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ThursdaySeptember 20,
2012(The Hertzsprung - Russell Diagram;
Nebulae )
The Launch PadThursday, 9/20/12
Name two factors that can increase the
luminosity of stars.sizesurface
temperature
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Assignment Currently Open
Summative or
Formative?Date Issued Date Due Date Into
GradeSpeed Final Day
Quiz 2 S2 9/7 9/7 9/7 9/21Lab – Timeline of the Universe
F4 9/11 9/13
WS – Star Stages
F5 9/12 9/13
Quiz 3 S3 9/14 9/14 9/14 9/28Lab – Distance and Spacing of
the PlanetsF6 9/17 9/18
Lab – Comparing the Terrestrial and Jovian Planets
F7 9/18 9/19
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Recent Events in ScienceUltra-Distant Galaxy Discovered Amidst Cosmic
'Dark Ages': May Be Oldest Galaxy Ever
In the big image at left, the many galaxies of a massive
cluster called MACS J1149+2223 dominate the
scene. Gravitational lensing by the giant cluster
brightened the light from the newfound galaxy, known as
MACS 1149-JD, some 15 times. At upper right, a
partial zoom-in shows MACS 1149-JD in more detail, and a deeper zoom appears to the
lower right. (Credit: NASA/ESA/STScI/JHU)
http://www.sciencedaily.com/releases/2012/09/120919135419.htm
Read all about it!
90% of all stars are in the main-sequence stage. They are varied in their size, color, luminosity,
and surface temperature.
The Hertzsprung - Russell Diagram
Red Giants and Supergiants are very large and very luminous, but
have relatively cool surface temperatures.
White Dwarfs are relatively dim, mid-
temperature stars that are the remains of low-
and mid-mass stars.
Interstellar Matter Between stars is the “vacuum of space”, which
actually contains varying amounts of “interstellar matter.”
A nebula (plural: nebulae) is a large cloud of dust and gases.
There are two major types of nebulae:
bright nebulaedark nebulae
Bright NebulaeBright nebulae glow if they are
close to a very bright star, or stars.
There are two types of bright nebulae:
•emission nebulae •reflection nebulae
Emission NebulaeEmission nebulae
are clouds of gases and dust
that absorb ionizing ultraviolet
radiation from nearby hot stars or star remnants and reemit it as visible
light.Crab Nebula
Emission Nebulae
The Rosette Nebula is an emission nebula.
The Orion Nebula is probably the most well-known emission nebula.
Reflection NebulaeReflection nebulae are clouds of interstellar
dust and gas which reflect the light of a nearby star or stars. The energy from the
nearby star or stars is insufficient to ionize the gas
of the nebula to create an emission nebula, but is enough to give sufficient
scattering to make the dust visible.
Reflection NebulaeThe Witch Head reflection
nebula, about 900 light years from Earth, is associated with
the bright star Rigel in the constellation Orion. The nebula
glows primarily by light reflected from Rigel, located just outside
the top right corner of the image. Fine dust in the nebula reflects
the light. The blue color is caused not only by Rigel's blue
color but because the dust grains reflect blue light more
efficiently than red.
Reflection NebulaeReflection Nebula
Messier 78
Dark NebulaeA dark nebula is a type of interstellar cloud that is so dense it obscures the light from the background emission or reflection
nebula (e.g., the Horsehead Nebula) or that it blocks out background stars (e.g., the Snake Nebula). The extinction of the light is caused by interstellar dust grains located in the coldest, densest parts of larger molecular clouds. Dark nebulae are not close to any bright
star, therefore they appear dark. Dark nebulae contain the material that forms stars and planets.
Dark NebulaeVan den Bergh 142
Elephant Trunk Nebula
Dark Nebulae
Eagle Nebula
Video SegmentHow the Universe
Works: Extreme Stars
A Star’s Energy
