Author Question: What of the following distance methods is used to determine the distance to the most distant ... (Read 92 times)

neverstopbelieb

  • Hero Member
  • *****
  • Posts: 534
What of the following distance methods is used to determine the distance to the most distant galaxies?
 
  a. radar echo
  b. supernova observations
  c. period-luminosity relationship of variable stars
  d. parallax

Question 2

Why are massive stars more luminous than low mass stars? That is, why is there a mass-luminosity relation?
 
  What will be an ideal response?



billybob123

  • Sr. Member
  • ****
  • Posts: 336
Answer to Question 1

b

Answer to Question 2

To understand the mass-luminosity relation, recall (1) the principle of hydrostatic equilibrium, which says that pressure balances weight, and (2) the pressure-temperature thermostat, which regulates energy production. A star that is more massive than the Sun has more weight pressing down on its interior, so the interior must have a higher pressure to balance that weight. That means the massive star's automatic pressure-temperature thermostat must keep the gas in its interior hot and the pressure high. A star less massive than the Sun has less weight on its interior and thus needs less internal pressure; therefore, its pressure-temperature thermostat is set lower. Massive stars are more luminous because they must make more energy to support their weight.



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
 

Did you know?

More than 4.4billion prescriptions were dispensed within the United States in 2016.

Did you know?

The National Institutes of Health have supported research into acupuncture. This has shown that acupuncture significantly reduced pain associated with osteoarthritis of the knee, when used as a complement to conventional therapies.

Did you know?

People with high total cholesterol have about two times the risk for heart disease as people with ideal levels.

Did you know?

Once thought to have neurofibromatosis, Joseph Merrick (also known as "the elephant man") is now, in retrospect, thought by clinical experts to have had Proteus syndrome. This endocrine disease causes continued and abnormal growth of the bones, muscles, skin, and so on and can become completely debilitating with severe deformities occurring anywhere on the body.

Did you know?

About 80% of major fungal systemic infections are due to Candida albicans. Another form, Candida peritonitis, occurs most often in postoperative patients. A rare disease, Candida meningitis, may follow leukemia, kidney transplant, other immunosuppressed factors, or when suffering from Candida septicemia.

For a complete list of videos, visit our video library