Author Question: What change slowly occurs during the main-sequence lifetime of a star? A) As hydrogen is used up ... (Read 75 times)

yoooooman

  • Hero Member
  • *****
  • Posts: 557
What change slowly occurs during the main-sequence lifetime of a star?
 
  A) As hydrogen is used up in the core, the fusion rate decreases and reduces the luminosity.
  B) It gathers more gas from interstellar space, increasing its mass and hence the luminosity.
  C) Its core temperature slowly increases, increasing the fusion rate and hence the luminosity.
  D) As the solar wind blows material into space, the decreasing mass reduces pressure in the core, which in turn reduces the fusion rate and the luminosity.

Question 2

The Doppler technique can be used to estimate the semimajor axis of a planet's orbit by
 
  A) measuring the time it takes for the star's line-of-sight velocity to cycle from peak to peak, and using Newton's version of Kepler's Third law.
  B) measuring the speed at which the star orbits the mutual center-of-mass of the star and planet, and using Newton's theory of gravity.
  C) measuring the asymmetries in the velocity curve.
  D) measuring the amount by which the starlight is reduced when the planet transits.



zoeyesther

  • Sr. Member
  • ****
  • Posts: 315
Answer to Question 1

C

Answer to Question 2

A



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question

yoooooman

  • Hero Member
  • *****
  • Posts: 557
Both answers were spot on, thank you once again




 

Did you know?

Though “Krazy Glue” or “Super Glue” has the ability to seal small wounds, it is not recommended for this purpose since it contains many substances that should not enter the body through the skin, and may be harmful.

Did you know?

Increased intake of vitamin D has been shown to reduce fractures up to 25% in older people.

Did you know?

The Centers for Disease Control and Prevention has released reports detailing the deaths of infants (younger than 1 year of age) who died after being given cold and cough medications. This underscores the importance of educating parents that children younger than 2 years of age should never be given over-the-counter cold and cough medications without consulting their physicians.

Did you know?

Most strokes are caused when blood clots move to a blood vessel in the brain and block blood flow to that area. Thrombolytic therapy can be used to dissolve the clot quickly. If given within 3 hours of the first stroke symptoms, this therapy can help limit stroke damage and disability.

Did you know?

The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole.

For a complete list of videos, visit our video library