On the origin of stars with and without planets
... shown that Rmean correlates with age5 in such a way that young objects (mostly younger than one Gyr) all have Rmean ≈ R , while older stars present a higher proportion of objects coming from different galactocentric radii. In Fig. A.4 we plot Rmean versus stellar age. One can note that there is a we ...
... shown that Rmean correlates with age5 in such a way that young objects (mostly younger than one Gyr) all have Rmean ≈ R , while older stars present a higher proportion of objects coming from different galactocentric radii. In Fig. A.4 we plot Rmean versus stellar age. One can note that there is a we ...
microquasars
... Microquasars have provided insight into: -THE PHYSICS OF RELATIVISTIC JETS FROM BH’s -THE CONNECTION BETWEEN ACCRETION & EJECTION -THE FORMATION OF BLACK HOLES AND NEUTRON STARS: Can stars of >40 Msolar end as neutron stars rather than BHs ? Do BHs of >10 Msolar form promptly rather than in bright S ...
... Microquasars have provided insight into: -THE PHYSICS OF RELATIVISTIC JETS FROM BH’s -THE CONNECTION BETWEEN ACCRETION & EJECTION -THE FORMATION OF BLACK HOLES AND NEUTRON STARS: Can stars of >40 Msolar end as neutron stars rather than BHs ? Do BHs of >10 Msolar form promptly rather than in bright S ...
THE PROPERTIES OF MAIN-SEQUENCE STARS - Cosmos
... in the Michigan catalogues and (ii) had spectroscopic parallaxes that placed them within 80 pc of the Sun. Of these, 3727 are well determined as luminosity class V and actually lie within 100 pc. From this subsample we can determine the distribution in MV of mainsequence stars of given spectral type ...
... in the Michigan catalogues and (ii) had spectroscopic parallaxes that placed them within 80 pc of the Sun. Of these, 3727 are well determined as luminosity class V and actually lie within 100 pc. From this subsample we can determine the distribution in MV of mainsequence stars of given spectral type ...
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... Despite its fragility, Li can be produced rather than destroyed under certain condition in stars via the so-called CameronFowler or 7 Be-transport mechanism (3 He(α,γ)7 Be(e− , ν)7 Li; Cameron & Fowler, 1971). The production of Li is always connected to mixing mechanisms at or below the bottom of th ...
... Despite its fragility, Li can be produced rather than destroyed under certain condition in stars via the so-called CameronFowler or 7 Be-transport mechanism (3 He(α,γ)7 Be(e− , ν)7 Li; Cameron & Fowler, 1971). The production of Li is always connected to mixing mechanisms at or below the bottom of th ...
A line-profile analysis of the large-amplitude β Cephei star ξ Canis
... Stars of spectral type B are very interesting objects upon which to perform asteroseismology. Indeed, they have a convective core which strongly determines the evolution of the star and as they will end as supernovae of type II they thus chemically enrich the interstellar matter. This is why several ...
... Stars of spectral type B are very interesting objects upon which to perform asteroseismology. Indeed, they have a convective core which strongly determines the evolution of the star and as they will end as supernovae of type II they thus chemically enrich the interstellar matter. This is why several ...
Visual Measurements of the Multiple Star
... pattern of (1) calibration of the eyepiece, (2) collecting Pulkowa. The principle instrument was an equatorial separation and position angle measurements on a refractor with a 15-inch objective lens. This was the “known “ double star (a system that has been exten- largest refractor in the world at t ...
... pattern of (1) calibration of the eyepiece, (2) collecting Pulkowa. The principle instrument was an equatorial separation and position angle measurements on a refractor with a 15-inch objective lens. This was the “known “ double star (a system that has been exten- largest refractor in the world at t ...
Sky Maps Teacher`s Guide - Northern Stars Planetarium
... Meteors are often called "falling stars" or "shooting stars." These streaks of light that fly rapidly across the sky are really tiny rocks falling through the Earth's upper atmosphere. Friction and compression between rock and the air create enough heat to make the object burn. Most meteors never re ...
... Meteors are often called "falling stars" or "shooting stars." These streaks of light that fly rapidly across the sky are really tiny rocks falling through the Earth's upper atmosphere. Friction and compression between rock and the air create enough heat to make the object burn. Most meteors never re ...
sections 12-15 instructor notes
... functions of some sort. In a way the most basic of such functions is the general luminosity function (GLF), which gives us the distribution function of absolute magnitude, M, for the average unit volume in the vicinity of the Sun. We require that basic distribution function to describe not only the ...
... functions of some sort. In a way the most basic of such functions is the general luminosity function (GLF), which gives us the distribution function of absolute magnitude, M, for the average unit volume in the vicinity of the Sun. We require that basic distribution function to describe not only the ...
The Gemini Observatory: Moving into Science Operations
... Astronomy & Astrophysics, Australian National University ...
... Astronomy & Astrophysics, Australian National University ...
RESOLVING INFORMATION ON ALGOL SYSTEMS Edwin Budding
... parallel with this track, suggesting some relevance to mass transfer theories of Algols evolution under conditions which may be comparable to the conservative case. It is notable, however, that at long periods and low r^ values, all the Algols lie above the curve - suggesting that angular momentum l ...
... parallel with this track, suggesting some relevance to mass transfer theories of Algols evolution under conditions which may be comparable to the conservative case. It is notable, however, that at long periods and low r^ values, all the Algols lie above the curve - suggesting that angular momentum l ...
Practice Paper Two
... One advantage of AC induction motors over other motors such as the universal motor is that AC induction motors: (A) ...
... One advantage of AC induction motors over other motors such as the universal motor is that AC induction motors: (A) ...
PowerPoint - Physics and Astronomy
... The rapid variation of brightness of quasars indicates a) the source of energy is very small. b) energy is coming from matter and antimatter. c) the energy source is rotating rapidly. d) a chain reaction of supernovas occurs. e) there are many separate sources of energy in the core. Explanation: ...
... The rapid variation of brightness of quasars indicates a) the source of energy is very small. b) energy is coming from matter and antimatter. c) the energy source is rotating rapidly. d) a chain reaction of supernovas occurs. e) there are many separate sources of energy in the core. Explanation: ...
Lecture 24 Early Universe - University of Maryland
... – Iron has the most stable nucleus – Fusing hydrogen to (eventually) iron releases energy (thus powers the star) – Further fusion of iron to give heavier elements requires energy to be put in… – Can only happen in the energetic environment of a supernova explosion – So, all heavier elements are crea ...
... – Iron has the most stable nucleus – Fusing hydrogen to (eventually) iron releases energy (thus powers the star) – Further fusion of iron to give heavier elements requires energy to be put in… – Can only happen in the energetic environment of a supernova explosion – So, all heavier elements are crea ...
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.