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Charles HakesFort Lewis College 1
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Charles HakesFort Lewis College 2
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Charles HakesFort Lewis College 3
“Dead” Stars
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Charles HakesFort Lewis College 4
Outline
• Test 3 Wednesday• Dead (?) Stars• Review (?)
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Charles HakesFort Lewis College 5
Test 3
• Review Spectroscopy (Wein, Stefan) and Doppler Shift
• The Sun (structure, fusion)• Magnitude• Parallax• Interstellar Medium• Stellar Evolution• Dead Stars
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Charles HakesFort Lewis College 6
More Precisely 12-1The Cycle of Stellar Evolution
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Charles HakesFort Lewis College 7
Supernovae
• On-line images• Supernova in M 74 http://www.rochesterastronomy.org/sn2003/n628s2.jpg• Supernova in NGC 1448
http://members.optushome.com.au/edobosz/images/1448_sn.jpg • Supernova in NGC 3169
http://www.astrooptik.com/Bildergalerie/PolluxGallery/NGC3169.htm• Supernova in NGC 3190
http://www.astrooptik.com/Bildergalerie/PolluxGallery/NGC3190.htm • Supernova in NGC 5965 http://www.nordita.dk/~dahle/ngc5965_sub.gif• Supernova in NGC 918 http://antwrp.gsfc.nasa.gov/apod/ap091112.html
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Charles HakesFort Lewis College 8
Chapter 13
• What is left after a Supernova?
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Charles HakesFort Lewis College 9
Figure 12.21Supernova Remnants
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Charles HakesFort Lewis College 10
Figure 13.1Neutron Star - from a type II Supernova
• typically ~20 km diameter
• mass > Msun
• thimbleful would weigh 108 tons
• rotate very quickly• have very strong
magnetic fields.
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Charles HakesFort Lewis College 11
Figure 13.2Pulsar Radiation
• The first observed neutron star was a pulsar
• Neutron stars rotate VERY quickly.
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Charles HakesFort Lewis College 12
Figure 13.3Pulsar Model
lighthouse model - if the beam sweeps past the Earth, we see a pulse.
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Charles HakesFort Lewis College 13
At a distance of 1 A.U., which would have the greatest gravitational force?
A) A 1 solar mass main sequence star
B) A 1 solar mass white dwarf
C) A 1 solar mass neutron star
D) They all have the same force.
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Charles HakesFort Lewis College 14
At a distance of 1 A.U., which would have the greatest gravitational force?
A) A 1 solar mass main sequence star
B) A 1 solar mass white dwarf
C) A 1 solar mass neutron star
D) They all have the same force.
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Charles HakesFort Lewis College 15
At the surface of the object, which would have the greatest gravitational force?
A) A 1 solar mass main sequence star
B) A 1 solar mass white dwarf
C) A 1 solar mass neutron star
D) They all have the same force.
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Charles HakesFort Lewis College 16
At the surface of the object, which would have the greatest gravitational force?
A) A 1 solar mass main sequence star
B) A 1 solar mass white dwarf
C) A 1 solar mass neutron star
D) They all have the same force.
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Charles HakesFort Lewis College 17
• A neutron star cannot be more than 3 Msun.
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Charles HakesFort Lewis College 18
• A neutron star cannot be more than 3 Msun.• Surface gravity will become so great that
not even light can escape. (Escape velocity > c)
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Charles HakesFort Lewis College 19
• A neutron star cannot be more than 3 Msun.• Surface gravity will become so great that
not even light can escape. (Escape velocity > c)
• Stars that began with > 25 Msun will probably become black holes.
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Charles HakesFort Lewis College 20
Black Holes
• Can black holes be made of things other than neutron stars?• Any object of any mass has a radius that
if it is compressed below that radius, light cannot escape.
• This is called the Schwarzschild radius.
• rS = 3km x M(solar masses)
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Charles HakesFort Lewis College 21
Black Holes
• Example Schwarzschild radii :• Sun = 3km• 3MsolarCore = 9km• Jupiter = 3m
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Charles HakesFort Lewis College 22
Black Holes
• Exercise - calculate the size required to compress a 70 kg person to make a black hole.
• recall:
rS = 3km x M(solar masses)
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Charles HakesFort Lewis College 23
Black Holes
• Example Schwarzschild radii :• Sun = 3km• 3MsolarCore = 9km• Jupiter = 3m• Earth = ~1cm• Person = ~1x10-25 m• Mobservable universe = ~robservable universe
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Charles HakesFort Lewis College 24
If the Sun were suddenly replaced by a one solar mass black hole:
A) we would immediately escape into deep space, driven out by its radiation.
B) our clocks would all stop.
C) life here would be unchanged.
D) we would still orbit it in a period of one year.
E) all terrestrial planets would fall in immediately.
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Charles HakesFort Lewis College 25
If the Sun were suddenly replaced by a one solar mass black hole:
A) we would immediately escape into deep space, driven out by its radiation.
B) our clocks would all stop.
C) life here would be unchanged.
D) we would still orbit it in a period of one year.
E) all terrestrial planets would fall in immediately.
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Charles HakesFort Lewis College 26
Practice Problem
• You observe a binary star system where the two stars are exactly the same temperature. The diameter of one star is 1.2 times the diameter of the second star. How many times more energy is emitted by the brighter star?
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Charles HakesFort Lewis College 27
Practice Problem
• You observe a binary star system where the two stars are exactly the same temperature. The diameter of one star is 1.2 times the diameter of the second star. How many times more energy is emitted by the brighter star?
A. 1.095x B. 1.2x C. 1.44x D. 2x
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Charles HakesFort Lewis College 28
Practice Problem
• You observe a binary star system where the two stars are exactly the same size. One star is 5500 K. The other star is 6100 K. How many times more energy is emitted by the brighter star?
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Charles HakesFort Lewis College 29
Practice Problem
• You observe a binary star system where the two stars are exactly the same size. One star is 5500 K. The other star is 6100 K. How many times more energy is emitted by the brighter star?
A. 1.11x B. 1.23x C. 1.51x D. 600x
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Charles HakesFort Lewis College 30
Review Questions
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Charles HakesFort Lewis College 31
An ordinary star becomes a Red Giant when:
A) A white dwarf companion star goes nova
B) There is no Hydrogen remaining in the star
C) Nutrino oscillations drive the outer layers
D) The core becomes almost entirely Helium
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Charles HakesFort Lewis College 32
An ordinary star becomes a Red Giant when:
A) A white dwarf companion star goes nova
B) There is no Hydrogen remaining in the star
C) Nutrino oscillations drive the outer layers
D) The core becomes almost entirely Helium
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Charles HakesFort Lewis College 33
A main sequence star of 19 solar masses will eventually be a:
A) A brown dwarf
B) A white dwarf
C) A type I supernova
D) A type II supernova
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Charles HakesFort Lewis College 34
A main sequence star of 19 solar masses will eventually be a:
A) A brown dwarf
B) A white dwarf
C) A type I supernova
D) A type II supernova
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Charles HakesFort Lewis College 35
A supernova is observed with very little H in the spectrum. It is most likely a:
A) type I
B) type II
C) type III
D) not enough information
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Charles HakesFort Lewis College 36
A supernova is observed with very little H in the spectrum. It is most likely a:
A) type I
B) type II
C) type III
D) not enough information
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Charles HakesFort Lewis College 37
A source of light is approaching us at 3,000 km/s. All its waves are:
A) Red shifted by 1%
B) Blue shifted by 1%
C) Not affected, as c is constant in all reference frames.
D) Red shifted out of the visible into the infrared
E) Blue shifted out of the visible into the ultraviolet
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Charles HakesFort Lewis College 38
A source of light is approaching us at 3,000 km/s. All its waves are:
A) Red shifted by 1%
B) Blue shifted by 1%
C) Not affected, as c is constant in all reference frames.
D) Red shifted out of the visible into the infrared
E) Blue shifted out of the visible into the ultraviolet
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Charles HakesFort Lewis College 39
How could you determine the temperature of the photosphere of the Sun?
A) only direct spacecraft measurement
B) Newton’s Law
C) Stefan’s Law
D) Wein’s law
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Charles HakesFort Lewis College 40
How could you determine the temperature of the photosphere of the Sun?
A) only direct spacecraft measurement
B) Newton’s Law
C) Stefan’s Law
D) Wein’s law
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Charles HakesFort Lewis College 41
If a star has a parallax of 0.05”, then its distance must be
A) 5 light years.
B) 5 parsecs
C) 20 light years.
D) 20 parsecs.
E) 200 parsecs
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Charles HakesFort Lewis College 42
If a star has a parallax of 0.05”, then its distance must be
A) 5 light years.
B) 5 parsecs
C) 20 light years.
D) 20 parsecs.
E) 200 parsecs
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Charles HakesFort Lewis College 43
Assume your naked eye limiting magnitude is 4. With a 70mm diameter telescope (100x
area of your pupil) which object would be barely visible?
A) Seventh magnitude Titan, Saturn’s largest moon.
B) Eighth magnitude Uranus.
C) Ninth magnitude Barnard’s Star
D) Eleventh magnitude Tethys, another Saturn moon
E) Thirteenth magnitude Pluto
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Charles HakesFort Lewis College 44
Assume your naked eye limiting magnitude is 4. With a 70mm diameter telescope (100x
area of your pupil) which object would be barely visible?
A) Seventh magnitude Titan, Saturn’s largest moon.
B) Eighth magnitude Uranus.
C) Ninth magnitude Barnard’s Star
D) Eleventh magnitude Tethys, another Saturn moon
E) Thirteenth magnitude Pluto
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Charles HakesFort Lewis College 45
On the H-R diagram, red supergiants like Betelguese lie:
A) top right
B) top left
C) about the middle
D) lower left
E) on the coolest portion of the main sequence
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Charles HakesFort Lewis College 46
On the H-R diagram, red supergiants like Betelguese lie:
A) top right
B) top left
C) about the middle
D) lower left
E) on the coolest portion of the main sequence
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Charles HakesFort Lewis College 47
From inside out, which is the correct order?
A) core, convective zone, radiative zone
B) photosphere, radiative zone, corona
C) radiative zone, convective zone, chromosphere
D) core, chromosphere, photosphere
E) convective zone, radiative zone, granulation
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Charles HakesFort Lewis College 48
From inside out, which is the correct order?
A) core, convective zone, radiative zone
B) photosphere, radiative zone, corona
C) radiative zone, convective zone, chromosphere
D) core, chromosphere, photosphere
E) convective zone, radiative zone, granulation
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Charles HakesFort Lewis College 49
If Vega is apparent magnitude zero, and Deneb first magnitude, then
A) Vega is about 100x brighter than Deneb..
B) Deneb is one magnitude brighter than Vega.
C) Vega appears 2.5x brighter than Deneb.
D) Deneb must be a main sequence star, and Vega a giant.
E) Vega must be 2.5x more luminous than Deneb.
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Charles HakesFort Lewis College 50
If Vega is apparent magnitude zero, and Deneb first magnitude, then
A) Vega is about 100x brighter than Deneb..
B) Deneb is one magnitude brighter than Vega.
C) Vega appears 2.5x brighter than Deneb.
D) Deneb must be a main sequence star, and Vega a giant.
E) Vega must be 2.5x more luminous than Deneb.
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Charles HakesFort Lewis College 51
Three Minute Paper
• Write 1-3 sentences.• What was the most important thing
you learned today?• What questions do you still have
about today’s topics?