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| The way an animal's brain combines the different information from it two eyes to perceive the distances to objects around it |
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| We measure ___ to nearby stars by comparing the view from opposite sides of Earth's orbit. |
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1.)the apparent shift in the position of one object relative to another object, caused by the changing perspective of the observer.
2.)In astronomy, the displacement of the apparent position of a nearby star caused by the changing location of Earth in its orbit |
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| A minute of arc('), a unit used for measuring agles. An arcminute is 1/60 of a degree of arc |
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| A second of arc("), a unit used for measuring very small angles. An arcsecond is 1/60 of an arcminute, or 1/3,600 of a degree of arc |
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| The distance that light travels in 1 year--about 9 trillion kilometers (km) |
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| The distance to a star with a parallax of 1 arcsecond using a base of 1 astronomical unit(AU). One parsec is approx. 3.26 light-years |
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| A system used by astronomers to describe the brightness or luminosity of stars. The brighter the star, the smaller its magnitude |
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| Astronomers try very hard to always use ___ to refer to how much light an observer receives and ___ to refer to how much light is emitted |
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| A measure of the apparent brightness of a celestial object, generally a star |
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| The total flux emitted by an object. Unit: watts (W) |
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| A measure of the intrinsic brightness of a celestial object, generally a star. Specifically, the apparent brightness of an object, such as a star, if it were located at a standard distance of 10 parasecs (pc) |
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| Brightness depends on the observer's ___; luminosity does not |
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| There are many more __-luminosity starts than __-luminosity stars |
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| hotter objects emit __ light |
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| Measuring the color of a star tells us its ______ |
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| An instrument element that transmits a limited wavelength range of electromagnetic radiation. For the optical range, such elements are typically made of different kinds of glass and take on the hue of the light they transmit |
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| The lowest possible energy state from a system or part of a system, such as an atom, molecule, or particle |
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| An energy level of a particular atom, molecule, or particle that is higher then its ground state |
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| When an atom drops to a lower energy state, the lost energy is carried away as a ___ |
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| An intensity peak in a spectrum that is due to sharply defined emission of electromagnetic radiation in a narrow range of wavelengths |
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| An intensity minimun in a spectrum that is due to the absorbtion of electromagnetic radiation at a specific wavelength determined by the energy levels of an atom or molecule |
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| A classification system for stars based on the presence and relative strength of absorption lines in their spectra. Spectral type is related to the surface temperature of a star. |
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| The complete sequence of spectral types of stars, from hottest to coolest is |
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| Radius of the sun is about _____km |
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| A system in which 2 stars are in gravitationally bound orbits about their common center of mass |
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| The location associated with an object system at which we may regard the entire mass of the system as being concentrated. The point in any isolated system that moves according to Newton's first law of motion |
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| Newtons version of Kepler's 3rd law give the ________ |
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| total mass of a binary system |
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| A binary system in which the 2 stars can be seen individually from Earth |
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| A binary star pair whose existence and properties are revealed only by the Doppler shift of its spectral lines. Most spectroscopic binaries are close pairs |
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| A binary system in which the orbital plane is oriented such that the 2 stars appear to pass infront of one another as seen from Earth. |
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| The Hertzsprung-Russell diagram, which is a plot of the luminosities versus the surface temperatures of stars. The evolving properties of stars are plotted as tracks across the H-R diagram |
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| The strip on the H-R diagram where most stars are found. Main sequence stars are fusing hydrogen to helium in their cores |
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| Use of the spectroscopically determined luminosity and the observed brightness of a star to determine the star's distance |
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| A spectral classification based on stellar size, from the largest supergiants to the smallest white dwarfs |
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| The complete spectral classification of a star includes both its spectral type, which tells us ___ and ___; and its luminosity class, which indicates ___. |
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| temperature and color; size |
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| The ___ of a main sequence star determines its fate |
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