Term
| What is apparent magnitude? |
|
Definition
| The brightness of the star as seen from Earth. |
|
|
Term
| A star of apparent magnitude +5 appears fainter than what other magnitudes? |
|
Definition
|
|
Term
| Absolute magnitude is what? |
|
Definition
| The intrinsic brightness all stars would have if placed 10pc from Earth. |
|
|
Term
| Light leaving a point source spreads out so that the apparent brightness l of light per unit area varies with distance d according to what law? |
|
Definition
| The inverse-square law, I oc 1/d^2 [oc means 'proportinal to'] |
|
|
Term
| Spectral types of stars (e.g., B, K, G, F, etc.) uniquely define what? |
|
Definition
| The stars "surface" temperatures. |
|
|
Term
| What spectral type and luminosity is our sun? |
|
Definition
|
|
Term
| The Hertzsprung-Russell diagram plots what? |
|
Definition
| Luminosity vs. spectral type (or "surface" temperature). |
|
|
Term
| Where on the H-R diagram do most local stars in our universe hang out? |
|
Definition
| Over 90% of local stars in universe are on the main-sequence. |
|
|
Term
| What percentage of local stars hang out on the main sequence? |
|
Definition
|
|
Term
| Compared to a star in the middle of the Hertzsprung-Russell diagram, a star in the upper right part of the diagram is what? |
|
Definition
|
|
Term
|
Definition
| A star of about the same size (diameter) as the Earth that appear in lower L of an H-R diagram. |
|
|
Term
| The space between stars contains what? |
|
Definition
| Gas, both atomic and molecular and dust. |
|
|
Term
| Luminosity classes (I, II, III, IV, or V) are most closely related to what? |
|
Definition
|
|
Term
| The most likely places in which stars and planetary systems are forming in the universe are |
|
Definition
| nebulae composed of gas and dust. |
|
|
Term
| How have complex molecules such as formaldehyde (H2CO) been detected in interstellar clouds? |
|
Definition
| by molecular emission lines |
|
|
Term
| New stars are formed from |
|
Definition
| huge, cool dust and gas clouds. |
|
|
Term
| Star formation takes place in |
|
Definition
|
|
Term
| What is the typical mass of a giant molecular cloud? |
|
Definition
| 100,000 to 1 million solar masses |
|
|
Term
| What is the name given to the space in our Galaxy that exits between the billions of stars? |
|
Definition
|
|
Term
| What is the most abundant element in the universe? |
|
Definition
|
|
Term
| What is the chemical symbol for the element nitrogen? |
|
Definition
|
|
Term
| What molecules are likely to be the most common in interstellar space? |
|
Definition
| H^2 molecules... note- question asks for molecules not free atoms |
|
|
Term
| The luminosity of a star is |
|
Definition
| its total energy output into all space per second, measured in Watts. |
|
|
Term
| How is gas distributed in interstellar space? |
|
Definition
| In clumps, concentrated in interstellar nebular clouds. |
|
|
Term
| What are the two physical parameters of stars that are plotted in the Hertzsprung-Russell diagram? |
|
Definition
| luminosity and surface temperature. The spectral classes (OBAFGKM) represent surface temperatures. |
|
|
Term
| What fraction of the stars surrounding the Sun are main-sequence stars? |
|
Definition
|
|
Term
| Compared with a star in the middle of the Hertzsprung-Russell diagram, a star in the upper right of the diagram is |
|
Definition
|
|
Term
| How do massive stars normally end their lives? |
|
Definition
| They explode... massive stars normally end their lives by blowing up. |
|
|
Term
| The mass of a star governs what? |
|
Definition
| The mass of a star governs its lifetime. |
|
|
Term
| Where is the most likely place where new stars and planetary systems are forming? |
|
Definition
| In interstellar nebulae composed of gases and dust |
|
|
Term
|
Definition
| A sphere of gas after collapse from an interstellar cloud, but before nuclear reactions have begun. |
|
|
Term
| Where are emission nebulae (H II regions) found? |
|
Definition
|
|
Term
| Accretion of matter in an interstellar leads to |
|
Definition
|
|
Term
| How far away are we from the nearest star in our Galaxy? |
|
Definition
| 1AU or 93,000,000 million miles = distance to our nearest star |
|
|
Term
| How will our G2V star end its life? |
|
Definition
| Our G2V star will stop thermonuclear fusion in its core, expand to a Red Giant class star, which will engulf and vaporize our entire solar system, in about 5 billion years. Then it will collapse to a white dwarf. |
|
|
Term
| How fast is the speed of light? |
|
Definition
| Light waves (all EM radiation) travel at 186,000 mi./sec. in every direction. |
|
|
Term
| Light leaving a point source spreads out so that the apparent brightness I of light per unit area varies with distance d according to which of the following laws (oc means "proportional to")? |
|
Definition
|
|
Term
| The spectral class of the star Enif is K2, while that of the Sun is G2. Which of the following conclusions can be drawn about Enif from this information? |
|
Definition
| Enif is cooler than the Sun. |
|
|
Term
| The luminosity class of a star (I, II, III, IV, or V) is most closely related to which physical characteristic of the star? |
|
Definition
|
|
Term
| The symbol ly represents the distance light travels in one year. How vast a distance is that? |
|
Definition
| 6,000,000,000,000 ie. 6 trillion miles |
|
|
Term
| The star Proxima Centauri, our Sun's nearest star neighbor, is at a distance of about 4.2 light years away. How far away is that in miles? |
|
Definition
|
|
Term
| A white dwarf star, the surviving core of a low-mass star toward the end of its life, can be found on the Hertzsprung-Russell diagram |
|
Definition
| below and to the left of the main sequence |
|
|
Term
| If you could travel in a spaceship flying 50,000 mph, how many years would it take for you to travel to our Sun's nearest star neighbor Proxima Centauri? |
|
Definition
| 57,077 years of space flight to reach the next nearest stellar object. |
|
|
Term
| What is Proxima Centauri? |
|
Definition
| a tiny Red Dwarf class star with only 10% of our Sun's mass and 0.006% of its luminosity. It is incapable of supporting human life and has no planets. (3rd member of the Alpha Centauri triple star system.) |
|
|
Term
| The most recent supernova explosion known to have occurred in our own Galaxy.. |
|
Definition
| ..created the supernova remnant Cassiopeia A. |
|
|
Term
|
Definition
| a large interstellar gas and dust cloud containing young stars. |
|
|
Term
| What point defines the end of the pre-main-sequence phase of a star's life and the start of the main-sequence phase? |
|
Definition
| Nuclear reactions begin in its core |
|
|
Term
| When any star on the main sequence was a protostar, it was |
|
Definition
|
|
Term
| The most recent supernova explosion to have occured in the Milky Way Galaxy |
|
Definition
| created the supernova remnant Cassiopeia A |
|
|
Term
| When a typical nova explodes, it brightens in a few hours by a factor of |
|
Definition
|
|
Term
| The Crab Nebula is a nearby example of what type of physical phenomenon? |
|
Definition
| remnant of a supernova explosion |
|
|
Term
| Is the Earth, a stellar body, a self-luminous object? |
|
Definition
|
|
Term
| What is the lowest mass an object can have and still be a star? |
|
Definition
|
|
