measuring the stars (part i). 3-d positions in space of the stars closest to our sun:
TRANSCRIPT
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Measuring the Stars(Part I)
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3-D Positions in Space of the Stars Closest to our Sun:
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Nearby Star Systems in Culture & Science Fiction:
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3-D Positions in Space of the Stars Closest to our Sun:
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3-D Positions in Space of the Stars Closest to our Sun:
X
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To Measure “Radial Motion” of Stars (towards/away from us)…
…but how to determine a Star’s “Tangential” (sideways/perpendicular) Motion??
Use Doppler Shifts!
The “Fix’d Stars”……do theymove?
Of Course
They do!
(butFAR Away,their Sky Positions appear to
changeslowly!)
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Barnard’s (“Runaway”) Star – The Largest “Proper Motion” in our sky! (~10’’/yr)
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Anything else “Unusual” about Alpha Centauri…? It’s a Triple (Multiple) Star!
…only ~1/3 of “Sun-like” stars are Single Stars!
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Some apparent “multiple” stars are just “Optical Doubles” (Astronomical illusions…)
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Others really are Multiple Star Systems (“Binary Stars”, “Triples”, “Quadruples”…)
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Some Multiple Star Systems can even Host Exoplanets!
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Some Multiple Stars can be Visually Separated…
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…and some Multiples cannot be visually separated…(“Spectroscopic Binaries”)
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Stellar Size: How Big is the Sun? (…as Stars go…)
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Link to Video, “Star Size Comparison”,
http://www.youtube.com/watch?v=HEheh1BH34Q
(Featuring music from “Alien”, “The Black Hole”, and “Bladerunner”)
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What does a picture of a Star look like, so far away? (Just a “point of light”?)
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How to find the size of a star that’s so far that it looks Point-like?
(AProportionality for Luminosity:
T = Star’s Surface Temperature,R = Radius of Star,L = Star’s Luminosity.
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What affects a star’s Apparent Brightness, besides Radius & Temp?
(
Proportionality for Apparent Brightness (“Flux”):
T = Star’s Surface Temperature,R = Radius of Star,L = Star’s Luminosity,D = Distance to the Star.
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The “Apparent Magnitude” Scale (as seen from Earth)
Mag. Scale “Oddities”:
• Brighter = Smaller Mag.
• Brightest = Negative Mag!
• Precision Fractional Mag.
• Scale “Logarithmic”
• App. Mag. Observer Position! (Distance)
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The “Absolute Magnitude” Scale (vs. True Brightness (“Luminosity”) = App. Mag. as seen from 10 parsecs away)
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How to tell a Star’s Temperature from its Spectrum (w/Planck Curves)
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A Star’s Spectral Lines actually depend upon Temperature, too! (indirectly…)
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(Bigger stars always hotter…?)
(Both K-type!)
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