Stars and Star Terminology Flashcards
A deck containing useful knowledge about the stars and many terms associated with them.
What is the absolute magnitude of a star?
It is the magnitude that a star would appear to have if it were at a distance of 10 pc from the Sun
What is the apparent magnitued of a star?
It is the brightness of an astronomical object, as observed on Earth and referred to the appearance of some objects chosen as standards. The scale of magnitudes is defined so that a difference of 5 magnitudes corresponds to a ratio of 100 in observed radiation intensity
What is a binary star?
A binary star is when two stars are in orbit around one another.
What is a black dwarf?
It is the final state of stellar evolution, when a star has used up all of its energy resources and can no longer radiate
What is a black hole?
Body that is so massive and so compact that no light can leave its surface. Suggested by General Theory of Relativity
What is a cepheid variable?
A cepheid variable is a type of star with regular variation in its brightness, named for Delta Cephei, the first star recognized of this type. These stars play an important role in the determination of the scale of distances to galaxies
What are circumpolar stars?
They are stars that are close enough to the celestial pole that they do not rise and set each night but can be seen to move around the pole in a circular path. Latitude of observer determines which stars appear circumpolar
What is a constellation?
A constellation is a group of stars that seemed to suggest the shape of some god, person, animal or object. Now a term used to designate a region of the sky, of which there are 88.
What is the Crab Nebula?
Remnant of the supernova observed in 1054 AD, now observable as an expanding and tangled cloud of gas, with a pulsar at the center
What is a dwarf star?
A dwarf star is a main-sequence star of low luminosity
What is an eclipsing binary star?
A binary star whose mutual orbit is viewed almost edge-on so that light observed is regularly decreased each time one star eclipses the other
What is an emission nebula?
A cloud of interstellar gas that glows because of ultraviolet radiation absorbed from a nearby hot star
What is a globular cluster?
It is a tight cluster of stars that is circular and symmetrical, as opposed to open or galactic clusters
What is luminosity?
The rate at which radiant energy is emitted by a star or other object, usually expressed in erg/sec
What is meantby luminosity class?
Classification of stars on the H-R diagram within the same spectral class