Brainscape's Knowledge GenomeTM

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


See full index

Stellar Structure and Evolution > Channel 1 and 2 > Flashcards

Channel 1 and 2 Flashcards

1
Q

What is stellar structure?

A

core - radiation zone - convection zone

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

What can we observe from nearby stars?

A

temperature and brightness

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

What can we observe from binary systems?

A

mass of a star

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

What does a colour-magnitude diagram measure?

A

The apparent brightness of stars in two different wavebands e.g B-lue and V-isual
The difference is a measure of colour and surface temperature.

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

What happens to apparent brightness if stars are at the same distance?

A

It is a measure of intrinsic brightness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a star cluster?

A

A group of stars bound together by gravity and formed out of the same material and at the same time

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

What are galactic or open clusters?

A

they are not well defined
distance to them is not well known
blue stars

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

What are globular clusters?

A

well defined
distance known reasonably well
crowded
yellow stars

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

What are extragalactic clusters?

A

distance well known

unresolved

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

How much is 1 mili arcsec?

A

1/1000 arcsec

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

How much is 1 arcsec?

A

1/3600 degrees

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

How can the position of a star be measured?

A

By looking at the declination and right ascension of the star (both in miliarcsecs)

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

What is the parallax of an object used to approximate?

A

The distance to an object

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

What is the equation for parallax?

A 
D = 1/p
(p = parallax angle observed and D is actual distance measured in parsecs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a parsec?

A

The distance at which an object has a parallax of 1 arcsecond

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

What is luminosity?

A

The total power integrated over all wavelengths

17
Q

What is flux?

A

Energy crossed unit area per unit time integrated over all wavelengths arriving at Earth
(Jm-2s-1 or Wm-2)

18
Q

How is the effective temperature of a star measured?

A

Directly from analysis of stellar spectrum

19
Q

What is the mass luminosity relationship?

A

L is proportional to M to the power 3.3

20
Q

How much hydrogen does a star which is 10x as massive as the Sun burn?
How quickly does it use up its fuel?

A

10x as much

as it is 10^3.3 times brighter, 10^3.3/10 = 200 times more quickly

21
Q

What the relationship between time and Mass?

A

t is proportional to M^-2.3

22
Q

Where do most stars lie on a CMD/HR diagram?

A

Most stars are on the MS

23
Q

Which characteristics do more massive stars have?

A

Brighter, bluer and have shorter lives

24
Q

What is the CMD/HR diagram?

A

The prime medium through which stellar evolution models are compared with observations

25
Q

What do clusters with short lived bright blue stars lack?

A

They have very few red giants

26
Q

What do clusters with many red giants lack?

A

They have no short-lived blue MS stars

27
Q

If we look at stellar clusters what do they show us?

A

Clues to stellar evolution

28
Q

Which assumptions are made about stars in order to study their structure?

A

STEADY STATE
equilibrium and not changing with time

SPHERICAL GEOMETRY
all variables are function of r only, rotational forces negligible, no magnetic forces

INITIAL COMPOSITION IS HOMOGENEOUS

29
Q

What affects the expected lifetime of a star?

A

Gravitational potential energy
(millions of years)

Chemical energy
(thousands of years)

Nuclear fusion of light elements
(billions of years)

30
Q

How much mass of a star has conditions that allow nuclear burning?

A

typically 10% of mass

31
Q

In a fusion reaction of H into He, how much of the mass if converted into energy?

A

0.7%

32
Q

What is a nuclear timescale?

A

Nuclear energy available divided by luminosity

33
Q

What is a thermal timescale?

A

The energy released is due to gravitational contraction

The thermal timescale is then the gravitational potential energy divided by luminosity

34
Q

What happens at several times in evolution?

A

star pressure-gravity imbalance occurs

35
Q

Which timescale dominates evolution of a star?

A

Nuclear timescale

Stellar Structure and Evolution (8 decks)

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