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Lecture 3

ASTA02H3 Lecture Notes - Lecture 3: Celestial Sphere, Ursa Major, Apparent Magnitude

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Parandis Khavari

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Chapter 2.1 to 2.4
September 11, 2017
7:47 PM
The stars
Asterism- a named grouping of stars that is not one of the recognized constellations
Celestial sphere
Constellation - a group of stars that form a pattern
The brightest stars starts there name with alpha and second beta so on
Some stars are named in Arabic, Greek and Latin
Most of the name of the stars are coming from Greek mythology ( Clash of Titan)
Modern Constellation
88 constellation to refer to different patches of the sky
Cygnus- x1 is a long suspected black hole
Ursa major is not seen but its part of big dipper
The stars that form a constellation do not have any relation with each other
They are all seen in the from called celestial sphere
Star's magnitude
The brightest stars are magnitude 1 and fainter 6 (as proceed by our eye)
Magnitude 1 is 100 times brighter than magnitude 6
When something is brighter it means it is creating more photons per sec
Apparent magnitude
Distance and size
Apparent brightness of a star depends on the flux that we receive
FLUX is defined as the energy ( measured in joules per second per 1 square meter
Flux is how brighter it appears
New system of magnitude
If something is negative that means its probably really bright
Sirius is close to us
Brightest star n the night sky is SIRIUS (-1.46)
How is flux related to magnitude
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