This week is going to be slightly more challenging, as I’ve included harder questions and for some – you’ll need to explain why.
The binary star Algol consists of a 3.7M sun main sequence star and a 0.8 M sun subgiant star. What’s odd about this pairing?
Stars are close enough that matter can flow from the sub-giant onto the main sequence star. The star that is now a subgiant was originally more massive. As it reached the end of its life and began to grow, it transferred mass to its companion star (mass exchange- can alter lives of stars w/ close companions).
Stages of low-mass star:
H to He in core, H to He fusion in shell around contracting core, He to C fusion in core, double-shell burning – becomes white dwarf (protostar, main-sequence, red giant, white dwarf)
Stages of high-mass star:
same as low-mass, multiple shell burning, supernova (iron core collapses) – becomes neutron star, black hole, or nothing.
Suppose that we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same time, which galaxy in the picture is the youngest?
The one that is farthest away
What are the necessities for life?
Nutrients, energy, liquid water
What clues to our galaxy’s history do halo stars hold?
They’re all old, w/ a smaller portion of heavy elements than disk stars, indicating that halos formed 1st.
What lies in the center of our galaxy?
Orbits of stas near the center of our galaxy indicate the existence of a black hole w/ 4 million times the mass of the sun.
What might dark matter be made of?
There does not seem to be enough normal (baryonic) matter to account for all the dark matter, so it is probably made of particles that haven’t been discovered yet (non-baryonic).
What force keeps you from sinking to the center of the Earth?
Magnetism
What were conditions like in the early universe?
It was so hot and dense that radiation was constantly producing particle-antiparticle pairs.
What aspects of the universe were originally unexplained by the Big Bang Theory?
The origin of structure, the smoothness of the universe on large scales, the nearly critical density of the universe.
What is the history of the universe according to the Big Bang?
As the universe cooled, particle production stopped, leaving matter instead of anti-matter. Fusion turned the remaining neutrons into helium.
Radiation traveled freely after the formation of atoms.
What causes gamma-ray bursts?
At least some come from supernova explosions.
What does our galaxy look like?
Our galaxy consists of a disk of stars and gas, w/ a bulge of stars at the center of the disk, surrounded by a large spherical halo.
What causes solar activity?
The stretching and twisting of magnetic field lines near the sun’s surface causes solar activity.
What is the sun’s structure?
Layers from inside out: core, radiation zone, convection zone, photosphere, chromosphere, corona.
What would happen inside the sun if a slight rise in core temp led to a rapid rise in fusion energy?
The core would expand and cool.
Why? Decline in core temp causes the fusion rate to drop, so the core contracts and heats up. Rise in core temp causes fusion rate to rise, so core expands and cools down.
What are the 2 types of star clusters?
Open clusters are loosely packed and contain up to a few thousand stars. They range in age from <10 million years old to >7 billion years old. Globular clusters are densely packed and contain hundreds of thousands of stars that are about 1 billion years old.
What would happen to a contracting cloud fragment if it were not able to radiate away its thermal energy?
It’s internal pressure would increase.
Why?
The cloud can prevent a pressure buildup by releasing heat (by converting thermal energy into infrared and radio photons that escape the cloud).
What would happen to a protostar that formed w/o any rotation at all?
It would not have any planets because planets need to rotate in order to be accreted.
What happens when a star can no longer fuse H to He in its core?
Core will shrink and heat up.
Post today sponsored by the Top Tree Removal Experts in Albany, NY. Visit their website for more information.