Conceptual Question 3 Flashcards
What is the Gamow Peak?
likelihood of a nuclear fusion reaction occurring at a given energy when particle collisions happen
the product of the Maxwellian distribution and tunneling probability.
relates speed of particles and number of particles
In the main thermonuclear reaction in the sun one element is converted to another element, what are
these elements? How many nuclei of the first element are converted into one nucleus of the 2 nd?
The thermonuclear reaction converts hydrogen into helium.
Four hydrogen atoms is converted into one helium.
What is the Eddington luminosity?
The maximum limit on the luminosity of a star while in hyrdostatic equilibrium
What causes the interstellar extinction (dimming of light) in our galaxy?
the dimming of the light of distant star is due to the presence of dust in the ISM along the line of sight.
What is the Jeans mass?
For a cloud with a given density and a temperature the Jeans mass is the minimum mass necessary
to initiate the spontaneous collapse of the cloud.
What is an eclipsing binary?
An eclipsing binary consists of two close stars moving in an orbit so placed in space in relation to Earth that the light of one can at times be hidden behind the other.
What is electron degeneracy pressure
Electron degeneracy pressure arises from two fermions not being allowed to occupy the same quantum state at the same time. Electrons are forced into higher energy states creating a pressure the can support the core of a white dwarf from collapse due to gravity.
Does temperature play a role in electron degeneracy pressure? Why or why not
It doesn’t depend on temperature because it depends on quantum mechanic properties.
What are the sizes of typical white dwarf and neutron stars?
WD are about the size of the Earth but much denser than it. a neutron star is quite small about 12 miles in diameter. However it is very dense too.
What is the doppler method for finding exoplanets
method for finding exoplanets from radial velocity measurements. this is done by measuring Changes in the parent’s stars spectra due to the star wobbling indicates another object is exerting a force on it.
What is the transit method for finding an exoplanet
The transit method of finding exoplanets is when a planet passes directly between an observer and the star it orbits, it blocks some of that star’s light. The dips in light can be measured indicating the presence of an exoplanet.
How does the combination of the doppler and transit methods yields the density of the exoplanet?
The Doppler method allows us to estimate the mass of a planet. And from transit techniques we can measure the planet’s size. This is a combination that can be used to derive the average density (mass/volume) of the planet.
