Unit 3

When were the first extrasolar planets found?

1992

It looks like the first extrasolar planet in the habitable zone of its host star was found in:

2001

Alpha Centauri A has a luminosity of 1.6 Suns and a spectral type closest to A. G0 B. B0 C. K0 D. D5 E. M0

A

In a high mass star, why does nuclear burning stop at iron? A. Nuclear reactions involving iron do not produce energy. B. Gravity is too intense and makes the core collapse before iron can burn. C. The density of the iron in the core is too high. D. The temperatures are too high for iron nuclei to collide. E. Iron does not have enough neutrons to react.

A

Looking at the Table in the Encyclopedia I see that a 60 solar mass star has a luminosity of ________ times the Sun's luminosity while a 0.1 solar mass star has a luminosity of only ________ times the Sun's luminosity. A. 800,000/0.003 B. 0.003/0.03 C.0.3/0.003 D. 60/0.1 E. 800,000/0.1

A

So it said there that most massive stars burn heavier and heavier elements in the core but that the heaviest thing produced is iron. Do you remember why it said that was? A. iron is the most stable nuclues B. iron is too cold to burn C. iron is too heavy to burn D. iron is too compact to burn E. iron has too many electrons

A

The nearest stars are: A. cooler and less luminous B. cooler and more luminous C. hotter and less luminous D. hotter and more luminous E. the same as the Sun

A

What spectral type is Achernar? A. B5 B. G0 C. M5 D. O5 E. A5

A

What spectral type is Canopus? A. F0 B. K0 C. M5 D. G0 E. A0

A

What spectral type is Lalande 21185? A. M5 B. K0 C. F5 D. G0 E. A0

A

What spectral type is Procyon? A. F5 B. K0 C. M5 D. G0 E. A0

A

What spectral type is Ross 248? A. M5 B. K0 C. F5 D. K5 E. A0

A

What spectral type is Wolf 359? A. M5 B. K0 C. F5 D. G0 E. A0

A

When it becomes a red giant the star A. decreases in temperature and increases in luminosity B. increases in temperature and increases in luminosity C. increases in temperature and decreases in luminosity D. decreases in temperature and decreases in luminosity

A

Which of the following statements is true? A. Nothing can travel faster than the speed of light B. There is a black hole at the center of our Solar System C. If the Sun were magically to turn into a black hole, Earth's orbit would immediately change D. Although visible light cannot escape from inside the event horizon of a black hole, high energy radiation, such as gamma rays, can escape E. Black holes defy the laws of gravity

A

Which star is the furthest away if all have the same apparent brightness? A. Type O main sequence star B. Type B main sequence star C. Type F main sequence star D. Type G main sequence star E. Type M main sequence star

A

Why are things torn apart when they near a black hole? A. The part of the object closer to the black hole feels a greater force B. Space itself is stretched around a black hole C. Black holes are after all cosmic vacuum cleaners D. The spin of a black hole causes objects to twirl around and stretch E. All the atoms in the object start acting as magnets and repel each other

A

In the Sun, the proton-proton chain makes 4He, the dominant form of Helium. 4He has A. two protons because it is helium and two neutrons to make 4 total particles in the nucleus B. two protons because it is helium and one neutron to make 1 total particle in the nucleus C. one proton because it is helium and three neutrons to make 4 total particles in the nucleus D. three protons because it is helium and one neutron to make 4 total particles in the nucleus E. four protons and no neutrons

A - Helium is the second simplest nucleus and its dominant form has 2 protons and 2 neutrons

What is the sun? A. It is a star just like the stars we see in the nighttime sky. B. It is a special star, much more powerful than any other. C. It is the largest planet in our Solar System.

A - it just happens to be the nearest star to us - the star that provides light to our own Solar System

What did you two get for the G0 star?

A planet that is 17 Earth radii, with a 5 day orbital period, and a temperature of 1584k - definitely not in the habitable zone

What did you two get for the K5 star?

A planet that is about an Earth mass, at a distance of 05AU and a temperature of 235K - in the habitable zone

What did you two get for the M5 star?

A planet that is about the same radius as Earth, and at 0.27AU - 136K temperature so too cold to be habitable

Absorption lines are: A. produced when electrons jump from higher to lower energy levels and emit photons of specific frequencies B. produced when photons of specific wavelengths are absorbed in a star's outer layers by the electrons of specific chemical elements C. produced when a blackbody emits light of specific wavelengths due to the presence of different chemical elements in its gas D. dusty regions in the Sun's outer layers that absorb the photons that come from within

B

Canopus is A. just like the Sun. I wonder why it looks so bright from Earth at this large distance. B. more luminous than all the other stars so far. That must be why it looks so bright even at this large distance. C. less luminous than all the other stars so far. That must be why it looks so bright even at this large distance.

B

Does the parallax angle vary directly with distance, or is it an inverse relation? A. The size of the parallax angle is directly proportional to the distance to the star. B. The size of the parallax angle is inversely proportional to the distance to the star.

B

How far out would you need to moved the bottom detector next to a 100 W bulb, to read the same as the top one at R=1 by the 25 W bulb? A. out to four times the distance (R=4) B. out to twice the distance (R=2) C. out to three times the distance (R=3) D. out to five times the distance (R=5)

B

If the radius of star A is twice the radius of star B, but both have similar temperatures, how do their luminosities compare? A. Star A is 2 times as luminous as star B. B. Star A is 4 times as luminous as star B. C. All stars have the same luminosities. D. Star A is 4 times less luminous than star B. E. Star A is 2 times less luminous than star B.

B

So "luminosity" refers to _________, whereas "brightness" must mean ___________. A. apparent output as observed at some distance / absolute power output at the source B. absolute power output at the source / apparent output as observed at some distance

B

So the sequence of events for the Sun-like star is A. planetary nebula, protostar, Sun-like star on main sequence, blue giant, red giant B. stellar nursery, protostar, Sun-like star on main sequence, red giant, planetary nebula, white dwarf C. stellar nursery, blue giant, Sun-like star on main sequence, red giant, Type II supernova, neutron star D. stellar nursery, protostar, Sun-like star on main sequence, Type II supernova, black hole E. black hole, neutron star, white dwarf, Sun-like star on main sequence, red giant, Type II supernova

B

The very highest mass stars will end their lives as A. white dwarfs B. black holes C. neutron stars D. pineapples E. marshmallow froth

B

What is the first step in the p-p chain? A. Helium-3 combines with Helium-3 to make Helium-6 B. a proton combines with a proton to make Hydrogen-2 (Deuterium) C. Helium-4 splits apart into two protons and two neutrons D. Hydrogen-2 combined with a proton to make Helium-3 E. Helium-3 combines with Helium-3 to make Helium-4 and 2 protons

B

What spectral type is Arcturus? A. F5 B. K0 C. M5 D. G0 E. A0

B

What spectral type is Epsilon Eridani? A. M5 B. K0 C. F5 D. G0 E. A0

B

When you drag the star farther away from the Earth, does the parallax angle (between the Earth, the star, and the Sun) get larger or smaller? A. larger B. smaller

B

Like how we humans, and animals, etc., all glow in ________? A. visible light B. infrared C. ultraviolet D. x-rays E. gamma rays

B - stars like the Sun emit all over the visible range, as well as some in the UV region, in the infrared region, and at other wavelengths

A planetary nebula: A. is what star and planets are made of B. is a fuzzy planet C. is the ejected outer layers of a low- to intermediate-mass star D. lasts very long in the life of every star E. contains a black hole at the center

C

After doubling the distance from the light source, the bottom detector's readout ________, to about _______ the top detector's value. A. increased ... twice B. decreased ... half C. decreased ... one quarter D. increased ... three times E. decreased ... one tenth

C

Alpha Centauri B has luminosity of 0.5 Suns and a spectral type of closest to A. G0 B. B0 C. K0 D. K5 E. M0

C

Can you figure out what is the distance to Barnard's star -- with a parallax of 0.56 arc seconds? A. 5.6 parsecs B. 0.56 parsecs C. 1.80 parsecs D. 1.80 light years E. 0.18 light years

C

How many times greater is the luminosity of Sirius A than Sirius B, the white dwarf? A. almost 10 times B. almost 100 times C. almost 1000 times D. almost 10000 E. almost 100000

C

In general they move from _________ on the HR diagram, onto the main sequence when their nuclear fusion "engines" turn on. A. bottom to top B. left to right C. right to left

C

It looks like the star moves up on the HR diagram, and it gets: A. bigger and bluer B. bigger and redder C. bigger and the color doesn't change D. smaller and redder E. smaller and the color doesn't change

C

It seems that A. Canopus is closer than any of the other stars we've looked at. B. Canopus is at a distance typical of the nearest stars we've already looked at. C. Canopus is a lot farther away than any of the nearest stars that we've looked at.

C

Luminosity is: A. how bright the star appears to us, depending on our distance from the star B. a direct measure of the temperature of a star, in units of Kelvin C. the absolute amount of energy a star produces in a second, like the Wattage of a lightbulb

C

Medium-mass stars end as A. supernovae than black holes B. planetary nebulae then white dwarfs C. Type II supernovae then neutron stars D. red giants then brown dwarfs E. planetary nebulae then red dwarfs

C

Procyon A. is much more luminous than any of the other star, and that is why it is one of the brightest as viewed from the Sun. B. isn't as luminous as any of the other stars, but it is farther away than they are and that is why it is one of the brighter ones. C. isn't quite as luminous as any of the others, but it can still appear bright because it is relatively closer to the Sun.

C

The 60 solar mass star has a lifetime of _________, while the 0.1 solar mass star has a lifetime of _________. A. 10,000/4,500 years B. 800,000/0.003 years C. 3,400,000/2,000,000,000,000 years D. 30,000,000/2,000,000 years E. 2,900/200,000,000,000 years

C

The area of a circle ... A. pi times its radius (pi*r) B. pi times its diameter (pi*d) C. pi times its radius squared (pi*r^2) D. pi divided by its radius squared (pi/r^2) E. pi times its diameter squared (pi*d^2)

C

The event horizon of a black hole is: A. the distance from which we can see inside the black hole B. the point of infinite density C. the minimum distance from which light can escape D. the distance at which a star is torn apart by tidal forces E. the distance at which a human body is torn apart by tidal forces

C

Using the parallax angle of 16.7 arcseconds, the distance from our current location at Proxima Centauri to Alpha Centauri AB, is about A. 16.7 parsecs B. 0.67 parcsecs C. 0.06 parcsecs D. 16.7 light years E. 0.67 light years

C

What spectral type is BL Ceti A? A. F5 B. K0 C. M5 D. G0 E. A0

C

What spectral type is BL Ceti B? A. F0 B. K0 C. M5 D. G0 E. A0

C

What spectral type is Betelgeuse? A. F5 B. K0 C. M0 D. G0 E. A0

C

When a star is burning Helium in its core and has puffed out its outer layers, it is: A. a protostar B. a main sequence star C. a red giant D. a planetary nebula E. none of the above

C

With a measured parallax angle of 0.747 arseconds, how far away is Alpha Centauri? A. 0.0134 parsec B. 0.747 parsec C. 1.34 parsecs D. 134 parsecs E. 747 parsecs

C

We've been peeling this sucker apart to see what makes it tick, but what physical process could generate that kind of energy? A. burning coal B. nuclear fission C. nuclear fusion D. matter-antimatter collisions E. ten billion hamsters on exercise wheels

C - the Sun is a gigantic nuclear furnace, wherein the energy produced by NUCLEAR FUSION reactions at its core helps balance out the forces of gravity that would otherwise bring all the outer layers crushing downward to the center

109 times the Earth's radius? Let's see, that would mean you could fit about ______ Earths inside the Sun's volume! A. a hundred B. a thousand C. ten thousand D. a million E. a billion

D

And after the variable stage the star A. becomes a red giant B. goes back to the main sequence C. becomes a black hole D. produces a planetary nebula

D

And then the core of the Sun-type star shrinks and becomes a A. neutron star, the size of a city B. black hole, an infinitesimal object C. protostar D. white dwarf, the size of the Earth E. pizza

D

Gravitational acceleration is ... A. directly proportional to the distance from an object (goes as x r) B. inversely proportional to the distance from an object (goes as 1/r) C. directly proportional to the square of the distance from an object (goes as x r^2) D. inversely proportional to the square of the distance from an object (goes as 1/r^2) E. inversely proportional to the cube of the distance from an object (goes as 1/r^3)

D

It looks like as the temperature increases the star moves to the ________ on the HR diagram, and it gets _______ and _________ A. left/larger/redder B. right/smaller/redder C. right/smaller/bluer D. left/smaller/bluer E. left/larger/bluer

D

On tripling the distance from light source, the bottom detector's readout _________, to about ________ the top detector's value. A. decreased ... one third B. decreased ... half C. increased ... twice D. decreased ... one ninth E. increased ... four times

D

So Proxima Centauri is in the lower right of this diagram, which seems to correspond to _________ temperatures and ___________ luminosities. A. high/high B. high/low C. low/high D. low/low

D

So this chart looks like a graph about stars. The vertical axis has the ________ and the horizontal axis has the _________. A. luminosity/surface temperature B. core temperature/luminosity C. luminosity/time D. mass/time E. lifetime/luminosity

D

Stars less massive than the Sun will also end their lives as A. black holes B. neutron stars C. planetary nebulae D. white dwarfs E. protostars

D

The habitable zone around the Sun includes A. Earth, Mars, and Jupiter B. Mercury, Venus, and Earth C. Mars and Jupiter only D. Earth, and almost Venus and Mars E. Mars, and almost Earth

D

What is the density at the center of a black hole? A. About the same as the atmosphere of Earth B. The same as a white dwarf C. The same as a neutron star D. Infinity E. The same as Earth's density at its core

D

What spectral type is Alpha Centauri A? A. F5 B. K0 C. M5 D. G0 E. A0

D

What spectral type is Lacaille 9352? A. M5 B. K0 C. F5 D. M0 E. F0

D

What spectral type is Ross 154? A. K5 B. K0 C. F5 D. M5 E. A0

D

What spectral type is this star, Capella? A. F0 B. K5 C. M5 D. G5 E. B0

D

Which of the following has the largest luminosity? A. coolest Main Sequence star B. Main Sequence star with the smallest radius C. Main Sequence star with spectral type K D. Most massisve Main Sequence star E. the Sun

D

Which of the following is the coldest at its surface? A. main sequence star with a radius ten times the Sun's radius B. 3 solar luminosity main sequence star C. blue main sequence star D. type K main sequence star E. type A main sequence star

D

Once you study that picture, can you tell me how many protons a Hydrogen atom has? A. one proton, and the different forms can have three or four neutrons B. two protons, and the different forms can have one or two neutrons C. two protons, and the different forms can have three or four neutrons D. one proton, and the different forms can have one or two neutrons E. three protons, and the different forms can have three or four neutrons

D - hydrogen is the simplest nucleus and its dominant form is simply one proton

And that means if I move the temperature slider down, the star moves to the ________ on the HR diagram, and it gets _______ and _______ A. left/larger/redder B. right/smaller/redder C. right/smaller/bluer D. left/smaller/bluer E. right/larger/redder

E

Do you remember what main sequence means? A. The curve on the HR diagram that the Sun follows, from the lower right to upper left, as it converts its hydrogen to helium. B. The location on the HR diagram that red giants occupy during the majority of their lifetime. C. The curve on the HR diagram that stars much more massive than the Sun follow, from upper left to lower right, as they convert their helium to carbon. D. The progression of a star on the HR diagram as it gets less massive over its lifetime. E. The curve on the HR diagram where stars of different masses are located while they are converting hydrogen to helium in their cores.

E

I'll get the same detector reading for a 500 W bulb, as you do at R=1 on the 20 W bulb, if I move the lower detector to _______. A. R=1 B. R=2 C. R=3 D. R=4 E. R=5

E

Star "A" is three times further away from the Sun than Star "B." The parallax angle of Star "B" is ... A. the same as that Star "A" B. nine times larger than that of Star "A" C. three times smaller than that of Star "A" D. nine times smaller than that of Star "A" E. three times larger than that of Star "A"

E

The lower left corner of the Hertzsprung-Russel diagram has: A. the coolest and least luminous stars B. all the red giants C. the hottest and most luminous star D. the coolest and most luminous stars E. the hottest and least luminous stars

E

The spectrum of the Sun is: A. A0 B. A5 C. F0 D. F5 E. G0

E

What spectral class is Barnard's Star? A. A0 B. G0 C. G5 D. K5 E. M5

E

What spectral type Sirius A? A. M5 B. K0 C. F5 D. G0 E. A0

E

What spectral type is Proxima Centauri closest to, do you think? A. A0 B. F5 C. G0 D. K0 E. M5

E

What spectral type is Sirius A? A. K5 B. K0 C. F5 D. M5 E. A0

E

What spectral type is Vega? A. F5 B. K0 C. M5 D. G0 E. A0

E

What spectral type is this star? A. F5 B. O0 C. M5 D. G0 E. A0

E

Which star is the closest if all have the same apparent brightness? A. a red giant B. a main sequence star with a luminosity 100 times that of the Sun C. a temperature 6000 K main sequence star D. a temperature 10000 K main sequence star E. a type M main sequence star

E

You measure the parallax angle of a star to be 0.05 arcseconds. How far away is it? A. 0.05 parsec B. 1 parsec C. 2 parsecs D. 10 parsecs E. 20 parsecs

E

And what about the mass - about 333,000 Earths? About how much of the total mass of all the objects in the Solar System is contained in the Sun, alone? A. 10% B. 25% C. 50% D. 75% E. 99%

E - it's more like 99.9% of all the mass in the entire Solar System in the Sun

Now what if the Sun were 1.2 times its present mass. What planet/s would be in the habitable zone?

Earth and Mars

The most successful early planet finding mission, launched in 2009, was called

Kepler

So we need a ________ type star because we know the planet has an orbit with a semimajor axis of 0.55 AU and we want the planet to be in the habitable zone. For any other type of star, an orbit at 0.55 AU would be _______ for life.

M / too hot

Stars that include Mercury in their habitable zone are

about or a little less than 0.75 times the mass of the Sun

When a planet passes in front of a star as seen from Earth

the brightness of the star diminishes for a time