Final Flashcards
A way to deduce data in between measured data points
Interpolation
An easy way to define the slope of a best fit line
Rise over run
A way of making a reasonable estimate of a value not contained within the measured data values
Extrapolation
A way to estimate the range of a specific data point
Consider the highest and lowest measurements representing that data point
Good estimate for the best value of multiple measurements
Take the average
Is it possible to have an absolutely precise measurement
No
It’s possible to determine the speed of an object by dividing
The distance traveled by the time it took to cover that distance
It’s possible to determine the time of an event by subtracting
The time it started by the time it ended
Credited as the first modern theoretical astronomer
Kepler
although they didn’t get along, they needed each others talents
Tycho and kepler
parallax uses the orbital diameter of the earth as a baseline of a triangle
true
Who first successfully measured a parallax
Frederick Bessel
Direct measurement of stellar distances
None
Equals 3.26 lightyears
Parsec
A parsec is a measurement used in
Parallax
The total power output of an object
Luminosity
An uncertainty is designated by which Greek letter
Loop with hook on top
Modern astronomers spend much of their time analyzing data in their offices
True
Determine the slope
Y-y/x-x
When graphing it’s ok to have a sharp corner in a best fit line
False
A best fit line is like connecting the dots
False
A graph is titled and displayed as
Y versus x
The best pre telescopic Astronomical observer
Tycho Brahe
A planet travels fastest when it is farthest from the sun
False
From hottest to coldest these are the suns spectral classes
OBAFGKM
Human error plagues all scientific experiments
False
A parsec equals about 3.26 ly
True
A parsec is a measurement used in
Parallax
Luminosity is defined as
The total power output of an object
main sequence stars burn which element in their cores
hydrogen
The early 20th century astronomer known for both his meticulous astrophotography work as well as his lack of formal education was
Milton Humason
the principle first elucidated in Kepler’s third law is still useful to astronomers today
true
the english 19th century astronomer known for both his study of small solar system objects as well as discovering that stellar magnitudes corresponded to a logarithmic progression was
Robert Pogson
Parallax uses actual stellar measurement
true
a noted woman astronomer who determined the correct order for the harvard college observatory’s stellar spectra was
Annie Jump Cannon
Cepheid variable measurements rely on having distinct spectra
false
Edwin Hubble using Humason’s galactic spectra discovered the expansion of the universe
true
A noted woman astronomer who used cepheid variable stars to determine distance was
Henrietta Leavitt
If the disk of Sirius replaced the disk of the sun
it would be larger and brighter
what technique can determine the surface temperature of a star?
Wein’s law
Spectroscopic parallax and cepheid variables are exactly the same thing
false
which type of magnitude could you use for determining stellar distance?
both of these together (absolute and apparent)
the birth of astrophysics was initiated by
both of these (herzprung and russell)
Luminosity refers to
the total energy or power output of an object
even if it’s not a straight line, a best fit line on a graph can be used to interpolate or extrapolate valuable scientific information
true
spectroscopic parallax doesn’t actually need a parallax degree measurement., but rather a distinct stellar spectrum
True
a cepheid variable can be used as a standard candle
true
astronomical objects used to measure distances to galaxies
standard candle
a method for measuring distances to stars. can be used to any main sequence star with a spectrum that can be recorded
spectroscopic parallax
galaxies containing a flat, rotating disk of stars, gas, and dust, with a central concentration of stars
spiral galaxy
a spiral galaxy with a bar shaped structure of stars
barred spiral galaxy
a spherical cluster of typically older stars on the outskirts of a galaxy
globular cluster
the first astronomer to realize the vastness of the milky way and observed globular clusters on mount wilson
harlow shapley
an astronomer who studied eclipses and believed there to be galaxies outside our own. Debated with Shapley over the size of the universe and the nature of spiral nebulae
Heber Curtis
specifies each point on a plane by two coordinates
cartesian coordinate system
the x coordinate
abscissa
the y coordinate
ordinate
a line drawn to be equal along coordinates
best fit line
a measure of steepness, rise over run
slope of a line
a system of gas, dust, and stars with their solar systems
galaxy
all points of a moving body moving in the same direction
translational motion
all points of an object circling around an axis
rotational motion
the squares of the orbital periods of the planets are directly proportional to the cubes of the semi major axes of their orbits
kepler’s third law
a unit of angular measuring, 1/60th of a degree. The distance travelled in one minute
arc minute
a uit of angular measuring, the distance travelled in one second.
arc second
the approximate distance from the center of the Earth to the center of hte sun
astronomical unit
the distance light travels in one year
light year
a unit used to measure and express distances to stars and galaxies. Equivalent to 3.26 light years
parsec
the apparent difference of an object seen from two different places
parallax
a German astronomer and the first to find reliable values for the distances to other stars from our sun using parallax
Friedrich Bessel
indicate a wider frequency or wavelength in the radiation of an object due to emission or absorption
broadening of spectral lines
an indicator of whether a star or galaxy is moving towards or away from us, with light stretching blue when towards and red when away
Doppler effect
wavelength of the stars and galaxies are stretched to red, it means that space is expanding
the cosmological redshift
splitting a spectral line into two or more different frequencies when in a magnetic field
zeeman effect
an american astronomer who co discovered a relationship between the absolute magnitude of a star and its spectral lines relative intensities, using these to determine the size of stars. Director of Wilson observatory, studied spectral and attempted to correlate spectral lines to absolute magnitude.
Walter S Adams
A german astronomer who worked at the Mount Wilson observatory where he studied the spectra of the sun with Walter S Adams
Ernst A Kohlshutter
a band of stars that have hot, dense cores that produces energy from hydrogen and helium
main sequence stars
occupying the upper part of the H R diagram, these develop when main sequence stars run out of hydrogen
super giant stars
main sequence stars after using up all nuclear fuel, bottom left
white dwarfs
A star in the final stages of stellar evolution, our sun will become this one day
red star
a supernova from a star up to fifty times the mass of a sun, comes from the rapid collapse of such a star
type two supernova
a supernova that takes matter from a neighboring star until a nuclear reaction is triggered
type one supernova
a harvard computer who discovered the cycle of fluctuation in cepheid variables and how to use them to find distances
Henrietta Leavitt
An Americanastronomer who discovered galaxies are moving away from us. Also discovered dark matter, the evolution of stars and galaxies, how solar systems form, and black holes
Edwin Hubble
An American astronomer who provided high quality photographs of stars and discovered Comet Humason. Was a janitor and had no stellar education
Milton Humason
Proposed the sun was stationary in the center of the galaxy, and the planets revolved around it.
Nicolas Copernicus
Confirmed the theory that the Earth revolved around the sun, and was the first to use a telescope to observe astronomical bodies.
Galileo
Split sunlight with prisms, created larger prism in 1800s that could observe 574 dark lines in continuous spectrum. Combination prism and telescope allowed spectra moon, mars, Venus, later used diffraction gratings. Came to the conclusion white light was all colors.
Newton
Collects first star catalogue, considered the greatest astronomical observer using Babylonian star records and accurate models of the motion of the sun and moon. Developed trigonometry and assigned magnitude 1-2 to brightest stars and marked their places on metal plate to divide them by six magnitude classes
Hipparchus
He discovered several minor planets and made observations on comets. He introduced a mathematical scale of stellar magnitudes with the ratio of two successive magnitudes being the fifth root of one hundred (~2.512) and referred to as Pogson’s ratio.
Robert Pogson
Comparing the known absolute magnitude of this celestial object with well known intrinsic luminosities with its measured apparent magnitude allows a highly accurate estimation of distances. Globular clusters
standard candle
Compares stars by plotting luminosity versus color (or energy versus temperature). Plots revealed if there were common properties governing behavior of stars, and correlations were obvious
HR diagram
Indirect method to measure distances. it does not rely on the geometric parallax effect. can be applied to any main sequence star for which a spectrum can be recorded. The method depends on the star being sufficiently bright to provide a measurable spectrum, one must measure the apparent magnitude of the star and know the spectral type of the star.
spectroscopic parallax
When an atom receives a precise level of incoming energy, electrons orbiting the nucleus of the atom absorb and transit it to a higher state. A dark line will be visible in the spectrum
absorption spectra
is an event that occurs when one object is hidden from the observer by another object that passes between them
occultation
all planets orbit the sun in an ellipse, with the sun as one of the focii
keplers first law
It states that a line between the Sun and the planet sweeps equal areas in equal times. Thus, the speed of the planet increases as it nears the Sun and decreases as it recedes from the Sun.
keplers second law
P² = a³, so the period of a planet’s orbit (P) squared is equal to the size semi-major axis of the orbit (a) cubed when it is expressed in astronomical units
keplers third law
a more general form of Kepler’s Third Law that could apply to any two objects orbiting a common center of mass. M1 + M2 = A3/P211. Kepler’s Law is T2R3 = K constant and T is period of traslation in orbit and R again, distance between Sun and Planet2.
Newton’s derivation of Keplers third law
The modern stellar classification scheme is based on spectral absorption or emission lines, which are sensitive mostly to the star’s surface temperatures, rather than differences in gravity, chemical composition, or luminosity.
Harvard observatory classification of stellar spectra
Electron must shed absorbed energy by emitting a photon of light at that exact energy level (color). When these pass through a prism, the spectrum is revealed
emission spectra
measure of an object from earth
apparent magnitude
10pc from the earth observed
absolute magnitude
a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or half-angle of inclination between those two lines.
parallax
the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation
spectroscopy
The amount can be calculated by gravitational lensing. At the cosmic scale, when there is a source large source of light L such as light from a galaxy which is located behind a body of large mass (visible + invisible matter) M, the mass of M acts as a lens and bends the light from L.
dark matter
A celestial object consisting of a nucleus of ice and dust and a tail of gas by the sun
Comet
A comet that only lasts less than 200 years and is found near the ecliptic
Short period comet
A comet with 200+ year orbital periods and possibly from the Oort cloud
Long period comet
A comet that passes close to the Sun at perihelion
Sun grazing comet
Circumstellar disc in the outer solar system larger than the asteroid belt
Kuiper belt
Predicted collection of icy objects found farther away than anything else in our solar system
Oort Cloud
Levy 9 broke apart and collided with Jupiter, providing the first direct observation of an extraterrestrial collision of solar system objects
Comet shoemaker
An American stronger who discovered the dirty snowball hypothesis
Whipple
key theoretical development for 20th-century astronomy and cosmology was the development of the theory of relativity, from 1905 to 1915, which eventually led to an explanation of the origin of the universe.
Einstein
