Classification of Stars

TEKS 8.8A describe components of the universe including stars, nebulae and

galaxies, and use models such as the Herztsprung-

Russell diagram for classification

TEKS 8.8B recognize that the Sun is a medium-sized star

near the edge of a disc-shaped galaxy of stars and

that the Sun is many thousands of times closer to the Earth than any other star

In the early twentieth century, astronomers

Henry Russell and Ejnar Hertzsprung

HertzsprungRussell

constructed a diagram comparing two properties of stars.

This graph, called the Hertzsprung-Russell Diagram (HR Diagram)

became one of astronomers’ most important tools.

Think of the HR

Diagram as a sort of family

portrait of the stars.

It shows stars at different ages and stages of

their evolution.

The HR diagram

serves as a tool to reveal

the relationships

and differences

among stars.

The HR Diagram compares the

luminosity and surface temperature of stars.

Luminosity is the total amount of

energy that the star radiates or simply

put; the brightness of the star.

The surface temperature of a star is determined directly by observing the star’s color and the spectral patterns.

Astronomers classify stars into

stellar groups based on their

surface temperatures.

The groups are O, B, A, F, G, K and M.

Group O stars are the blue-white and

hottest, while group M stars are red and

coolest.

Copy and answer in journal

1. This is called the “family portrait” of the stars _________________________.2.It shows stars at different _________ and _________ of their evolution.3.The HR diagram compares _______________ and ___________________ of stars.4.Luminosity is the total amount of _________ that a star radiates, which is the ________________ of a star.5.Surface temperatures is determined directly observing the star’s __________ and ________________________.6.Blue star’s are ______________ while red star’s are _________________.7.Astronomers classify stars into groups by their ______________________________.

• Star A--- 5500 C/K Luminosity Low• Star B--- 2500 C/K Luminosity Low-Med• Star C--- 3350 C/K Luminosity High• Star D--- 25000 C/K Luminosity High Med• Star E--- 26000 C/K Luminosity 1 sun• Star F--- 11000 C/K Luminosity 104 sun• Star G--- 9000 C/K Luminosity 10 -2

• Star H--- 22500 C/K Luminosity 10 -4

• Star I---2850 C/K Luminosity Medium• Star J--- 15000 C/K Luminosity 10 -1

• Challenge Plot a star of your choice-Use ED

Assignment

In your TEXTBOOK

Complete your test review-this will count as your quiz grade

Page 337-340