Stars and the Universe：練習題

Which description correctly defines a galaxy such as the Milky Way?

A star of mass significantly greater than the Sun has used up its hydrogen in the core. Which of the following describes the correct subsequent sequence of stages in its life cycle?

The Hubble constant \(H_0\) is defined as the ratio of the recession speed \(v\) to the distance \(d\) of a galaxy. If a galaxy is at a distance of \(6.0 \times 10^{24} \text{ m}\) and the Hubble constant is taken as \(2.2 \times 10^{-18} \text{ s}^{-1}\), what is the calculated recession speed of the galaxy and what does the ratio \(\frac{1}{H_0}\) represent?

Which statement correctly defines one light-year?

Light from a distant galaxy is observed on Earth. Astronomers notice that the wavelength of the light has increased.

What is the name of this phenomenon and what does it indicate about the galaxy?

Identify the type of celestial object the Sun is in terms of its size and name the specific galaxy in which it is located.

Describe how a protostar is formed and explain the physical process that causes its internal temperature to increase during this stage.

A distant galaxy is moving away from Earth at a speed of \(1.3 \times 10^{7} \text{ m/s}\). Given the Hubble constant \(H_0 = 2.2 \times 10^{-18} \text{ s}^{-1}\), calculate the distance to this galaxy in light-years. (\(1 \text{ light-year} = 9.5 \times 10^{15} \text{ m}\))

The Sun is a medium-sized star that provides energy to the Solar System.
(a) Identify the two primary chemical elements that make up the Sun. (1)
(b) The Sun emits radiation across various parts of the electromagnetic spectrum. Name the three specific regions where the majority of this energy is radiated. (2)

The Sun is a stable star of medium size. Describe the life cycle of the Sun from its current stable state until it reaches its final stage.

In your answer, include the names of the stages and the nuclear processes involved. (4)