Article Reference - Archive ouverte UNIGE
... (radial velocities or transits), the occurrence rate of hot Jupiters orbiting solar-type stars is low. It has been estimated to be as high as 1.5 ± 0.6% by Cumming et al. (2008) from radial velocity surveys, and as low as 0.5 ± 0.1% by Howard et al. (2012) from the Kepler results. Johnson et al. (20 ...
... (radial velocities or transits), the occurrence rate of hot Jupiters orbiting solar-type stars is low. It has been estimated to be as high as 1.5 ± 0.6% by Cumming et al. (2008) from radial velocity surveys, and as low as 0.5 ± 0.1% by Howard et al. (2012) from the Kepler results. Johnson et al. (20 ...
(1) and
... By nuclear fusion, massive stars accumulate heavy elements in the interior (1) >10 M◎ : Fe core Core collapse supernova (CC SN: He, C, Ne, O) ...
... By nuclear fusion, massive stars accumulate heavy elements in the interior (1) >10 M◎ : Fe core Core collapse supernova (CC SN: He, C, Ne, O) ...
Astronomy 112: The Physics of Stars Class 14 Notes: The Main
... that of the Sun. Of course this argument is a bit of a cheat: the way we got the homology argument in the first place is by assuming a particular scaling for the nuclear reaction rate with temperature ν, and, if the temperature gets too low, ν will change. Thus the limit is a bit more complicated. N ...
... that of the Sun. Of course this argument is a bit of a cheat: the way we got the homology argument in the first place is by assuming a particular scaling for the nuclear reaction rate with temperature ν, and, if the temperature gets too low, ν will change. Thus the limit is a bit more complicated. N ...
Supernovae - University of Texas Astronomy Home Page
... Although there are counterarguments and some controversy, both Tycho's and Kepler's supernovae are widely regarded to be the kind of event modern astronomers label Type Ia. Shortly after Kepler came Galileo and his telescope and then Newton with his new understanding of the laws of mechanics and gra ...
... Although there are counterarguments and some controversy, both Tycho's and Kepler's supernovae are widely regarded to be the kind of event modern astronomers label Type Ia. Shortly after Kepler came Galileo and his telescope and then Newton with his new understanding of the laws of mechanics and gra ...
Lecture 4
... When we looks at young clusters and globular clusters their colour-magnitude diagrams appear very different Globular clusters consist of ~half a million stars gravitationally bound, and located above the plane of the galaxy. They are old metal poor stars. Show extensive red-giant,AGB and horizontal ...
... When we looks at young clusters and globular clusters their colour-magnitude diagrams appear very different Globular clusters consist of ~half a million stars gravitationally bound, and located above the plane of the galaxy. They are old metal poor stars. Show extensive red-giant,AGB and horizontal ...
Chandra and NIR Observations of Galactic HII Regions
... many nearby O stars whose winds are thought to drive instabilities and X-ray emitting shocks. • The O stars in NGC 6611 are to be contrasted with those in the younger Orion Nebula Cluster with hard, time-variable X-rays and higher LX/Lbol, most likely produced by magnetic activity. ...
... many nearby O stars whose winds are thought to drive instabilities and X-ray emitting shocks. • The O stars in NGC 6611 are to be contrasted with those in the younger Orion Nebula Cluster with hard, time-variable X-rays and higher LX/Lbol, most likely produced by magnetic activity. ...
Where to begin the adventure with variable stars?
... In this way we have found the stars and we can begin photometric observations. Their result will probably impress not only us, but also other students and our friends. Also the acquired skills of navigating in the sky will be a source of satisfaction! ...
... In this way we have found the stars and we can begin photometric observations. Their result will probably impress not only us, but also other students and our friends. Also the acquired skills of navigating in the sky will be a source of satisfaction! ...
Population synthesis of Be/white dwarf binaries in the Galaxy
... since they must have evolved from massive progenitors, perhaps close to the maximum mass for white dwarf progenitor stars, and they are likely themselves to be much more massive than the mean for white dwarfs in general (0.57 M , Finley et al. 1997). The presence of a component of spectral class B ...
... since they must have evolved from massive progenitors, perhaps close to the maximum mass for white dwarf progenitor stars, and they are likely themselves to be much more massive than the mean for white dwarfs in general (0.57 M , Finley et al. 1997). The presence of a component of spectral class B ...
Binaries
... From the study of the binaries we learn the mass of the stars. When we plot the mass of the stars vs. the light we receive from them, we see that there is a very strong dependence of luminosity on mass. Luminosity Mass ...
... From the study of the binaries we learn the mass of the stars. When we plot the mass of the stars vs. the light we receive from them, we see that there is a very strong dependence of luminosity on mass. Luminosity Mass ...
The Milky Way - Chandra X
... other spiral arms of the Galaxy come into view along with the central bulge, where the Galaxy's supermassive black hole is located. Finally, from a distance of a few million light years, we see the Galaxy as part of the Local Group. From the tranquil, wide-open spaces between the galaxies of the Loc ...
... other spiral arms of the Galaxy come into view along with the central bulge, where the Galaxy's supermassive black hole is located. Finally, from a distance of a few million light years, we see the Galaxy as part of the Local Group. From the tranquil, wide-open spaces between the galaxies of the Loc ...
Using exoplanet systems with highly elliptical orbits to search for star
... We are investigating the planet induced chromospheric activity of each star by examining the Ca II H&K, Ca II IRT, and Hα lines in our phase observed spectra. To ensure any modulations in the chromospheric lines are not a result of intrinsic stellar activity, we are also monitoring photospheric line ...
... We are investigating the planet induced chromospheric activity of each star by examining the Ca II H&K, Ca II IRT, and Hα lines in our phase observed spectra. To ensure any modulations in the chromospheric lines are not a result of intrinsic stellar activity, we are also monitoring photospheric line ...
Skinner Chapter 3
... 46. The Sun is considerably more massive than Jupiter, so temperatures and pressures in the core of the Sun are high enough for nuclear fusion to occur. Nuclear fusion does not occur in the core of ...
... 46. The Sun is considerably more massive than Jupiter, so temperatures and pressures in the core of the Sun are high enough for nuclear fusion to occur. Nuclear fusion does not occur in the core of ...
Document
... The driving region located too deep the amplitude of the temperature variations is very small and the layer will absorb too small amount of energy to be efficient ...
... The driving region located too deep the amplitude of the temperature variations is very small and the layer will absorb too small amount of energy to be efficient ...
Stellar Magnitudes and Distances
... • the direction and speed a star is moving • its mass • its brightness or luminosity • its chemical composition • its size • its age • its temperature ...
... • the direction and speed a star is moving • its mass • its brightness or luminosity • its chemical composition • its size • its age • its temperature ...
CP2: KUPKA et al.: Observational signatures of atmospheric velocity
... moments of the distributions of velocity, temperature, density, pressure, etc. These model are reaching the point where it is useful to compare them with velocity fields observed through their effects on stellar line profiles in a variety of stars. We have acquired at the CFHT a sample of spectra of ...
... moments of the distributions of velocity, temperature, density, pressure, etc. These model are reaching the point where it is useful to compare them with velocity fields observed through their effects on stellar line profiles in a variety of stars. We have acquired at the CFHT a sample of spectra of ...
Black Holes Essay Research Paper Stars can
... be made into it. The photon-sphere however is the point when light is forced to orbit the star, but is not pulled into the event horizon. The point at which the star s mass is centered is called singularity. This, in his equation, lay at the very center of the black hole, and is considered to center ...
... be made into it. The photon-sphere however is the point when light is forced to orbit the star, but is not pulled into the event horizon. The point at which the star s mass is centered is called singularity. This, in his equation, lay at the very center of the black hole, and is considered to center ...
lab 14B - atomic challenge
... atoms together to make other elements, such as helium. Along the way, a few protons get converted into neutrons and electrons. In this investigation, you will learn how these subatomic particles are arranged to make up the structure of an atom by playing the game of Atomic Challenge. ...
... atoms together to make other elements, such as helium. Along the way, a few protons get converted into neutrons and electrons. In this investigation, you will learn how these subatomic particles are arranged to make up the structure of an atom by playing the game of Atomic Challenge. ...
Ch. 19 - Astro1010
... Mass Loss Among Red Giants Stars just larger than 1.4 M lose their extra mass through accelerated stellar wind Stars with masses up to 8 or 9 M often have their outer layers go unstable and explode. The result is a Nova [email protected] ...
... Mass Loss Among Red Giants Stars just larger than 1.4 M lose their extra mass through accelerated stellar wind Stars with masses up to 8 or 9 M often have their outer layers go unstable and explode. The result is a Nova [email protected] ...
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.