White dwarf Sirius B · 2019. 10. 21. · White dwarf Sirius B Sirius binary at 2.6 pc Orbital...
Transcript of White dwarf Sirius B · 2019. 10. 21. · White dwarf Sirius B Sirius binary at 2.6 pc Orbital...
White dwarf Sirius BSirius binary at 2.6 pcOrbital period: 50.1 y
Sirius AM = 2.1 Msun-star (main seq.)Teff = 9900 KL = 25.4 LsunR à 1.7 Rsun
Sirius BM = 1.0 Msun - white dwarfTeff = 25'000 KL = 0.027 LsunR à 0.0086 Rsun
R follows from: L=4πR2σT4
Astrophysics I, Lecture Slides – Chapter 6, ETH Zurich
1
Mass-radius relation for white dwarfs
≈ 0.01 Rsun
2
Regions in the density – temperature diagram
from Choudhuri
Indicated:- center of the sun: - run of parameters from center towards surface (dashed line)
3
Nuclear burning regions in the ρ – T diagram
Indicated in red:- location of
central stellar parameters for different nuclear burning stages
p-p
CNO 3α
C+C
Si-burn.O+O
4
Evolution of stars in ρ – T diagram
Indicated in blue:evolution of central parameters for- planets - low mass stars- sun- high mass stars
p-p
CNO 3α
C+C
Si-burn.O+O
~0.01 Msun
~0.2 Msun
~1 Msun
~20 Msun
5
6
Pulsar signals
7from Choudhuri
Pulsar period glitches
8from Choudhuri
Pulsar statistics
9from Choudhuri
Mass transfer in binaries
10from Choudhuri
Mass estimates for nutron stars
11from Choudhuri