HW 8: The Birth of Stars

Name the telescope that is currently primarily observing in infrared radiation and would help shed more light on star formation, and also look at distant galaxies and first light.

James Webb Space Telescope

Name the famous photographed nebula observed by the Hubble Space Telescope, which was nicknamed the pillars of creation.

Eagle Nebula

What are the dense and cool lumps of gas within a molecular cloud called which act as embryos of stars?

Core

Which of the following two conditions determine the onset of gravitational collapse leading to a star formation?

High mass and low temperature

What planets detected beyond our local solar system called?

Exoplanets

The Orion nebula in the Orion nebula is a very well-studied stellar nursery. What does the interstellar gas in this nebula primarily emit in? 

Infrared

What is the stage of a star called when the core has started gravitationally collapsing but has not yet started nuclear fusion reactions?

Protostar

If you wanted to observe stars behind a molecular cloud, in what wavelength of light should you observe?

Infrared

On what properties does the thermal pressure within a gas depend on?

Density and Temperature

On what propertie(s) does the strength of gravity within a molecular cloud depend(s) on?

Density only  

The water molecules now in your body were once part of a molecular cloud. Only about one-millionth of the mass of a molecular cloud is in the form of water molecules, and the mass density of such a cloud is roughly 10^-21 g/cm³. What is the volume of a piece of molecular cloud that has the same amount of water as your body? An average human has about 10 gallons of water in their body. (Use 1 gallon = 3.79 kg)

3.79 x 10³¹cm³

Assume a molecular cloud of mass 1000 M_sun. If the average density of this cloud is 10^-21 g/cm³, what is the radius of the cloud in ly? Hint: First calculate the cloud's volume from its mass and density. Then determine the cloud's radius using the formula for the radius of a sphere, using the fact that volume of sphere = (4/3)πr³, where r is the radius of the sphere.

8.24 ly