The Traveling Exhibit. Alien Earths. Science Background Part B: Star & Planet Formation. prepared by Dr. Cherilynn Morrow for the Space Science Institute Boulder, CO. B. Star and Planet Formation. KEY QUESTIONS: Where do stars & planets we observe in the galaxy come from?
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Part B: Star & Planet Formation
prepared by Dr. Cherilynn Morrow for the Space Science Institute Boulder, CO
Where do stars & planets we observe in the galaxy come from?
Around which kinds of stars should we look for signs of life?
“One important object of this original spectroscopic investigation* of the light of the stars and other celestial bodies, namely to discover whether the same chemical elements as those of our earth are present throughout the universe, was most satisfactorily settled in the affirmative; a common chemistry, it was shown, exists throughout the universe.”
- Sir William Huggins
*In 1859, Huggins began observing the stars using Bunsen's and Kirchhoff's discoveries that spectral emission and absorption lines could reveal the composition of the source.
Where do stars and planets come from?
Early star-planet system in formation
Why search for planets and life around Sun-like stars ?
Cat Eye Nebula
Stars have “life cycles”. They are “born” and they “die” but are not alive like us.
Stars like the Sun “die” by “puffing” off their outer layers of gas and dust. This process creates a beautiful variety of NEBULAE in the Milky Way GALAXY.
Stars Have “Life” Cycles
Crab Nebula: Supernova Remnant
Supernovas help ensure that heavier elements and complex molecules are found throughout interstellar space.
Artist’s concept of the formation of OUR SOLAR SYSTEM
1. Something (perhaps a supernova) triggers the gravitational collapse of a nearby interstellar cloud. The cloud naturally heats up and spins faster as it collapses. Collisions between particles flatten the cloud into a disk.
2. The Sun and planets start to form in this spinning, flattened disk (proto-planetary disk), with the Sun at the hottest central part.
3. In our Solar System, Earth formed in the inner region of the disk where rocky & metallic material could condense in the greater heat. Ices & hydrocarbons settled in the outer regions where gas giants like Jupiter form.
4. Computer models tell us that Jupiter’s gravity played a strong role in causing comet & asteroid impacts to supply water & organic materials to Earth from the outer solar system, thus contributing to its habitability.
These large clouds of gas and dust in our Milky Way galaxy are the types of regions where many stars are forming: Orion and Eagle NEBULAS.
Our entire solar system would fit in this small nub
Proto-planetary disks around young stars in the Orion Nebula.
The disks range in size from 2 to 8 times the diameter of our Solar System.
Where do stars and planets come from?
NASA’s Spitzer Spacecraft
looking down at nebula
The monitor displays what the IR camera is “seeing”
Our hands look red on the screen. We emit IR light!
Yes! I wonder what’ll happen if we put our eyeglasses under the IR camera?
Heat source beneath the nebula on the round table
Infrared (IR) Camera Interactive
star forming region
There are round heat sources beneath the nebula on the table which cannot be seen with the human eye, but which are being “seen” by the infrared camera and recorded on the monitor. The IR light “shines” right through the table! In a similar way, the Spitzer Telescope can detect infrared radiation shining through dusty interstellar clouds revealing young stars in formation.
Design a Solar System
“Hey, I can drag a bunch of planets in orbit around a star and then let them zoom around to see if they will fly out of the system, or crash into each other, or be gobbled up by the star!”
Based on real, multi-body model simulations of the stability of planetary orbits.
Elements heavier than Hydrogen & Helium form inside stars and then are released back into the galaxy when stars “die”. Thus materials that are the “building blocks” for life & Earth-like planets are found throughout interstellar space.Planets sometimes form along with a central star out of a common swirling disk of gas and dust. Our search for life beyond our Solar System requires knowing where and how this process occurs. Perhaps the best chance to find an “Alien Earth” is to look around stars that are most like our Sun.