PowerPoint Presentation - 18. The Bizarre Stellar Graveyard
... masses collapses beyond electron degeneracy, to a much denser object, where neutron degeneracy holds the object up against gravity - neutron star, seen from some angles looks like a pulsing object (pulsar) • Cores > 3 solar mass collapse beyond this, to a black hole we have no physical model for wha ...
... masses collapses beyond electron degeneracy, to a much denser object, where neutron degeneracy holds the object up against gravity - neutron star, seen from some angles looks like a pulsing object (pulsar) • Cores > 3 solar mass collapse beyond this, to a black hole we have no physical model for wha ...
Lecture 9: Supernovae
... The light-curve behaved exactly as expected: after the initial increase, it faded quickly until June 1987. Then it settled into a much slower fade, of about 1% a day, for two years. This corresponds exactly to the laboratory-measured half-life of 56 Co (77 days), which is the result of the (rapid) d ...
... The light-curve behaved exactly as expected: after the initial increase, it faded quickly until June 1987. Then it settled into a much slower fade, of about 1% a day, for two years. This corresponds exactly to the laboratory-measured half-life of 56 Co (77 days), which is the result of the (rapid) d ...
Using AO to Measure the Star Formation Histories of Massive Galaxies
... The Star Formation Histories of Disk ...
... The Star Formation Histories of Disk ...
Protogalaxies Encyclopedia of Astronomy & Astrophysics eaa.iop.org S G Djorgovski
... motions. Thus, any disk galaxy is unlikely to have had a major merger since its disk was formed, but accretion of smaller satellites is still possible. Conversely, one often hears assertions that (some) ellipticals are made by merging spirals, which is indeed observed in the nearby universe. Obvious ...
... motions. Thus, any disk galaxy is unlikely to have had a major merger since its disk was formed, but accretion of smaller satellites is still possible. Conversely, one often hears assertions that (some) ellipticals are made by merging spirals, which is indeed observed in the nearby universe. Obvious ...
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... 2. Evolution of stellar populations: based on stellar evolution models, and fairly well understood. Lots of parameters: the ...
... 2. Evolution of stellar populations: based on stellar evolution models, and fairly well understood. Lots of parameters: the ...
A Supermassive Black Hole in the Andromeda Galaxy
... • the P3 stellar population is dominated by A-type stars. It is very unlikely that these can be formed in collisions of low mass stars. • a 200 Million year old starburst population provides the best explanation for P3’s spectrum and the power spectrum of P3’s surface brightness fluctuations. • P3 c ...
... • the P3 stellar population is dominated by A-type stars. It is very unlikely that these can be formed in collisions of low mass stars. • a 200 Million year old starburst population provides the best explanation for P3’s spectrum and the power spectrum of P3’s surface brightness fluctuations. • P3 c ...
Article PDF - IOPscience
... the simulations were run with the binary parameters turned off. Since for this study we required detailed information regarding the companion stars and their orbital properties, these were added after the fact as follows. From the TRILEGAL output, we constructed a distance-limited sample with maximu ...
... the simulations were run with the binary parameters turned off. Since for this study we required detailed information regarding the companion stars and their orbital properties, these were added after the fact as follows. From the TRILEGAL output, we constructed a distance-limited sample with maximu ...
Search for giant planets in M67 - III. Excess of hot Jupiters in dense
... frequency of HJs in M67, Hyades, and Praesepe, we may argue that the frequency of HJs depends on stellar metallicity, mass, or on dynamical history, and therefore environment. The dependence of planet frequency on stellar metallicity is complex: even if established very early (Johnson et al. 2010; U ...
... frequency of HJs in M67, Hyades, and Praesepe, we may argue that the frequency of HJs depends on stellar metallicity, mass, or on dynamical history, and therefore environment. The dependence of planet frequency on stellar metallicity is complex: even if established very early (Johnson et al. 2010; U ...
On the Frequency of Giant Planets in the Metal
... For at least 4 metal-rich stars (HD 209458, OGLE-TR-56, OGLE-TR-132, and WASP-1) very similar to TrES-4, their transiting planets have radii so large that even coreless models underestimate their sizes. ...
... For at least 4 metal-rich stars (HD 209458, OGLE-TR-56, OGLE-TR-132, and WASP-1) very similar to TrES-4, their transiting planets have radii so large that even coreless models underestimate their sizes. ...
v1 - ESO
... evolution of the galaxy distribution. The directly observable components of any galaxy are gas, dust and stars, and there is an intimate link between them. Stars form from gas, and synthesise elements in their interiors and the stars that explode at death disperse these elements into the gas from wh ...
... evolution of the galaxy distribution. The directly observable components of any galaxy are gas, dust and stars, and there is an intimate link between them. Stars form from gas, and synthesise elements in their interiors and the stars that explode at death disperse these elements into the gas from wh ...
Protogalaxies
... motions. Thus, any disk galaxy is unlikely to have had a major merger since its disk was formed, but accretion of smaller satellites is still possible. Conversely, one often hears assertions that (some) ellipticals are made by merging spirals, which is indeed observed in the nearby universe. Obvious ...
... motions. Thus, any disk galaxy is unlikely to have had a major merger since its disk was formed, but accretion of smaller satellites is still possible. Conversely, one often hears assertions that (some) ellipticals are made by merging spirals, which is indeed observed in the nearby universe. Obvious ...
Bright 22 μm excess candidates from the wise all-sky
... With the release of the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010) all-sky data, observations at 22 μm will undoubtedly provide an opportunity to search for more IR-excess stars across the whole sky (Wu et al. 2012). Some work related to 22 μm WISE searches has been published. Ke ...
... With the release of the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010) all-sky data, observations at 22 μm will undoubtedly provide an opportunity to search for more IR-excess stars across the whole sky (Wu et al. 2012). Some work related to 22 μm WISE searches has been published. Ke ...
asteroseismological study of massive zz ceti stars with
... stars populating the high-mass component are likely to have carbon–oxygen cores, formed during the stable helium burning phase in the pre-white dwarf evolution. However, evolutionary computations show that stars with stellar mass in the zero age main sequence (ZAMS) of 7 M reach stable carbon igni ...
... stars populating the high-mass component are likely to have carbon–oxygen cores, formed during the stable helium burning phase in the pre-white dwarf evolution. However, evolutionary computations show that stars with stellar mass in the zero age main sequence (ZAMS) of 7 M reach stable carbon igni ...
Star Formation in Disks: Spiral Arms, Turbulence, and Triggering
... There are many types and sources of energy in the ISM and many possible causes for triggering. Energy types include thermal, magnetic, turbulent, cosmic ray, and rotational. The first four are all comparable and equal to several tenths of an eV cm−3 . Rotational energy is much denser, several hundred ...
... There are many types and sources of energy in the ISM and many possible causes for triggering. Energy types include thermal, magnetic, turbulent, cosmic ray, and rotational. The first four are all comparable and equal to several tenths of an eV cm−3 . Rotational energy is much denser, several hundred ...
Neutron stars as probes of extreme energy density matter
... pycno-nuclear reactions that release energy [27] which heats the crust. During the quiescent periods, the heated crust cools and radiates detectable X-rays [28]. Due to the lack of evidence for significant magnetic fields, such as pulsations or cyclotron frequencies, the observed spectra are general ...
... pycno-nuclear reactions that release energy [27] which heats the crust. During the quiescent periods, the heated crust cools and radiates detectable X-rays [28]. Due to the lack of evidence for significant magnetic fields, such as pulsations or cyclotron frequencies, the observed spectra are general ...
Why do some galaxies stop making new stars?
... A distinctive feature of elliptical galaxies is their ellipsoidal shapes, much like an Aussie rules or rugby ball. The Milky Way, and many other large star-forming galaxies, are spiral galaxies. In spiral galaxies, ...
... A distinctive feature of elliptical galaxies is their ellipsoidal shapes, much like an Aussie rules or rugby ball. The Milky Way, and many other large star-forming galaxies, are spiral galaxies. In spiral galaxies, ...
The two components of the evolved massive binary LZ Cephei
... fills up its Roche lobe. The dynamical masses are about 16.0 M (primary) and 6.5 M (secondary). The latter is lower than the typical mass of late-type O stars. The secondary component is chemically more evolved than the primary (which barely shows any sign of CNO processing), with strong helium an ...
... fills up its Roche lobe. The dynamical masses are about 16.0 M (primary) and 6.5 M (secondary). The latter is lower than the typical mass of late-type O stars. The secondary component is chemically more evolved than the primary (which barely shows any sign of CNO processing), with strong helium an ...
Lithium abundances for 185 main-sequence stars
... advantage of improved photometric and spectroscopic determinations of effective temperature and metallicity as well as mass and age derived from Hipparcos absolute magnitudes, offering an opportunity to investigate the behaviour of Li as a function of these parameters. An interesting result from thi ...
... advantage of improved photometric and spectroscopic determinations of effective temperature and metallicity as well as mass and age derived from Hipparcos absolute magnitudes, offering an opportunity to investigate the behaviour of Li as a function of these parameters. An interesting result from thi ...
Astronomy 401 Lecture 8 Spiral Galaxies II 1 The Tully
... Leading theory for the origin of spiral structure is the Lin-Shu density wave theory. This says that spiral structure is due to long-lived quasistatic density waves. These are regions in the galactic disk where the mass density is ∼10 to 20% higher than average. Stars and gas clouds move through the ...
... Leading theory for the origin of spiral structure is the Lin-Shu density wave theory. This says that spiral structure is due to long-lived quasistatic density waves. These are regions in the galactic disk where the mass density is ∼10 to 20% higher than average. Stars and gas clouds move through the ...
Formation of Globular Clusters: In and Out of Dwarf
... Globular clusters can form in giant molecular clouds within the disks of high-redshift galaxies, resolved by hydrodynamical simulations: same microphysics as for young clusters in interacting galaxies model explains observed ages, sizes, masses metallicities correspond to blue/metal-poor clust ...
... Globular clusters can form in giant molecular clouds within the disks of high-redshift galaxies, resolved by hydrodynamical simulations: same microphysics as for young clusters in interacting galaxies model explains observed ages, sizes, masses metallicities correspond to blue/metal-poor clust ...
L17 SHELL-SHOCKED DIFFUSION MODEL FOR THE LIGHT
... circumstellar envelope, created when ∼10 M, was ejected in the decade before the supernova in an eruption analogous to that of h Carinae. The supernova light is produced primarily by diffusion of thermal energy following the passage of the blast wave through this shell. This model differs from tradi ...
... circumstellar envelope, created when ∼10 M, was ejected in the decade before the supernova in an eruption analogous to that of h Carinae. The supernova light is produced primarily by diffusion of thermal energy following the passage of the blast wave through this shell. This model differs from tradi ...
A 25 micron search for Vega-like disks around main
... the 25 µm sample. The stars were selected on the following selection criteria: (1) all stars are within 25 pc of the Sun; (2) a spectral type later than B9 but earlier than M, and only dwarfs of type IV–V or V; (3) a predicted photospheric flux at 60 µm of at least 30 mJy; (4) no (optical) binaries ...
... the 25 µm sample. The stars were selected on the following selection criteria: (1) all stars are within 25 pc of the Sun; (2) a spectral type later than B9 but earlier than M, and only dwarfs of type IV–V or V; (3) a predicted photospheric flux at 60 µm of at least 30 mJy; (4) no (optical) binaries ...
Galaxies - Center for Astrostatistics
... years, become red giants, and return heavy elements like CNO into the interstellar medium via planetary nebulae and supernova remnants. The abundance of heavy elements thus increases with time; this is called chemical evolution of the Galaxy. Planets like Earth (made of silicon, iron, oxygen, ...) c ...
... years, become red giants, and return heavy elements like CNO into the interstellar medium via planetary nebulae and supernova remnants. The abundance of heavy elements thus increases with time; this is called chemical evolution of the Galaxy. Planets like Earth (made of silicon, iron, oxygen, ...) c ...
Chapter 9 Red Giant Evolution
... • The triple-α reaction will be triggered when the core temperature reaches about 0.8 × 108 K. • The onset of helium burning corresponds to the cusp shown in the above figure at point number 7, and signals the end of red giant branch evolution. • The ignition of the core helium is qualitatively diff ...
... • The triple-α reaction will be triggered when the core temperature reaches about 0.8 × 108 K. • The onset of helium burning corresponds to the cusp shown in the above figure at point number 7, and signals the end of red giant branch evolution. • The ignition of the core helium is qualitatively diff ...
File - Astronomy Home
... The constellation Pegasus represents the white, winged horse of Greek mythology. This beautiful figure can be seen high in the sky starting near the end of summer and continuing through autumn if you live in the Northern Hemisphere. If you are below the Equator, look for Pegasus in late winter and t ...
... The constellation Pegasus represents the white, winged horse of Greek mythology. This beautiful figure can be seen high in the sky starting near the end of summer and continuing through autumn if you live in the Northern Hemisphere. If you are below the Equator, look for Pegasus in late winter and t ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.