Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics > Classification of Stars COPY > Flashcards

Classification of Stars COPY Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

Is absolute magnitude subjective or not?

A

Not subjective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where does fusion stop in smaller stars?

A

Carbon and oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the distance in parsecs in terms of the parallax angle?

A

Distance in parsecs = 1 / parallax angle (arc seconds)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What spectral classes are the Balmer lines dominant?

A

B & A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the formation of a neutron star

A
  • The stars core is 1.4 times the suns mass
  • The quantum effect from the electrons cannot stop it collapsing
  • The electrons get pushed onto atomic nuclei and form neutrons and neutrinos
  • The core is made of neutrons
  • The outer layers continue to collapse until the core cannot be compressed further
  • The outer layers rebound off the core
  • Causes a supernova
  • Only core (neutron star) is left
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the difference in brightness between two stars one magnitude apart?

A

2.51

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does the number of electrons in the different energy levels depend on?

A

Temperature of the gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How many times brighter is a magnitude 1 star compared to a magnitude 6 star?

A

100

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define the parsec

A

The distance to a point in space where the radius of the Earth’s orbit of the Sun subtends an angle of 1 arc second.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How dense are neutron stars?

A

4 x1017 kgm-3 which is the density of nuclear matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define a supernova

A

Where a giant star explodes at the end of its life. It has a rapid and short-lives increase in absolute magnitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When is an absorption spectrum formed?

A

When a continous spectrum of white light is passed through a cool gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What can the darkness of the Balmer lines be used to determine?

A

The temperature of the gas - and therefore the spectral class

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define absolute magnitude

A

What the apparent magnitude would be of the star/galaxy was 10 parsecs away from the sun

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do you go from seconds to degrees?

A

multiply by 1 / 60

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the Intensity of a star measured in?

A

Wm^-2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the absolute magnitude of the sun?

A

+4.77

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define what is meant by ‘the intensity of radiation hitting Earth from a star’

A

The energy each second from the star hitting 1 square metre on earth at right angles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the equation for Weins Law?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When does a star turn into a white dwarf?

A

ONLY THE CORE OF THE STAR

at the end of their life (after red giant stage)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a main sequence star?

A

Where the star goes into an equilibrium state, where it will stay for many millions of years, until the hydrogen in the core runs out.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the most energetic event in the universe?

A

When burst of high energy gamma rays are emitted when they supernova

They usually last minutes but can last hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the equation for Stefan’s Law?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Which spectral class are white dwarfs?

A

O/B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Is apparent magnitude subjective or not?

A

It is subjective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the equation for the schwarzchild radius

A

R = 2GM / c2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the prominent absorption lines linked to each spectral class?

A

O - He+, He, H

B - He, H

A - H (strongest), ionised metals

F - ionised metals

G - ionised & neutral metals

K - neutral metals

M - neutral atoms, TiO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

When does a star begin to turn into a neutron star?

A

When its core is 1.4 times the sun’s mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Define the astronomical unit

A

The mean distance from the Sun to the Earth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the equation that links the intensity of a star to the luminosity of the star?

A
31
Q

The star Capella is approximately 100 times more luminous than the sun. What is Capellas absolute magnitude?
If its apparent magnitude is measured at 0.08, how far away is it in parsecs?

A
32
Q

What can the parallax method only been used on?

A

Closeby stars

33
Q

Define the apparent magnitude of a star

A

It is a measurement of how bright (just visible wavelengths) the star appears to us on Earth. It is subjective in that it depends on how far the observer is from the star

34
Q

Describe a red giant in terms of luminosity and temperature

A

High luminosity

Relatively low temperature

35
Q

What are the spectral classes of stars?

A

O B A F G K M

36
Q

Where is the main sequence “saddle” located on a Hertzsprung-Russell diagram?

A

At an absolute magnitude of around 4

37
Q

What is the Balmer absorption spectrum?

A

The visible absorbtion spectrum in hydrogen.

38
Q

Give four facts about neutron stars

A
  • Very dense (4 x1017 which is the density of nuclear matter)
  • Very strong magnetic field
  • Spinning neutron star is called a pulsar and is a strong radio source
  • Only a few 10’s of metres in diameter
39
Q

What is a black hole?

A

An object where the escape velocity is greater than the speed of light

40
Q

Define the Intensity of a star

A

The energy each second from the star hitting 1m^2 perpendicular to the radiation on Earth.

41
Q

what does the equation that links intensity and luminosity assume?

A

Energy is not lost / no radiation is sbsorbed or scattered

42
Q

Draw the Hertzsprung-Russell diagram

A
43
Q

What is an emission spectrum given off by?

A

Hot gases

Gases with an electric field passed through it

44
Q

Why is the equation for the Schwarzchild radius only approximate?

A

Newton’s gravitational equations do not work in intense gravitational fields

45
Q

How do you go from seconds to arc seconds?

A

Multiply by 60

46
Q

How do you go from arc seconds to degrees?

A

multiply by 1 / 3600

47
Q

What are the axis on the Hertzsprung-Russell diagram?

A

Temperature: 50 000 - 2 500

Absolute Magnitude: -10 - 15

48
Q

What are standard candles?

A

Objects in the sky whose absolute magnitude are known

49
Q

What is a continous spectrum given off by?

A

Hot solids

50
Q

What is the event horizon?

A

The boundary of the black hole, where the escape velocity is the speed of light

51
Q

What is spectral class and temperature of the sun?

A

G2

5 800K

52
Q

What are cephid variables?

A

Stars which grow brighter and dimmer over a number of days

53
Q

Alinam is 1350 light years from Earth. It has an apparent magnitude of 1.7. What is its absolute magnitude?

A
54
Q

What is the life cycle of a very large star?

A

Main sequence, giant, supergiant, supoernova, black hole/neutron star

55
Q

Define the Luminosity of a star

A

The total amount of electromagnetic radiation it emits each second, measured in J/s or W. It is the power of the star

56
Q

What is the surface area of a sphere?

A
57
Q

What is a white dwarf?

A

The core of a star, which is very hot and with a small diameter.

58
Q

What is the stuff you need to know about the sun?

(Temp, Absolute magnitude, Spectral class)

A
  • Temp: 5 800
  • Absolute magnitude: +4.77
  • Spectral class: G2
59
Q

Define light year

A

The distance that light travels in a year

60
Q

What are quasars?

A

Supermassive black holes at the centre of galaxies which are very strong emitters of radio waves

61
Q

What is the highest absolute magnitude (brightest value) on a Hertzsprung-Russell diagram?

A

-10

62
Q

Where does the visible absorption spectrum in hydrogen come from?

A

The electrons in the n=2 level abrosbing photons

63
Q

Why is an absorption spectrum seen when the spectrum from a galaxy or star is viewed?

A

Light from stars is emitted from the hot centre of the star and then passes through cooler gases neaar to the surface of the star.

Some wavelengths are absorbed by the cooler gases.

64
Q

When do stars become red giants?

A

As they come to the end of their lives adter they have been on main sequence

65
Q

What colour is linked to each spectral class?

A

O - Blue

B - Blue

A - Blue-white

F - white

G - yellow-white

K - orange

M - red

66
Q

Why do stars obey Weins Law?

A

They are black bodies

67
Q

What is rthe Schwarzchild radius?

A

The distance between the centre of the black hole

68
Q

Define a black body

A

A black body completely absorbs all wavelengths of radiation falling on it and can all wavelengths

69
Q

What temperatures are linked to each spectral class?

A

O - 25 000 - 50 000

B - 11 000 - 25 000

A - 7 500 - 11 000

F - 6 000 - 7 500

G - 5 000 - 6 000

K - 3 500 - 5 000

M - <3 500

70
Q

What is the link between the distance from a star and the intensity of the star?

A

There is an inverse square relationship (distance doubles, the intensity quarters)

71
Q

Draw the Hertzsprung-Russell diagram to show the stellar evolution of the sun / a star similar to the sun

A
72
Q

Where does the fusion stop for very large stars?

A

Iron

73
Q

Draw a black body curve for an object that has a maximum wavelength of 250nm

A
74
Q

What is the energy output of a type 1a supernova?

A

1044J

This is similar to the energy given out by the sun in its lifetime

Physics (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions