天文与天体物理知识（astronomy and astrophysic knowledge）

北极星有什么特别之处？

What is special about Polaris(North star)?

• 光谱特殊，与其他恒星不一样。

  It has an unique spectrum.

• 和恒星背景有相对运动，类似行星。

  It has a planet-like relative motion against the stellar background.

• 位于北天极，在夜空中不会相对地景移动。

  It is positioned at the North celestial pole, so it does not move relative to the ground.

• 特别亮，可以达到类似木星冲日时的亮度。

  It is extremely bright, to the level of Jupiter at opposition.

太阳系中质量最大的行星是哪个，它有哪些特性？

What is the most massive planet in the solar system and what properties does it have?

• 木星，自传轴与黄道面平行。

  Jupiter, its axis of rotation is parallel to ecliptic plane.

• 木星，磁场强度在行星中最高。

  Jupiter, it has the strongest magnetic field.

• 木星，行星中公转周期最快。

  Jupiter, it has the fastest revolution period.

• 土星，行星中密度最小。

  Saturn, it has the lowest density.

小恒星（主序星阶段，光谱为M或K）内主要的核聚变方式是？

What are the main fusion method occuring in small stars (Main sequence stars with a spectrum of M or K)?

• p-p反应

  p-p chain

• 氦3反应

  He-3 fusion

• CNO反应

  CNO cycle

• triple-alpha反应

  triple-alpha process

假如一个卫星在远点减速，它的轨道会如何变化？

If a satellite deaccelerate at the furthest point in an orbit, how will its orbit change?

• 远点不变，近点变近

  Furthest point unchanged, nearest point becomes closer

• 远点变近，近点不变

  Furthest point becomes closer, nearest point unchanged

• 远点不变，近点不变

  Furthest point unchanged, nearest point unchanged

• 远点变近，近点边远

  Furthest point becomes closer, nearest point becomes closer

在一个恒定轨道中，卫星的哪些量是不变的？

What values are constant for a satellite in a fixed orbit?

• 动量，动能，角动量，机械能

  momentum, kinetic energy, angular momentum, mechanical energy

• 动量，动能，角动量

  momentum, kinetic energy, angular momentum

• 动量，动能，机械能

  momentum, kinetic energy, mechanical energy

• 角动量和机械能

  angular momentum and mechanical energy

一个在太阳轨道中的卫星向太阳加速，它的哪些值不会变？

For a satellite in a solar orbit accelerating towards the sun, what values are constant?

Hint: torque

• 远点位置

  Aphelion position

• 轨道周期

  Orbital period

• 机械能

  Mechanical energy

• 角动量

  Angular momentum

以下哪种恒星的数量最多？

Of the following star types, which one is the most abundant?

• M-型

  M-type

• K-型

  K-type

• G-型

  G-type

• O-型

  O-type

在太阳核心处主要发生哪种散射？

What type of scattering occurs in the core of the Sun?

• 康普顿散射

  Compton Scattering

• 瑞利散射

  Rayleigh Scattering

• 汤姆逊散射

  Thompson Scattering

• 无散射

  No scattering

有一双星系统，两颗恒星的视星等分别为2和3，它们的总视星等为？

For a binary star system, its two stars has an apparent brightness of 2 and 3. What is its total apparent magnitude?

Hint:m=-2.5log(l/l_0)

• 0.64

• 1.64

• 2.64

• 3.64

相对于恒星背景，在近日点附近的彗星的角速度大概是？

Relative to the stellar background, the angular velocity of a comet near perihelion is roughly?

Hint: ω≈v/r

• 20°/s

• 2°/s

• 0.2°/s

• 2*10^-6°/s