Karteikarten
Definitions Astrophysics
Karten in diesem Stapel (45)
- 1Time for Earth to do one full revolution23 hours 56 minutes
- 2Precessionturning effect, pulling the axis of rotation slightly out of line
- 3Time for Moon to orbit Earth27,3 days
- 4Official defiition of a planet, International Astronomical Union (IAU)A 'planet' is a celestial body that (a) is in orbit around the sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit
- 5MercuryOrbit radius (m): 5.79 x 10^10
Mass (kg): 3.3 x 10^23
Radius (m): 2.44 x 10^6
Period: 88.0 days - 6VenusOrbit radius (m): 1.08 x 10^11
Mass (kg): 4.87 x 10^24
Radius (m): 6.05 x 10^6
Period: 224.7 days - 7EarthOrbit radius (m): 1.50 x 10^11
Mass (kg): 5.98 x 10^24
Radius (m): 6.38 x 10^6
Period: 365.3 days - 8MarsOrbit radius (m): 2.28 x 10^11
Mass (kg): 6.42 x 10^23
Radius (m): 3.40 x 10^6
Period: 687.0 days - 9JupiterOrbit radius (m): 7.78 x 10^11
Mass (kg): 1.90 x 10^27
Radius (m): 6.91 x 10^7
Period: 11.86 years - 10SaturnOrbit radius (m): 1.43 x 10^12
Mass (kg): 5.69 x 10^26
Radius (m): 6.03 x 10^7
Period: 29.42 years - 11UranusOrbit radius (m): 2.88 x 10^12
Mass (kg): 8.66 x 10^25
Radius (m): 2.56 x 10^7
Period: 83.75 years - 12NeptuneOrbit radius (m): 4.50 x 10^12
Mass (kg): 1.03 x 10^26
Radius (m): 2.48 x 10^7
Period: 163.7 years - 13Asteroidssmaller orbiting bodies
- 14Cometssmall orbiting body, unlike asteroids it's made up of loose particles of ice and rock, forming a tail
- 15Starsall shapes, sizes and colours
massive balls of plasma - 16Constellations'join the dots'
the stars are not related by anything physical except maybe that they are all bright - 17Stellar clustergroup of stars that are physically close together rather than looking as if they are
formed by the collapse of a gas cloud - 18Astronomical Unit (AU)1.5 x 10^11 m
distance between Sun and Earth - 19Light year (ly)9.46 x 10^15 m
distance travelled by light in one year - 20Parsec (pc)3.26 ly
defined in terms of the angle subtended at the star
defined by making a triangle between Earth, Sun and distant object. if the angle at the distant object is 1 arcsec then it is 1 parsec away - 21Galaxylarge collection of stars held together by gravity, between 10^3 and 10^5 ly across
- 22Stable starisn't getting bigger or smaller
- 23Luminosity (L)the total amount of energy emitted by the star per second
- 24Apparent brightness (b)the amount of energy per second receiver per unit area
b=L/4(pi)d^2
unit: W m^-2 - 25Stefan-Boltzmann lawpower per unit area =(S-B constant)T^4
- 26If a star has surface area A, temperature T, then the total power emitted (L) is given by...L= (S-B constant)AT^4
- 27O B A F G K MTemperature, colour
30 000- 60 000, blue
10 000- 30 000, blue-white
7 500 -10 000, white
6 000- 7 500, yellow-white
5 000- 6 000, yellow
3 500- 5 000, orange
2 000- 3 500, red - 28Red (doppler) shiftlonger wavelength
moving away - 29Blue (doppler) shiftshorter wavelength
moving closer - 3090% of stars on H-R diagrammain sequence stars
- 31Giantscool star that gives out lots of energy
- 32Supergiantsvery big cool star
- 33White dwarfssmall hot stars
- 34Variable starshas a changing luminosity, position on H-R diagram is not constant
this is due to a change in size of the star, this variation is sometimes cyclid as in a Cepheid variable - 35Binary starspairs of stars that orbit eachother
- 36Visual binariescan be seen to rotate around eachother
some binaries are too far away or too small to resolve the individual stars; we only know they are binaries due to fluctuations in the light we receive - 37Eclipsing binariesbinary stars which orbits causes them to periodically pass between the Earth and each other, causes a reduction in the stars apparent brightness
- 38Spectroscopic binarybinary stars which, in their orbit, are sometimes moving towards the Earth and sometimes away,
this will cause a varying Doppler shift in the light received on Earth - 39Stellar parallax...?
- 40Spectroscopic parallax...?
- 41Secondone degree can be split up into 60 arc minutes and each arc minute into 60 arc seconds, so there are 3 600 arc seconds in one degree
in radians, 1 arc second is therefore (1/3600) x (2(pi)/360) - 42Standard candle (Cepheid variables)knowing the luminosity of a candle you can use it to measure distance.
the further away, the dimmer.
since the luminosity of Cepheid variables is known they can be used in the same way - 43Cepheid variableunstable star that undergoes periodic expansions and contractions, leading to a periodic change in the apparent brightness
- 44Apparent magnitude (m)a+1 was 100 times brighter than a+6
starting from the dimmest each step in magnitude is therefore 2.512 times brighter than the previous - 45Absolute magnitudemeasure of luminosity
the magnitude of a star viewed from a distance of 10 pc
Informationen
- Beschreibung
- physics HL, chapter 10 Don't know if any of these are redundant though
- Erstellt von
- Moa Lindström
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- 70
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