Presentation first term fisics and chemestry

1. LIFE OF STARS

2. Birth of stars
What is a Star?

3. The Eagle nebula, a stellar nursery illuminated by ultraviolet
light which is emitted from the newborn stars.

4. Death
Sun-like Stars
(under 1.5 times
the mass of the Sun)
Red Giant
Planetary
nebula
Huge Stars
(between 1.5 and 3 times
the mass of the Sun)
Red Super
Giant
Supernova
Neutron Star
Giant Stars
(more than 3 times
the mass of the Sun)
Red Super
Giant
Supernova
Black hole
White dwarf
Black dwarf

5. Nuclear fusion
Small stars:
Hydrogen
Helium
Medium-size stars (like the Sun):
Hydrogen
Helium
Oxygen and
carbon
Massive Stars:
Hydrogen
Helium
Oxygen and
carbon
Neon, sodium,
magnesium, sulfur
and silicon
Iron, nickel,
chromium,copper
and others
Materials heavier
than iron

7. Types of stars
The Sun is a as a
G2V type star, a
yellow dwarf and a
main sequence
star.

8. St
ar
T
yp
e
Colo
r
Approximat
e Surface
Temperatur
e
Average
Mass
(The Sun
= 1)
Average
Radius
(The Sun
= 1)
Average
Luminosity
(The Sun =
1)
Main Characteristics
Exam
ples
O
Blue
over 25,000
K
60
15
1,400,000
Singly ionized helium lines (H I)
either in emission or absorption.
Strong UV continuum.
10
Lacert
ra
B
Blue
11,000 -
25,000 K
18
7
20,000
Neutral helium lines (H II) in
absorption.
Rigel
Spica
A
Blue
7,500 -
11,000 K
3.2
2.5
80
Hydrogen (H) lines strongest for
A0 stars, decreasing for other A's.
Sirius,
Vega
F
Blue
to
Whit
e
6,000 - 7,500
K
1.7
1.3
6
Ca II absorption. Metallic lines
become noticeable.
Canop
us,
Procy
on
G
Whit
e to
Yell
ow
5,000 - 6,000
K
1.1
1.1
1.2
Absorption lines of neutral
metallic atoms and ions (e.g. onceionized calcium).
Sun,
Capell
a
K
Oran
ge to
Red
3,500 - 5,000
K
0.4
Metallic lines, some blue
continuum.
Arctur
us,
Aldeb
aran
Some molecular bands of titanium
oxide.
Betelg
euse,
Antar
es
M
Red
under 3,500
K
0.8
0.3
0.9
0.4
0.04
(very faint)

9. Dwarf stars

11. Big or Massive stars

13. •Binary Stars
•Variable Stars Stars that Vary in
Luminosity
•Giant and
Supergiant Stars Old, Large Stars
•LUMINOSITY

14. Dead stars

18. Why the stars twinkle??Which are
the brightest?’

19. It shows that the
temerature
coincides with the
luminosity, the
hotter the star the
higher the
luminosity the
star has. You can
also tell the size
of each star from
the graph as the
higher the radius
the higher the
temperature and
luminosity.

20. Sirius is the brightest star in the sky, and
a familiar sight to astronomers. But did
you know that Sirius is actually a double
star? If you look carefully, you’ll see the
dim companion star almost lost in the
glow of the much larger, brighter Sirius A.
Is a photo of one of the most
famous collections of stars, the
Pleiades star cluster. The stars
in this cluster are fairly young,
less than 100 million years old.
With the unaided eye, you can
see 14 of the stars in the
cluster, but it’s estimated that
there are a total of 800 solar
masses in the entire cluster.
Anglo-Australian
Observatory/Royal Observatory

21. SOME BRIGHT THAT CAN BE
SEEN FROM THE EARTH

22. Rank
Star
Absolute
Magnitude
Apparent
Magnitude
Distance from
Earth
(light-years)
.
The Sun
+4.8
-26.72
.
1
Sirius (in Canis
Major)
+1.4
-1.46
8.6
2
Canopus (in
Carina)
-2.5
-0.72
74
5
Vega (in Lyra)
+0.6
0.03
25
6
Capella (in
Auriga)
+0.4
+0.08
41
7
Rigel (in
Orion)
-8.1
+0.12
900
8
Procyon (in
Canis Minor)
2.8
+0.38
11
10
Betelgeuse (in
Orion)
-7.2
+0.50
1,500

23. This photograph of
a “star” was
captured by NASA’s
SOHO spacecraft in
the infrared
spectrum. This is
the highest energy
light that’s pouring
off the Sun,
normally invisible to
our eyes.
Ultraviolet view of the Sun.

26. Constellations

28. Nebulae

29. Galaxies