Stars 2 Flashcards

1
Q

Problem with making a census

A

Intrinsically faint stars are hard to see

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2
Q

What’s our nearest star system

A

Alpha Centauri

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3
Q

Binary stars

A

More than half of all stars are found in pairs or larger groups

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4
Q

Visual binary

A

A binary that can be seen through a telescope as two separate stars

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5
Q

Optical double

A

Two very close stars that are not gravitationally bound to each other

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6
Q

Spectroscopic binary

A

A binary that shows two sets of spectral lines

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7
Q

Eclipsing binary

A

A binary in which stars take turns blocking each other in our view

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8
Q

Binary stars orbit____ of the system

A

The center of mass

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9
Q

What is the most important property of any star

A

Mass

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10
Q

What is the typical range of mass of stars

A

100-250

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11
Q

The vast majority of stars have ____ masses

A

Low

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12
Q

What percent of stars are on the main sequence

A

90

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13
Q

What percent of stars are white dwarfs

A

10

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14
Q

What percent of stars are giants or supergiants

A

Less then 1

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15
Q

In which type of binary do we observe the Doppler shift as stars move around each other

A

Spectroscopic binary

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16
Q

Why are brown dwarfs not considered stars

A

They cannot fuse hydrogen to helium in their cores

17
Q

Which spectral lines are prominent in O type stars

A

Neutral, ionized helium

18
Q

What’s the suns luminosity class

A

V

19
Q

Which molecules lines are particular to Y type brown dwarfs

A

Ammonia

20
Q

In which type of binary does each star periodically block part or all of the other stars light

A

Eclipsing

21
Q

What’s on the X axis of the HR diagram

A

Temp

22
Q

What’s on the y axis of the HR diagram

A

Luminosity