Today in Astronomy 142
... Depending upon how they are formed and what their mass is, such objects are called brown dwarfs or giant planets. ! Because they cannot replace the energy that leaks away in the form of light, they simply remain at the size determined by degeneracy pressure, and cool off forever. ! Thus if they are ...
... Depending upon how they are formed and what their mass is, such objects are called brown dwarfs or giant planets. ! Because they cannot replace the energy that leaks away in the form of light, they simply remain at the size determined by degeneracy pressure, and cool off forever. ! Thus if they are ...
chapter 14 - Astronomy
... (b) Type Ia result from white dwarfs. 6. A Type Ia supernova reaches maximum brightness in a few days, fades quickly for about a month, and then declines in brightness more gradually until it dissipates in about a year. 7. Models indicate that the energy of a Type Ia supernova (following the explosi ...
... (b) Type Ia result from white dwarfs. 6. A Type Ia supernova reaches maximum brightness in a few days, fades quickly for about a month, and then declines in brightness more gradually until it dissipates in about a year. 7. Models indicate that the energy of a Type Ia supernova (following the explosi ...
AST 301 Introduction to Astronomy - University of Texas Astronomy
... But the core will be the left-over white dwarf. The gas put back out into space will come from the red giant’s envelope, which hasn’t been hot enough for fusion to make new elements. Most of the elements in space were put there by supernova explosions. ...
... But the core will be the left-over white dwarf. The gas put back out into space will come from the red giant’s envelope, which hasn’t been hot enough for fusion to make new elements. Most of the elements in space were put there by supernova explosions. ...
STAR FORMATION
... • If the protostar's mass is less than about 8% of the Sun's mass it is insufficient to compress the center to temperatures and densities adequate to allow ordinary fusion -- THE LOWER MASS LIMIT • Such failed stars are called brown dwarfs. • Most astronomers make a further distinction between brown ...
... • If the protostar's mass is less than about 8% of the Sun's mass it is insufficient to compress the center to temperatures and densities adequate to allow ordinary fusion -- THE LOWER MASS LIMIT • Such failed stars are called brown dwarfs. • Most astronomers make a further distinction between brown ...
File - Mr. Catt`s Class
... above the Chandrasekhar limit, electron degeneracy can no longer support the star, and it collapses. – The collapse raises the core temperature, – runaway carbon fusion begins, – which ultimately leads to the star exploding ...
... above the Chandrasekhar limit, electron degeneracy can no longer support the star, and it collapses. – The collapse raises the core temperature, – runaway carbon fusion begins, – which ultimately leads to the star exploding ...
Basic Properties of Stars
... O stars are hot, luminous, most massive; M are stars cool, faint, least massive ...
... O stars are hot, luminous, most massive; M are stars cool, faint, least massive ...
The Stellar Graveyard
... Generally speaking, all stars with main sequence masses less than 5 solar masses will end up becoming white dwarfs because there is so much mass loss during the various phases of stellar evolution following hydrogen core exhaustion. Measuring the current mass of a white dwarf, therefore, does not ...
... Generally speaking, all stars with main sequence masses less than 5 solar masses will end up becoming white dwarfs because there is so much mass loss during the various phases of stellar evolution following hydrogen core exhaustion. Measuring the current mass of a white dwarf, therefore, does not ...
Transit surveys for Earths in the habitable zones of white dwarfs
... To date the search for habitable Earth-like planets has primarily focused on nuclear burning stars. I propose that this search should be expanded to cool white dwarf stars that have expended their nuclear fuel. I define the continuously habitable zone of white dwarfs, and show that it extends from ≈ ...
... To date the search for habitable Earth-like planets has primarily focused on nuclear burning stars. I propose that this search should be expanded to cool white dwarf stars that have expended their nuclear fuel. I define the continuously habitable zone of white dwarfs, and show that it extends from ≈ ...
Direct Detection of Galactic Halo Dark Matter
... galaxy’s spiral disk. A substantial portion of this unseen matter may be old, very cool white dwarfs (1–4). A white dwarf is the extremely dense end-state in the evolution of stars with masses less than about eight times the mass of the sun (MJ). Once a star becomes a white dwarf, it no longer produ ...
... galaxy’s spiral disk. A substantial portion of this unseen matter may be old, very cool white dwarfs (1–4). A white dwarf is the extremely dense end-state in the evolution of stars with masses less than about eight times the mass of the sun (MJ). Once a star becomes a white dwarf, it no longer produ ...
CHAPTER 14
... the stage where it has a carbon core, the heat from the shrinking core ignites helium fusion in a shell around it, while hydrogen is fusing in a second shell beyond the first. 11. The star slowly enters a new red giant phase and its position on the H-R diagram moves to the right and upward. 12. Star ...
... the stage where it has a carbon core, the heat from the shrinking core ignites helium fusion in a shell around it, while hydrogen is fusing in a second shell beyond the first. 11. The star slowly enters a new red giant phase and its position on the H-R diagram moves to the right and upward. 12. Star ...
observations of white dwarfs in the solar neighborhood
... The candidates NLTT 529, NLTT 19138, and NLTT 40607 were observed using the modular spectrograph attached to the Hiltner 2.4 m telescope at the Michigan-Dartmouth-MIT Observatory (MDM) on 2002 December 16, 2003 February 3, and June 22. We used the SITE 2048 2048 CCD and the 600 line mm1 grating t ...
... The candidates NLTT 529, NLTT 19138, and NLTT 40607 were observed using the modular spectrograph attached to the Hiltner 2.4 m telescope at the Michigan-Dartmouth-MIT Observatory (MDM) on 2002 December 16, 2003 February 3, and June 22. We used the SITE 2048 2048 CCD and the 600 line mm1 grating t ...
11 Stellar Remnants - Journigan-wiki
... carbon and oxygen with a thin surface layer of hydrogen and helium. There is far too little gas to ever combust, however. White dwarfs simply continue to cool and reach a core temperature of around 20,000 K. ...
... carbon and oxygen with a thin surface layer of hydrogen and helium. There is far too little gas to ever combust, however. White dwarfs simply continue to cool and reach a core temperature of around 20,000 K. ...
White Dwarfs
... c. These stars have multiple concentric layers of active fusion. d. We cannot see the interior stars that are below this temperature, as they are too dim. e. Planetary nebulae glow due to the ionization of low-density gas by a hot interior star. ...
... c. These stars have multiple concentric layers of active fusion. d. We cannot see the interior stars that are below this temperature, as they are too dim. e. Planetary nebulae glow due to the ionization of low-density gas by a hot interior star. ...
Spectroscopy Lecture 10
... replaced by water, metal hydrides (FeH, CrH) Alkali metal lines strengthen (note K I in the L8 dwarf) Spectral types determined from red, far red spectra (blue too faint!) ...
... replaced by water, metal hydrides (FeH, CrH) Alkali metal lines strengthen (note K I in the L8 dwarf) Spectral types determined from red, far red spectra (blue too faint!) ...
Chapter 20: Stellar Evolution: The Death of Stars PowerPoint
... • Name given because they look somewhat like planets • No suggestion that they have, had, or will form planets ...
... • Name given because they look somewhat like planets • No suggestion that they have, had, or will form planets ...
this PDF file - University of Leicester Open Journals
... White dwarfs are a glimpse into our solar system’s future. They are what is left behind after stars have used all of their fuel and collapsed under the force of gravity. We have progressed from thinking we live in an eternal and unchanging universe to one where even the stars themselves will one day ...
... White dwarfs are a glimpse into our solar system’s future. They are what is left behind after stars have used all of their fuel and collapsed under the force of gravity. We have progressed from thinking we live in an eternal and unchanging universe to one where even the stars themselves will one day ...
Brock physics - Brock University
... 35. Neutron stars with masses greater than about 3 solar masses do not exist because neutron degeneracy pressure is not strong enough to balance gravity, and so (a) the neutron star explodes into a Type II supernova. (b) the neutron star explodes into a Type Ib supernova. (c) * the neutron star coll ...
... 35. Neutron stars with masses greater than about 3 solar masses do not exist because neutron degeneracy pressure is not strong enough to balance gravity, and so (a) the neutron star explodes into a Type II supernova. (b) the neutron star explodes into a Type Ib supernova. (c) * the neutron star coll ...
Slide 1
... Max. distance at which WD disc is detectable 0.5 Msolar WD with a disc mass of 10-2 Mearth, observed with Spitzer at 70um ...
... Max. distance at which WD disc is detectable 0.5 Msolar WD with a disc mass of 10-2 Mearth, observed with Spitzer at 70um ...
White dwarfs that crossed the Chandrasekhar limit
... Thus, our Sun is destined to eject out a planetary nebula and end up as a white dwarf. Chandrasekhar estimated that, as long as the end stage of a less massive star resulting from a planetary nebula is less than 1.44 times the mass of the Sun [M], it survives as a faintly visible white dwarf (Box 1 ...
... Thus, our Sun is destined to eject out a planetary nebula and end up as a white dwarf. Chandrasekhar estimated that, as long as the end stage of a less massive star resulting from a planetary nebula is less than 1.44 times the mass of the Sun [M], it survives as a faintly visible white dwarf (Box 1 ...
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).