Possible Planet near newly formed protostars in a molecular cloud in Taurus.
It might have been dismissed as a background star if not for the presence of a bizarre
130-billion-mile-long filamentary structure that bridges the space between the
binary pair and the candidate protoplanet.
The candidate protoplanet is now 130 billion miles from the parent stars and
predicted to be hurtling into interstellar space at speeds up to 10 kilometers/sec
-- destined to forever drift among the Milky Way's starry population.
If the object is a few hundred thousand years old, the same age as the
newly formed star system which appears to have ejected it, then it is estimated
to be 2-3 times the mass of Jupiter, the largest gas giant planet in our Solar
System.
Properties of the Solar System [likely a result of the method of formation of the system] 1. Discrete Planets well separated 2. Nearly Circular Orbits 3. All Orbits in nearly the same Plane 4. All Planets and most satellite orbit counterclockwise (as seen from the north) 5. Rotation of Most Planets and Satellites is counterclockwise 6. Terrestial and Jovian Planets quite distinct in properties (Solar System Differentiated) 7. Asteroid Belt at boundary of Jovian and Terrestial Systems contain different from both and ancient 8. Comets are primitive, and orbit very far from the Sun. 'Recent' Properties of the Solar System Objects [due to processes since formation of the Solar System] 1. Spin-Orbit coupling of Mercury-Sun and Venus-Earth and most of the Satellites of Jupiter and Saturn 2. Kirkwood gap in asteroid orbits, and shepherding of ring 3. Retrograde motion of satellites of Jupiter, Saturn, and Neptune Our Solar System is not unique in the Galaxy 1. beta Pictoris (nebular disk) See figure 15.2 2. Giant Planet seen by HST in Taurus (see above) 3. Many planets detected around pulsar and other stars [Interlude 15-1] 51 Pegasis 0.5 MJ at 0.05 AU 70 Viginis 8.0 MJ at 0.6 AU 47 Ursa Majoris 2.5 MJ at 2.2 AU [Method uses very sensitive measurements of the doppler shifts of star to determine very slight wobbles of the Star due to motion about its center of mass which is not at the center of the star due to a massive planet orbiting the star]
Conservation of Angular Momentum and Collapsing Planetary Nebulae
Since there are no torques acting on the rotating object,
its angular momentum will not change.
Angular Momentum ~ Mass x (size)2 x angular velocity
In this case the 'size' is represented by its radius
As the radius decreases the angular velocity must increase as
the inverse of the square of the radius.
If the nebula collapses to 1/10 its original radius, its angular
velocity will increase 100 times the origin angular velocity.
ie. if the nebula rotated once every 20,000 years then when it collapsed
it would rotate once every 200 years.
NOTE: Why is the Sun not rotating faster?
The sun has most of the mass of the Solar System and should therefore
have most of the angular momentum - BUT it does not Jupiter does.
Angular momentum Sun -> 0.000006
Jupiter -> 0.02
Solar nebula was ionized and interacted with the Sun's magnetic field
=> Magnetohydrodynamic Braking
Angular Momentum was transferred to the Solar Nebula
Planet Formation in the Solar Nebula
Proto-planety Disk
Image of a circumstellar dust disk being
evaoported by nearby energetic stars. (Size ~ 100 AU)
Image of Trapezium stars (Orion) in which it occurs
Content: Gas (hydrogen and helium + trace other gases)
Dust (formed in the atmosphere of cool stars)
Condensation and collapse of the nebula
1. nuclei for condensation
2. radiation of infrared to cool the nebula
and allow it to collapse
Planet Formation
1. Matter accumulates around dust grains
1 cm, 10 cm, then 30 cm in size
2. 'Soft' Collision and sticking = Accretion
Planetesimal Size 1 km - 100 km
3. Increased gravitation spheres of influence
and 'Hard' Collision and Fragmentation
4. A few planetismal survive to grow to Planet Size
1000 - 10000 km size by 100,000,000 years
5. Clearing the Solar System
a. Sweeping up of gas by Jovian Planets
b. Heavy bombardment of Planet and planet satellite
surfaces by planetismals
c. Ejection of cometary material by the gravity of the large
planets to the outer solar system
and formation of the Kuiper Belt
[1 billion years]
Differentiation
1. Heating of the Solar Nebula during collapse
~ 3000 K at center
~ 100 K at 10 AU
2. Evaporation of dust grains near the center
3. Gas nebula cools
4. Condensation of dust grains at various distances
from the Sun depending on the condensation
temperature of the material
water -> 273 K
iron -> 1300 K
Silicon -> 1400 K
Potassium -> 1100 K
Sulfur -> 700 K
5. Volatiles under represented in the Inner Solar System
(including water)
6. Gases and volatives collected by the Jovian Planets
and satellites
Gravitational Effects of Giant Planets
1. Distrupted Asteroid Belt area - no accretion
Asteroids made of ancient solar materials
2. Ices and Planetismals of outer solar system
flung into Kuiper Belt area
(Comets and distant asteroids)
Catastrophic Collisions and other gravitational effects on Solar System
1. Mercury's Large Iron core => collision of two planets
2. Venus' Slow Retrograde Rotation => collision and merging
3. Earth-Moon System => Collision formed Moon
4. Mars' Volcanic North hemisphere and cratered southern,
=> planetesimal hit and melted northern hemisphere
5. Uranus 98 deg axial tilt => Grazing collision?
6. Miranda's bizarre surface due to a collision
7. Retrograde Satellites of Jovian Planets => asteroids and planetismal
8. Pluto => one of the many Kuiper Belt objects
Astronomy 2 Next Term - The Sun, Stars, Clusters, Nebula, Galaxies, and the Universe