ASTRO 1P02 - Test #1

The youngest stars are plotted in this part of the H-R diagra
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Terms in this set (50)
The youngest stars are plotted in this part of the H-R diagra
upper-left corner
Main-sequence stars are in hydrostatic equilibrium, which means the inward gravita- tional forces are balanced by outward forces due to
gas pressure
For a star in hydrostatic equilibrium, the main way in which energy is transported in the star's interior is
gas or radiation
In the Sun, the radiative zone is
between the core and the surface of the Sun
Young stars
have lots of gas and dust surrounding them
As a contracting protostar heats up, if the core temperature reaches ___________ then fusion of hydrogen into helium begins and the protostar becomes a main-sequence star
10 million degrees
High temperatures and pressures are required to produce nuclear reactions because this helps
to overcome the electrical repulsion between atomic nuclei
Reflection nebulae appear
blue
As a main-sequence star evolves, steadily converting hydrogen to helium in its core, the core of the star gradually
becomes hotter and contracts
The net flow of heat in a star is
from its core to its surface
As a main-sequence star evolves, steadily converting hydrogen to helium in its core, the outer layers of the star graduallybecome cooler and expand.The evolution of a main-sequence star depends primarily on itsmassFor a low-mass main-sequence star, hydrogen is fused into helium mainly bythe proton-proton chainFor a high-mass main-sequence star, hydrogen is fused into helium mainly bythe CNO cycleA planet like Jupiter can be considered to be abrown dwarfThe formation of "heavy elements" (nucleosynthesis) occurs primarily duringthe core collapse of a high-mass starAn important way that astronomers measure distances to other galaxies is usingthe method of Cepheid Variables proposed by Henrietta Swan Leavitt in 1912The mass of Star A is much less than the mass of Star B, and they are both main- sequence stars. The rate at which Star A consumes its hydrogen fuel is ___________ the rate at which Star B consumes its hydrogen fuelless thanRed dwarfs are possibly the most numerous type of star in the universe, but they are difficult to observe because they arenot very luminousA planetary nebula is a cloud of gas and dust surroundinga starThe distances to the most distant galaxies are measured usingType Ia supernovaeThe surface temperature of a typical white dwarf isgreater than the Sun's surface temperatureProxima Centauri (one of the stars in the triple-star system Alpha Centauri) isthe star that is closest to us besides our own SunDegenerate matter is foundin the core of a neutron starGravitational redshift is theincrease in wavelength of light as it moves from a star to regions of weaker gravityMost of the energy produced in Type II supernovae explosions is carried away byneutrinosClock A and Clock B are identical. Clock A is located at sea level on Earth and Clock B is located at the top of a high mountain on the Earth.Clock A runs slower than Clock B.In a white dwarf, equilibrium is maintained by a balance ofelectron degeneracy pressure and gravityThe density of a white dwarf isgreater than the Sun's density.When a type Ia supernova explodes, it leaves behindno central remnantWhen a type II supernova explodes, it leaves behinda neutron star as a central remnant or a black hole as a central remnantWhite dwarfs typicallyhave larger diameters and are less dense than neutron starsBinary pulsars emit ___________ that can be used to test _________gravitational waves / Einstein's theory of general relativityType Ia supernovaedo not have hydrogen spectral lines in their spectraType II supernovaehave hydrogen spectral lines in their spectraWhen stars collapse into neutron stars, their rotation rateincreasesAs the 20th century began, astronomers generally believed that the Sun was located near the centre of a wheel-shaped star system that they estimated had a diameter ofabout 15,000 light-yearsThat the Milky Way is made up of an enormous number of individual stars was con- firmed by Galileo in 1609, but was first suggested byAnaxagoras and Democritus in 400 BCEThe first reasonably good approximation for the size of the Milky Way was determined byHarlow ShapleyThe first reasonably good approximation for the size of the Milky Way was determined by measuring the distances toglobular star clustersEarly 20th-century astronomers observed that the Milky Way's globular star clusters appeared to be centred at a point many thousands of light-years away in the direction of the constellationThomas Wright and Immanuel KantOne way astronomers deduce the mass of the Milky Way is to studythe orbital motions of stars in the galaxyA WIMP is aweakly-interacting massive particleA MACHO is amassive astrophysical compact halo objectPopulation I stars are typically found in the Milky Way'sspiral arms, have approximately circular orbits, and have relatively high heavy- element contentPopulation II stars are typically found in the Milky Way'shalo and bulge, have eccentric orbits, and have relatively low heavy-element contentA galactic rotation curve indicates how fast stars movecompared to their distances from the galactic centreMost of the Milky Way's younger stars are located in itsdiskAccording to current theories of the Milky Way's evolution, the shape of the Milkyway is predicted to become __________ as it evolvesflatterThe concept of dark matter was first introduced byFritz Zwicky in 1933