PHYS 005 Study Guide - Midterm Guide: Beyondblue, Chemical Element, Dark Energy

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5 Jul 2018

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Light year is a measure of DISTANCE

●How far you can travel in a year if you travel as fast as light

●Constant

●Nothing faster in the universe

Life of stars

●Low, intermediate mass, massive

●Starts in star nebula- collapses on itself into a protostar (star baby)

○Low mass- less than half mass of sun

■Start their lives as red dwarves-how long do they live?

■Become white dwarfs

○Intermediate mass stars- YELLOW STARS

■.8-10x mass of sun

■10 billion years

■Red giant

■Planetary nebula- dissolves into space, with core left

■White dwarf

○Massive stars

■MORE THAN 10x-100x mass of sun

■Live 100 million yrs- burn quickly

■Red SUPERgiant

■Explode to SUPERNOVA

●Implodes before it explodes

■If it is too heavy- black hole

■If not too heavy- neutron stars (smaller than NYC)

●Pulsars- lighthouses

●Magnetars- same thing w. Magnetic field

Terrestrial planets- rocky planets (first 4)

Jovian planets- gaseous planets

●*no dwarf planets, etc.

8 light minutes to reach Earth from Sun

To reach end of solar system- 4 Hours

Transforms 4 hydrogen into HELIUM- creates energy

●*what makes a star, a star

Jupiter- 67 moons

● Europa- liquid oceans underneath a very THICK layer of ice

○Warm core

○6 mi. Thick layer protects oceans from outside atmosphere

Saturn

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●Enceladus

○Thick layer of ice, warm core

●Difference: ** Enceladus has GEYSERS

○Can spewer life into outer space

Parsecs- UNIT OF DISTANCE equivalent to 3 light years ( 3.25 ly)

Photons- particles of LIGHT

Galileo wanted to know how fast light travels

●Galileo measured w. His heartbeat

●Conclusion: light is too fast to measure

You can see moons of jupiter periodically

●In front & behind (eclipsed) Jupiter

Romer- light takes LONGER to reach earth if earth was BEHIND the sun

●Basic calculation of the speed of light thanks to the moons of jupiter

○Remember NUMBERS

■16 mins further from 40 light minutes

Wavelength- distance btw 2 cusps/ 2 valleys

Visible lights- green

Red- infrared, right

● Less energy- long wavelengths

Beyond blue- ultraviolet, x-ray, gamma ray

● More energy- short wavelengths

Every chemical element makes a distinct color- spectra

●Sound moving toward you- HIGHER frequency

●Sound moving away fr you- LOWER frequency

With light: blueshift & redshift

●Toward you- BLUESHIFT, higher energy

●Away fr you- REDSHIFT, lower energy

Exposure time

Bigger the aperture, more collecting area of light

●So you can see further, dimmer, more difficult to see things

Sensitivity

●Increasing amts of electrons in detector-> keep more light inside

○NOISER

○Low ISO (sensitivity)

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Document Summary

How far you can travel in a year if you travel as fast as light. Starts in star nebula- collapses on itself into a protostar (star baby) Low mass- less than half mass of sun. Planetary nebula- dissolves into space, with core left. If it is too heavy- black hole. If not too heavy- neutron stars (smaller than nyc) 8 light minutes to reach earth from sun. To reach end of solar system- 4 hours. Europa- liquid oceans underneath a very thick layer of ice. Parsecs- unit of distance equivalent to 3 light years ( 3. 25 ly) Galileo wanted to know how fast light travels. Conclusion: light is too fast to measure. Romer- light takes longer to reach earth if earth was behind the sun. Basic calculation of the speed of light thanks to the moons of jupiter. 16 mins further from 40 light minutes. Every chemical element makes a distinct color- spectra. Sound moving away fr you- lower frequency.

Related Questions

1. The Jeans instability occurs when
Athe pressure in a gascloud is less than its gravitationalforce.
Bthe pressure in a gascloud is greater than its gravitationalforce.
Cthe temperature in acollapsing cloud is hot enough to fuseHydrogen.
Dthe temperature in acollapsing cloud is hot enough to fuse Helium.

2. At what stage in its life does a star pass through theprotostarphase?
AAfter condensationbut before nuclear reactions begin in itscore.
BWhile it is convertinghydrogen into helium in its core.
CAfter nuclear reactionsend in its core, but before the red giantphase.
DWhen it is expanding insize as a red giant or supergiant.

3. The characteristics of an open cluster of stars are
Aa few hundredmembers, often very young and still embedded in thegas and dustfrom which they were formed.
Bmany thousand members, ofdifferent ages.
Ca few dozen members, theremnant of a globular cluster of starsfrom which most of themembers have escaped.
Dhundreds of thousands ofmembers, all very old, and no or verylittle interstellar gas anddust.

4. What is a protostar?
AA star near the endof its life, before it explodes as asupernova.
BA sphere of gas aftercollapse from an interstellar cloud butbefore nuclear reactionshave begun.
CA small interstellarcloud, before it collapses to become astar.
DA shell of gas left behindfrom the explosion of a star as asupernova.

5. What is an H II region?
AA region of hot,ionized hydrogen around one or more O and Bstars.
BA region of molecularhydrogen inside a giant molecularcloud.
CA region of neutral,atomic hydrogen in interstellar space.
DA region of gas and dustformed by the explosion of a massive star.

6. The total time that the Sun will spend as a main sequencestaris
Aabout 4.5 millionyears.
Bat least 200 billion yearsyears.
Cabout 1 millionyears.
Dabout 10 billionyears.

7. How is a star's lifetime related to its mass?
AThe lifetimes ofstars are too long to measure, so it is not knownhow (or if) theirlifetimes depend on mass.
BA star's lifetime does notdepend on its mass.
CLower-mass stars runthrough their lives faster and have shorterlifetimes.
DHigher-mass stars runthrough their lives faster and have shorterlifetimes.

8. In the Hertzsprung-Russell diagram, how does the position ofatypical star change while it is at the main sequence phase ofitsevolution?
AA star's position onthe main sequence is determined only by itsmass and not its age,and so, stars do not move along the mainsequence duringevolution.
BMassive stars (4 solarmasses) move toward the upper left as theirluminosity increases,while lower-mass stars move toward the lowerright as theirtemperature decreases.
CStars move from upperright to lower left while they are on themain sequence.
DStars move from upper leftto lower right while they are on themain sequence.

9. Why does the core of the Sun contain more helium andlesshydrogen than does the surface of the Sun?
AHelium condenses moreeasily so, when the Sun was forming the corebecame helium-rich;vast quantities of hydrogen were added onlyafter the core becamemassive enough.
BThe hydrogen has beenlifted out of the core by the Sun's magneticfield.
CHelium is heavier thanhydrogen, and has sunk toward the center ina process of chemicaldifferentiation.
DThermonuclear reactionshave converted much of the originalhydrogen in the core intohelium.

10. In terms of nuclear reactions, what is the next stage ofastar's life after the end of hydrogen burning in thecore?
AHydrogen burning ina thin shell around the core.
BHelium burning in thecore.
CCarbon burning.
DDeath (it becomes eithera supernova or a white dwarf).