IB Physics HL E.5.4 Stellar mass and evolution

[Maximum number: 3]

Alpha Centauri A and B form the closest binary star system to the Earth. This binary star system is the third brightest stellar object in the night sky.

(a)

Proxima Centauri is a main sequence star with a mass of $0.12 M_{\odot}$ .

Compare the times for which Proxima Centauri and Alpha Centauri A are main sequence stars.

[ 2 ]

$\ll \mathrm{L}=\mathrm{E} / \mathrm{t}$ and E proportional to M so >t inversely proportional to $M^{2.5}$
OR

Marking guidance:

Award [1] for a correct but incomplete reason, e.g. larger luminosity, or smaller
mass, with the correct conclusion.

$\frac{t_{P}}{t_{\alpha}}=\left(\frac{1.12}{0.12}\right)^{2.5}$

OR faster fusion rate to hydrogen available in Alpha Centauri A

Proxima Centauri stays longer on main sequence OR
$t_{P}=270 t_{\alpha}$

(b)

Explain the relationship between binary star systems and type I a supernovae.

[ 1 ]

IB Physics HL E 5 4 Stellar Mass and Evolution Questions

Exam points

IB Physics HL E 5 4 Stellar Mass and Evolution Questions question 1

Question (a)

Question (b)