Interim Report
DESCRIPTION:
The main focus of our project is to look
at Supernovae as one possible end result in stellar evolution. Over
the course of this quarter we’re trying to understand the historical significance
of how different cultures in the past have interpreted supernovae, specifically
the differences between how the Chinese and the European cultures incorporated
supernovae into their cosmologies. We’re also investigating the current
scientific understanding of the physics behind how supernovae work and
the conditions necessary for a star to go supernova. And we will
also observe stars that are in their last stages and we will try to determine
whether they have enough mass to actually become a supernova and the possible
outcomes (i.e. neutron star, black hole).
PROGRESS:
Chinese and European cultures historically
have had contrasting views of the structure of the cosmos in general.
Prior to Brahe and Kepler there are few supernovae recorded in Europe.
This is a surprise considering there were many sightings in China, Japan,
and the Middle East that should have been visible in Europe. This
is due to the prevailing view accepted in Europe, but put forth by the
Greek philosopher Aristotle that the “heavens” are unchanging. According
to Aristotle the Earthly world was changing but the celestial realm of
stars and planets was not. (Hawley and Holcomb p. 26) The Chinese
on the other hand viewed the cosmos as spontaneously self-generating with
no outside forces acting upon it (Ren p.100). Chinese Emperors relied
on astronomers/astrologers to constantly observe and record changes in
the heavens which were interpreted to be connected to future changes within
the political arena, social stability, and natural phenomena. Because
of this, they recorded many celestial events including comets, meteor showers,
changes in the weather, and “guest stars”. These records give us
the most complete and continuous astronomical record of events prior to
Brahe and Kepler.
Type II supernovae are one possible
end result of stellar evolution. It involves stars so massive that
they produce high enough temperatures through gravitational energy to continue
the chain of nuclear reactions beyond the main sequence. These stars
are known as giants but not all giants are massive enough to become a supernova.
In stars that develop iron cores that reach the weight of more then 1.4
solar masses, the electrons orbiting the iron nuclei do not provide enough
force to hold up the mass of the star. This causes the core to be
compressed until it reaches nuclear density, the density in the nucleus
of an atom. The protons and electrons are fused together by the force
of gravity releasing countless neutrinos. The sudden halt in the compression
results in an outward moving shockwave that is contained by the outer layers
of the star falling toward the core. It is thought that the energy
released in neutrinos is enough to propel the shockwave through the collapsing
outer layers blowing off most of the outer mass. The outer mass expands
from the explosion eventually forming a nebula. The remaining star
can form a neutron star or it can keep collapsing into a black hole depending
upon it’s initial mass.
We’ve done a few observations of Betelgeuse,
and Antares. We still need to find spectra for these stars and determine
if they are massive enough to go supernova. And possible results
after the core collapse.
GOALS:
Our goals are to observe more K and M Type Stars,
obtain spectra, and luminosity data for these stars, analyze data to determine
possible remnant type star, organize our web page, making a list of sites
we want to link to, and gather pictures and graphics for our site.
TASKS:
Jesse: Cosmology (draft) Chinese emphasis, gather
data for observations, web page design
Scott: Science (draft) observe, cosmology (European
emphasis)
Team: Rewrite science and cosmology aspects, observe,
and work on web page together