Astrophysics - Option Flashcards
What is parallax?
Parallax is the apparent shift in position of a close object against a distant background due to a change in position of the observer.
What is interferometry?
It is a technique used to combine the data from several elements of an antenna array in order to achieve a higher resolution.
What is one parsec (pc) or parallax-second?
It is the distance that corresponds to an annual parallax of one second of arc.
What is a light-year?
It is the distance travelled through space in one year by light or other electromagnetic wave. It corresponds to a distance of 0.3066 parsecs or 9.4605x10^12km
What is a spectroscope?
It is a device used to spread a light into its spectrum. It can be attached to the eyepiece of a telescope to examine the spectra of starlight.
What is photometry?
It is the measurement of the brightness of a source of light or other radiation.
What is apparent magnitude (m) ?
It is the magnitude given to a star as viewed from Earth.
What is absolute magnitude (M) ?
It is the magnitude that a star would have if it was viewed from a standard distance of 10 parsecs.
What are active optics?
Active optics use a slow feedback system to correct sagging or other deformities in the primary mirror of large modern reflector telescopes.
What are adaptive optics?
Adaptive optics use a fast feedback system to attempt to correct for effects of atmospheric turbulence.
What is trigonometric parallax?
It is a method of using trigonometry to solve the triangle formed by parallax to determine distance.
What does incandescent mean?
It means bright or glowing. Like black bodies, most substances become incandescent when they become hot enought.
What is a photon?
It is a quantum (or discrete packet) of electromagnetic radiation. It can be thought of as an elementary particle with zero rest mass and charge, travelling at the speed of light.
What is stellar spectroscopy?
It is the examination of the spectra of stars in order to learn more about their composition, surface temperature, velocity, density, etc.
What is spectroscopic parallax?
It is a method of using the H-R diagram and the distance modulus formula (m-M) to determine the approximate distance of a star.
