bellwork You have 9 minutes to do both Please read and answer the 3 following questions What is luminosity Where does our Sun rank among stars How are color and brightness ID: 536191
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Slide1
You have an article to read after your bellwork. You have 9 minutes to do both.
Please
read
and
answer
the 3 following questions:
What is luminosity?
Where does our Sun rank among stars?
How are
color
and
brightness
related?
(think about it)Slide2
Learning Goals: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?
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
.Slide3
No more late work from last week. It’s been more than 5 daysYou have already taken the testSorry, but welcome to growing up.Slide4
What main characteristic of stars are the “spectral classes” (O, B, A, F, G, K, M) based on?Slide5
Star sizes and colors
Are stars all the same size and color? Slide6
What is different about how these stars are drawn?What do you think that stands for?Slide7
Stellar Magnitude: Questions of the dayHow 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.Slide8
You’ve seen this before…Slide9
What happens to light as you recede from a star?Slide10
The Magnitude System - historicalSystem 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)Slide11
The Magnitude System -currentWith 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. Slide12
The Magnitude System -currentIn 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
a
sixth magnitude object and 10,000 times dimmer than a first
The scale is logarithmic, not linear
Vega is point zero.Slide13
Which star is going to seem brighter? A red star with a magnitude of 1 or a blue star with a magnitude of 4?Slide14
Which star is hotter? A red star with a magnitude of 1 or a blue star with a magnitude of 4?Slide15
Which star is bigger? A red star with a magnitude of 1 or a blue star with a magnitude of 4?Slide16
Apparent vs. AbsoluteApparent 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. Slide17
Absolute magnitude is the measure of a celestial object's actual brightness.
Apparent vs.
AbsoluteSlide18Slide19Slide20
How do we measure this?
LOWER numbers are BRIGHTER than higher numbers!!!Slide21
*Hubble’s Sight: 30 (J.W.S.T.: 34) *Human Sight:6 *ISS: -5.9 *
Sirius: −1.46
*Venus: -4.89
*
Full Moon: -12.62
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
-7.2Slide22
Visible to
typical
human eye
Apparent
magnitude
Brightness
relative
to Vega
Number of stars
brighter than
apparent magnitude
Yes
−1
250%
1
0
100%
4
1
40%
15
2
16%
48
3
6.3%
171
4
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 000Slide23
Answer the questions of the dayHow do we measure a star’s brightness? What characteristics about a star must we know to do this?Slide24
Listen for and write down 2 things that he mentions that you did not know at the beginning of this class and 1 thing you did.https://www.youtube.com/watch?v=9P8Veb_AlJ0Slide25
Last Thing Google ClassroomDue Tomorrow!