ASTR3007/4007/6007, Tutorial 4: Deuterium Burning in Protostars
... the polytropic constant KP in terms of M , R, ξ1 , and dΘ/dξ|ξ=ξ1 . Exercise 2. Using the polytropic constant KP from exercise 1, and the relationship between central density ρc and KP , to express the central density in terms of M , R, ξ1 , and dΘ/dξ|ξ=ξ1 . Exercise 3. Finally, express the central ...
... the polytropic constant KP in terms of M , R, ξ1 , and dΘ/dξ|ξ=ξ1 . Exercise 2. Using the polytropic constant KP from exercise 1, and the relationship between central density ρc and KP , to express the central density in terms of M , R, ξ1 , and dΘ/dξ|ξ=ξ1 . Exercise 3. Finally, express the central ...
Answer Key
... 20. The distance to the globular cluster M55 has been determined to be 6500 pc by analysis of the variable RR Lyrae stars in the cluster. How does the apparent brightness of these stars compare with the apparent brightness of the Sun? (Hint: RR Lyrae stars are believed to have a luminosity of about ...
... 20. The distance to the globular cluster M55 has been determined to be 6500 pc by analysis of the variable RR Lyrae stars in the cluster. How does the apparent brightness of these stars compare with the apparent brightness of the Sun? (Hint: RR Lyrae stars are believed to have a luminosity of about ...
bildsten
... • Acoustic waves seen in nearly all evolved stars with amplitudes of 3-200 parts per million. • Measured frequency spacing and maximum observed frequency give R, M and D for >10,000 stars across the galaxy. Great test for GAIA and new galactic science enabled. • Useful diagnostics for extra-solar pl ...
... • Acoustic waves seen in nearly all evolved stars with amplitudes of 3-200 parts per million. • Measured frequency spacing and maximum observed frequency give R, M and D for >10,000 stars across the galaxy. Great test for GAIA and new galactic science enabled. • Useful diagnostics for extra-solar pl ...
The Hertzsprung-Russell diagram and the nature of stars
... up? • Physical argument 2: what powers the stars (where do they get their energy supply?) ...
... up? • Physical argument 2: what powers the stars (where do they get their energy supply?) ...
All_Stars
... outwards against the gravitational forces. At the same time the gas cloud will be losing thermal energy through radiation so this increase in pressure is usually not enough to halt the collapse. ...
... outwards against the gravitational forces. At the same time the gas cloud will be losing thermal energy through radiation so this increase in pressure is usually not enough to halt the collapse. ...
Lecture Nine (Powerpoint format) - Flash
... Most of a star’s lifespan is spent on the main sequence burning hydrogen. The later phases of its lifespan occur progressively quicker and account for a shorter portion of its lifespan. ...
... Most of a star’s lifespan is spent on the main sequence burning hydrogen. The later phases of its lifespan occur progressively quicker and account for a shorter portion of its lifespan. ...
That is an irrelevant question, Ms Gajda, there was no
... 5. Gravity begins forming stars and galaxies after 1 billion years 9. What existed before the Big Bang? What was created at the Big Bang? That is an irrelevant question, Ms Gajda, there was no time before the Big Bang therefore is there no “before”. Time, space, matter, energy were created with the ...
... 5. Gravity begins forming stars and galaxies after 1 billion years 9. What existed before the Big Bang? What was created at the Big Bang? That is an irrelevant question, Ms Gajda, there was no time before the Big Bang therefore is there no “before”. Time, space, matter, energy were created with the ...
2.5.4 astronomical distances Parallax and Distances to Stars
... is NOT a definition of time. It is the distance that light can travel through a vacuum in 1 year. If you work it out it is – 9.461 x 1015m When you consider the ridiculous distance involved in astronomy, it makes sense to have large units! ...
... is NOT a definition of time. It is the distance that light can travel through a vacuum in 1 year. If you work it out it is – 9.461 x 1015m When you consider the ridiculous distance involved in astronomy, it makes sense to have large units! ...
10.2 Galaxies
... • If the nebula cloud is massive enough, gravity within the cloud will be large enough to shrink it and to raise its temperature above 10 000 000 degrees celsius, a temperature at which atomic fusion happens, releasing huge amounts of energy in the form of all kinds of electromagnetic radiation (gam ...
... • If the nebula cloud is massive enough, gravity within the cloud will be large enough to shrink it and to raise its temperature above 10 000 000 degrees celsius, a temperature at which atomic fusion happens, releasing huge amounts of energy in the form of all kinds of electromagnetic radiation (gam ...
Star Formation - University of Redlands
... Cold clouds can be tens of parsecs across. Thousands of times the mass of the Sun. Temperatures 10 – 100 K. In such a cloud: – Something makes a region denser than normal. – Force of gravity draws material to denser region. – Gravitational collapse begins. ...
... Cold clouds can be tens of parsecs across. Thousands of times the mass of the Sun. Temperatures 10 – 100 K. In such a cloud: – Something makes a region denser than normal. – Force of gravity draws material to denser region. – Gravitational collapse begins. ...
Earth Science – Quiz 2
... 40. Using the absolute magnitude scale, one can conclude a. the smaller the star, the brighter the star. b. the smaller the star, the bluer the star c. the bigger the star, the brighter the star d. big stars are huge celebrities. 41. The HR-diagram classifies a star using a. brightness and magnitude ...
... 40. Using the absolute magnitude scale, one can conclude a. the smaller the star, the brighter the star. b. the smaller the star, the bluer the star c. the bigger the star, the brighter the star d. big stars are huge celebrities. 41. The HR-diagram classifies a star using a. brightness and magnitude ...
Neutron Stars and Black Holes - School
... Before any evidence of black holes existed they were known to be a theoretical possibility. After a supernova explosion there remains an incredibly dense neutron star. If the mass of the Sun from which it originated was great enough then the neutron star could be a black hole. The gravitational fiel ...
... Before any evidence of black holes existed they were known to be a theoretical possibility. After a supernova explosion there remains an incredibly dense neutron star. If the mass of the Sun from which it originated was great enough then the neutron star could be a black hole. The gravitational fiel ...
Variable Stars
... A change in an object’s direction due to a change in the observer’s position. ...
... A change in an object’s direction due to a change in the observer’s position. ...
Lab 5 Takehome
... Figure 2 shows the same stars, but here what’s plotted is the apparent brightness of the star as seen from the Earth, instead of the luminosity. The vertical axis is scaled so that 1.0 represe ...
... Figure 2 shows the same stars, but here what’s plotted is the apparent brightness of the star as seen from the Earth, instead of the luminosity. The vertical axis is scaled so that 1.0 represe ...
Earth
... What is known about stars? What is the sun made of? The sun is a huge, glowing sphere of hot gas. Most of this gas is hydrogen (about 70%) and helium (about 28%). Carbon, nitrogen and oxygen make up 1.5% and the other 0.5% is made up of small amounts of many other elements such as neon, iron, silic ...
... What is known about stars? What is the sun made of? The sun is a huge, glowing sphere of hot gas. Most of this gas is hydrogen (about 70%) and helium (about 28%). Carbon, nitrogen and oxygen make up 1.5% and the other 0.5% is made up of small amounts of many other elements such as neon, iron, silic ...
Part 2
... • At low T (solar center), the cycle is too slow to be important, but the C → N transformation is working. • Equivalent cycles involving Na and Mg exist and operate partially at higher temperature (≈ 5 · 107 K). • With increasing temperature, the CNO-cycle becomes more dominant. ...
... • At low T (solar center), the cycle is too slow to be important, but the C → N transformation is working. • Equivalent cycles involving Na and Mg exist and operate partially at higher temperature (≈ 5 · 107 K). • With increasing temperature, the CNO-cycle becomes more dominant. ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.