ASTR 1020 Stellar and Galactic Astronomy

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ASTR 1020Stellar and Galactic Astronomy

• Dr. Brooke Skelton

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Messier Objects

• These are objects that Charles Messier saw as
  fuzzy through his telescope in the 1700s
• FIRST, describe your object
• NEXT, sort yourselves into groups
• FINALLY, answer the questions on your worksheet

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Our FIVE groups

• Group 1

• Group 2

• Group 3

• Group 4

• Group 5

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Open Clusters

• Stars all the same age - tens to hundreds of
  millions of years old (relatively young!)
• Stars that formed together from large cloud of
  gas
• Stars loosely held together by gravity

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Globular Clusters

• Stars all the same age - tens of billions of
  years old (OLD!)
• Stars are among the oldest objects in the
  universe
• Stars tightly held together by gravity

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Nebulae

• Hot, glowing gas and dust
• Variety of types
• HII regions sites of recent star formation
• Planetary nebulae atmospheres of sun-like stars
  that are dying
• Supernova remnants from the explosive death of
  stars larger than the Sun

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Elliptical Galaxies

• Composed of mostly old stars
• Very little gas or dust
• Are ellipsoidal in all dimensions can be
  elongated or spherical

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Spiral Galaxies

• Composed of stars, clusters of stars, nebulae of
  a variety of ages
• Regular spiral pattern
• Can be barred or round in the center

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Guiding Questions

• What steps does an astronomer go through in order
  to determine the nature of a newly discovered
  object?
• What are some of the categories of objects we
  will be studying this semester?
• Which is larger, a cluster or a galaxy? Explain
  how you know. What are the building blocks of
  both clusters and galaxies?
• What are nebulae made of? Roughly describe three
  types of nebulae.
• Are all galaxies similar to one another? Explain
  your answer.