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Rayon plus petit !

Relation masse-rayon pour les naines blanches. M ~ cte · R -3. Rayon plus petit !. Nébuleuse planétaire. Typiquement, M NB ~ 0.5  1.2 M  , R NB ~ 0.01 R  (6900 km). ρ NB ~ 10 6 ρ . ~ 10 6 g cm -3. 20 cm. L’étoile la plus brillante du ciel. Sirius A. Alvan Graham Clark (1862).

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Rayon plus petit !

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  1. Relation masse-rayon pour les naines blanches M ~ cte · R-3 Rayon plus petit !

  2. Nébuleuse planétaire

  3. Typiquement, MNB~ 0.5  1.2 M , RNB~ 0.01 R (6900 km)

  4. ρNB~ 106ρ ~ 106g cm-3 20 cm

  5. L’étoile la plus brillante du ciel Sirius A

  6. Alvan Graham Clark (1862)

  7. Densité devient tellement élevée que les électrons deviennent relativistes

  8. Électrons relativistes… énergie incluant la masse au repos Limite ultra-relativiste Taylor (UR)

  9. On minimise E = K + U Rayon d’équilibre : on doit avoir A–B > 0 R2 = (A-B) / C dE/dR = - (A-B) / R2 + C = 0 Masse de Chandrasekhar Nobel 1983

  10. À partir d’un calcul plus réaliste, nous obtenons MC ~ 1.4 M (limite de Chandrasekhar)

  11. Si M > MC : e– + p+  n (fermion) ρΛ(neutrons) ~ d  neutrons dégénérés Étoile à neutrons

  12. 10 km Manhattan

  13. ρÉN~ 1015ρ ~ 1015g cm-3 0.2 mm

  14. Little green men !

  15. Étoile à neutrons M ~ 1.5 M R ~ 10 km ω ~ 1000 s-1

  16. Comme pour les étoiles naines blanches, le gaz de neutrons devient éventuellement relativiste, et au-delà d’une certaine masse critique MOppenheimer-Volkoff~ 6.9 M l’étoile ne peut résister à l’effondrement gravitationnel. L’étoile devient alors un...

  17. ... trou noir

  18. Mots d’introduction de "States of Matter" par D.L. Goodstein : Ludwig Boltzmann who spent much of his life studying statistical mechanics, died in 1906, by his own hand. Paul Ehrenfest, carrying on the work, died similarly in 1933. Now it is our turn to study statistical mechanics. Perhaps it will be wise to approach the subject cautiously.

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