Details Title: ASTRONOMY CHAPTER 7 Description: from book and outline paper Total Flash Cards: 56 Created: 03/05/2009 17:34:15		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Astronomy Flashcards
Cards in this set: Term What is an atom? Definition consists of a nucleus surrounded by a cloud of electrons Term what does the nucleus consist of? Definition positively-charged protons and uncharged neutrons Term What does the number of protons in an atom determine? Definition which element it is Term What are isotopes? Definition atoms of the same element (same # of protons) but have different number of neutrons Term what is an ion? Definition an atom that has lost or gained an electron Term A neutron is surrounded by a number of negatively charged electrons equal to what? Definition the number of protons in the nucleus Term What forms a molecule? Definition two or more atoms joined together Term how are the electrons in an atom attracted to the nucleus? Definition The Coulomb force (binding energy that holds electrons in at atom) Term What does the size of an electron's orbit depend on? Definition it's energy (orbits can be thought of as energy levels) Term Why are an electrons orbits thought of as energy levels? Definition because the size of an electrons orbit depends on the energy Term What is an excited atom? Definition an electron is excited to a higher orbit by a collision between atoms or absorption of a photon. Term What is the lowest possible orbit known as? Definition the ground state Term What is thermal energy? Definition the agitation among the atoms and molecules of an object Term What is the flow of thermal energy? Definition heat Term what does temperature refer to? Definition the intensity of the thermal energy (the agitation) Term What causes the emission of black body radiation? Definition the motion among the particles in a body Term The hotter an object is, does it radiate more or less? does it have a shorter/longer wavelength of maximum intensity? Definition radiates more and has a shorter wavelength Term When can an atom emit or absorb a photon? Definition when an electron makes a transition between orbits Term What types of series does the Hydrogen atom have for each spectrum? Definition 1. Lyman Series of lines in Ultraviolet 2. Balmer Series in the visible 3. Paschen Series in the infrared Term What does the strength of spectral lines depend on? Definition the temperature of the star Term What is the star's spectral class determined by? Definition the absorption lines in its spectrum Term Why is the spectral sequence important? Definition because it is a temperature sequence Term What does the astronomer learn by classifying the star? Definition the temperature of the stars surface Term What can a spectrum tell you about the star? Definition the chemical composition Term What is the Doppler EffecT? Definition the change in the wavelength of radiation due to relative radial motion of source and observer Term What is a blue shift? Definition when a star is approaching and you observe slightly shorter wavelengths Term What is a red shift? Definition when a star is receding and you observe longer wavelengths Term what does the doppler effect reveal? Definition the stars radial velocity Term What is doppler broadening of spectral lines caused by? Definition motions of the atoms in a hot gas Term what is collisional broadaning caused by? Definition colliding of atoms Term What does broadening depend on? Definition temperature and density Term List six things that astronomers can study about a star just by receiving its light. Definition 1. total energy output 2. surface temperature 3. radius 4. chemical composition 5. velocity relative to earth 6. rotation period Term What are the particles that make up a nucleus? Definition protons and neutrons Term What is the most abundant atom? Definition Hydrogen Term TRUE OR FALSE: any energy can excite an electron Definition false, it has to be exactly the right amount of energy Term What does the color of the star tell us about? Definition temperature Term What is the spectrum of a stars light, or any nearly thermal spectrum, called? Definition black body spectrum Term the hotter the object is, what does it emit more of? Definition energy Term What is the first law of black body radiation? Definition the hotter an object, the more energy it emits Term According to the Wein's displacement law, as temperature increases, what does the peak wavelength of a blackbody spectrum do? Definition shifts toward shorter wavelengths Term What is the second law of Black Body Radiation? Definition That as the temperature increase, the peak wavelength of a blackbody spectrum shifts to shorter wavelengths Term A solid, liquid, or dense gas that is excited to emit light produces what kind of spectrum? Definition continuous spectrum Term A low density gas excited to emit light produces what kind of spectrum? Definition emission spectrum Term If light comprising a continuous spectrum passes through a cool, low-density gas, what will the result be? Definition an absorption spectrum Term If light comprising a continuous spectrum passes through a cool, low-density gas, what will the result be? Definition an absorption spectrum Term What are Kirchoff's three laws of radiation? Definition 1. a solid, liquid, or dense gas excited to emit light produces a continuous spectrum 2. a low-density gas excited to emit light produces an emission spectrum 3. if light comprising a continuous spectrum passes through a cool, low-density gas, the result is an absorption spectrum Term What kind of spectra are the spectra of starS? Definition absorption spectra Term What are the most prominent lines in many astronomical objects called? Definition Balmer lines of Hydrogen Term List the Spectral classes from highest temperature to lowest temperature. Definition O B A F G K M (Oh Be A Fine Guy, Kiss Me!) Term What can relative strengths of absorptions lines tell us about stars? Definition the composition of the stars Term If a light source is moving towards an observer what kind of shift is there? Definition a blue shift Term if a light source is moving away from an observer, what kind of shift is there? Definition a red shift Term What is radial velocity? Definition the component of velocity along your line of sight Term Does light excite electrons into higher or lower energy states? Definition higher Term the longer the wavelength, the higher or lower the temperature? Definition lower Term what is energy flux? Definition energy given off in form of radiation