# ASTR Midterm 1

 Given distance to object and object's disk in degree Asked to find diameter of object convert degree to arcsec Given semi-major axis of object orbiting the Sun Asked to find sidereal period Semi-major axis must be in AUsidereal period in seconds Given objects length (diameter) and angle it subtends Asked to find distance to object angle in arcsec Given mass of object (or ratio of mass) and semi-major axis Asked to find gravitational force Mass in kg and radius in meters Given force and object's mass Asked to find acceleration acceleration in meters/second Given sidereal period and semi-major axis of exoplanet Asked to find mass of star (allowed to assume mass of planet is negligible) a (semi-major axis) in metersP (sidereal period) in seconds Given objects distance from Sun and perihelion and aphelion Asked to find sidereal period  sidereal period in secondssemi-major axis in AU Given perihelion and aphelion Asked to find eccentricity of object's orbit e ⋅ a= semi-major axis - perihelion a is semi-major axis in AU Given exoplanet's mass and diameter Asked to determine weight on planet weight is forcemost likely asked to compare and set up ratio Given surface temperature star Asked to wavelength star radiates the most energy λ in meter Given surface temperature and radius of star Asked to find luminosity L=4⋅(pi)⋅R²⋅σ⋅T4 R in meters Given frequency of wave  Asked to find wavelenght Given wavelength of wave or photon Asked to find energy of wave or photon Given frequency of wave or photon Asked to find energy of wave of photon Given semi-major axis and period of planetary satellite Asked to find mass of planet (not satellite) P is secondsa in meters Given stellar luminosity and semi-major of orbiting planet Asked to find flux of star at planet L in watts d in metersF in W/m2 Given observed wavelength and laboratory wavelength Asked to determine is star is moving toward or away from observer Δλ=λobserved - λlaboratory Δλ is positive it is a redshift (moving away)Δλ is negative it is a blueshift (moving toward) Given observed and laboratory wavelengths Asked to determine velocity Given diameter of telescope Asked to find light gathering power light gathering power = d2  Given diameter of telescope and wavelength of light Asked to find resolving power θ=2.5×105 (λ÷D)  θ in arcsecλ in metersD in meters Given resolving power of telescope and distance to observable object Asked to determine size of smallest features the telescope can resolve α in arcsec Given surface temperature Asked to find flux F = σT4 F in W/m2 Given energy of wave or photon Asked to find wavelength Given luminosity and % mass converted to energy Asked to determine mass that is converted to maintain luminosity Three parts: Part one: Luminosity is measured in W which = J/s (convert is needed or just make connection)Part Two: Part Three: divide mass of part two by % mass Given parallax Asked to determine distance from us p in arcsecd in parsec Given distance and proper motion Asked to find tangential velocity vt = 4.74μd μ in arcsec per yeard in kmvt in km/s Given observed and laboratory wavelength Asked to find radial velocity Given radial velocity and tangential velocity Asked to find space velocity Given apparent brightness compared to Sun's and distance Asked to find luminosity of star Given star's distance and comparative brightness to star seen without telescope Asked for distance to be seen without telescope Given apparent magnitude of star and two telescope diameters Asked to determine magnitude of dimmest star seen through larger telescope Two Parts: Part One: Compare light gathering power to get ratio of brightness between viewed starsPart Two: Given apparent magnitude and parallax Two parts: Part One: Part Two: Given absolute magnitude of star (star1) and a ratio of luminosity  Asked to find absolute magnitude of another star (star2) Given apparent magnitude and absolute magnitude Asked to find distance to star Given semi-major axis and sidereal period of binary star system Asked to find sum of masses of two stars Masses in solar mass Given age of star cluster Asked to find mass of turn off star Authornikachan ID305620 Card SetASTR Midterm 1 DescriptionDeriving formulas from given information Updated2015-07-24T01:07:27Z Show Answers