Question 18M.3.SL.TZ1.11

the wavelengths of the dips correspond to the wavelength in the emission spectrum

the absorption lines in the spectrum of star X suggest it contains predominantly hydrogen

OR

main sequence stars are rich in hydrogen

[2 marks]

peak wavelength: 290 ± 10 «nm»

T = $\frac{2.9\times {10}^{-3}}{290\times {10}^{-9}}$ = «10 000 ± 400 K»

Substitution in equation must be seen.

Allow ECF from MP1.

[2 marks][

35 ± 5L_s

[1 mark]

$\frac{L_{\text{X}}}{L_{\text{s}}}=\frac{R_{\text{X}}^2\times {\text{T}}_{\text{X}}^4}{R_{\text{s}}^2\times {\text{T}}_{\text{s}}^4}$

OR

$R_{\text{X}}=\sqrt{\frac{L_{\text{X}}{\text{T}}_{\text{s}}^4}{L_s{\text{T}}_{\text{X}}^4}}\times R_{\text{s}}$

$R_{\text{X}}=\sqrt{\frac{35\times {6000}^4}{10{000}^4}}\times R_{\text{s}}$ (mark for correct substitution)

R_X = 2.1R_s

Allow ECF from (b)(i).

Accept values in the range: 2.0 to 2.3R_s.

Allow TS in the range: 5500 K to 6500 K.

[3 marks]

M_X = $(35{)}^{\frac{1}{3.5}}$M_s

M_X = 2.8M_s

Allow ECF from (b)(i).

Do not accept M_X = (35)${}^{\frac{1}{3.5}}$ for first marking point.

Accept values in the range: 2.6 to 2.9M_s.

[2 marks]

the star «core» collapses until the «inward and outward» forces / pressures are balanced

the outward force / pressure is due to electron degeneracy pressure «not radiation pressure»

[2 marks]