Analysis of Two Pulsating X-ray Sources
... Calculations and Interpretations: The acceleration due to gravity (g) on the surface of a star (according to Newton’s Universal Law of Gravitation) is given by g = (GM)/R2 where G = 6.67 X 10-11 Nm2/kg2, M=star’s mass and R = star’s radius Centripetal acceleration (ac) of an object on the surface o ...
... Calculations and Interpretations: The acceleration due to gravity (g) on the surface of a star (according to Newton’s Universal Law of Gravitation) is given by g = (GM)/R2 where G = 6.67 X 10-11 Nm2/kg2, M=star’s mass and R = star’s radius Centripetal acceleration (ac) of an object on the surface o ...
Stellar Remnants - Sierra College Astronomy Home Page
... Earth’s), and a teaspoon of white dwarf material would weigh 2 tons. ...
... Earth’s), and a teaspoon of white dwarf material would weigh 2 tons. ...
The Hertzsprung-Russell Diagram
... In general the hotter the star is the brighter it will be. Thus you would expect stars of the same size but different temperatures to form a diagonal line called an equal radius line. Equal Radius lines can be added to an H-R diagram ...
... In general the hotter the star is the brighter it will be. Thus you would expect stars of the same size but different temperatures to form a diagonal line called an equal radius line. Equal Radius lines can be added to an H-R diagram ...
Lecture 30
... Energy generation rate per unit mass: q µ r T …where b - the temperature sensitivity of the nuclear reaction rate, is at least +4 and sometimes +20 or more. Suppose temperature in the core momentarily drops, reducing ...
... Energy generation rate per unit mass: q µ r T …where b - the temperature sensitivity of the nuclear reaction rate, is at least +4 and sometimes +20 or more. Suppose temperature in the core momentarily drops, reducing ...
White Dwarfs
... Eventually at ρ greater than about 10 7 g cm −3 electrons in the central part of the white dwarf start to move close to the speed of light. As the mass continues to grow, a larger fraction of the star is supported by relativistic electron degeneracy pressure. Consider the limit: GM ρ ...
... Eventually at ρ greater than about 10 7 g cm −3 electrons in the central part of the white dwarf start to move close to the speed of light. As the mass continues to grow, a larger fraction of the star is supported by relativistic electron degeneracy pressure. Consider the limit: GM ρ ...
14.1 Introduction - University of Cambridge
... ure 13.11) following the ejection of the star’s outer layers in the planetary nebula stage. In either case, without an internal source of energy, white dwarfs simply cool off at an essentially constant radius as they slowly deplete their supply of thermal energy. ...
... ure 13.11) following the ejection of the star’s outer layers in the planetary nebula stage. In either case, without an internal source of energy, white dwarfs simply cool off at an essentially constant radius as they slowly deplete their supply of thermal energy. ...
Talk
... Shell helium and hydrogen fusion (asymptotic giant phase) White dwarf phase, fusion completed This series of stages is similar for all stars with initial masses in the range 0.4 – 4.0 MŸ. More massive stars are able to start fusion reactions involving carbon and oxygen Ø next week. ...
... Shell helium and hydrogen fusion (asymptotic giant phase) White dwarf phase, fusion completed This series of stages is similar for all stars with initial masses in the range 0.4 – 4.0 MŸ. More massive stars are able to start fusion reactions involving carbon and oxygen Ø next week. ...
A new low proper motion catalogue of bright M
... habitable zone as well as favourable contrast ratios between the planet and the host star. Though M dwarfs are the most numerous type of stars in the Galaxy, because of their colour and low luminosity they often can be confused for reddened stars or distant red giants. Because of this their identifi ...
... habitable zone as well as favourable contrast ratios between the planet and the host star. Though M dwarfs are the most numerous type of stars in the Galaxy, because of their colour and low luminosity they often can be confused for reddened stars or distant red giants. Because of this their identifi ...
Oscillating White Dwarf Stars Background on White Dwarfs
... (sidelobes). This can only done by „closing up the gaps“. However for stellar observations the sun gets in the way so you always have 1-day aliases. ...
... (sidelobes). This can only done by „closing up the gaps“. However for stellar observations the sun gets in the way so you always have 1-day aliases. ...
HW7-3
... (260) RQ 3: What is a brown dwarf? A brown dwarf is a “failed star.” They are balls of gas without fusion. The upper end of brown dwarfs is well defined: 8% M☉ = 80 Jupiters. There is a not-so-welldefined line between small brown dwarfs and large planets. (260) RQ 6: Why do expanding stars become co ...
... (260) RQ 3: What is a brown dwarf? A brown dwarf is a “failed star.” They are balls of gas without fusion. The upper end of brown dwarfs is well defined: 8% M☉ = 80 Jupiters. There is a not-so-welldefined line between small brown dwarfs and large planets. (260) RQ 6: Why do expanding stars become co ...
Gravity Defied From Potato Asteroids to Magnetised Neutron Stars
... Once formed, the stars spend most of their life fusing hydrogen, in the phase known as ‘main sequence’. During main sequence, the stars get progressively hotter and brighter (higher luminosity). Depending on the mass, the stars then enter into subsequent phases of nuclear fusion involving helium and ...
... Once formed, the stars spend most of their life fusing hydrogen, in the phase known as ‘main sequence’. During main sequence, the stars get progressively hotter and brighter (higher luminosity). Depending on the mass, the stars then enter into subsequent phases of nuclear fusion involving helium and ...
The Later Evolution of Low Mass Stars (< 8 solar masses)
... http://en.wikipedia.org/wiki/Ring_Nebula AGB stars are known to lose mass at a prodigious rate during their final stages, around 10-5 - 10-4 solar masses per year. This obviously cannot persist for much over 100,000 years. The mass loss is driven in part by the pulsational instability of the thin he ...
... http://en.wikipedia.org/wiki/Ring_Nebula AGB stars are known to lose mass at a prodigious rate during their final stages, around 10-5 - 10-4 solar masses per year. This obviously cannot persist for much over 100,000 years. The mass loss is driven in part by the pulsational instability of the thin he ...
Evolution of a Protostar
... The contraction of a cloud fragment slows when thermal pressure builds up because infrared and radio photons can no longer escape. ...
... The contraction of a cloud fragment slows when thermal pressure builds up because infrared and radio photons can no longer escape. ...
White Dwarfs and Neutron Stars
... • Is no longer actively creating energy through thermonuclear fusion • Peak emission in Ultraviolet • Radius comparable to Earth’s • Mass limit of about 1.4 solar masses • Can explode into novae and supernovae ...
... • Is no longer actively creating energy through thermonuclear fusion • Peak emission in Ultraviolet • Radius comparable to Earth’s • Mass limit of about 1.4 solar masses • Can explode into novae and supernovae ...
Linking Asteroids and Meteorites through Reflectance
... White Dwarf • The remaining core becomes a white dwarf • White dwarfs are usually composed of carbon and oxygen (can not fuse carbon) • Oxygen-neon-magnesium white dwarfs can also form (hot enough to fuse carbon but not neon) • Helium white dwarfs can form ...
... White Dwarf • The remaining core becomes a white dwarf • White dwarfs are usually composed of carbon and oxygen (can not fuse carbon) • Oxygen-neon-magnesium white dwarfs can also form (hot enough to fuse carbon but not neon) • Helium white dwarfs can form ...
ASTR100 Class 01 - University of Maryland Department of
... Degeneracy pressure halts the contraction of objects with mass < 0.08 MSun before the core temperature becomes hot enough for fusion. Star-like objects not massive enough to start fusion are brown dwarfs. ...
... Degeneracy pressure halts the contraction of objects with mass < 0.08 MSun before the core temperature becomes hot enough for fusion. Star-like objects not massive enough to start fusion are brown dwarfs. ...
Introduction to Astronomy
... the Sun & size comparable to the Earth – Shines from residual (left-over) heat produced in core during normal lifetime ...
... the Sun & size comparable to the Earth – Shines from residual (left-over) heat produced in core during normal lifetime ...
The Hertzsprung-Russell Diagram
... Equal Radius Lines In general the hotter the star is the brighter it will be. Thus you would expect stars of the same size but different temperatures to form a diagonal line called an equal radius line. Equal Radius lines can be added to an H-R diagram ...
... Equal Radius Lines In general the hotter the star is the brighter it will be. Thus you would expect stars of the same size but different temperatures to form a diagonal line called an equal radius line. Equal Radius lines can be added to an H-R diagram ...
Dark Matter Burners
... “old stars masquerading as young” or “hot dwarfs – stripped cores of red giants” ...
... “old stars masquerading as young” or “hot dwarfs – stripped cores of red giants” ...
What is a white dwarf?
... • Adding mass to a white dwarf increases its gravity, forcing electrons into a smaller space • In order to avoid being in the same state in the same place some of the electrons need to move faster. That increases the temperature, but not the pressure degeneracy pressure doesn't depend on tempe ...
... • Adding mass to a white dwarf increases its gravity, forcing electrons into a smaller space • In order to avoid being in the same state in the same place some of the electrons need to move faster. That increases the temperature, but not the pressure degeneracy pressure doesn't depend on tempe ...
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).