Indistinct Mumblings of an Unsound Mind

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In-class workbook. Pages 31-33


Luminosity = total energy given off per second (Area=4(Pi)R^2) <– Spread of Light is Spherical from it’s point of origin.
Inverse square law is that apparent brightness is = Luminosity/distance^2

Star A is 10(sun↓L); D = 8 lightyears (ly)
Star B is 1x(sun↓L); D = 1ly

Star A is brighter beasue 1/1 > 5/32

Magnitudes are a conceptual nomenclature for perceived brightness of a star as visible to the human eye.

Absolute magnitude (M) is the brightness of a star as it would be seen were it 10 parsecs from earth. (Rephrase: M is the brightness of a star if it were placed 10 parsecs from earth)

Magnitudes go up 100 units for every 5 stops. Example: A star with a m/M of 5 is 100x more bright that a star with a m/M of 10. 10-5=5, then 5 is equal to 10o

Star Trillian m=-2 M=+2
Star Zaphod m=0 M=+6

Which appears brighter? Star Trillian
Which has greater luminosity? Insufficient Data, no distance given. Wrong. M conveys distances relative to itself.
Magnitude is give (M) and is comparable to (m). +2 is > than +6, therefore Star Trillian is the star with the Greatest Luminosity.
Powerpoints are on Canvas.

45:30 – Parallax Shift. Could not see the shift because of limitations of the human eye.

Freidrich Bessel: 1838

Degrees <– 60 Arcminutes
Arcminute <– 60 Archeconds
(Personal: Why do we split things into 60 and/or 360?)
An object that shows a parallax of 1 arcsecond lies at a distance of 1 parsec (pc).

50:59 – Distance in Parsecs is calculated as  (pc) = 1/parallax in arcseconds
1 pc is equal to 3.26 ly or 206,265 au.  1pc = 3.26ly = 206,265au

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