Characteristics of Stars - PowerPoint PPT Presentation

1 / 16
About This Presentation
Title:

Characteristics of Stars

Description:

It's a body of gases that gives off lots of energy in the form of light and heat ... The red ones are the coolest and the blues are the hottest ... – PowerPoint PPT presentation

Number of Views:33
Avg rating:3.0/5.0
Slides: 17
Provided by: staf3
Category:

less

Transcript and Presenter's Notes

Title: Characteristics of Stars


1
Characteristics of Stars
  • Section 27.1

2
Definition of a star
  • Its a body of gases that gives off lots of
    energy in the form of light and heat
  • They vary in size and mass, some are smaller that
    20 km in diameter or up to a 1000 times the size
    of our sun!

3
Variations in composition and temperature
  • Using a spectrometer, scientists can determine
    what type of gases compose a star
  • Every chemical element has a characteristic
    spectrum

4
(No Transcript)
5
Temperature
  • The temperature of a star is indicated by its
    color
  • The red ones are the coolest and the blues are
    the hottest
  • Most Temps range between 2800C to 24,000C.

6
Star Temperatures
7
Motion
  • Actual motion can only be measured by high
    powered telescopes since stars are so far away
  • Apparent motion of stars is what we see and is
    only due to the motion of the earth

8
(No Transcript)
9
Actual Motion of Stars
  • They rotate on an axis, they revolve around other
    stars, and they move towards or away from earth
  • Dont forget the red shift

10
Distance to the Stars
  • Its measured in light years- the distance that
    light travels in one year ( about 9.5 trillion
    km)
  • Light from the sun takes about 8 minutes to reach
    earth

11
Parallax
  • Scientists can use this to measures stars within
    1000 light years of accuracy by measuring the
    angle between a stars apparent position over a
    period of 6 months
  • The closer the star, the larger the angle

12
Stellar Magnitudes
  • The visibility of a star depends on its
    brightness and distance from earth
  • Over 3 billion stars can be seen through a
    telescope, but only 6000 can be seen with the
    naked eye
  • The 2 scales that scientists use to measure
    brightness are apparent magnitude and absolute
    magnitude

13
Apparent Magnitude
  • The brightness of a star as is appears from earth
  • The most powerful telescopes can detect stars
    with an apparent magnitude of about 29
  • Those stars are 1.5 billion times fainter than
    those seem with a naked eye

14
Apparent magnitude
15
Absolute Magnitude
  • How bright a star would be if it were 32.6 light
    years away
  • Scientists use this distance because its equal
    to one parsec

16
Classification of stars
  • Main-sequence stars- stars that are visible in
    the night sky, this includes the sun
  • Super giants are bright because they have so
    much surface area to project light
  • White dwarfs- these stars are hot and dim because
    of their size
Write a Comment
User Comments (0)
About PowerShow.com