Astronomy – Astronomy – Flashcards

Variable star whose luminosity changes in a characteristic way. All RR Lyrae stars have more or less the same average luminosity.

What kind of celestial bodies have cores that consist primarily of neutral particles in a superfluid state and are thought to have evolved from stars with masses more than about 1.4 times the Chandrasekhar limit?

-Stronger magnetic fields than pulsars (~1000 times stronger

A rapidly spinning neutron star that produces radio waves.

Which of these phenomena provides a way for us to (indirectly) observe black holes?

stars that increase in brightness and then get dim

The brightest star in the Large Magellanic Cloud (LMC), one of the brightest stars known, and the prototype for the class of variable known as S Doradus stars (luminous blue variables). It lies in the young open cluster NGC 1910 on the northern rim of the LMC's central bar.

One of two small, irregular galaxies (the other is the Small Magellanic Cloud) located about 150,000 light-years away; it probably orbits the Milky Way Galaxy.

These two "large" and "small" irregular galaxies are named for a 16thC navigator. Visible in the southern hemisphere, they form part of the Milky Way subgroup.

A gigantic explosion in which a massive star collapses and throws its outer layers into space a star that explodes and becomes extremely luminous in the process

a system of two stars that revolve around each other under their mutual gravitation

These result from some binary star systems in which a carbon-oxygen white dwarf is accreting matter from a companion. (What kind of companion star is best suited to produce Type Ia supernovae is hotly debated.) In a popular scenario, so much mass piles up on the white dwarf that its core reaches a critical density of 2 x 109 g/cm3. This is enough to result in an uncontrolled fusion of carbon and oxygen, thus detonating the star.

Stage in which a star has used up its helium and its outer layers escape into space, leaving behind a hot, dense core that contracts

These supernovae occur at the end of a massive star's lifetime, when its nuclear fuel is exhausted and it is no longer supported by the release of nuclear energy. If the star's iron core is massive enough, it will collapse and become a supernova.

Gravity gives the supernova its energy. For Type II supernovae, mass flows into the core by the continued formation of iron from nuclear fusion. Once the core has gained so much mass that it cannot withstand its own weight, the core implodes. This implosion can usually be brought to a halt by neutrons, the only things in nature that can stop such a gravitational collapse. Even neutrons sometimes fail depending on the mass of the star's core. When the collapse is abruptly stopped by the neutrons, matter bounces off the hard iron core, thus turning the implosion into an explosion.

Apparent change in the position of a star in the sky due to the change in the Earth's position as the Earth moves around the sun

of or relating to the use of an optical device for the purpose of creating or observing a spectrum of light or radiation

A method of finding a star's distance from its absolute magnitude and spectral type or color.

A star of variable luminosity. The luminosity increases sharply and falls off gently with a well-defined period. The period is related to the absolute luminosity of the star and so can be used to estimate the distance to the star.

like red giants but cooler, more luminous, and bigger (largest structures in universe yet not most massive)

an early stage in the evolution of a star, after the beginning of the collapse of the gas cloud from which it is formed, but before sufficient contraction has occurred to permit initiation of nuclear reactions at its core.