Test #3 Definitions & Examples Flashcards
Definition of star?
a fixed luminous point in the night sky which is a large, remote incandescent body like the sun.
EX: star.
Definition of an apparent magnitude?
the measure of the brightness or luminosity of a star or other astronomical object.
EX: The Sun is -26.7
Definition of black hole?
a region of space having a gravitational field so intense that no matter or radiation can escape.
EX: Sagittarius A is one of the famous black holes, its at the heart of the milky way.
Definition of absolute magnitude?
the magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs. EX: Sirius has an absolute magnitude of only 1.4, which is still brighter than the Sun.
Definition of main sequence?
a series of star types to which most stars belong, represented on a Hertzsprung–Russell diagram as a continuous band extending from the upper left (hot, bright stars) to the lower right (cool, dim stars).
EX: One of the main sequence stars is Betelgeuse.
Definition of electromagnetic radiation?
Electromagnetic radiation is energy that is transmitted at the speed of light through electric and magnetic fields.
EX: infared waves.
Definition of nebula?
a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.
EX: The Cat’s Eye Nebula, is a planetary nebula.
Definition of light-year?
a unit of astronomical distance equivalent to the distance that light travels in one year, which is 5.88 trillion miles.
EX: An example of a light-year is over five trillion miles.
Definition of supergiant?
a very large star that is even brighter than a giant, often despite being relatively cool.
EX: Antares
Definition of nuclear reaction?
a change in the identity or characteristics of an atomic nucleus that results when it is bombarded with an energetic particle, as in fission, fusion, or radioactive decay.
EX: The most notable nuclear reactions are the nuclear chain reactions in fissionable materials that produce induced nuclear fission
Definition of gravity?
the force that attracts a body toward the center of the earth, or toward any other physical body having mass.
EX: The force that causes a glass you drop to fall to the floor.
Definition of white dwarf?
a small very dense star that is typically the size of a planet. A white dwarf is formed when a low-mass star has exhausted all its central nuclear fuel and lost its outer layers as a planetary nebula.
EX: Sirius B is a white dwarf star.
Definition of nucleosynthis?
the cosmic formation of atoms more complex than the hydrogen atom.
EX: carbon-14, produced from nitrogen-14 in the atmosphere by cosmic rays.
Definition of H-R diagram?
a scatter plot of stars showing the relationship between the stars’ absolute magnitudes or luminosities versus their stellar classifications or effective temperatures.
EX: It’s a chart to show the specifics of the relationships stars have with their terms.
Definition of giant?
an imaginary or mythical being of human form but superhuman size.
EX: Goliath in the story of “David and Goliath.”
Definition of positron?
a subatomic particle with the same mass as an electron and a numerically equal but positive charge.
EX: A positron is the antimatter partner of an electron.
Definition of stellar parallax?
Stellar parallax is the apparent shift of position of any nearby star against the background of distant objects.
EX: Proxima Centauri’s parallax is 1.301 parsecs.
Definition of neutron star?
A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses.
EX: PSR B1257+12 – the first neutron star discovered with planets
Definition of hydrogen burning?
Hydrogen burning is the fusion of 4 hydrogen nuclei (protons) into a single helium nucleus (2 protons + 2 neutrons).
EX: In a flame of pure hydrogen gas, burning in air, the hydrogen reacts with oxygen to form water and releases energy.
Definition of luminosity?
The total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical object.
EX: How bright something is.
Definition of fusion?
Fusion occurs when two light atoms bond together, or fuse, to make a heavier one.
EX: An example of Fusion reaction happening in real life is the Sun.
Definition of proton-proton chain?
one of two known sets of nuclear fusion reactions by which stars convert hydrogen to helium.
EX: It operates inside the Sun and stars of similar mass.
