lecture24 - Astronomy Picture of the Day Sand dunes on the...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Astronomy Picture of the Day Sand dunes on the Foor of Mars’s Proctor Crater
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The magnitude scale: review Magnitudes are a logarithmic scale to describe the apparent brightness of stars A difference of 5 magnitudes corresponds to a ratio of exactly 100 in brightness A difference of 1 magnitude corresponds to a ratio of about 2.52 in brightness Smaller number for the magnitude = brighter star
Background image of page 2
Absolute Magnitude The apparent magnitude scale describes the apparent brightness of stars Absolute magnitudes are a way to describe a star’s luminosity, using a magnitude scale Every step on the absolute magnitude scale corresponds to a ratio of 2.52 in luminosity The sun’s absolute magnitude is +4.8 Very luminous stars have negative absolute magnitudes
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Temperature hot cool low high Luminosity blue red Color If we make a plot of temperature vs. luminosity for many stars, where do the stars lie in the plot? Absolute Magnitude positive negative Spectral type: O B A F G K M
Background image of page 4
Color- magnitude diagrams Also called the Hertzsprung-Russell (H-R) Diagram X axis: stellar temperature, or color, or spectral type Y axis: luminosity or absolute magnitude
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 22

lecture24 - Astronomy Picture of the Day Sand dunes on the...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online