A.​​​ easuring​ ​and​ ​Comparing​ ​Stars 1.​​ ​The​ ​apparent​ ​brightness​ ​of​ ​a​ ​star​ ​is​ ​determined​ ​by​ ​distance​ ​and​ ​intrinsic​ ​brightness (luminosity) a)​​ ​luminosity-​ ​measure​ ​brightness,​ ​distance,​ ​and​ ​calculate​ ​the​ ​luminosity 2.​​ ​Parallax​-​ ​the​ ​shift​ ​with​ ​respect​ ​to​ ​the​ ​background​ ​objects a)​​ ​depth​​ erception​ ​comes​ ​from​ s ​ tereoscopic​ v ​ ision b)​​ ​The​ ​greater​ ​the​ arallax​ ​the​ ​smaller​ t​ he​​ istance. 1)​The​ ​parallaxes​ ​of​ r​ eal​ ​stars​ ​ar​ iny c)​​ ​make​ ​two​ ​ easurements,​ 6 ​​ ​ ​months​ ​ part 3.​​ ​​Angular​ ​separation​-​ ​p(arcsec)=​ ​1/d(parsec) a)​​ ​parsec​ ​3.26​ ​light​ ​years 4.​​ ​​Luminosity​-​ ​the​ ​amount​ ​of​ ​light​ ​emitted​ ​by​ ​an​ ​object a)​​​ tar’s​ ​intrinsic​ ​brightness 1)​​ ​a​ ​dim​ ​star​ ​could​ ​have​ ​a​ ​low​ ​luminosity​ ​or​ ​be​ ​far​ ​away;​ ​a​ ​bright​ ​star could​ ​be​ ​close​ ​ r​ ​have​ ​a​ ​high​ ​luminosity b)​​ ​Surface​ ​temperature​ ​of​ ​stars-​ ​use​ ​Wien’s​ ​law​ ​​ ​0.29cm*K/t(k) 1)​​ ​The​ ​​Stefan​ ​Boltzmann​ ​law​​ ​hotter​ ​blackbody​ ​emits​ ​more​ ​radiation​ ​at every​ w ​ avelength​ ​than​ ​does​ ​a​ ​cooler​ ​blackbody (a)​​