Astronomy Final Review
Which star has a larger diameter? Rigel (1.08E8km) or Deneb (2.8E8km)
Deneb
T/F: If the apparent visual magnitude of a star is 7.3, then the star is not visible with the unaided eye.
True
T/F: Navigators can find their latitude in the northern hemisphere by measuring the angle from the northern horizon to the north celestial pole (marked by the North Star, currently Polaris).
True
T/F: Only 50 brightest stars are identified by names; the rest of the stars are identified by the location on Celestial sphere.
True
T/F: The center of the Milky Way galaxy shows signs of past eruptions.
True
T/F: The look-back time is numerically equal to the distance to a galaxy in light-years.
True
T/F: The night sky is dark because the universe is neither static nor infinitely old.
True
T/F: The rapid rotation in the outer disk suggests that our galaxy is more massive than previously thought.
True
T/F: When a large galaxy collides with a small galaxy, the smaller galaxy may be pulled apart by tidal forces.
True
T/F: When two galaxies collide, they pass trough each other and their stars almost never collide.
True
Place the following types of electromagnetic radiation wavelengths in order from shortest to longest. I. Infrared II. X-Ray III. Radio IV. Ultra Violet V. Gamma Ray VI. Visual VII. Microwave
V, II, IV, VI, I, VII, III. Gamma, X-Ray, UV, Visual, Infrared, Microwave, Radio
What is the matching constellation to the stars listed below? Vega Deneb Alteir Polaris
Vega-Lyra Deneb-Cyngus(the Swan) Alteir-Aquila (the Eagle) Polaris-Ursa Minor (the Little Bear)
What is the color of the shortest wavelength light visible to the human eye?
Violet
What type of radiation can pass through the Earths atmosphere?
Visible Light
launched in 2001; extensive measurements of the spatial distribution of the cosmic background radiation were made using this
WMAP
An observer in the Northern Hemisphere takes a time exposure photograph of the night sky. If figure 1 depicts the photograph taken by the observer, which direction was the camera pointing?
West
Which two ingredients are needed to make an emission nebula?
hot O-B stars and interstellar gas
What is the correct order of occurrence?
formation of particle from gamma ray photons; formation of nuclei; formation of neutral atoms; formation of first stars
Marked the end of the dark age and the beginning of the age of stars and galaxies in which we live in now.
Re-Ionization Era
When is a stellar object is considered a main sequence star?
When the Object is in Hydrostatic equilibrium and when hydrogen fusion takes place in the core of the object.
The wavelength of the peak radiation of a star is 400nm. What is the temperature of the photosphere of this star in degrees of Kelvin?
7500 K T= 3,000,000/400
Convert 7E-7 m to micrometers.
7E-1
Convert 9.5E17 km to m.
9.5E20
What is typically found in the center of a double-lobed radio source?
A giant elliptical galaxy
How is a group of 100,000 to 1,000,000 population II stars firmly bound by gravity called?
A globular cluster
The primary source of the Sun's energy is
fusion of hydrogen nuclei into helium by proton-proton chain.
Type I Supernova, RR Lyra, Cepheids, Hubble's Law
"Standard Candles" that can be used to measure distances in space.
The bust of hot gas off the solar photosphere which follows lines of magnetic field is called___.
Prominence
T/F: Sooner or later, gravity wins.
True
The average distance from Earth to the sun is
1 AU
Photons of red light...
have a longer wavelength than photons of blue light.
launched in 1992; detected the largest-scale variations, but the sizes of the smaller variations are critical for testing the theory.
COBE
T/F: Employing active optics greatly enhances the image quality and seeing with optical and infrared telescopes.
True
If a galaxy has a radial velocity of 8,473 km/sec and the Hubble Constant is 70 km/sec/Mpc, what is the distance to this galaxy?
121 pc
How many kilometers are there in 1AU? Meters?
150,000,000 km 150,000,000,000 m
When was the last supernova explosion in our galaxy?
1604
Write 1000000000000 in powers of ten notation.
1E12
Write .00000023 in powers of ten notation.
2.3E-7
COBE and WMAP measure the temperature of the cosmic background radiation to be ____________K
2.7K
The orientation to the Sun's magnetic field changes, repeating a full cycle every
22 years
Star Vega is 25 light years from the Sun. If humans could travel with the speed of light (3.00E5), how long would it take them to reach this star?
25 years not light years
What is the wavelength of a radio wave of a frequency 100 MHz?
3 meters Math: 300,000/100=3000 convert to meters move 3 deci places and get 3.
What is the average temperature of a red star
4,000 K
If it takes about 8 minutes for the sunlight to reach Earth, then how long would it take to reach Jupiter which is about 5 AU away from the Sun?
40 Minutes Cross Multiply: 1/8 *5/?
A telescope of 200mm aperture has a focal length of 2000mm. What should be the focal length of an eyepiece to give a magnification of 50 times to this telescope?
40mm Math: 2000/50=40mm
If the measured parallax of a star is 0.025, what is its distance from the Earth in parsecs?
40pc d= 1/.025
What is the average temperature of a green/yellow star?
5,000 K
Based on the information that the Sun's photosphere is 5800K, calculate the wavelength at which the Sun emits most radiation.
517.24nm ?=3,000,000/5800
If a star emits maximum radiation at wavelength 570nm, what is the temperature of that star?
5263.16 K 570nm=3,000,000/?
What is the average temperature of a blue star
7,000 K
If Polaris, the North Star, appears 75 degrees above your northern horizon, what is your latitude?
75 degrees North.
What are the reasons why we should expect galaxies to collide with each other fairly often?
A galaxy's size is comparable to (but smaller than) the average distance between galaxies. AND Galaxies occur in clusters
T/F: Every red dwarf star that ever joined the main sequence is still there today.
True
What does the explosion of a supernova typically leave behind?
A shell of hot, expanding gas with a pulsar at the center.
Which from the list below is a planetary nebula? A. Ring Nebula (M57) B. Orion Nebula (M42) C. Crab Nebula (M1) D. Horse Head Nebula
A. Ring Nebula (M57)
What is a good estimation of the density of a neutron star?
About the same as an atomic nucleus
a rotating disk of matter formed by accretion around a massive body (such as a black hole) under the influence of gravitation.
Accretion Disk
What is the name of the technique where shapes of the telescopic mirror is undergoing constant computerized adjustment to compensate for the atmospheric disturbance?
Adaptive Objects
Which statement is false from the list below? Gravity is the weakest of the four universal forces. Gravity is a result of curved space-time. Gravity is directly proportional to mass.
All are correct
Group of widely scattered stars (10 to 1000) moving together through space; not gravitationally bound into a cluster.
Association
The milky way galaxy is classified as a _____
Barred Spiral Galaxy
Draw an Sbc Galaxy
Barred with one wing on each side
Why is our galaxy is suspected to be surrounded by a galactic corona?
Because the disk of the galaxy rotates faster than expected in its outer region.
When an atom gains electrons it:
Becomes negative ion.
Both Large and Small Megallanic Clouds are belonging to which of one of the classes below? A. Barred Spiral B. Spiral C. Irregular D. Elliptical E. Peculiar
C. Irregular
What is the name of an instrument that converts light energy of photons into electric current while digitizing the image?
CCD
T/F: Except for hydrogen and most of helium, all the elements have ben formed by stellar nuclear fusion.
True
What is the name of a gamma rays' space telescope?
Chandra Telescope
Compare to surrounding regions on the photosphere, sunspots are
Cooler
All of the energy of the Sun is generated in the ______.
Core
What is the correct order of solar layers from inward to outward?
Core, Radiative Zone, Convective Zone, Photosphere, Chromosphere, Corona
The assumption that the universe is isotropic and homogeneous is called the ________ principle.
Cosmological
The assumption that any observer in any galaxy sees the same general features of the Universe.
Cosmological Principle
What is the Nebula that is a remnant of a supernova?
Crab Nebula (M1)
Which statement below is true? A. Big Dipper is common known example of a constellation. B. Stars in constellations are physically close to one another. C. Constellations are no longer used by astronomers. D. Constellations are useful for mapping the sky. E. One star could be in two different constellations.
D. Constellations are useful for mapping the sky.
Which is not considered a component of the interstellar medium? A. HI Clouds B. Coronal Gas C. Molecular Clouds D. Water Vapor E. Intercloud
D. Water Vapor
The period of a few hundred million years during which the Universe expanded in darkness. Extends from soon after the big bang glow faded into the infrared to the formation of the first stars.
Dark Age Era
Which star appears to be the dimmest and brightest to an observer on Earth? A. _Cma -1.46 B. _Cet 2.53 C. _Dra 3.07 D. _Per 3.98 E. Nim 8.07
Dimmest Answer: E.Nim Brightest Answer: A. _Cma
Who is not a standard Candle
Doppler Effect
Galaxies of what type do contain mostly lower-main sequence stars and giants?
Elliptical
Where on Earth would one see Polaris on the horizon.
Equator
T/F: A protostar of 20 solar masses forms a star that will stay on the main sequence 20 times longer than the sun.
False
T/F: Elliptical galaxies are primarily made up of massive O and B stars.
False
T/F: Interstellar matter is distributed very evenly throughout the galaxy.
False
T/F: Many pulsars have periods that are gradually increasing as the spinning neutron stars lose energy.
False
T/F: Orange region of a flame is hotter than blue region.
False
T/F: Population II stars contain more metals than Population I Stars.
False
T/F: Resolving Power of the telescope is directly proportional to the focal distance of the telescope.
False
T/F: The celestial equator always passes directly overhead.
False
T/F: The disk of the Milky Way galaxy is older than the halo.
False
T/F: The event horizon marks the boundary inside which the escape velocity is less than the speed of light. .
False
T/F: The magnitude scale is used to measure the temperature of a star
False
T/F: The red shifts of the galaxies imply that the universe is expanding and that we are at the center.
False
T/F: The sun will eventually become a supernova.
False
T/F: When a star becomes a red giant, its core expands to a roughly proportional larger size too.
False
List the measurements in order from greatest to smallest
Giga, Mega, Kilo, Hecto, Deca, Basic Unit, Deci, Centi, Mili, Micro, Nano
The linear relation between the distance to a galaxy and its radial velocity.
Hubble's Law
Of the normal elements around us, which ones were produced during early Universe before stellar fusion?
Hydrogen and some Helium
Arrange the following distances in order from largest to smallest. I. Kilometer II. Light Year III. Meter IV. Astronomical Unit
IV, III, II, I
What observational evidence supports the expansion of the universe?
Increase in the redshift of distant galaxies with distance.
Which event triggers the formation of protostars?
Instability in an interstellar cloud
Which one of the telescopes listed below has the least light-gathering power? The Most light gathering power? Diameter of objective (aperture), mm A. 90 B. 130 C. 250 D. 400 E. 10,000
Least LGP: A Most LGP: E
The ___ of a telescope is a measure of its ability to show extremely faint objects and depends on the diameter of the objective.
Light-Gathering Power
Milky Way and Andromeda galaxies are the part of galaxy cluster called
Local Group
Which of the following types of electromagnetic radiation has the longest wavelength? Shortest? A. Y-rays B. UV C. Infrared Radiation D. X-Rays E. Radio
Longest: E. Radio Shortest: A. Gamma Rays
What is the key factor that determines the pace of evolution of a star?
Mass
What kind of radiation is the cosmic background radiation?
Microwaves
Are there any nearby Quasars?
NO
How is resurrection of a white dwarf in a close binary system called?
Nova
The duration of formation of the subatomic particles from photons is called...
Nucleosynthesis Era
The conflict between observation and theory as to why the night sky should or should not be dark.
Olbers's Paradox
A cluster of 10 to 10,000 stars with an open, transparent appearance and stars not tightly grouped; usually relatively young and located in the disk of the galaxy
Open Cluster
What is the name of the Nebula that is an active star formation region?
Orion Nebula
The light we see from the Sun comes from which layer?
Photosphere
They are primarily found in the disk of the galaxy. They contain more heavy metals than population II stars.
Population I Stars
Star poor in atoms heavier than helium; nearly always a relatively old star found in the halo, globular clusters, or the nuclear bulge of a galaxy.
Population II Stars
A series of three nuclear reactions that build a helium atom by adding together protons the main energy source in the Sun.
Proton-Proton Chain
A source of short, precisely timed radio bursts; thought to be a spinning neutron star.
Pulsar
Small, Powerful source of energy thought to be the active core of a very distant galaxy
Quasar
What is the most distant active galaxy type?
Quasars
How does the study of quasars reveal information of the history of the universe?
Quasars are very distant so we can view how galaxy evolution occurred in the past.
When falling temperature of the Universe reached 3000K, protons were able to capture and hold free electrons to form neutral hydrogen atoms.
Re-Combination Era
Stars of what type last the longest? Shortest?
Red Dwarfs; Red Giants
The mass of a single galaxy might be found by what method?
Rotational Curve
Draw an E0 Galaxy...
Rounded Oval, Beginning stage
The center of our galaxy lies in the direction of the constellation of
Sagittarius
What factors are important when trying to classify an elliptical galaxy?
Shape
Geomagnetic storms on Earth are caused by
Solar Flares
Some regions of the Milky Way's disk appear dark because
Stars in that direction are obscured by interstellar dust.
T/F: How bright a star appears to an eye results from the star's luminosity and the distance it is from Earth.
True
What does the Chandrasekhar limit tell us about?
That white dwarfs heavier than 1.4 solar masses cannot exist.
What is a planetary nebula?
The Ejected envelope, of a red giant surrounding a stellar core remnant.
The future of the universe depends on the average density of matter int he universe (critical density). Why is it?
The density of matter determines the strength of the gravity.
What evidence supports acceleration in the expansion rate of the universe?
The discovery that type 1a supernova in distant galaxies are 25 percent fainter than expected.
T/F: Brown dwarfs are failed stars that never ignite their hydrogen fusion.
True
T/F: CCD has multiple advantages over a photographic plate including a digital recording.
True
T/F: Electromagnetic radiation (light) can behave as a particle and as a wave.
True
How would the number of circumpolar stars (stars that never go below horizon) change for an observer sailing south toward decreasing latitude (from Maine to Florida along the Atlantic coast)?
The number of circumpolar stars will decrease.
The Doppler Effect is used by astronomers to figure out____.
The radial velocity of the star.
West to East is the direction of
The true orbital motion of Earth as viewed from the North.
What are properties of the universe?
The universe is accelerating, flat, and expanding.
What are two primary functions of a telescope?
To gather and focus light from distant objects
Seen through the northern latitudes, the star Polaris:
is always above the northern horizon.
A telescope that uses a mirror to focus light is called a _____ telescope.
re-flector
A telescope that uses a lens to focus light is called a _____ telescope.
re-fractor
Galactic cannibalism refers to.....
the merging of galaxies
The assumption of a homogeneous universe states that...
the universe is the same everywhere.