Determining the Origin of Inner Planetary System Debris Orbiting the
... Kenyon & Bromley (2006), in particular their simulation of the growth of terrestrial planets in an annular ring spanning 0.84-1.16 AU around a Solar-mass star. This ring is seeded with a parent planetesimal population having a specified surface density distribution Σ0 . It is then evolved using the h ...
... Kenyon & Bromley (2006), in particular their simulation of the growth of terrestrial planets in an annular ring spanning 0.84-1.16 AU around a Solar-mass star. This ring is seeded with a parent planetesimal population having a specified surface density distribution Σ0 . It is then evolved using the h ...
The contribution of Wide-Field surveys to the search for planetary
... So far, so good, so what? PNe with binary central stars David Jones ...
... So far, so good, so what? PNe with binary central stars David Jones ...
Slide 1
... Norman Pogson proposed a quantitative scale of stellar magnitudes, which was adopted by the astronomical community. Each increment in magnitude corresponds to an increase in the amount of energy by 2.512, approximately. A fifth magnitude star is 2.512 times as bright as a sixth, and a fourth magnitu ...
... Norman Pogson proposed a quantitative scale of stellar magnitudes, which was adopted by the astronomical community. Each increment in magnitude corresponds to an increase in the amount of energy by 2.512, approximately. A fifth magnitude star is 2.512 times as bright as a sixth, and a fourth magnitu ...
Second and Third Black Hole Lecture
... dynamics agree within a factor of 3. This is 'great' but – dyanmical masses very difficult to ...
... dynamics agree within a factor of 3. This is 'great' but – dyanmical masses very difficult to ...
ET_at_Science_Cafe
... Try to avoid details (which we cannot know) here, consider big picture. Guess at energy input: take deposition time of roughly speed of sound crossing nucleus (~0.1 s). Take power to be 10% of stellar core output. Need Pwr ~10-6 Lceph . Few day Cepheid, would need 1028 J! Could be much less needed… ...
... Try to avoid details (which we cannot know) here, consider big picture. Guess at energy input: take deposition time of roughly speed of sound crossing nucleus (~0.1 s). Take power to be 10% of stellar core output. Need Pwr ~10-6 Lceph . Few day Cepheid, would need 1028 J! Could be much less needed… ...
Oort Cloud Evolu on in a Long
... forming a Vght inner core • For the large mass, the cluster Hde would send many OC comets into the inner solar system (~1%) • For the lower range of cluster mass, there is a reasonable chance ...
... forming a Vght inner core • For the large mass, the cluster Hde would send many OC comets into the inner solar system (~1%) • For the lower range of cluster mass, there is a reasonable chance ...
γ The Potential for Intensity Interferometry with –
... Figure 1: Possible layout for CTA. Small red dots are the 85 100m2 dishes, large blue dots are the 4 600 m2 dishes. ...
... Figure 1: Possible layout for CTA. Small red dots are the 85 100m2 dishes, large blue dots are the 4 600 m2 dishes. ...
Introduction and first data set
... The IRAS images were very disappointing. None of the fuzzballs emitted any detectable mid-IR flux. The only thing detected was the Southern Blue Spot, and even it was quite weak in the mid-IR. Mid-IR radiation is emitted by objects with temperatures of around 100K. This usually means interstellar d ...
... The IRAS images were very disappointing. None of the fuzzballs emitted any detectable mid-IR flux. The only thing detected was the Southern Blue Spot, and even it was quite weak in the mid-IR. Mid-IR radiation is emitted by objects with temperatures of around 100K. This usually means interstellar d ...
Collapse: Method 2
... the gas becomes opaque to the dust radiation even at 300 microns. The energy released is trapped and the temperature rises. As the temperature ascends, the opacity also ascends. The core suddenly switches from isothermal to adiabatic. Stage 4. The high thermal pressure resists gravity and this ends ...
... the gas becomes opaque to the dust radiation even at 300 microns. The energy released is trapped and the temperature rises. As the temperature ascends, the opacity also ascends. The core suddenly switches from isothermal to adiabatic. Stage 4. The high thermal pressure resists gravity and this ends ...
Folie 1
... If molecular clouds are the sites of star formation what conditions must exist for collapse to occur? • James Jeans investigated this with simplified assumptions, considering the effects of small deviations from hydrostatic equilibrium with spherical symmetric collapse and neglecting the effects due ...
... If molecular clouds are the sites of star formation what conditions must exist for collapse to occur? • James Jeans investigated this with simplified assumptions, considering the effects of small deviations from hydrostatic equilibrium with spherical symmetric collapse and neglecting the effects due ...
Key Areas covered
... What happens to the colour of objects as they are heated? • When an object is heated it does not initially glow, but radiates large amounts of energy as infrared radiation. We can feel this if we place our hand near, but not touching, a hot object. • As an object becomes hotter it starts to glow a ...
... What happens to the colour of objects as they are heated? • When an object is heated it does not initially glow, but radiates large amounts of energy as infrared radiation. We can feel this if we place our hand near, but not touching, a hot object. • As an object becomes hotter it starts to glow a ...
Globular cluster absolute ages from cooling brown dwarfs
... In order to probe the evolution of brown dwarfs, we ran a suite of models (Paxton et al. 2011) for different initial masses and the metal content of the globular cluster 47 Tucanae. The specifications of our models are explained in Appendix A. From the models, we can see that in the early stages of ...
... In order to probe the evolution of brown dwarfs, we ran a suite of models (Paxton et al. 2011) for different initial masses and the metal content of the globular cluster 47 Tucanae. The specifications of our models are explained in Appendix A. From the models, we can see that in the early stages of ...
Ch16_MilkyWayGalaxy
... • Some energetic event, perhaps a supernova explosion, violently disturbed the center in the not-to-distant past • Deep within the core lies an incredibly small (10 AU diameter) radio source known as Sgr A* • A 5 ×106 M black hole may occupy the very center of the galaxy! ...
... • Some energetic event, perhaps a supernova explosion, violently disturbed the center in the not-to-distant past • Deep within the core lies an incredibly small (10 AU diameter) radio source known as Sgr A* • A 5 ×106 M black hole may occupy the very center of the galaxy! ...
PH607 – Galaxies 2
... formation event a few million years ago. The existence of these relatively young (though evolved) stars there was of a surprise to experts, who would have expected the tidal forces from the central black-hole to prevent their formation. They are much too young to have migrated far, but it seems even ...
... formation event a few million years ago. The existence of these relatively young (though evolved) stars there was of a surprise to experts, who would have expected the tidal forces from the central black-hole to prevent their formation. They are much too young to have migrated far, but it seems even ...
The Death of a Star - hrsbstaff.ednet.ns.ca
... ‘cloud’. The nebula that we are about to talk about, however, is so much more than just a cloud. So what is a nebula? A nebula is an interstellar cloud in outer space that is made up of dust, hydrogen and helium gas, and plasma. It is formed when portions of the interstellar medium collapse and clum ...
... ‘cloud’. The nebula that we are about to talk about, however, is so much more than just a cloud. So what is a nebula? A nebula is an interstellar cloud in outer space that is made up of dust, hydrogen and helium gas, and plasma. It is formed when portions of the interstellar medium collapse and clum ...
Chapter 16 Option E: ASTROPHYSICS
... local cluster is another cluster of galaxies, the Virgo cluster, which contains about a thousand galaxies. here are other clusters that can contain as many as ten thousand galaxies. Amazingly, all these diferent clusters are grouped into a socalled “super cluster”. Between these superclusters are va ...
... local cluster is another cluster of galaxies, the Virgo cluster, which contains about a thousand galaxies. here are other clusters that can contain as many as ten thousand galaxies. Amazingly, all these diferent clusters are grouped into a socalled “super cluster”. Between these superclusters are va ...
model of convection
... • Disk and star are aligned, like in the solar system • Does the star and the planet rotate the same way ? ...
... • Disk and star are aligned, like in the solar system • Does the star and the planet rotate the same way ? ...
lecture25
... Stars form from dense gas in molecular clouds Stars age and then give up their outer layers (via solar wind, planetary nebula, or supernova) The ejected gas eventually finds its way back into an overly dense region and become part of the next generation of stars. This process is repeated as long as ...
... Stars form from dense gas in molecular clouds Stars age and then give up their outer layers (via solar wind, planetary nebula, or supernova) The ejected gas eventually finds its way back into an overly dense region and become part of the next generation of stars. This process is repeated as long as ...
Lecture 29 Our Galaxy: "Milky Way"
... Galactic Rotation Galactic material must be in some kind of orbit around the center, or gravity would pull everything into the center! • Rotation of Galaxy is real tough to measure (can't actually see rotation in our lifetime), but get a rough idea as follows, mainly from doppler radial velocities: ...
... Galactic Rotation Galactic material must be in some kind of orbit around the center, or gravity would pull everything into the center! • Rotation of Galaxy is real tough to measure (can't actually see rotation in our lifetime), but get a rough idea as follows, mainly from doppler radial velocities: ...
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.