Stellar Metamorphosis
... system formation because these stars should have already squeezed together to make one single star. According to the mainstream dogma solar systems have a central star which centralizes the majority of the material that forms the theorized disk surrounding it, therefore these stars should not be sep ...
... system formation because these stars should have already squeezed together to make one single star. According to the mainstream dogma solar systems have a central star which centralizes the majority of the material that forms the theorized disk surrounding it, therefore these stars should not be sep ...
The role of neutron star mergers in the chemical evolution of the
... Aims. We explore the problem of the production site of Eu. We also use the information present in the observed spread in the Eu abundances in the early Galaxy, and not only its average trend. Moreover, we extend our investigations to other heavy elements (Ba, Sr, Rb, Zr) to provide additional constr ...
... Aims. We explore the problem of the production site of Eu. We also use the information present in the observed spread in the Eu abundances in the early Galaxy, and not only its average trend. Moreover, we extend our investigations to other heavy elements (Ba, Sr, Rb, Zr) to provide additional constr ...
Astronomy 112: The Physics of Stars Class 1 Notes
... surface temperature, so the spectral classes correspond to different ranges of surface temperature. O is the hottest, and M is the coolest. Today we know that both surface temperature and spectrum are determined by stellar mass, as we’ll discuss in a few weeks. Thus the spectral classes correspond t ...
... surface temperature, so the spectral classes correspond to different ranges of surface temperature. O is the hottest, and M is the coolest. Today we know that both surface temperature and spectrum are determined by stellar mass, as we’ll discuss in a few weeks. Thus the spectral classes correspond t ...
The Universe - the Scientia Review
... Of the various types of galaxies, the spiral galaxy is by far the most common. In fact, About 77% of all known galaxies are spiral. There are a few main features that are found in all spiral galaxies, including a disc-like shape and a galactic bulge. The discs are usually This image of a spiral gala ...
... Of the various types of galaxies, the spiral galaxy is by far the most common. In fact, About 77% of all known galaxies are spiral. There are a few main features that are found in all spiral galaxies, including a disc-like shape and a galactic bulge. The discs are usually This image of a spiral gala ...
EXPLORING STELLAR EVOLUTION MODELS OF sdB STARS
... stars were determined to be significantly less than halfway through their He-burning lifetimes, having consumed only about 20%–40% of the helium fuel in their cores. Standard stellar evolution, without any additional mixing at the boundary of the convective core, predicts a constant convective core m ...
... stars were determined to be significantly less than halfway through their He-burning lifetimes, having consumed only about 20%–40% of the helium fuel in their cores. Standard stellar evolution, without any additional mixing at the boundary of the convective core, predicts a constant convective core m ...
PDF only - at www.arxiv.org.
... temperature drops below 2000 K, an upper limit above which many of the molecules studied undergo thermal dissociation 2.2 Photochemical Rate Constant Corrections ...
... temperature drops below 2000 K, an upper limit above which many of the molecules studied undergo thermal dissociation 2.2 Photochemical Rate Constant Corrections ...
The Evolution of Elements and Isotopes
... form or another, for example, the neutron-rich outflows region are formed. At that point the star has squeezed out from a neutron star forming as a result of a supernova as much nuclear energy as it can, and the formation of explosion (FIG. 1), or the matter ejected during the merging heavier elemen ...
... form or another, for example, the neutron-rich outflows region are formed. At that point the star has squeezed out from a neutron star forming as a result of a supernova as much nuclear energy as it can, and the formation of explosion (FIG. 1), or the matter ejected during the merging heavier elemen ...
Stellar physics revealed by planet transits
... Spot anomalies detected with high-precision photometry are now a common and useful tool for measuring rotation periods and obliquities in transiting systems (complementary to the R-M effect). They can also serve to characterize the spot distribution. R. Sanchis-Ojeda ...
... Spot anomalies detected with high-precision photometry are now a common and useful tool for measuring rotation periods and obliquities in transiting systems (complementary to the R-M effect). They can also serve to characterize the spot distribution. R. Sanchis-Ojeda ...
Young Galaxies Grow - Astronomical Society of the Pacific
... galaxies form are very extended, but are also very sparse in their outer regions. Stars form when clouds of gas and dust condense until nuclear reactions ignite in their cores. The density of gas beyond the bright central galaxy was believed to be too low for star formation to occur. ...
... galaxies form are very extended, but are also very sparse in their outer regions. Stars form when clouds of gas and dust condense until nuclear reactions ignite in their cores. The density of gas beyond the bright central galaxy was believed to be too low for star formation to occur. ...
Astronomy Astrophysics
... rotation axis under which the star is seen. The long-term photometry of the young single star LQ Hya, although not included in the initial project, is also used in the present analysis to enlarge the investigated sample. We determined for LQ Hya three different starspot cycles and an antisolar patte ...
... rotation axis under which the star is seen. The long-term photometry of the young single star LQ Hya, although not included in the initial project, is also used in the present analysis to enlarge the investigated sample. We determined for LQ Hya three different starspot cycles and an antisolar patte ...
Boson Stars: Alternatives to primordial black holes?
... mass of the W boson would be small. Above 1.2 TeV/c2 , however, the self–interaction U (Φ) of the Higgs field is so large that the perturbative approach of the standard model becomes unreliable. Therefore a conformal extension of the standard model with gravity included could be necessary, see [35]. ...
... mass of the W boson would be small. Above 1.2 TeV/c2 , however, the self–interaction U (Φ) of the Higgs field is so large that the perturbative approach of the standard model becomes unreliable. Therefore a conformal extension of the standard model with gravity included could be necessary, see [35]. ...
Discovery probability of transiting extragalactic planets and
... the planetary motion laws and at the end of 17th century, P. Laplace and E. Kant suggested the first scientific theory for planetary creation. In early 19th century, measurments of the temperature of stars, astronomers found out that stars are too hot to harbour life. The German astronomer Otto Stru ...
... the planetary motion laws and at the end of 17th century, P. Laplace and E. Kant suggested the first scientific theory for planetary creation. In early 19th century, measurments of the temperature of stars, astronomers found out that stars are too hot to harbour life. The German astronomer Otto Stru ...
THE ORIGIN AND EVOLUTION OF PLANETARY NEBULAE
... The first catalog devoted exclusively to PN was made by Curtis (1918), which contained photographs of 78 PN. This number was increased to 134 in the catalog of Vorontsov-Velyaminov (1934). The catalog of Galactic Planetary Nebulae by Perek and Kohoutek in 1967 has over 1000 PN included. In the Stras ...
... The first catalog devoted exclusively to PN was made by Curtis (1918), which contained photographs of 78 PN. This number was increased to 134 in the catalog of Vorontsov-Velyaminov (1934). The catalog of Galactic Planetary Nebulae by Perek and Kohoutek in 1967 has over 1000 PN included. In the Stras ...
Photometry Review from Some Constellations of Autumn in the
... atmospheric extinction. This is often in addition to correcting for their temporal variations, particularly when the objects being compared are too far apart on the sky to be observed simultaneously. When doing the calibration from an image that contains both the target and comparison objects in clo ...
... atmospheric extinction. This is often in addition to correcting for their temporal variations, particularly when the objects being compared are too far apart on the sky to be observed simultaneously. When doing the calibration from an image that contains both the target and comparison objects in clo ...
ASTR 31: Descriptive Astronomy
... This is where the neon in neon signs come from – Viva Las Vegas! Helium capture The triple-alpha reaction and the major carbon and oxygen burning reactions are helium capture reactions. The capture of helium nuclei continues until silicon is created, at which point the supply of helium nuclei in ...
... This is where the neon in neon signs come from – Viva Las Vegas! Helium capture The triple-alpha reaction and the major carbon and oxygen burning reactions are helium capture reactions. The capture of helium nuclei continues until silicon is created, at which point the supply of helium nuclei in ...
Carbon-enhanced metal-poor stars: the most pristine - HAL
... giant branch). A large percentage of the CEMP-s or -rs stars indeed shows radial velocity variations: this observed percentage is so large that it suggests (Lucatello et al. 2005) that all these stars are binaries. The AGB companions have different masses and abundances. However, the abundance patte ...
... giant branch). A large percentage of the CEMP-s or -rs stars indeed shows radial velocity variations: this observed percentage is so large that it suggests (Lucatello et al. 2005) that all these stars are binaries. The AGB companions have different masses and abundances. However, the abundance patte ...
Downloadable Full Text
... mass. Since the values of β typically lie between ∼ 0.7 and 1.0, and therefore not much mass is lost, our results are not highly sensitive to the exact choice for α. We have also verified this by running a number of evolutionary models where α = 0.5 and α = 1.5. The main effect of adopting higher va ...
... mass. Since the values of β typically lie between ∼ 0.7 and 1.0, and therefore not much mass is lost, our results are not highly sensitive to the exact choice for α. We have also verified this by running a number of evolutionary models where α = 0.5 and α = 1.5. The main effect of adopting higher va ...
Can Planets survive Stellar Evolution?
... the simplified formalism of Nelemans & Tauris (1998) we find that planets with masses less than 0.014 M⊙ or 15 MJ (where MJ is the Jupiter mass) will evaporate inside the envelope of an AGB star with main sequence mass of 1 M⊙ . This mass limit is much higher, ∼ 120 MJ (0.11 M⊙ ) well into the stell ...
... the simplified formalism of Nelemans & Tauris (1998) we find that planets with masses less than 0.014 M⊙ or 15 MJ (where MJ is the Jupiter mass) will evaporate inside the envelope of an AGB star with main sequence mass of 1 M⊙ . This mass limit is much higher, ∼ 120 MJ (0.11 M⊙ ) well into the stell ...
Coming Home - Marcia Bartusiak
... now realize that the bright, visible nebulas are mere blis ters on the sides of huge, in visible molecular clouds that spawn clusters of stars. Each new generation of stars digs ever deeper into the dark cloud, kindling a wave of star formation that surges through the cloud like the successive bur ...
... now realize that the bright, visible nebulas are mere blis ters on the sides of huge, in visible molecular clouds that spawn clusters of stars. Each new generation of stars digs ever deeper into the dark cloud, kindling a wave of star formation that surges through the cloud like the successive bur ...
Pioneering Women in the Spectral Classification of Stars
... categories. Relatively little progress followed until the advent of dry-plate photography. Then both Edward C. Pickering, Director of Harvard College Observatory, and Henry Draper made great strides in the accumulation of photographs of stellar spectra. Henry Draper (1837 – 1882) was a pioneer in st ...
... categories. Relatively little progress followed until the advent of dry-plate photography. Then both Edward C. Pickering, Director of Harvard College Observatory, and Henry Draper made great strides in the accumulation of photographs of stellar spectra. Henry Draper (1837 – 1882) was a pioneer in st ...
Chapter 2 Stellar Dynamics in Galaxies
... the galaxy might evolve with time, as a result only of the internal encounters between stars. The truth, however, is rather different. Close star-star encounters are extremely rare and even the effects of distant encounters are so slight that it takes an extremely long time for the dynamics of galax ...
... the galaxy might evolve with time, as a result only of the internal encounters between stars. The truth, however, is rather different. Close star-star encounters are extremely rare and even the effects of distant encounters are so slight that it takes an extremely long time for the dynamics of galax ...
The Big Bang and Stellar Evolution
... atoms! 5 - There is no way to expand it. How can you expand what isn’t there? Even if that magical vacuum could somehow be pulled together by gravity, what would then cause the pile of emptiness to push outward? The “gravity” which brought it together would keep it from expanding. 6 - Nothingness ca ...
... atoms! 5 - There is no way to expand it. How can you expand what isn’t there? Even if that magical vacuum could somehow be pulled together by gravity, what would then cause the pile of emptiness to push outward? The “gravity” which brought it together would keep it from expanding. 6 - Nothingness ca ...
The deep OB star population in Carina from the VST Photometric Hα
... The number of objects in this initial selection was 37 971. All candidates are then cross-matched against the Two Micron All-Sky Survey (2MASS), the only available near-infrared (NIR) survey covering the whole region. The maximum cross-match distance was set to 1 arcsec in forming optical near-infra ...
... The number of objects in this initial selection was 37 971. All candidates are then cross-matched against the Two Micron All-Sky Survey (2MASS), the only available near-infrared (NIR) survey covering the whole region. The maximum cross-match distance was set to 1 arcsec in forming optical near-infra ...
Diapositiva 1 - Yale University
... Over the past 15 years four catalogues -with well over a million entries each- have been published. They are called MEGA Catalogues: ...
... Over the past 15 years four catalogues -with well over a million entries each- have been published. They are called MEGA Catalogues: ...
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.