Exam 9: The Formation and Structure of Stars

The lower edge of the main-sequence band is known as ________ and represents the location in the H-R diagram at which stars begin their lives as main-sequence stars.

The creation of ________ require(s) that a young hot star (T ≈ 25,000 K) be relatively nearby.

Absorption lines due to interstellar gas

Due to the dust in the interstellar medium, a distant star will appear to an observer on Earth to be

Some young star clusters contain large numbers of protostars.

-The above image is an example of a/an ____________.

Explain what keeps the nuclear reactions in a star under control; i.e., what would happen if too large an amount of energy is released in the center

In the collapse of a protostar ____________________ energy is converted to ____________________ energy.

The lowest-mass object that can initiate thermonuclear fusion of hydrogen has a mass of about

A(n) ____________________ is a cool, dense cloud of dust and gas that is undergoing gravitational contraction.

What observations demonstrate the existence of an interstellar medium

Why are massive stars more luminous than low mass stars That is, why is there a mass-luminosity relation

What causes the outward gas pressure that balances the inward pull of gravity in a main-sequence star

-The above image is a/an _________ wavelength image of a reflection nebula.

in the following cartoon image of Orion, where would you find the Orion nebula

How long can a 1-solar-mass star live

_________ are small luminous nebulae excited by nearby young stars.

What evidence indicates protostars have formed

Energy transport by ____________________ is important when photons cannot readily travel through a gas.

A ZAMS star evolves __________ and to the __________ on the H-R diagram because ________________.