Alien Worlds Discovered
... About twice the mass of our Sun 100 to 300 million years old A coronagraph on the Hubble Space Telescope was used to block the star’s light in this picture so we can see the disc of material around it Planets are somewhere in size between Neptune and 3 times the size of Jupiter ...
... About twice the mass of our Sun 100 to 300 million years old A coronagraph on the Hubble Space Telescope was used to block the star’s light in this picture so we can see the disc of material around it Planets are somewhere in size between Neptune and 3 times the size of Jupiter ...
Lec2015_22
... via beta-decay - s-process, where s is for slow • In case when the half-life for beta-decay is long compared to the timescale for neutron capture then obtain neutron-rich nuclei - rprocess, where r is for rapid • r-process takes place following core collapse in supernovae and possibly also close to ...
... via beta-decay - s-process, where s is for slow • In case when the half-life for beta-decay is long compared to the timescale for neutron capture then obtain neutron-rich nuclei - rprocess, where r is for rapid • r-process takes place following core collapse in supernovae and possibly also close to ...
Gravitational mass defect
... phenomenon does not find its thus far explanation and are not known those energy sources, which can lead to so immense an explosion. The process of the collision of neutron stars examined can be precisely such source. In its essence this explosion - this is the explosion of the nuclear charge of ver ...
... phenomenon does not find its thus far explanation and are not known those energy sources, which can lead to so immense an explosion. The process of the collision of neutron stars examined can be precisely such source. In its essence this explosion - this is the explosion of the nuclear charge of ver ...
Celestial Distances
... One of the two special types of variable stars used for measuring distances are the cepheids They are are large, yellow, pulsating stars named for the first-known one of the group, Delta Cephei ...
... One of the two special types of variable stars used for measuring distances are the cepheids They are are large, yellow, pulsating stars named for the first-known one of the group, Delta Cephei ...
The physics of high-mass star formation
... Importance of high-mass stars • Bipolar outflows, stellar winds, HII regions destroy molecular clouds but may also trigger star formation • Supernovae enrich ISM with metals affect star formation • Sources of: energy, momentum, ionization, cosmic rays, neutron stars, black holes, GRBs • OB st ...
... Importance of high-mass stars • Bipolar outflows, stellar winds, HII regions destroy molecular clouds but may also trigger star formation • Supernovae enrich ISM with metals affect star formation • Sources of: energy, momentum, ionization, cosmic rays, neutron stars, black holes, GRBs • OB st ...
Stellar Evolution
... … another one, observed Energy equivalent to the entire mass by us with the MDM 1.3 m of the sun (E = mc2), converted into gamma-rays in just a few seconds! telescope on Kitt Peak! ...
... … another one, observed Energy equivalent to the entire mass by us with the MDM 1.3 m of the sun (E = mc2), converted into gamma-rays in just a few seconds! telescope on Kitt Peak! ...
Lecture 29: Ellipticals and Irregulars
... Methods of learning about what’s in galaxies: Images: use blue and red filters to measure colors and make H-R diagram from individual stars Integrated light/spectra Emission lines, particularly from neutral hydrogen and molecular gas. ...
... Methods of learning about what’s in galaxies: Images: use blue and red filters to measure colors and make H-R diagram from individual stars Integrated light/spectra Emission lines, particularly from neutral hydrogen and molecular gas. ...
Lecture 15
... • The collapse of a molecular cloud is relatively slow and complicated • The molecular cloud will fragment as it collapses, resulting in multiple knots of dense gas Computer simulation of star formation during collapse of a molecular cloud: ...
... • The collapse of a molecular cloud is relatively slow and complicated • The molecular cloud will fragment as it collapses, resulting in multiple knots of dense gas Computer simulation of star formation during collapse of a molecular cloud: ...
15.1 Introduction
... We saw in Lecture 13 that low- and intermediate-mass stars (with M ≤ 8M ) develop carbon-oxygen cores that become degenerate after central He burning. The electron degenerate pressure supports the core against further collapse; as a consequence, the maximum core temperature reached in these stars i ...
... We saw in Lecture 13 that low- and intermediate-mass stars (with M ≤ 8M ) develop carbon-oxygen cores that become degenerate after central He burning. The electron degenerate pressure supports the core against further collapse; as a consequence, the maximum core temperature reached in these stars i ...
Journey to the Stars Educator`s Guide
... Every star forms in a huge cloud of gas and dust. Over time, gravity causes the cloud to contract, drawing the gas closer and closer together. As more gas accumulates at the center, it becomes denser and pressure increases. This causes it to heat up and begin to glow. Its gravity continues to pull i ...
... Every star forms in a huge cloud of gas and dust. Over time, gravity causes the cloud to contract, drawing the gas closer and closer together. As more gas accumulates at the center, it becomes denser and pressure increases. This causes it to heat up and begin to glow. Its gravity continues to pull i ...
On the nature and detectability of Type Ib/c supernova progenitors
... a correction to the radii of their WR star models to take into account the radial extension of the star due to an optically thick wind, following Langer (1989) and Maeder (1990). This correction is particularly large as they employed high WR mass-loss rates for which the effect of wind clumping was ...
... a correction to the radii of their WR star models to take into account the radial extension of the star due to an optically thick wind, following Langer (1989) and Maeder (1990). This correction is particularly large as they employed high WR mass-loss rates for which the effect of wind clumping was ...
New Theory of Nuclear Fusion Processes in Sun and other
... elements gets synthesised in a particular spot as different elements have different nuclear binding energies for their respective nuclei’s and each element will get synthesised in a particular set of conditions only. Most of the elements synthesised by this process will form the core of the cooling ...
... elements gets synthesised in a particular spot as different elements have different nuclear binding energies for their respective nuclei’s and each element will get synthesised in a particular set of conditions only. Most of the elements synthesised by this process will form the core of the cooling ...
Answer to question 1 - Northwestern University
... expands and “over shoots the point where the internal heat (and light) pressure will hold up the envelope. •The result is that the envelope then comes falling down, • Over shoots inward • Then starts over ...
... expands and “over shoots the point where the internal heat (and light) pressure will hold up the envelope. •The result is that the envelope then comes falling down, • Over shoots inward • Then starts over ...
Classifying Stellar Spectra
... how to use the classification tools. **Note, you may have to classify more than 4 stars to do this because some of the stars you encounter may be Red Giants or White Dwarfs. Remember, main-sequence stars have the luminosity class, V. So, if the star is a main sequence star, it’s spectral type will b ...
... how to use the classification tools. **Note, you may have to classify more than 4 stars to do this because some of the stars you encounter may be Red Giants or White Dwarfs. Remember, main-sequence stars have the luminosity class, V. So, if the star is a main sequence star, it’s spectral type will b ...
Extension worksheet – Topic 6 - Cambridge Resources for the IB
... so requires knowledge of luminosity and apparent brightness; apparent brightness can easily be measured with a CCD camera; the luminosity can be determined if we know the temperature of the star (obtained form its spectrum) and the stellar type so the HR can be used to find luminosity. ...
... so requires knowledge of luminosity and apparent brightness; apparent brightness can easily be measured with a CCD camera; the luminosity can be determined if we know the temperature of the star (obtained form its spectrum) and the stellar type so the HR can be used to find luminosity. ...
AST4930 Star and Planet Formation
... Spectroscopic analysis can identify if an early type star is in main-sequence or already leaving the main sequence. In the first case, it follows a given temperature-luminosity relation, which can be exploited to determine their distance (but reddening must be corrected for). ...
... Spectroscopic analysis can identify if an early type star is in main-sequence or already leaving the main sequence. In the first case, it follows a given temperature-luminosity relation, which can be exploited to determine their distance (but reddening must be corrected for). ...
Stellar Temperatures
... Stellar Spectral Energy Distributions Stellar temperatures range from ~3000 K to ~100,000 K (although there are exceptions). To zeroth order, they can be considered blackbodies, with stellar absorption lines on top. There is a great variety of stellar absorption lines; the strength of any individua ...
... Stellar Spectral Energy Distributions Stellar temperatures range from ~3000 K to ~100,000 K (although there are exceptions). To zeroth order, they can be considered blackbodies, with stellar absorption lines on top. There is a great variety of stellar absorption lines; the strength of any individua ...
Document
... Globular clusters: halo RR Lyr stars: halo T Tau stars : near densest clouds. White dwarfs: everywhere (but only seen locally because too faint) Planetary nebulae: everywhere, but not many seen. Red giants: everywhere, easiest halo stars to see. AGB: everywhere O stars: dust lanes B stars: plane of ...
... Globular clusters: halo RR Lyr stars: halo T Tau stars : near densest clouds. White dwarfs: everywhere (but only seen locally because too faint) Planetary nebulae: everywhere, but not many seen. Red giants: everywhere, easiest halo stars to see. AGB: everywhere O stars: dust lanes B stars: plane of ...
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.