I’m coming around to check your apple pie story and diagram!
Learning Goals: 4. Complex Knowledge: demonstrations of learning that go aboveand above and beyond what was explicitly taught. 3. Knowledge: meeting the learning goals and expectations. 2. Foundational knowledge: simpler procedures, isolated details, vocabulary. 1. Limited knowledge: know very little details but working toward a higher level. How do stars differ from moons and planets, and from one another? How does the classification of stars help us understand how they evolve over their lifetimes? What are the different types of stars? What happens when different types of stars die? Why is it important for us to understand stars?
Bell Work 2-25-16 What main characteristic of stars are the “spectral classes” (O, B, A, F, G, K, M) based on?
Star sizes and colors Are stars all the same size and color?
What is different about how these stars are drawn? What do you think that stands for?
Stellar Magnitude Inverse square law: How do we measure a star’s brightness? What characteristics about a star must we know to do this? Inverse square law: The amount of light an object receives from a source decreases by the square of the distance between the object and the source.
What happens to light as you recede from a star?
The Magnitude System - historical System was originally devised by Hipparchus (Greek Astronomer, 150 BC) Brightest=1 Next brightest=2 Dimmest =6 (you can’t see anything dimmer than 6 with your naked eye)
The Magnitude System -current With the invention of the telescope and other observational aids the number of new objects soared and a modification was needed to the system in order to accurately categorize so many new objects.
The Magnitude System -current In 1856 Norman Robert Pogson formalized the magnitude scale by defining: a sixth magnitude object is an object that is 100 times dimmer than a first magnitude object An eleventh magnitude object is 100 times dimmer than an sixth magnitude object and 10,000 times dimmer than a first The scale is logarithmic, not linear Vega is point zero.
Which star is going to seem brighter? A red star with a magnitude of 1 or a blue star with a magnitude of 4?
Which star is hotter? A red star with a magnitude of 1 or a blue star with a magnitude of 4?
Which star is bigger? A red star with a magnitude of 1 or a blu star with a magnitude of 4?
Apparent vs. Absolute Apparent magnitude is dependent on 2 factors: The luminosity of the star (total energy per second radiated) The distance of the star from Earth It is the brightness of an object as perceived from earth.
Apparent vs. Absolute Absolute magnitude is the measure of a celestial object's actual brightness.
How do we measure this? LOWER numbers are BRIGHTER than higher numbers!!!
*Hubble’s Sight: 30 *Human Sight:6 star Distance (ly) Apparent magnitude Absolute magnitude Sun .00001581 -26.72 4.8 Sirius 8.6 -1.46 1.4 Aldebaran 60 .85 -.3 Vega 25 .03 .6 Procyon 11.4 .38 2.6 Rigel 1400 .12 -8.1 Betelgeuse 1500 .5 -7.2 *Hubble’s Sight: 30 *Human Sight:6 *ISS: -5.9 *Sirius: −1.46 *Venus: -4.89 *Full Moon: -12.62
Visible to typical human eye Apparent magnitude Brightness relative to Vega Number of stars brighter than apparent magnitude Yes −1 250% 1 100% 4 40% 15 2 16% 48 3 6.3% 171 2.5% 513 5 1.0% 1 602 6 0.40% 4 800 No 7 0.16% 14 000 8 0.063% 42 000 9 0.025% 121 000 10 0.010% 340 000
Read the FYI Record your answers in your science journal to the two questions Remember: Test questions will come from these.
Listen for and write down 2 things that he mentions that you did not know at the beginning of this class. https://www.youtube.com/watch?v=9P8Veb_AlJ0
Stellar Magnitude How do we measure a star’s brightness? What characteristics about a star must we know to do this?