ASTR 124
Terms
undefined, object
copy deck
- why can a good blacksmith judge the temperature of a piece of heated iron by its color?
- hot objects emit more black body radiation
- why do hot starts look bluer than cold stars
- hotter objects emit more blue
- use black body radiation to explain why you can light a cig with a match but not a bonfire
- ?????
- difference b/w a neutral atom, and ion, and an excited atom?
-
-ion-atom that has lost 1+ electrons
-excited atom-move electron in atom to higher energy level - how do energy levels in an atom determine which wavelength photons it can absorb or emit?
- atom drops from high to low energy level, emits photons. ?????
- what spectrum would you record observing molten lava? through glasses?
- continuous spectrum, w/ absorption lines caused by gases above.
- why does the strength of the Balmer lines depend on the temp. of the star?
- measure only absorption lines in 2nd energy level. cool stars have fewer violent collisions, excited atoms.
- why does a stellar spectrum tell us about the surface layers but not the deeper layers of the star?
- ?????
- why do we not see TiO bands in the spectra of hot stars?
- Absorption bands due to the molecule titanium dioxide (TiO). They are prominent in the spectra of K stars and M stars, which are cool enough for TiO to survive.
- if no visible lines of element in star, is element not present?
- star can be too hot or cold to produce certain lines of elements
- if star moves directly perpendicular to a line connecting to earth, will dopler effect change its spectrum?
- no, doppler effect can not be used to measure perp. lines
- why would we expect star that rotates rapidly to have broad spectral lines? what else could broaden lines?
- yes, motion smears spectral line. collision broadening smears spectral lines too. colliding atoms realease dif. levels of energy.
- human body temp. is 310K, at what wavelength do humans radiate the most energy? what kind of radiation?
- =3,000,000/T=9677.42
- star w/ surface temp. of 20000k, what wavelength will it radiate most energy?
- 3,000,000/20000=
- IR observations show that star is most intense at 2000 nm. what is temp. of star's surface?
- 3000000/2000=
- double black body temp. by what factor will total energy radiated per second per sq. meter increase?
- ??????
- star w/ temp. 6000 K, other star w/ temp. 7000 K, how much more energy/second will hotter star radiate from each sq. meter of its surface?
- 62,653,500
- transition A produces light w/ wavelength 500 nm. transition B involves 2x as much energy. what wavelength light does it produce?
- i have no fucking clue