Describe two key features of the black-body radiation curve for a typical star, when plotted on axes of spectral intensity against wavelength.
Outline how a star's black-body radiation curve can be used to estimate its surface temperature, making explicit reference to the SI units of all physical quantities involved in the calculation.
Two stars, HD 198287 A and HD 198287 B, are observed in close proximity within the constellation Cygnus. Historically, astronomers debated whether they represent a true gravitationally bound binary pair or are simply an optical double (aligned by chance along the same line of sight). Table 1 lists some of their measured properties.
Table 1
| Star | Temperature / K | Radius / km | Apparent magnitude |
|---|---|---|---|
| HD 198287 A | 9600 | 1.2×1061.2 \times 10^61.2×106 | 3.4 |
| HD 198287 B | 7200 | 9.2×1059.2 \times 10^59.2×105 | 5.2 |
Evaluate whether these data support the suggestion that the two stars form a binary system. In your answer you should:
What is the spectral class of HD 198287 A?
