Download Galaxies part 1

THIS PRESENTAION HAS BEEN RATED
TG-13
TEACHERS’ GUIDANCE STRONGLY ADVISED
Some Material May Be Unintelligible For Students Under 13.
Intense Frames of Scientific Instruction, Analysis, Comparing
and Contrasting, Description, and for Some Vocabulary.
BY THE
CLASSIFICATION AND RATING ADMINISTRATION
© 1852 All Rights Reserved
VOID WHERE PROHIBITED BY LAW
PBIS ANTI-VACUITY
The authorized reproduction or distribution of
this copyrighted work is highly encouraged.
Lethargic obtuseness is insubordinate and is
discouraged by PBIS, as it may result in little
or no monetary gain after secondary
education or a fine of $250,000.
© 1852 All Rights Reserved
VOID WHERE PROHIBITED BY LAW
ASTRONOMY
The Milky Way
Galaxy
OBJECTIVES
By the end of this presentation, students will
be able to
• describe the structure of the Milky Way;
• describe the contents of the Milky Way:
• multiple star systems.
• clusters.
• nebulae.
Milky Way
Roughly 120,000 ly in diameter;
20,000 ly thick at its core.
The sun is located at a distance of
about ⅔ the radius from the
galactic core on the edge of the
“Orion Spiral Arm.”
Sagittarius
Arm
Our Milky Way
Galaxy
Core
Milky Way galactic center
Milky Way in Ophiuchus
Milky Way
Contains an estimated
400,000,000,000 stars.
140 stars per cu. ly. at the core.
0.0026 stars per cu. ly. near the sun.
Stars make up an estimated 15% of
the galactic mass.
85% of the mass is “unseen material”
called dark matter.
Milky Way
Contains an estimated
400,000,000,000 stars.
Roughly 70% are red dwarfs;
9% are white dwarfs;
7.5% are yellow main sequence
stars, like our sun.
0.5% are red giants.
0.4% are red supergiants.
Milky Way
Contains an estimated
400,000,000,000 stars.
Roughly 30% are multiple stars
• Orbits are highly elliptical, non-coplanar,
non-concentric, and rather hierarchical.
• Binary star systems, trinary, and
quadruple star systems.
Many other stars are bound in clusters.
Multiple Star Systems
The distance between stars has its limits.
Roche Limit – the minimum distance
between stars before the tidal forces
tear the stars apart.
Rc = a 3mo
mp
⅓
( )
Multiple Star Systems
Binary Stars – two stars orbiting each
other.
No planets can exist
within the Roche limit.
Multiple Star Systems
Trinary Stars – three stars; two
orbiting each other; orbiting a third.
Multiple Star Systems
Quadruple Stars – two stars
orbiting each
other;
orbiting two
other stars
orbiting each other.
Clusters – stars grouped together
and bound by gravitational forces
Open clusters – moderately close knit,
irregularly shaped grouping of stars.
• Containing 100 to 1000 stars.
• Subclass of open clusters include
Associations and Galactic Clusters.
PLieades
Clusters – stars grouped together
and bound by gravitational forces
Globular clusters – massive, tightly
packed, symmetrical grouping of
stars.
• Containing 20,000 + stars.
• May span 16 to 82 ly.
Clusters – stars grouped together an
bound by gravitational forces
Globular clusters – massive, tightly
packed, Cluster
symmetrical
grouping
of
Beehive
Cluster
Hercules
in Cancer
stars.
• Containing 20,000 + stars.
• May span 16 – 82 ly.
In Sagittarius
In Ophiuchus
Nebulae
Dark Nebula – cloud rich in dust that
happen to be silhouetted against
bright background clouds or stars.
Diffuse Nebula – gas cloud that looks
brighter than the background due to
emitted or scattered light.
Nebulae
Emission Nebula – subclass of diffuse
nebulae, near enough to a star,
whose heat causes the gas to
fluoresce, producing spectral
emissions of various colors.
• Relatively bright and red due to
the amounts of H and He present.
• A blue color indicates the
presence of N and/or O.
Nebulae
Planetary Nebula – subclass of
emission nebulae consisting of a
hollow shell, bubble, or ring of gas
surrounding a hot dwarf star.
• So named for their spherical shape.
Supernova Remnant – subclass of
emission nebulae usually curved,
wispy segments and much larger
than planetary nebulae.
Helix Nebula
Ring Nebula
Dumbbell Nebula
Crab Nebula
Carinae Nebula
Carinae Nebula
ANT Nebula
Eta Carinae
Trifid Nebula
Trifid Nebula close up
The Horsehead Nebula in
Orion
Emission Nebula in
Ophiuchus
Bubble Nebula
Rosette Nebula
Eagle Nebula
Eagle Nebula
Close up
Veil Nebula
N. American Nebula
Eskimo Nebula
Homunculus nebula
Supernova
eruption in 1843
ASTRONOMY
The Milky Way
Galaxy