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Astronomy > Exploring Starlight > Flashcards

Exploring Starlight Flashcards

1
Q

What is Apparent Magnitude?

A

Apparent Magnitude is the brightness of a object in the sky from Earth

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2
Q

What is Absolute Magnitude?

A

Absolute Magnitude is the brightness of a celestial object at 10 parsec

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3
Q

Which is brighter? A star with a magnitude of 6 or a star with a magnitude 2?

A

The star with magnitude of 2 is brighter then the star with a magnitude of 6.

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4
Q

How many times brighter is a star with a magnitude of 5 compared to a magnitude of 6?

A

Magnitude 5 is 2.5x brighter then magnitude 6, each time the magnitude goes up by 1 it is 2.5x brighter

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5
Q

What is the distance modulus formula

A

M = m+5 - (5 log d)

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6
Q

What does the distance modulus formula find out?

A

The distance modulus formula determines the apparent or absolute magnitude of a star

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7
Q

What information can be obtained from a stellar spectrum.

A

Chemical Composition, Temperature, radial velocity, sunspot cycle, wavelength

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8
Q

Understand how stars are classified according to the spectral type?

A

It uses the Morgan Keenan System (O,B,A,F,G,K,M) with M being the coolest of the stars and O being the hottest.

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9
Q

How are stars colour and spectral type related to their temperature.

A

The surface temperature of a star determines the colour light it emits. Blue stars are hotter then yellow stars, which are hotter then red stars

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10
Q

How does a stars life cycle relate to the Hertz Sprung Russel Diagram(Those weird clumped up areas of stars diagram)

A

Stars life cycle relates to the OBAFGKM which determines its position on the HR diagram with M being the longest living and O being the shortest

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11
Q

What the inverse square relationship between distance and brightness/intensity.

A

1/d2 or I/d2

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12
Q

How many arc seconds are in a arc minute

A

60 arc seconds

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13
Q

How many arc seconds are in a degree?

A

3600 arc seconds (60 arc minutes)

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14
Q

What is a parsec?

A

The distance to a star.

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15
Q

How to use the Hertz Sprung Russel Diagram to determine the distance to a star

A

Use Spectroscopic parallax which uses luminosity and temperature which you can use from the HR Diagram

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16
Q

What is a binary star?

A

A binary star is a stellar system consisting of two stars orbiting around their centre of mass.

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17
Q

What is a eclipsing binary?

A

An eclipsing binary is two stars moving in an orbit in line to Earth . That the light at one time can be hidden behind the other like a eclipse.

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18
Q

Which of the following are used by astronomers to show how the brightness of a star varies over time.
A. Light Curve
B.Light Graph
C.Light Sabre

A

A. Light Curve

19
Q

What is a cataclysmic star?

A

A star which irregularly increases in brightness by a large factor then drop back down

20
Q

What is a Cephied star?

A

A Cephied variable is a type of star that pulsates radially varying in both diameter and temperature and produces changes in brightness

21
Q

When a star expands does its temperature fall or increase?

A

When a star expands the temperature falls.

22
Q

Using primary and secondary star, explain the cause of the variability in an eclipsing binary.

A

The primary and secondary stars are not aligned giving rise to constant brightness. The smaller/secondary dip occurs when the secondary star occurs is behind the primary star.

23
Q

How do you find apparent magnitude using distance modulus formula.

A

m = M - 5 + (5 log d) (d = parsec)

24
Q

Name one the following are not bound together by gravitation?

A

Double stars

25
Q

What is a RR Lyrae variable.

A

RR Lyrae variable stars are periodic variable stars commonly found in global clusters.

26
Q

HR Diagram/Spectroscopic: Which object splits up light from astronomical objects into a spectrum?

A

Diffraction grating

27
Q

Hertzsprung russell diagram are usually obtained by plotting? etc luminosity to temperature

A

luminosity against spectral type

28
Q 
Which star is the hottest?
A. B4
B. A9
C. B8
D. A6
A

A.B4

29
Q

What is the spectral type of the sun

A

G2

30
Q

Explain the connection line between dark absorption lines and the chemical composition of the stars

A

Light passing through outer layers of a star is made of all wavelengths/energies; some of this light has the correct wavelength/energy to excite atoms in the stars outer layer

When the atoms de-excite

They emit radiations/photons of the same wavelengths energy but in a random direction

31
Q

Exploring starlight: How many times does star a appear brighter than star b.

Star a = 0.8
Star b = 1.8

A

2.5x brighter

32
Q

How many times does star B appear brighter than star y

Star b = 1.8
Star y = 3.8

A

6.25x brighter

How to do it: 3.8 - 1.8 = 2.5^2(to the power of 2) = 6.25

33
Q

how many light years are in 1 parsec

A

3.26 ly

34
Q

In a constellation, star b appears brighter then star e by a factor of 16

The apparent magnitude of e is 3.7; deduce the apparent magnitude of B

A

square root 16 to the power of 2.5 which rounded is equal to 3 and do 3.7-3 = 0.7

Apparent magnitude of b = 0.7

35
Q

In a constellation, the brightest star a appears 40 times brighter than the faintest star N

The apparent magnitude of a is 0.3 deduce the star of magnitude of N

A

Square root 40 to the power of 2.5 = 4.37

36
Q

At its faintest, A sco is 250x brighter than a globular cluster that lies close to Scorpius

Deduce the apparent magnitude of the globular cluster
A = 0.9

A

Square root 250 by 2.5 = 9.1 - 0.9 = 8.2 apparent magnitude

37
Q

What is a astronomical unit

A

Average distance from the centre of the earth to the distance to the centre of the sun.

38
Q

How do you find distance in parsec.

A

Distance = 1/parralax angle

Parralax angle = 1/distance

39
Q

How many arc seconds and arc minutes are in half a degree.(0.5)

A

1800 seconds are in half a degree which is 30 arc minutes in a degree

40
Q

A star has a parallax angle of 0.25 degrees how far away is the star.

A

distance = 1/parallax angle = 1/0.25 = 4 parsec

41
Q

Which types of telescopes can be located at sea level?

A. infra red and optical telescopes
B. optical and radio telescopes
C. Radio and gamma-ray telescopes
D. X-ray and optical telescopes

A

B. optical and radio telescopes

42
Q

Which two types of electromagnetic radiation are not blocked by the Earths Atmosphere

A

Visible light and radio waves do not get blocked

43
Q

To determine the structure and rotation of our Galaxy (the Milky Way), astronomers often use electromagnetic radiation with a wavelength of 21 cm. In which region of the electromagnetic spectrum does this radiation lie?

A

Radio Waves

44
Q

The ratio of the diameters of objective elements for a radio telescope and an optical telescope is 6000:1. The corresponding ratio of wavelengths is 360000:1
Determine the ratio: resolution of optical telescope / resolution of radio telescope

A

360000/6000 = 60 or 1/60 if inverse square law

Astronomy (8 decks)

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