Astronomical Distances and Measurement Techniques

Vocabulary flashcards based on the key concepts from the lecture notes regarding astronomical distances and measurement techniques.

Astronomical Unit (AU)

The average distance from the Earth to the Sun, approximately 149.6 million kilometers.

Light-Year

The distance that light travels in one year, equivalent to about 9.46 trillion kilometers.

Parallax

The apparent shift in position of a nearby star against a background of distant stars as viewed from different points in Earth's orbit.

Parsec (pc)

A unit of distance equal to 3.26 light-years; defined as the distance at which one astronomical unit subtends an angle of one arcsecond.

Cepheid Variable

A type of pulsating star whose brightness varies in a regular cycle, allowing astronomers to determine distances based on their period-luminosity relationship.

Period-Luminosity Relation

The relationship that associates the pulsation period of cepheid variable stars with their intrinsic luminosity.

RR Lyrae star

A type of pulsating variable star with a period of less than one day, often used to measure distances.

Triangulation in Astronomy

A method used to measure distances to stars using the baseline created by Earth's motion around the Sun.

Hertzsprung-Russell Diagram (H–R Diagram)

A scatter plot of stars showing the relationship between their absolute magnitudes (luminosities) versus their stellar classifications or effective temperatures.

Luminosity Class

A classification of stars according to their luminosity; for example, main-sequence stars (V), giants (III), and supergiants (I).