ASP Stellar Astronomy and Star Life Cycles 3

Question 1

What is the Kelvin-Helmholtz mechanism?

Accepted Answer

Gravitational contraction that converts potential energy into thermal energy in stars

Answer

The Kelvin-Helmholtz mechanism describes how a star generates heat through gravitational contraction, converting gravitational potential energy to thermal energy, relevant during stellar formation before fusion begins.

Question 2

What is a T Tauri star?

Accepted Answer

A young pre-main-sequence star still contracting toward the main sequence

Answer

T Tauri stars are young stellar objects (less than ~10 million years old) that are still gravitationally contracting before reaching the main sequence and beginning stable hydrogen fusion.

Question 3

What is the Hayashi track on the H-R diagram?

Accepted Answer

The nearly vertical evolutionary path of a protostar contracting toward the main sequence

Answer

The Hayashi track is the nearly vertical path on the H-R diagram followed by a fully convective protostar as it contracts toward the main sequence at nearly constant surface temperature.

Question 4

What determines where a star will fall on the main sequence?

Accepted Answer

Its mass

Answer

A star's position on the main sequence is primarily determined by its mass, as mass controls core pressure, temperature, and the rate of nuclear fusion, thus setting luminosity and surface temperature.

Question 5

What is an asymptotic giant branch (AGB) star?

Accepted Answer

A late-stage giant star fusing helium in a shell around an inert carbon-oxygen core

Answer

AGB stars are late-stage evolved stars of low to intermediate mass that have exhausted core helium burning and now fuse hydrogen and helium in shells around an inert carbon-oxygen core.

ASP - Astronomical Society of the Pacific Exam Practice Test

ASP - Astronomical Society of the Pacific Exam Practice Test

ASP Stellar Astronomy and Star Life Cycles 3