![Page 1: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/1.jpg)
Classification of Stars – HR diagram
Objectives:• understand the differences between near and bright visible stars
• learn how to use the HR-diagram to classify stars (temperature vs. brightness)
• use the HR-diagram to observe the evolution of stars (when a star is born and dies)
Lab Books:pages 52-54worksheet, page 115
Lab Books:pages 52-54worksheet, page 115
![Page 2: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/2.jpg)
HR-diagram – classifies stars using temperature magnitude (brightness)HR-diagram – Hertzbrung-Russell diagram
![Page 3: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/3.jpg)
Star color and Temperature
Lets review the visible color spectrum.“What do our eyes see”?
wavelength
R O Y G B I V
Low Energy High Energy
![Page 4: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/4.jpg)
Star Color and TemperatureStar Color and Temperature
R O Y G B I V R O Y G B I V
30,000 K2,500 6,000
Long wave lengths Short wavelengths
Cool stars Hot stars
REDYellow Blue
![Page 5: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/5.jpg)
Measuring the Brightness of a Star“Stellar Brightness”
Magnitude – the brightness of a star
Apparent Magnitude• a stars brightness as it appears from earth
• factors controlling apparent magnitude:
• how big the star• how hot the star• how far away star
Which is brighter? -5 star or 5 star ?
Magnitude is measured using (-) and (+) numbers
the more (-) the number, the brighter the more (+), the dimmer the star
![Page 6: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/6.jpg)
SUNFull
Moon Venus SiriusNorthStar
Nakedeye
Pluto HSTOBJECT
ApparentMagnitude -26.5 -12.5 - 4.1 -1.4 2.0 6.0 15 28
Apparent Magnitude of various objects
bright dimdim
![Page 7: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/7.jpg)
Absolute Magnitude• measures the “actual” brightness• two stars with the same absolute magnitude would not be the same apparent magnitude
WHY?• To compare absolute brightness
• use a standard distance of 32.6 light-years away from earth
Example:
-26.7 +5
32.6 ly
Apparent Magnitude Absolute magnitude
Earth
bright dim
![Page 8: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/8.jpg)
Distance, Apparent Magnitude, and AbsoluteMagnitude of Some Stars
Name DistanceLight-years
ApparentMagnitude
AbsoluteMagnitude
Sun NA -26.7 5.0
Alpha Centauri 4.27 0.0 4.4
Sirius 8.70 -1.4 1.5
Arcturus 36 -0.1
-5.5
-0.3
Betelgeuse 520 .08
Deneb 1600 1.3 -6.9
32.6 lyView from Earth
So, which star is biggest to smallest?
![Page 9: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/9.jpg)
Brightness scale – Using Absolute Magnitude
The brighter, the bigger the starThe brighter, the bigger the star
0 1 3 5 7 9
Bright Dim
-1-3-5-7
SunSun
Centa
uri
Centa
uri
Sirius
Sirius
Arctu
rs
Arctu
rs
Betel
geuse
Betel
geuse
Deneb
Deneb
![Page 10: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/10.jpg)
Surface Temperature (K)30005000700010,00014,00020,000
How are stars classified? – the Hertzsprung-RussellDiagram (HR-diagram)
-10
-5
0
+5
+10
+20
Ab
solu
te M
ag
nit
ud
e
Very Bright
Very Dim
O B A F G K M
![Page 11: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/11.jpg)
Oh, Be A Fine Guy (or Gal), Kiss MeOh, Be A Fine Guy (or Gal), Kiss Me
O0O1…..O9 B0…..B9 A0…..A9 F……………HottestHottest CoolestCoolest
Spectral class: based on their spectrum (color they emit resulting from the chemical make-up)Spectral class: based on their spectrum (color they emit resulting from the chemical make-up)
O B A F G K MO B A F G K M
![Page 12: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/12.jpg)
HR-Diagram
Surface Temperature (K)30005000700010,00014,00020,000
Cool, brightCool, bright
Hot, dimHot, dim
The Brighter, The Hotter
The cooler, the dimm
er
![Page 13: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/13.jpg)
OO BB AA FF GG KK MM
![Page 14: Classification of Stars – HR diagram Objectives: understand the differences between near and bright visible stars learn how to use the HR-diagram to classify](https://reader035.vdocuments.mx/reader035/viewer/2022062423/5697bf711a28abf838c7e06d/html5/thumbnails/14.jpg)
Surface Temperature (K)30005000700010,00014,00020,000
Dust andgassesProtostar
Main SequenceStar
Red GiantStage
VariableStar stage
PlanetaryNebulaStage
White DwarfBlack
Hole Stage
Stellar evolution HR-Diagram