Term
| What is the Golden Rule of Stellar Evolution? |
|
Definition
| The more massive the star, the faster it evolves. |
|
|
Term
| What are the Stages of Stellar Evolution? |
|
Definition
1.Pre-Main Sequence Stage (cannot see with telescope due to dust on body)
2.Main Sequence Stage
3.Post-Main Sequence Stage
4.Endpoints |
|
|
Term
| What does Interstellar space indicate due to its effects on starlight? |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| Define Gas and give its typical density. |
|
Definition
Individual atoms of any type or molecules of any type
Typical density = 1 atom/cm3 |
|
|
Term
| Define Dust and give it's density. |
|
Definition
Collections of thousands or millions of atoms stuck together
Typical density = 1 particle per cubic kilometer |
|
|
Term
| What are the three types of Visible Nebula's, define each? |
|
Definition
Bright-
-Red light from hot (10,000K) hydrogen gas.
Reflection-
-Blue light reflected off microscopic dust particles around hot stars.
Dark-
-Black, Interstellar dust blocks starlight, (It dims and reddens it). |
|
|
Term
| Why can't interstellar hydrogen gas (H I) emit visible light? |
|
Definition
| Because the electrons are all in the ground state. |
|
|
Term
| If the spins of atoms are in the same sense, does it release slightly more or less energy? |
|
Definition
|
|
Term
| How many types of molecules have been detected in space? |
|
Definition
| • More than 100 different types of molecules have been detected in space by the radio and infrared emissions they produce. |
|
|
Term
| What are the most common Interstellar Molecules? |
|
Definition
hydrogen
carbon monoxide
water
ammonia |
|
|
Term
| What three ways does interstellar dust show its presence? |
|
Definition
1) If no star is imbedded in a dust cloud it can obscure light from stars behind it producing the “dark” nebulas.
2) If a hot, blue star is imbedded in or near a dust cloud, UV and blue light reflects off myriad microscopic dust particles producing a “reflection” nebula.
3) Dust dims and reddens starlight in a process called “Interstellar Reddening” |
|
|
Term
| What are Primary Comic Ray? |
|
Definition
| Very high speed (High energy) protons and other nuclei. |
|
|
Term
| What are Secondary Cosmic Rays? |
|
Definition
| Parts of the nuclei of nitrogen and oxygen molecules produced by primary cosmic rays striking air molecules. |
|
|
Term
| How are Cosmic Rays formed? |
|
Definition
| From Supernovas and Neutron stars. |
|
|
Term
| What does G.M.C. stand for? |
|
Definition
|
|
Term
| How many GMC's have been discovered in the disk of the Galaxy? |
|
Definition
|
|
Term
| How far across in a G.M.C.? What about temperature, and mass? |
|
Definition
| Typically, a GMC would be about 150 LY across, have a temperature of ~10oK, and a mass of 1,000,000 M0 |
|
|
Term
| What is Random Density Fluctuations in reference to triggering star formation? |
|
Definition
| The movement of gases and dust in a cloud cause localized pots to reach critical density |
|
|
Term
| What is a Supernova Shock wave in reference to triggering star formation? |
|
Definition
| The explosion of a nearby massive star causes a compression of regions in a cloud to trigger contraction. |
|
|
Term
| What is H II Expansion in reference to triggering star formation? |
|
Definition
| The expanding hot gas of an H II region can compress the gas and dust also |
|
|
Term
| What kind of a galaxy do we live in? |
|
Definition
|
|
Term
| What is Rotation of the Galaxy in reference to triggering star formation? |
|
Definition
| Spiral density waves are set up in the rotating disk. These compress the gas and dust. |
|
|
Term
| Once triggered, a “cloud core” will undergo _________________? |
|
Definition
| Gravitational Contraction. |
|
|
Term
| In order to begin gravitational contraction, a portion of an interstellar gas and dust cloud must achieve a critical density. What is this density? |
|
Definition
| ~one million atoms or molecules/cm3 |
|
|
Term
| When the critical temperature for hydrogen fusion of _____________ is reached |
|
Definition
| A proto-star turns into a true star. |
|
|
Term
| What does the Spin of the cloud produce? |
|
Definition
| The disk from which planets form. |
|
|
Term
| What are Accretion Disks? |
|
Definition
| A spinning nebula flattens into a disk. Material from the nebula continues to fall onto the “accretion” disk. |
|
|
Term
| What are Bi-Polar Outflows, Winds, Jets? |
|
Definition
| Material headed for the central proto-star is deflected and shot out of the two poles of the disk. |
|
|
Term
| What does “Exoplanets” stand for? |
|
Definition
|
|
Term
| As of ______ there have been _______ planets orbiting nearby solar-type stars that have been detected. |
|
Definition
|
|
Term
| How have most Exoplanets been discovered? |
|
Definition
| Most have been detected indirectly using the Doppler Effect. |
|
|
Term
| Mayor and Queloz discovered the first Exoplanet orbiting the nearby Sun-like star called __________ in 1995. |
|
Definition
|
|
Term
| How may planetary systems have been found? |
|
Definition
|
|
Term
| How many multiple-planet systems have been found? |
|
Definition
|
|
Term
| What is the longest stage of a star's existence, and why? |
|
Definition
| Main sequence; It is extremely stable because there is an exact balance between two opposing forces. |
|
|
Term
| The gas pressure inside a star is due to ____________________. |
|
Definition
| the energy released by the fusion process. |
|
|
Term
| During the Post Main sequence eventually all hydrogen in the core is converted into ______. |
|
Definition
|
|
Term
|
Definition
| When the shrinking core heats to 108o K, a 2nd level of fusion starts (He → C). |
|
|
Term
| The most planets found for a given star is ______ for the star HD 10180. |
|
Definition
|
|
Term
| What is the Post-Main sequence evolution dependent upon? |
|
Definition
|
|
Term
| How many stars consist in an open star cluster, what shape, what age? Give an example... |
|
Definition
`10s to 1,000s stars.
`Don’t have symmetric shapes.
`Can be young, medium, or old.
`Example (Pleiades in Taurus) |
|
|
Term
| How many stars consist in a Globular Cluster, what shape, what age? Provide an example... |
|
Definition
`10,000s to 100,000s stars.
`Always symmetrical (round).
`Are all old.
`Example (M13 in Hercules) |
|
|
Term
| How many stars consist in a Association Cluster, what shape, what age? Provide an example... |
|
Definition
3. Association: 10s of stars.
a. No symmetry
b. Very young.
i. Example (Belt stars of Orion) |
|
|
Term
| He fusion occurs at ______________ K. |
|
Definition
|
|
Term
|
Definition
| Creations of the elements |
|
|
Term
| What is a Planetary Nebula, and how far across are they? |
|
Definition
| A bubble or shell of hot gas surrounding a small, blue-hot, low luminosity star. It is about ½ LY across. |
|
|
Term
| Planetary Nebula's gas expands at what rate? |
|
Definition
|
|
Term
| How fast can a nova brighten suddenly, and how fast can its gas expand? |
|
Definition
| A star or system that brightens suddenly by 100,000x its original value. After months it gradually fades back to obscurity. Gas from explosion expanding at 1,000 km/sec |
|
|
Term
| How fast can a Supernova brighten suddenly, and how fast can its gas expand? |
|
Definition
| A star or system that brightens suddenly by 100 million X its original value. Like the nova it gradually fades back to obscurity in months. Gas from explosion expanding at 10,000 km/sec |
|
|
Term
| What are the two types of supernovas and what are their absolute magnitudes? |
|
Definition
Type Ia:
•M=-18 No Hydrogen lines in spectrum
Type II
•M=-15 Hydrogen shows in spectrum |
|
|
Term
| Which of the two types of supernovas would show hydrogen lines in the spectrum? |
|
Definition
|
|
Term
| Which Supernova has a larger absolute magnitude? |
|
Definition
Type Ia with -18
vs.
Type II with -15 |
|
|
Term
| Which Supernova has a larger absolute magnitude? |
|
Definition
Type Ia with -18
vs.
Type II with -15 |
|
|
Term
| What is the diameter of a white dwarf? |
|
Definition
10,000km (6,000 miles)
~size of Earth |
|
|
Term
| All of the stars in a given cluster are assumed to have about the same what three things? |
|
Definition
~Distance from the Earth (or Sun)
~Age
~Chemical Composition |
|
|
Term
| Evolution carries higher mass stars away from the Main Sequence at the ___________. |
|
Definition
|
|
Term
| The Cluster “turn-off” point is a measure of the _____ of a star cluster. |
|
Definition
|
|
Term
| What happens to a supergiant when Hydrogen runs out? |
|
Definition
| It will balloon into a red supergiant |
|
|
Term
| A low mass star loses its envelope after becoming a red giant for the __________. What is the core left behind as __________? |
|
Definition
2nd time
as a white dwarf. |
|
|
Term
| Nebula fades after how many years? |
|
Definition
|
|
Term
| • The white dwarf will gradually cool and fade into a ________, but will maintain its size and density due to its ____________. |
|
Definition
Black Dwarf
“degenerate electron gas pressure” |
|
|
Term
| What is the Average density of a White dwarf? |
|
Definition
Average density:
20 tons/in3 |
|
|
Term
| A high mass star undergoes H fusion as a ___________ (but faster). |
|
Definition
|
|
Term
| Accretion of H from companion Supernova Type Ia causes entire white dwarf to do what? |
|
Definition
| to collapse and undergo huge explosion. |
|
|
Term
| When a high-mass star reaches end of its evolution, what happens? |
|
Definition
| iron core collapses → explosion |
|
|
Term
| What is the diameter of a Neutron Star? |
|
Definition
| (15 miles) ~ size of a city |
|
|
Term
| Would you weigh more on a Neutron Star or a White Dwarf? |
|
Definition
|
|
Term
| Collisions among H atoms put some into the ______? |
|
Definition
|
|
Term
| How have we mapped the spiral structure of our Galaxy? |
|
Definition
| Studies of the 21-cm radio emission from the cold H I clouds |
|
|
Term
| ______ ________supplies energy to heat the center of a proto-star. |
|
Definition
| Gravitational contraction |
|
|
Term
| Why is it so difficult to directly detect Exoplanets, or Extra Solar Planets? |
|
Definition
1) Planet = dimmer than the parent star and would be lost in its glare.
2) The angle between star & planet = tiny. |
|
|
Term
| Planets with mass similar to Jupiter cause a slight wobble in the motion of the parent star, which is detected as small, regular blue and red shifts in the spectrum of the star, what is this called? |
|
Definition
|
|
Term
| If the spectrum of a terrestrial-mass Exoplanet were to show oxygen, it would be an indication of what? |
|
Definition
|
|
Term
| When does a star become a main sequence star? |
|
Definition
| Once hydrogen fusion begins in the core. |
|
|
Term
Gravity always tries to contract stars and produces a force that is radially _________.
A) Inward
B) Outward |
|
Definition
|
|
Term
| Where does fusion take place in a star? |
|
Definition
|
|
Term
| What happens when there is no fusion heat to provide gas pressure in a star? |
|
Definition
| Gravity starts to shrink the core. |
|
|
Term
| After a Helium Flash what happens to the core? |
|
Definition
The core stops shrinking because now there is gas pressure to support it.
~The entire process repeats its self through different elements.~ |
|
|
Term
| Thermal pulses drive the envelope away from the star in episodes. What does an expanding envelope produce? |
|
Definition
|
|
Term
Core He Fusion occurs during which branch?
A) Horizontal Branch
B) Red Giant Branch
C) Asymptotic Giant Branch. |
|
Definition
|
|
Term
| What is the 2nd ascent to the RGB is know as? |
|
Definition
| AGB = Asymptotic Giant Branch. |
|
|
Term
| During which branch is He completely used up in the core? |
|
Definition
| AGM = Asymptotic Giant Branch |
|
|
Term
|
Definition
| Is a white dwarf in a close binary system with a red giant. Hydrogen from R.G. falls on surface of the white dwarf, heats, and explodes from H fusion. Both survive. |
|
|
Term
What would happen if a very massive star were to have a collapsing core?
What about if a average star were to have a collapsing core? |
|
Definition
`A black hole should form.
`A neutron star should form. |
|
|
Term
| Due to the excessively intense gravity on White Dwarf star, what happens to the electrons? |
|
Definition
| Electrons are forced into the protons of the nuclei in the core, converting them into neutrons and neutrinos. |
|
|
Term
| At the time of formation of the neutron star, an intense burst of what is emitted? |
|
Definition
|
|
Term
An object so dense that is would consist of only neutrons packed tightly together is known as a what?
A) Red Giant
B) White Dwarf
C) Collapsed Star
D) Black hole |
|
Definition
|
|
Term
|
Definition
| A rapidly rotating neutron star. |
|
|
Term
| The neutron star should maintain its size and density due to what? |
|
Definition
| Degenerate neutron gas pressure. |
|
|
Term
| Where was Kepler's SN or Super Nova located? |
|
Definition
|
|
Term
| Why was Supernova 1987a remarkable in several ways? |
|
Definition
~It was the first nearby SN studied with modern telescopes and equipment.
~Neutrinos from the explosion were detected nearly simultaneously with the light signal from the event! |
|
|
Term
| What is Nucleosynthesis II? |
|
Definition
| HEAVY elements being created during the brief time that it takes a supernova to explode. |
|
|
Term
| What were Newton's Laws unable to explain? |
|
Definition
| The observed “precession” of Mercury’s orbit. |
|
|
Term
| What is Einsteins Special Theory of Relativity? |
|
Definition
| An extension to Newtons laws of relativity. |
|
|
Term
| What is Einsteins General Theory of Relativity? |
|
Definition
| An extension to Newtons Law of gravity. |
|
|
Term
|
Definition
| Mathematical surface at which escape velocity equal c. |
|
|
Term
| What is the Principle of Equivalence? |
|
Definition
| No way to distinguish between free-fall and floating in interstellar space. |
|
|
Term
|
Definition
| Mathematical point to which the imploded core of a massive star is reduced. |
|
|
Term
| How can we detect a black hole? |
|
Definition
`It must be in the vicinity of another star
`be within a binary star system to see the affects of the black hole on the companion star forming an accretion disk. |
|
|
