Direct Imaging and Spectroscopy of a Candidate Companion Below
... Sensitive optical to (sub)millimeter data reveal no clear evidence for circumstellar gas or dust (e.g. Cieza et al. 2007; Andrews and Williams 2007). We initially identified a candidate 3rd member of the ROXs 42B system located at a projected separation of ≈ 1.′′ 16 as a part of a general search for ...
... Sensitive optical to (sub)millimeter data reveal no clear evidence for circumstellar gas or dust (e.g. Cieza et al. 2007; Andrews and Williams 2007). We initially identified a candidate 3rd member of the ROXs 42B system located at a projected separation of ≈ 1.′′ 16 as a part of a general search for ...
Multiple scattering polarization
... sources [23,24]. A log-normal particle size distribution that intends to capture the doubledpeaked size distribution in terrestrial rain clouds is adopted. The present model uniquely predicts the mean particle size and particle number density along the atmospheric depth which plays a crucial role in ...
... sources [23,24]. A log-normal particle size distribution that intends to capture the doubledpeaked size distribution in terrestrial rain clouds is adopted. The present model uniquely predicts the mean particle size and particle number density along the atmospheric depth which plays a crucial role in ...
Scientific Justification
... amount of time. All objects were examined visually using the SPOT imaging tools to verify that bright objects do not fall in regions which could scatter light into the IRAC field of view. IRS Staring Observations - We request a total of 21.76 hours using all four SL and LL modules of IRS in staring ...
... amount of time. All objects were examined visually using the SPOT imaging tools to verify that bright objects do not fall in regions which could scatter light into the IRAC field of view. IRS Staring Observations - We request a total of 21.76 hours using all four SL and LL modules of IRS in staring ...
Lecture 11
... – Hot gas in accretion disks can emit X-rays – The accretion disk can dump material which may become hot and dense enough to under nuclear fusion. • What is a white dwarf supernova – White dwarf accretes gas from companion until it exceeds 1.4 solar masses – which undergoes collapse and destruct ...
... – Hot gas in accretion disks can emit X-rays – The accretion disk can dump material which may become hot and dense enough to under nuclear fusion. • What is a white dwarf supernova – White dwarf accretes gas from companion until it exceeds 1.4 solar masses – which undergoes collapse and destruct ...
Turning over a new leaf
... have to know a little bit about how both types of radiation are created. Cool stars have a surface temperature of just a few thousand degrees, but are surrounded by a much hotter atmosphere of ionized gases (plasma), known as the corona. Despite plasma temperatures reaching a few million degrees, th ...
... have to know a little bit about how both types of radiation are created. Cool stars have a surface temperature of just a few thousand degrees, but are surrounded by a much hotter atmosphere of ionized gases (plasma), known as the corona. Despite plasma temperatures reaching a few million degrees, th ...
Powerpoint - Physics and Astronomy
... b) repeated helium fusion flashes in red giants. c) rapid collapse of a protostar into a massive O star. d) the explosion of a low-mass star. e) the birth of a massive star in a new cluster. Explanation: Sudden, rapid fusion of new fuel dumped onto a white dwarf causes the star to flare up, and for ...
... b) repeated helium fusion flashes in red giants. c) rapid collapse of a protostar into a massive O star. d) the explosion of a low-mass star. e) the birth of a massive star in a new cluster. Explanation: Sudden, rapid fusion of new fuel dumped onto a white dwarf causes the star to flare up, and for ...
Starspots (AIP – Klaus G
... Magnetic fields likely play an important role in almost any astrophysical target, from the early Universe to the Sun, Earth, and its environment. While numerical 3-D MHD simulations became more and more sophisticated in the previous years, magnetic-field observations are still extremely rare (except ...
... Magnetic fields likely play an important role in almost any astrophysical target, from the early Universe to the Sun, Earth, and its environment. While numerical 3-D MHD simulations became more and more sophisticated in the previous years, magnetic-field observations are still extremely rare (except ...
MEarth
... been assumed that the rotational synchronization expected of close-in habitable zone planets would lead either to atmospheric collapse or to steep temperature gradients and climatic conditions not suitable for life. Works reviewed in Scalo et al. and Tarter et al. argue that atmospheric heat circula ...
... been assumed that the rotational synchronization expected of close-in habitable zone planets would lead either to atmospheric collapse or to steep temperature gradients and climatic conditions not suitable for life. Works reviewed in Scalo et al. and Tarter et al. argue that atmospheric heat circula ...
Chapter 12 Star Stuff How do stars form?
... pressure kicks in… Fusion never starts… And the protostar never becomes a hydrogenfusing star Objects with mass <0.08MSun will not heat up enough before degeneracy pressure halts their collapse And such objects end up as brown dwarfs ...
... pressure kicks in… Fusion never starts… And the protostar never becomes a hydrogenfusing star Objects with mass <0.08MSun will not heat up enough before degeneracy pressure halts their collapse And such objects end up as brown dwarfs ...
Finding habitable earths around white dwarfs with a robotic
... • If the white dwarf progenitor has a planetary system at large enough semi-major axis to survive the asymptotic-giant phase and has a companion star, the mass loss of the progenitor will modify the orbital elements of the binary, possibly resulting in instability of the planetary system, in some ca ...
... • If the white dwarf progenitor has a planetary system at large enough semi-major axis to survive the asymptotic-giant phase and has a companion star, the mass loss of the progenitor will modify the orbital elements of the binary, possibly resulting in instability of the planetary system, in some ca ...
Today in Astronomy 102: electron degeneracy pressure and white
... period (plus Newton’s laws), we know that the mass of Sirius B is 1.00M . q From its observed color (blue-white), we know that its temperature is rather high: T = 29,200 K, compared to 5,800 K for the Sun and 10,000 K for Sirius A. q Its luminosity is only 0.003L , much less than that of Sirius A ...
... period (plus Newton’s laws), we know that the mass of Sirius B is 1.00M . q From its observed color (blue-white), we know that its temperature is rather high: T = 29,200 K, compared to 5,800 K for the Sun and 10,000 K for Sirius A. q Its luminosity is only 0.003L , much less than that of Sirius A ...
Helium Fusion What Will Happen When There Is No More Helium in
... • Main sequence lifetimes are much shorter • Early stages after main sequence – Similar to a low mass star, but happen much faster • No helium flash ...
... • Main sequence lifetimes are much shorter • Early stages after main sequence – Similar to a low mass star, but happen much faster • No helium flash ...
IAU GA, Prague, Aug 2006 - Spanish Virtual Observatory
... star-formation regions (e.g Taurus-Auriga). Depending on the ejection velocity BDs may have travelled far from their birth sites and not revealed by the previously mentioned surveys. Check the ejection model by cross-correlating IPHAS and 2MASS to search young BD by their Hα emission and IR colo ...
... star-formation regions (e.g Taurus-Auriga). Depending on the ejection velocity BDs may have travelled far from their birth sites and not revealed by the previously mentioned surveys. Check the ejection model by cross-correlating IPHAS and 2MASS to search young BD by their Hα emission and IR colo ...
Chapter 13 The Stellar Graveyard
... Because the mass of white dwarfs when they explode as supernovae is always around 1.0 M⊙, its luminosity is very consistent, and can be used as a standard candle for the measurement of distance to distant galaxies (Chapter 15). The amount of energy produced by white dwarf supernovae and massive star ...
... Because the mass of white dwarfs when they explode as supernovae is always around 1.0 M⊙, its luminosity is very consistent, and can be used as a standard candle for the measurement of distance to distant galaxies (Chapter 15). The amount of energy produced by white dwarf supernovae and massive star ...
Slide 1
... Calculate the ages of the coolest white dwarf stars: White dwarf cosmochronology • Critical theoretical uncertainties for dating the coolest WDs – Outer layers • Convection, degeneracy, and radiative opacity ...
... Calculate the ages of the coolest white dwarf stars: White dwarf cosmochronology • Critical theoretical uncertainties for dating the coolest WDs – Outer layers • Convection, degeneracy, and radiative opacity ...
Chapter 14 Stellar Corpses Stellar Corpses White Dwarfs White
... about that of the Earth • Despite their high surface temperature of about 25,000 K, they are very dim due to their small size • Their light is generated from residual heat (no fusion) in the star’s interior ...
... about that of the Earth • Despite their high surface temperature of about 25,000 K, they are very dim due to their small size • Their light is generated from residual heat (no fusion) in the star’s interior ...
structure and evolution of white dwarfs and their
... ideas remain unchanged. However, importantly, they have also hardly been tested by direct observation. Theoretical and observational study of stellar evolution has placed white dwarfs as one possible end point of the process. In general terms, all stars with masses below about eight times that of th ...
... ideas remain unchanged. However, importantly, they have also hardly been tested by direct observation. Theoretical and observational study of stellar evolution has placed white dwarfs as one possible end point of the process. In general terms, all stars with masses below about eight times that of th ...
white dwarfs and the age of the universe
... convective, that completely controls the emergent flux of energy. Its behavior is the result of: 1. A non–standard initial chemical composition resulting from hydrogen and helium shell burning in AGB stars, 2. A very efficient gravitational settling that induces the stratification of the envelope in ...
... convective, that completely controls the emergent flux of energy. Its behavior is the result of: 1. A non–standard initial chemical composition resulting from hydrogen and helium shell burning in AGB stars, 2. A very efficient gravitational settling that induces the stratification of the envelope in ...
Level 2 Science (90764) 2011 Assessment Schedule
... Sun (electromagnetic radiation). On the other hand a brown dwarf has insufficient mass to start fusion process of hydrogen nuclei. Brown dwarfs are small in comparison to the sun and (emit only infra-red radiation). No luminosity. Evidence can be obtained from a labelled diagram. ...
... Sun (electromagnetic radiation). On the other hand a brown dwarf has insufficient mass to start fusion process of hydrogen nuclei. Brown dwarfs are small in comparison to the sun and (emit only infra-red radiation). No luminosity. Evidence can be obtained from a labelled diagram. ...
Assessment Schedule
... Sun (electromagnetic radiation). On the other hand a brown dwarf has insufficient mass to start fusion process of hydrogen nuclei. Brown dwarfs are small in comparison to the sun and (emit only infra-red radiation). No luminosity. Evidence can be obtained from a labelled diagram. ...
... Sun (electromagnetic radiation). On the other hand a brown dwarf has insufficient mass to start fusion process of hydrogen nuclei. Brown dwarfs are small in comparison to the sun and (emit only infra-red radiation). No luminosity. Evidence can be obtained from a labelled diagram. ...
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).