STARS• Luminous Balls OF GASES, MOSTLY

AND

held together by own gravity

• Are all stars the same color?

• NO!

• Color- determined by surface temperature.

• 1. Blue- young and hottest

• Ex. Rigel (above 30,000 degrees Celsius

• 2. White - usually old and hot

Ex. Sirius (10,000 o

C)

3. Yellow – Average (5000-6000

oC )temperature and middle age

• Ex. The sun

•4 – Red- coolest and growing old •Ex. Betelgeuse less than 3,500 o

C

All radiant energy that travels the speed of

light in waves

Electromagnetic Spectrum

shortest longestInfraredUltraviolet

^

Composition, temperature and motion

Spectroscope

• Attaches to an optical telescope– Analyzes light

from the stars

Bright line spectrum

•Separates visible light by its different wavelengths

•Each element is then identified by its own spectrum

•Shows direction, movement and composition

Spectrum___

Longest to shortest wavelength

DOPPLER EFFECT

**THE APPARENT SHIFT IN WAVELENGTH DUE TO A MOVING OBJECT

Red shift- moving away

Blue shift- moving toward

DISTANCE LIGHT TRAVELS IN ONE YEAR

• 6,000,000,000,000 MILES (186,000 mi/sec) or • 300,000 km/s

• AU: Astronomical unit • Distance from Earth to Sun

• 149,597,870,700 m or just 1 AU

• Distance is measured by using PARALLAX-

• THE APPARENT SHIFT IN MOTION over time

• Ex. • Hold out one arm and give a thumbs up

• Close one eye and cover the Red Star• Now switch eyes

• That apparent change is parallax!

• 2. Apparent Brightness (Magnitude)

– A. The brightness we see from earth

– B. Depends on size, distance and surface temperature.

C. Star’s Brightness

• 1. Luminosity or absolute magnitude.

– A. Actual brightness of the star

– B. found by using the distance and apparent magnitude.

OPTICAL TELESCOPES

1. REFRACTING TELESCOPE

**uses lenses to

bend light to a

focus point

person

2. Reflecting Telescope

– Uses mirrors – Concave mirror

reflects light to a flat mirror

– Ex. Hubble Space Telescope•Hale telescope

3. Catadioptric Telescope

– Uses mirrors – AND Lenses– Ex. Celestron 8

Problems with Optical telescopes• Light pollution

EM (electromagnetic) spectrum

Jansky 1905-1950• Discovered radio

waves in space 1931

Reber- 1911-2002• Built the first radio

telescope (1937)Collects radio waves from space

Can be used at anytime or weather

VLA in New Mexico

ASTRONOMICAL INSTRUMENTS

Radio Telescopes• Operate in the radio

frequency portion of the EM spectrum where they can detect and collect data on radio sources.

• Used anytime, no light pollution or weather problems

Scientific Terms

a (testable) proposed explanation for a phenomenon

a well-confirmed type of explanation of nature, made in a way consistent with scientific method

"Big Bang theory"

Alvarez hypothesis“Meteor-impact”

describes some aspects of the universe or phenomenon

“gravity”

D. Classification

• 1. H. R. diagram (Hertzsprung – Russell)

• 2. Classifies by surface temperature and absolute magnitude.

• 3. Main sequence stars- stars of similar composition and size– A. “average” stars

• 4. Outside of main sequence

– A. Red super giants and red giants

– B. Blue Giants.

– C. White Dwarfs

Betelgeuse

Rigel Betelgeuse

Sirius

Sun

E. Life Cycle Of Stars• STEP 1. Begins as a nebula- a cloud of dust

and gas. (mostly H and He)

• STEP 2. Protostar- gravity forms a ball-shaped pocket and temperature increases.

STEP 3. Nuclear fusion• 4 hydrogen fuse to make helium plus

energy• Occurs in the core• Must be 10 mil

– degrees C

STEP 4. Main Sequence Star• Must have enough mass to have nuclear

fusion for its energy

STEP 5. RED GIANTSa) Size of giants depends on

the initial mass

b) Could be a super red giant like Betelgeuse

c)No more H(very little), He turns into C

More energy HHe and HeC, gravity cant hold on ahhh!

STEP 6. Supernova or white dwarf

• a) white dwarf- small, hot, older star no shell, only core left to cool

– 1. Ex. Sirius or the Sun (some day)

• b) supernova- gigantic explosion of a large mass star like Betelgeuse

• Chinese recorded one in 1054 AD

Supernova Feb.24, 1987

170,000LY

c) NEUTRON STAR

1. Extremely dense; like the mass of our sun into a 8 mi diameter

• d) Black hole-

• 1. An object so dense that not even light can escape its

surface

• Pulsars- – a neutron star

that spins rapidly and sends out radio waves

Quasars-

Very powerful source of

energy

most distant objects in space

GALAXIES

3 TYPES• SPIRAL- 2-4 arms

– EX. ANDROMEDA

• IRREGULAR – – EX. MAGELLANIC CLOUDS

• ELLIPTICAL