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Table 2 shows some properties of the four brightest stars in the constellation Canis Minor - AQA - A-Level Physics - Question 2 - 2019 - Paper 4
Question 2
Table 2 shows some properties of the four brightest stars in the constellation Canis Minor. **Table 2** | Name | Apparent magnitude | Absolute magnitude | Sp... show full transcript
Worked Solution & Example Answer:Table 2 shows some properties of the four brightest stars in the constellation Canis Minor - AQA - A-Level Physics - Question 2 - 2019 - Paper 4
Step 1
Discuss, with reference to the Hipparcos scale, why many star maps show only two stars in the constellation Canis Minor.
Answer
The Hipparcos scale ranks stars based on their apparent brightness as seen from Earth. It can detect stars from 1st magnitude down to 6th magnitude. In many star maps, only the two brightest stars (Gomeisa and Procyon) are shown because they are easily visible under good conditions, while stars like Gamma A and HD 66141 are much dimmer and may not be visible without appropriate equipment.
Step 2
State and explain which star in Table 2 has the most prominent Hydrogen Balmer absorption lines.
Answer
From the spectral classes listed in Table 2, Gomeisa (B class star) is the one with the most prominent Hydrogen Balmer absorption lines. B class stars have a higher temperature and have the energy necessary for the excitation of hydrogen atoms, allowing them to absorb more light at specific wavelengths, thus creating distinctive absorption features in their spectra.
Step 3
Deduce which star, Gamma A or HD 66141, has the larger diameter.
Answer
Using Stefan's Law, which states that luminosity is proportional to the fourth power of the temperature and the square of the diameter, we can compare the two stars. Since both Gamma A and HD 66141 have similar absolute magnitudes, but Gamma A is cooler, it will have a larger diameter due to its lower temperature allowing it to maintain a similar luminosity.
Step 4
Describe the main features of the radial velocity method in the detection of planets.
Answer
The radial velocity method involves measuring the changes in the spectrum of a star as it moves towards or away from the Earth, which occurs due to the gravitational pull of an orbiting planet. When a planet orbits a star, it causes the star to 'wobble' slightly, altering its radial velocity. The method uses Doppler shifts in the star's light spectrum, allowing astronomers to infer the existence of the planet based on periodic changes in the star's velocity.
Step 5
Calculate the distance from the Earth to Procyon. Give an appropriate unit for your answer.
Answer
To calculate the distance to Procyon, we can use the formula:
where:
- is the apparent magnitude (0.34)
- is the absolute magnitude (2.65)
Substituting values:
Thus, the distance from Earth to Procyon is approximately 5.48 parsecs.