AST251H1 Lecture : AST251 MARCH 19.docx

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salmondog80

24 Mar 2012

School

UTSG

Department

Astronomy & Astrophysics

Course

AST251H1

Professor

Susan Pfieffer

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Document Summary

Mars warmer, may have liquid water on mars today. Jupiter 62 moons saturn 60 and uranus 27 and 13 for neptine. By galileo, looked at jupiter dots always appeared in line and orbited jupiter as jupiter moved not fixed stars. Obkects circle jup not outrageous circle around sun. Biggest moon staurn was tian by huygens after the probe. Io eurp, gan and calisto distance closer to far, size of moon, 4 moons part of the large jovian moons. Gan big the mercury and pluto can deform rocks in circle shape and orbit in equatorial plane of planet. Sun in middle, gas disk in middle for planetismals, gaseous outer planets have own disks, centur jupoiter around form seprearte planetiskmals mini solar systems same rot as big planet. One exception is trition opp of neptune and not in equatroal plane it was captured triton like. Pluto happen come to close and captured by it.

Related Questions

Which, if any, of the following statements is/are true?

1)Our galaxy, The Milky Way, is a member of The Local Group, whichis one of several groups of galaxies located in the VirgoSupercluster.
2)Most astrophysicists believe that our Solar System formed from animmense cloud of gas and dust about 4-1/2 million years ago.
3)Planets are believed to have formed by a process known asaccretion.
4)Two key elements in the Condensation Theory of PlanetaryFormation are 5)Conservation of Angular Momentum and CondensationNuclei.
6)The name of the second largest object in the Universe is TheSouthern Wall.
7)In our Solar System, the four jovian planets, Jupiter, Saturn,Uranus, and Neptune, are separated from the four terrestrialplanets, Mercury, Venus, Earth, and Mars, by the Kuiper Belt.
8)Our star, The Sun, is located on the Orion Arm, about 26,000light-years from the center of the Andromeda Galaxy.
9)It takes a photon of light about 4-1/5 years to travel from ourSolar System to the second closest star to Earth, ProximaCentauri.
10)The full range of human knowledge about our Universe spans about40 or 41 orders of magnitude on a spatial scale and about 13.7billion years on a temporal scale.
11)It takes a photon of light about 5-1/2 hours to travel from theSun to the orbit of the former planet Pluto.

An extrasolar planet can be detected by observing the wobble itproduces on the star around which it revolves. Suppose anextrasolar planet of mass mb revolves around its star of mass ma .If no external force acts on this simple two-object system, thenits CM is stationary. Assume ma and mb are in circular orbits withradii ra and rb about the system's CM.

(a) Show that ra =(mb/ma)rb

(b) Now consider a Sun-like star and a single planet with the samecharacteristics as Jupiter. That is, mb = (1.0 x 10^-3)ma and theplanet has an orbital radius of 8.0 x 10^11 meters. Determine theradius ra of the star's orbit about the system's CM.

(c) When viewed from Earth, the distant system appears to wobbleover a distance of 2ra . If astronomers are able to detect angulardisplacements ? of about 1 milliarcsec (1 arcsec = 1/3600 of adegree), from what distance d (in light years) can the star'swobble be detected (1 ly = 9.46 x 10^15 m)?

(d) That star nearest to our Sun is about 4 ly away. Assuming starsare uniformly distributed throughout our region of the Milky WayGalaxy, about how many stars can this technique be applied to inthe search for extrasolar planetary systems?

An extrasolar planet can be detected by observing the wobble itproduces on the star around which it revolves. Suppose anextrasolar planet of mass mb revolves around its star of mass ma .If no external force acts on this simple two-object system, thenits CM is stationary. Assume ma and mb are in circular orbits withradii ra and rb about the system's CM.

(a) Show that ra =(mb/ma)rb

(b) Now consider a Sun-like star and a single planet with the samecharacteristics as Jupiter. That is, mb = (1.0 x 10-3)ma and theplanet has an orbital radius of 8.0 x 1011 meters. Determine theradius ra of the star's orbit about the system's CM.

(c) When viewed from Earth, the distant system appears to wobbleover a distance of 2ra . If astronomers are able to detect angulardisplacements ? of about 1 milliarcsec (1 arcsec = 1/3600 of adegree), from what distance d (in light years) can the star'swobble be detected (1 ly = 9.46 x 1015 m)?

(d) That star nearest to our Sun is about 4 ly away. Assuming starsare uniformly distributed throughout our region of the Milky WayGalaxy, about how many stars can this technique be applied to inthe search for extrasolar planetary systems?

AST251H1 Lecture : AST251 MARCH 19.docx

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