Download Astronomy pt. 2

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
o
Ex. Sirius (10,000 C)
3. Yellow – Average (5000-6000 C )
temperature and middle age
o
• Ex. The sun
•4 – Red- coolest and
growing old
•Ex. Betelgeuse less than
3,500 C
o
Ultraviolet
shortest
Infrared
^
longest
Electromagnetic Spectrum
All radiant energy that
travels the speed of light
in waves
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___
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
1) Red super giants and red giants
2) Blue Giants.
3) White Dwarfs
Betelgeuse
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
Alvarez
"Big Bang
hypothesis
“Meteor-impact” theory"
describes some
aspects of the
universe or
phenomenon
“gravity”
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 ballshaped 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 GIANTS
a) 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 HHe
and HeC, 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
QuasarsVery powerful
source of
energy
most distant
objects in
space
• Pulsars– a neutron star
that spins
rapidly and
sends out radio
waves
GALAXIES
3 TYPES
• SPIRAL- 2-4 arms
– EX. ANDROMEDA
• IRREGULAR –
– EX. MAGELLANIC CLOUDS
• ELLIPTICAL