts and becomes neutronized by reverse Beta decay Collapse either is stopped by degeneracy

binh
Download Presentation

Stellar Corpses and Other Space Oddities

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. Stellar Corpses and Other Space Oddities Black Holes, Neutron Stars, Nova and other creatures in the stellar zoo

  2. End of a Massive Star • Core contracts and becomes neutronized by reverse Beta decay • Collapse either is stopped by degeneracy • Or, for very massive core (3M) collapse isn’t halted

  3. Neutron Stars • Core Mass 1.4-3M • Very dense ( 1 teaspoon= 1billion tons) • Small in size (10-30km) • STRONG magnetic field • Likely spinning rapidly • Postulated in 1930’s • Not widely accepted until 1968

  4. Neutron Stars and Pulsars • Pulsars discovered in 1968 • Beaming “pulses” of EM waves at regular intervals • LGM at first! • Lighthouse Model • All Neutron Stars may be Pulsars

  5. Lighthouse Model Rotation Axis Beamed Radiation Magnetic Field Neutron Star

  6. Pulsars • Millisecond Pulsars • Pulsars are slowing • Can be in Binary systems • Maybe a source of X-ray Binaries • Neutron Star is accreting material from companion

  7. Black Holes • If collapse is not halted • Mass collapses to a singularity • Singularity is a point • “Punches a hole” in space-time • Curvature of spacetime • Gravity is extremely strong

  8. Black Holes • Escape Velocity greater than c • Like standing on a rubber sheet holding an anvil (2D analogy) • Black holes are actually 3D objects • Think Flatland! • Event horizon-boundary between BH and observable universe • Schwarzschild Radius

  9. Black Holes • Strong Gravity Tidal Forces • Relativity takes over (time slows) • No way to get knowledge from interior • Much indirect evidence for Black Holes • Also form X-ray binaries • Use formula to find mass of unseen companion

  10. Black Holes Have No Hair • Matter in a black hole becomes simple in form • Loses all identifying features except • Electric Charge • Mass • Angular Momentum • No protons, electrons, neutron etc

  11. Two Types of Black Holes • Schwarzschild Black Hole – “classic” non-rotation • Kerr Black Hole- rotating, can escape from (maybe) • Black Holes may be evaporating from Hawking Radiation

  12. Black Hole Binary Systems Roche Lobe Overflow Wind X-ray Jets Black Hole Companion Star Accretion Disk

  13. Nova • A WD in binary system • Accretes matter from companion • Gets stellar “indigestion” • Flares up and brightens • Calms back down • Process begins again • Doesn’t disrupt star

  14. Type I Supernova • Same setup as Nova • Accretion occurs much faster • Star can’t “burp” off material • Exceeds Chandre mass • Star begins a rapid collapse w/core bounce • Supernova that completely destroys WD

  15. Supernova Comparison • Type I much more luminous that Type II • Both form Supernova Remnants (SNR) • Type I have less material in SNR • Material is moving much faster in Type I • Type I have no Hydrogen in spectra • Type II do

  16. Hypernova and Gamma Ray Bursts • New idea • Very powerful supernovae • Could be generating BH instead of NS • Collapse of BH leads to Gamma Ray Burst • Gamma Ray bursts are random • No one knows what they are!

  17. Summary • Massive stars can leave behind unusual corpses • Supernova come in different types

More Related