... & fuse – form heavier
Lecture13 - University of Waterloo
... neutrinos (by a factor 2-3) than were expected from the PP-chain
reactions. This problem existed for about 30 years.
The solution to the problem was
suggested by results from the
Super-Kamiokande detector in
The Sun - University of Redlands
... At and above the corona:
Gas is very hot
Like steam above our boiling pot of water, the gas
• Wind passes out through Coronal Holes
• Solar Wind carries away a million tons of Sun’s
mass each second!
• Only 0.1% of total Sun’s mass in last 4.6 billion
... One way out: maybe neutrinos do have mass (unlike
photons), in which case they can spontaneously
transform into other types of neutrinos, along their path
from the earth to the sun, which would not be detected
by the experiments. These possible transormation
among neutrinos are called “neutrino osc ...
... • Class G
• Color Yellow
• Surface Temperature 5,000 – 6,000 ºC
• Elements hydrogen and helium
• Greek word for Sun is Helios
... The center of the sun
Very, very hot
At the core, gravity pulls
all of the mass inward
and creates an intense
pressure. The pressure is
high enough to force
atoms of hydrogen to
come together in nuclear
fusion reactions -something we try to
mirror here on Earth.
... a. Stability of the Sun: balance between gravity and pressure (so-called hydrostatic equilibrium –
meaning static water, but the sun is not made of water!)
b. Zones of the Sun: energy production (at the core) and transport (from the core out of the Sun).
c. Characteristics of the outer layers – phot ...
Comparing Earth, Sun and Jupiter
... The density, pressure and temperature are
related by the equation of state, which can
usually be approximated as the ideal gas law.
... —The Deep Insight Pursued by Ray Davis
The “missing solar neutrinos” problem was real
Contributions from Canadian and Japanese scientists
Efficiency of the proton-proton chain reactions
Introduction to Astronomy
... • This heat allows fusion to occur in a shell of material
surrounding the core…
• Due to the higher central temperature, the star’s
luminosity is greater than before…
• This increased energy production causes the outer part
of the star to expand and cool (counterintuitive!)…
• We now have a very lar ...
Sun: The Nearest Star
... It contains approximately 98% of the total solar system mass.
It is a G2 type star.
Its interior could hold over 1.3 million Earths.
The Sun's outer visible layer is called the photosphere and has a temperature of 6,000°C (11,000°F).
The core has a temperature (15,000,000° C; 27,000,000° F) and pres ...
sep04 neutrinos - Charles J Horowitz
... ½… The mass of the neutrons should be of the same order as the
electron mass and in any event not larger than 0.01 proton
masses. The continuous beta spectrum would then be explained
by the assumption that in beta decay a neutron is emitted in
addition to the electron such that the sum of the energi ...
... that we can see
The “surface” of the
The sun does not
have a solid surface,
just a giant ball of gas
... • If the photon has the right energy, it will be absorbed by an atom and raise an
electron to a higher energy level
• Creates absorption spectra, a unique “fingerprint” for the star’s composition.
The strength of this spectra is determined by the star’s temperature.
... these as well as:
density in atmosphere
gravity at surface
velocity of star towards or from us
Helioseismology and the Helium Abundance
... It takes only a brief scrutiny of the equations describing the structure and
dynamical evolution of the Sun (it is not quite so brief to derive them) and the
equations governing the low-amplitude seismic modes of oscillation to
appreciate what broadly can, at least in principle, be reliably inferred ...
Standard solar model
The standard solar model (SSM) is a mathematical treatment of the Sun as a spherical ball of gas (in varying states of ionisation, with the hydrogen in the deep interior being a completely ionised plasma). This model, technically the spherically symmetric quasi-static model of a star, has stellar structure described by several differential equations derived from basic physical principles. The model is constrained by boundary conditions, namely the luminosity, radius, age and composition of the Sun, which are well determined. The age of the Sun cannot be measured directly; one way to estimate it is from the age of the oldest meteorites, and models of the evolution of the Solar System. The composition in the photosphere of the modern-day Sun, by mass, is 74.9% hydrogen and 23.8% helium. All heavier elements, called metals in astronomy, account for less than 2 percent of the mass. The SSM is used to test the validity of stellar evolution theory. In fact, the only way to determine the two free parameters of the stellar evolution model, the helium abundance and the mixing length parameter (used to model convection in the Sun), are to adjust the SSM to ""fit"" the observed Sun.