ASTR 1102-002 2008 Fall Semester

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# ASTR 1102-002 2008 Fall Semester - PowerPoint PPT Presentation

ASTR 1102-002 2008 Fall Semester. Joel E. Tohline, Alumni Professor Office: 247 Nicholson Hall [Slides from Lecture02]. Course Syllabus ( corrected Final Exam time!). Evaluation of Coursework. Corrected final exam time!. Chapter 17: The Nature of Stars. Describe Population (of stars).

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### ASTR 1102-0022008 Fall Semester

Joel E. Tohline, Alumni Professor

Office: 247 Nicholson Hall

[Slides from Lecture02]

Evaluation of Coursework

Corrected final exam time!

Describe Population (of stars)

• Location
• Coordinate position
• Distance
• Motion
• Across the photo/sky
• Toward/away from us
• Intrinsic properties
• Mass
• Color
• Brightness
• Age

Describe Population (of fans)

• Location
• Coordinate position
• Distance
• Motion
• Across the photo/sky
• Toward/away from us
• Intrinsic properties
• Mass (weight)
• Color (clothes)
• Brightness (?)
• Age
Location – Determine exact location of every fan!
• Coordinate position (x-y coordinate on photo)
• Distance (distance from photographic lens)
Location – Determine exact location of every fan
• Coordinate position (x-y coordinate on photo) straightforward
• Distance (distance from photographic lens)
Location – Determine exact location of every fan
• Coordinate position (x-y coordinate on photo)
• Distance (distance from photographic lens) not so straightforward!

• Location – or … using GPS system …
• Coordinate position (latitude & longitude)
• Distance (altitude above sea level)
Location – Determine exact location of every star!
• Coordinate position (“declination” & “right ascension”)
• Distance (from Earth)

Straightforward: Analogous to “latitude” & “longitude”; e.g., Google Sky

Textbook ‘Box 2-1’

pp. 30-31

• Location – Determine exact location of every star!
• Coordinate position (“declination” & “right ascension”)
• Distance (from Earth)
Location – Determine exact location of every star!
• Coordinate position (“declination” & “right ascension”)
• Distance (from Earth) not so straightforward!
Determining Distances to Astronomical Objects
• Not at all straightforward!
• Only direct method is “Stellar Parallax”
• See textbook discussion associated with Figs. 17-1 and 17-2
• Other indirect methods will be discussed later
Individual Stars…
• Location in Space
• Coordinate (angular) position on the sky
• Distance from Earth
• Motion through Space
• Motion across the sky (“proper” motion)
• Motion toward/away from us (radial velocity)
• Intrinsic properties
• Brightness (luminosity/magnitude)
• Color (surface temperature)
• Mass
• Age
Individual Stars…
• Location in Space
• Coordinate (angular) position on the sky
• Distance from Earth
• Motion through Space
• Motion across the sky (“proper” motion)
• Motion toward/away from us (radial velocity)
• Intrinsic properties
• Brightness (luminosity/magnitude)
• Color (surface temperature)
• Mass
• Age

Motion

• Across the photo/sky
• Toward/away from us
• Location
• Coordinate position
• Distance

Motion

• Across the photo/sky
• Toward/away from us
• Location
• Coordinate position
• Distance

Motion

• Across the photo/sky
• Toward/away from us
• Location
• Coordinate position
• Distance
Motion Across the Sky(“proper” motion)

http://www.psi.edu/~esquerdo/jim/astfov.gif

Motion

• Across the photo/sky
• Toward/away from us
• Location
• Coordinate position
• Distance
Determining Motion of Astronomical Objects toward/away
• Surprisingly straightforward!
• Doppler effect
• See textbook discussion in Chapter 5, §5-9
Doppler Effect (§5-9)
• The measured frequency (wavelength) of light changes if the light source is moving toward or away from you
• Light is “blue-shifted” if the object is moving toward you
• Light is “red-shifted” if the object is moving away from you
• Direct analogy with the behavior of sound waves
Individual Stars…
• Location in Space
• Coordinate (angular) position on the sky
• Distance from Earth
• Motion through Space
• Motion across the sky (“proper” motion)
• Motion toward/away from us (radial velocity)
• Intrinsic properties
• Brightness (luminosity/magnitude)
• Color (surface temperature)
• Mass
• Age
Individual Stars…
• Location in Space
• Coordinate (angular) position on the sky
• Distance from Earth
• Motion through Space
• Motion across the sky (“proper” motion)
• Motion toward/away from us (radial velocity)
• Intrinsic properties
• Brightness (luminosity/magnitude)
• Color (surface temperature)
• Mass
• Age