White dwarfs, black holes, dark matter
... p is momentum = mass × velocity h is side of cube ( Planck constant) electron: 0,00072 m/s proton: 0,000 000 4 m/s White dwarfs, black holes, dark matter ...
... p is momentum = mass × velocity h is side of cube ( Planck constant) electron: 0,00072 m/s proton: 0,000 000 4 m/s White dwarfs, black holes, dark matter ...
The Age and Progenitor Mass of Sirius B
... ary. Girardi et al. (2002) use an “overshoot” prescription based on a single parameter. As alluded to in § 2, TYCHO includes the effects of hydrodynamics in the convective boundary and radiative regions in a predictive, physically-motivated fashion. This treatment may give more accurate predictions ...
... ary. Girardi et al. (2002) use an “overshoot” prescription based on a single parameter. As alluded to in § 2, TYCHO includes the effects of hydrodynamics in the convective boundary and radiative regions in a predictive, physically-motivated fashion. This treatment may give more accurate predictions ...
White dwarf binaries
... survey of CVs that definitively established their binary nature. The presence of a white dwarf in these systems as the primary was first demonstrated observationally by Crawford and Kraft (1956). These events and others are given chronologically in Table 1, and the properties of a selection of dwarf ...
... survey of CVs that definitively established their binary nature. The presence of a white dwarf in these systems as the primary was first demonstrated observationally by Crawford and Kraft (1956). These events and others are given chronologically in Table 1, and the properties of a selection of dwarf ...
hwd_ewd_v3 - X-ray and Observational Astronomy Group
... is largely determined by the principle photospheric component, either H or He (usually), At lower temperatures, below ~10,000K, even if present, the signatures of H and He become difficult and eventually impossible to detect. The physics of the atmospheres of these cooler objects is quite different, ...
... is largely determined by the principle photospheric component, either H or He (usually), At lower temperatures, below ~10,000K, even if present, the signatures of H and He become difficult and eventually impossible to detect. The physics of the atmospheres of these cooler objects is quite different, ...
The Chemical Composition of an Extrasolar Kuiper-Belt
... and Ni are detected, with nitrogen observed for the first time in extrasolar planetary debris. The nitrogen mass fraction is ∼2%, comparable to that in comet Halley and higher than in any other known solar system object. The lower limit to the accreted mass is ∼1022 g, which is about one hundred thou ...
... and Ni are detected, with nitrogen observed for the first time in extrasolar planetary debris. The nitrogen mass fraction is ∼2%, comparable to that in comet Halley and higher than in any other known solar system object. The lower limit to the accreted mass is ∼1022 g, which is about one hundred thou ...
A search for a new class of pulsating DA white dwarf stars in the DB
... While DAs can be found at all temperatures under 170 000 K down to the low temperature limit set by the age of the Galaxy, it is a remarkable and intriguing fact that few helium atmosphere white dwarfs occur in the effective temperature range between 45 000 ≥ T eff ≥ 30, 000 K. The DOs and DBs are f ...
... While DAs can be found at all temperatures under 170 000 K down to the low temperature limit set by the age of the Galaxy, it is a remarkable and intriguing fact that few helium atmosphere white dwarfs occur in the effective temperature range between 45 000 ≥ T eff ≥ 30, 000 K. The DOs and DBs are f ...
Astronomy Astrophysics
... Below this and depending on the choice of gravity the atmospheres become convective, however the convection is inefficient and has almost no influence on the atmospheric structure as long as T eff > ∼ 12 500 K. In Paper II LTE models were used that account for convection (mixing length theory using ML2 ...
... Below this and depending on the choice of gravity the atmospheres become convective, however the convection is inefficient and has almost no influence on the atmospheric structure as long as T eff > ∼ 12 500 K. In Paper II LTE models were used that account for convection (mixing length theory using ML2 ...
Discovery of White Dwarfs—8 Oct
... Main-sequence or dwarf stars Giants Horizontal-branch stars White dwarfs are too faint for these observations. A star lives a long time as a dwarf. It is on the main sequence. When it runs out of fuel, it becomes a giant and subsequently “traces out the giant branch.” ...
... Main-sequence or dwarf stars Giants Horizontal-branch stars White dwarfs are too faint for these observations. A star lives a long time as a dwarf. It is on the main sequence. When it runs out of fuel, it becomes a giant and subsequently “traces out the giant branch.” ...
Dyson Spheres around White Dwarfs arXiv:1503.04376
... will be the perfect place of disposal. Moreover, the trash will hit the surface of the WD with kinetic energy approximately equal to GM m/R, which for a WD of Solar mass and Earth radius, will get converted into heat energy equal to 2.3 × 10−4 mc2 , comparable to energy released in fission reactions ...
... will be the perfect place of disposal. Moreover, the trash will hit the surface of the WD with kinetic energy approximately equal to GM m/R, which for a WD of Solar mass and Earth radius, will get converted into heat energy equal to 2.3 × 10−4 mc2 , comparable to energy released in fission reactions ...
The DBV stars: Progress and problems
... While it is possible that most or all of the cooler (Teff < 20,000 K) DA white dwarfs are the spawn of hydrogen-rich planetary nebula nuclei, the picture is less certain for the DBV and DB ’whitedwarfs. There are at least two possible progenitors of DB white dwarfs: the PG 1159 stars and the interac ...
... While it is possible that most or all of the cooler (Teff < 20,000 K) DA white dwarfs are the spawn of hydrogen-rich planetary nebula nuclei, the picture is less certain for the DBV and DB ’whitedwarfs. There are at least two possible progenitors of DB white dwarfs: the PG 1159 stars and the interac ...
Y-band Imaging of Extragalatic Fields and High redshift
... Red line is SF galaxy evolution and blue line represents QSOs as z goes higher ...
... Red line is SF galaxy evolution and blue line represents QSOs as z goes higher ...
Chapter 11 White Dwarfs and Neutron Stars
... shrink to the very hot, very dense objects that we call white dwarfs. • An even more dense object termed a neutron star can be left behind after the evolution of more massive stars terminates in a core-collapse supernova explosion. Technically, white dwarfs and neutron stars are stellar corpses, not ...
... shrink to the very hot, very dense objects that we call white dwarfs. • An even more dense object termed a neutron star can be left behind after the evolution of more massive stars terminates in a core-collapse supernova explosion. Technically, white dwarfs and neutron stars are stellar corpses, not ...
Chapter 13 White Dwarfs and Neutron Stars
... shrink to the very hot, very dense objects that we call white dwarfs. • An even more dense object termed a neutron star can be left behind after the evolution of more massive stars terminates in a core-collapse supernova explosion. Technically, white dwarfs and neutron stars are stellar corpses, not ...
... shrink to the very hot, very dense objects that we call white dwarfs. • An even more dense object termed a neutron star can be left behind after the evolution of more massive stars terminates in a core-collapse supernova explosion. Technically, white dwarfs and neutron stars are stellar corpses, not ...
Extrasolar Cosmochemistry
... atmosphere. These stars are typically the radius of Earth and slowly cool from an initial outer temperature above 100,000 K. Once the effective temperature of the atmosphere falls below 20,000 K, radiative levitation—the process of supporting an element in the atmosphere by the upward flow of radiati ...
... atmosphere. These stars are typically the radius of Earth and slowly cool from an initial outer temperature above 100,000 K. Once the effective temperature of the atmosphere falls below 20,000 K, radiative levitation—the process of supporting an element in the atmosphere by the upward flow of radiati ...
The white dwarf population within 40 pc of the Sun
... by a simple gravothermal process. However, although the basic picture of white dwarf evolution has remained unchanged for some time, we now have very reliable and accurate evolutionary tracks, which take into account all the relevant physical processes involved in their cooling, and which allow us t ...
... by a simple gravothermal process. However, although the basic picture of white dwarf evolution has remained unchanged for some time, we now have very reliable and accurate evolutionary tracks, which take into account all the relevant physical processes involved in their cooling, and which allow us t ...
The white dwarf population within 40 pc of the Sun
... evolution of white dwarfs is determined by a simple gravothermal process. However, although the basic picture of white dwarf evolution has remained unchanged for some time, we now have very reliable and accurate evolutionary tracks, which take into account all the relevant physical processes involve ...
... evolution of white dwarfs is determined by a simple gravothermal process. However, although the basic picture of white dwarf evolution has remained unchanged for some time, we now have very reliable and accurate evolutionary tracks, which take into account all the relevant physical processes involve ...
The white dwarf population within 40 pc of the Sun
... For each of the synthetic white dwarf populations described below, we generated 50 independent Monte Carlo simulations employing different initial seeds. Furthermore, for each of these Monte Carlo realizations, we increased the number of simulated Monte Carlo realizations to 104 using bootstrap tech ...
... For each of the synthetic white dwarf populations described below, we generated 50 independent Monte Carlo simulations employing different initial seeds. Furthermore, for each of these Monte Carlo realizations, we increased the number of simulated Monte Carlo realizations to 104 using bootstrap tech ...
CFBDSIR J1458+ 1013B: A Very Cold (> T10) Brown Dwarf in a
... Over the last 15 years, stellar and exoplanetary studies have been propelled through the study of brown dwarfs. Residing at the extremes of low mass, luminosity and temperature, brown dwarfs serve as laboratories for understanding gas-giant extrasolar planets as well as the faint end of the star for ...
... Over the last 15 years, stellar and exoplanetary studies have been propelled through the study of brown dwarfs. Residing at the extremes of low mass, luminosity and temperature, brown dwarfs serve as laboratories for understanding gas-giant extrasolar planets as well as the faint end of the star for ...
Transcript - Chandra X
... in the southern constellation Doradus. The population of stars within clusters is more complex than years ago when they were considered to all be about the same age of older population II stars. However, the discovery of a planetary nebula in NGC 1846 pushes the envelope of age disparity for a globu ...
... in the southern constellation Doradus. The population of stars within clusters is more complex than years ago when they were considered to all be about the same age of older population II stars. However, the discovery of a planetary nebula in NGC 1846 pushes the envelope of age disparity for a globu ...
A trio of metalrich dust and gas discs found orbiting candidate white
... in UKIDSS K-band observations. Six of the science targets were selected from 16 785 DA star candidates identified either spectroscopically or photometrically within SDSS DR7, spatially cross-correlated with H K detections in UKIDSS DR8. Thus, the selection criteria are completely independent of stel ...
... in UKIDSS K-band observations. Six of the science targets were selected from 16 785 DA star candidates identified either spectroscopically or photometrically within SDSS DR7, spatially cross-correlated with H K detections in UKIDSS DR8. Thus, the selection criteria are completely independent of stel ...
MPhil Thesis - Final - Suzanne Knight
... low mass planets as it ascends the red giant and asymptotic giant branch evolutionary tracks, but larger mass objects and those further out will survive.! A substellar companion detected around a white dwarf would prove that it could survive the final stages of stellar evolution and place constraint ...
... low mass planets as it ascends the red giant and asymptotic giant branch evolutionary tracks, but larger mass objects and those further out will survive.! A substellar companion detected around a white dwarf would prove that it could survive the final stages of stellar evolution and place constraint ...
Stars: Their Life and Afterlife
... overcome the electron degeneracy pressure, and the star would contract and heat to the point where further fusion – and evolution – were possible. Second, at about this mass a process called “neutronization” becomes possible: the most energetic electrons in the gas would have enough energy to bind w ...
... overcome the electron degeneracy pressure, and the star would contract and heat to the point where further fusion – and evolution – were possible. Second, at about this mass a process called “neutronization” becomes possible: the most energetic electrons in the gas would have enough energy to bind w ...
Equations of State for White Dwarfs Elena Heikkilä Kandidaatin
... dwarfs below the regime of neutron drip, which means densities less than 4 × 1011 g cm−3 . White dwarfs — also called degenerate dwarfs, composed mostly of electron-degenerate matter — are luminous and the color of the light they are emitting is white, hence their name. [1] Most observed white dwarf ...
... dwarfs below the regime of neutron drip, which means densities less than 4 × 1011 g cm−3 . White dwarfs — also called degenerate dwarfs, composed mostly of electron-degenerate matter — are luminous and the color of the light they are emitting is white, hence their name. [1] Most observed white dwarf ...
Brown dwarf
Brown dwarfs are substellar objects not massive enough to sustain hydrogen-1 fusion reactions in their cores, unlike main-sequence stars. They occupy the mass range between the heaviest gas giants and the lightest stars, with an upper limit around 75 to 80 Jupiter masses (MJ). Brown dwarfs heavier than about 13 MJ are thought to fuse deuterium and those above ~65 MJ, fuse lithium as well. Brown dwarfs may be fully convective, with no layers or chemical differentiation by depth.The defining differences between a very-low-mass brown dwarf and a giant planet (~13 MJ) are debated. One school of thought is based on formation; the other, on the physics of the interior.Part of the debate concerns whether ""brown dwarfs"" must, by definition, have experienced fusion at some point in their history.Stars are categorized by spectral class, with brown dwarfs being designated as types M, L, T, and Y. Despite their name, brown dwarfs are of different colors. Many brown dwarfs would likely appear magenta to the human eye, or possibly orange/red. Brown dwarfs are not very luminous at visible wavelengths.Some planets are known to orbit brown dwarfs: 2M1207b, MOA-2007-BLG-192Lb, and 2MASS J044144bAt a distance of about 6.5 light years, the nearest known brown dwarf is Luhman 16, a binary system of brown dwarfs discovered in 2013. One brown dwarf, DENIS-P J082303.1-491201 b, from an ultracool binary system, has a mass of about 28 MJ, making it the largest known exoplanet (as of March 2014).