Self-Regulation of Star Formation in Low Metallicity Clouds
... there are other populations of luminous objects, which precedes normal galaxies. Thus, a theoretical approach to reveal the formation mechanism of such unseen luminous objects is very important. The formation process of a luminous object is roughly divided into three steps, formation of cold clouds ...
... there are other populations of luminous objects, which precedes normal galaxies. Thus, a theoretical approach to reveal the formation mechanism of such unseen luminous objects is very important. The formation process of a luminous object is roughly divided into three steps, formation of cold clouds ...
mats project at fair
... along the regions of extremely neutron-rich nuclides which have yet to be discovered. For this reason, the task of the MATS project will be not only to measure the mass of these nuclides but at first to discover them. The knowledge of the right position of the r-process pathway in combination with t ...
... along the regions of extremely neutron-rich nuclides which have yet to be discovered. For this reason, the task of the MATS project will be not only to measure the mass of these nuclides but at first to discover them. The knowledge of the right position of the r-process pathway in combination with t ...
threshold 1— the big bang
... • The quest for knowledge has not always required the separation of the disciplines into distinct spheres. Socrates, for example, emphasized questions and did not strictly separate the different disciplines and their questions. Today, scholars tend to emphasize the need for separation. • An importan ...
... • The quest for knowledge has not always required the separation of the disciplines into distinct spheres. Socrates, for example, emphasized questions and did not strictly separate the different disciplines and their questions. Today, scholars tend to emphasize the need for separation. • An importan ...
ICP-MS and Planetary Geosciences
... ICP-MS data contribute to understanding the origin of our Solar System and, in fact, the history of the region of interstellar space where the Sun formed. For example, the variability of the amount of 60 Fe and 26 Al (both are short-lived, now extinct, isotopes) might conceivably mean that 60 Fe was ...
... ICP-MS data contribute to understanding the origin of our Solar System and, in fact, the history of the region of interstellar space where the Sun formed. For example, the variability of the amount of 60 Fe and 26 Al (both are short-lived, now extinct, isotopes) might conceivably mean that 60 Fe was ...
The National Ignition Facility and Basic Science
... ++n9Be is the “Gatekeeper” for the r-Process • If this reaction is strong, 9Be becomes abundant, +9Be 12C+n is frequent, and the light nuclei will all have all been captured into the seeds by the time the r-process seeds get to ~Fe • If it’s weak, less 12C is made, and the seeds go up to mass ...
... ++n9Be is the “Gatekeeper” for the r-Process • If this reaction is strong, 9Be becomes abundant, +9Be 12C+n is frequent, and the light nuclei will all have all been captured into the seeds by the time the r-process seeds get to ~Fe • If it’s weak, less 12C is made, and the seeds go up to mass ...
Stellar models and stellar stability
... laws of thermodynamics. Eq. (6.4) is generalized to include both the cases of radiative and convective energy transport. The term ∆∇ is the superadiabaticity of the temperature gradient that must follow from a theory of convection (in practice, the mixing length theory); for the interior one can ta ...
... laws of thermodynamics. Eq. (6.4) is generalized to include both the cases of radiative and convective energy transport. The term ∆∇ is the superadiabaticity of the temperature gradient that must follow from a theory of convection (in practice, the mixing length theory); for the interior one can ta ...
How plausible are the proposed formation scenarios of CEMP
... [Fe/H] < −1. Stars with higher iron abundances in the SAGA database do not show large enrichments in either barium or europium, and therefore we exclude them from our sample. We select the MP stars with observed abundances of barium and europium, and we ignore systems in which only upper or lower li ...
... [Fe/H] < −1. Stars with higher iron abundances in the SAGA database do not show large enrichments in either barium or europium, and therefore we exclude them from our sample. We select the MP stars with observed abundances of barium and europium, and we ignore systems in which only upper or lower li ...
The accretion properties of the intermediate mass Herbig Ae/Be stars
... Accretion rate correlates with mass But: different slope Ae and Be objects Occurs at similar mass as other such findings Vink+ 2002 (see also Muzerolle+ 2004, Grady+ 2010, Oudmaijer+ 2011, Alecian+ 2013, Cauley & Johns-Krull 2015) ...
... Accretion rate correlates with mass But: different slope Ae and Be objects Occurs at similar mass as other such findings Vink+ 2002 (see also Muzerolle+ 2004, Grady+ 2010, Oudmaijer+ 2011, Alecian+ 2013, Cauley & Johns-Krull 2015) ...
Manoel Couder
... Since the present technical possibilities appear to be exhausted, a reduction of the remaining uncertainty can probably only be achieved in an underground laboratory, where the cosmic-ray induced γ background can be avoided. M. Heil et al., Phys. Rev. C 78, 025803 (2008) ARUNA 2014 ...
... Since the present technical possibilities appear to be exhausted, a reduction of the remaining uncertainty can probably only be achieved in an underground laboratory, where the cosmic-ray induced γ background can be avoided. M. Heil et al., Phys. Rev. C 78, 025803 (2008) ARUNA 2014 ...
**** 1 - Asiaa
... 4. Summary 1. Absorption line systems in optical/UV spectra of quasars are a useful tool for exploring gaseous systems, but if there is a very high column density system exists in front of a background quasar, the quasar itself is dropped from the original selection because of strong extinction. 2. ...
... 4. Summary 1. Absorption line systems in optical/UV spectra of quasars are a useful tool for exploring gaseous systems, but if there is a very high column density system exists in front of a background quasar, the quasar itself is dropped from the original selection because of strong extinction. 2. ...
Make Your Own Star Bracelet
... cool stars. Much cooler than their bright blue-white cousins. Stars that are cooler than this type cannot be seen with eyes or optical telescopes. We must look for them by their heat, looking at their infrared radiation." "The next two beads tell us of two possible endings for stars." (pick up the ...
... cool stars. Much cooler than their bright blue-white cousins. Stars that are cooler than this type cannot be seen with eyes or optical telescopes. We must look for them by their heat, looking at their infrared radiation." "The next two beads tell us of two possible endings for stars." (pick up the ...
Presentation in PDF format.
... O stars: >20 M The brightest main-sequence stars. O stars have convective cores and radiative envelopes. Hydrogen-burning is by the CNO-cycle. O stars are always observed close to sites of current or recent star formation. Because of their high luminosities, O stars have very strong stellar winds, ...
... O stars: >20 M The brightest main-sequence stars. O stars have convective cores and radiative envelopes. Hydrogen-burning is by the CNO-cycle. O stars are always observed close to sites of current or recent star formation. Because of their high luminosities, O stars have very strong stellar winds, ...
FP11: DRAKE et al. - Astronomical Institute WWW Homepage
... rotational phase) than the minima of the light curve. It may be caused by the large epoch difference (about 27 years) between photometrical and spectral observations. A small uncertainty in the rotational ephemeris could result in such discrepancy. Nevertheless, since lithium is concentrated in smal ...
... rotational phase) than the minima of the light curve. It may be caused by the large epoch difference (about 27 years) between photometrical and spectral observations. A small uncertainty in the rotational ephemeris could result in such discrepancy. Nevertheless, since lithium is concentrated in smal ...
Spectral modeling of nebular-phase supernovae Anders Jerkstrand Department of Astronomy
... Massive stars live fast and die young. They shine furiously for a few million years, during which time they synthesize most of the heavy elements in the universe in their cores. They end by blowing themselves up in a powerful explosion known as a supernova (SN). During this process, the core collaps ...
... Massive stars live fast and die young. They shine furiously for a few million years, during which time they synthesize most of the heavy elements in the universe in their cores. They end by blowing themselves up in a powerful explosion known as a supernova (SN). During this process, the core collaps ...
Progenitors and Hydrodynamics of Type II and lb Supernovae
... though the 56 Ni mass they assume (0.03 M Q ) may be too large for this class of model. More work is needed both on the explosion model and the pre-explosive mass loss to clarify the observational properties of these supernovae. The range 10 to 12 M Q also gives rise to interesting and uncertain evo ...
... though the 56 Ni mass they assume (0.03 M Q ) may be too large for this class of model. More work is needed both on the explosion model and the pre-explosive mass loss to clarify the observational properties of these supernovae. The range 10 to 12 M Q also gives rise to interesting and uncertain evo ...
1. Basic Properties of Stars
... Between the classes there were 10 subdivisions numbered 0 to 9. For example, our Sun is a G2 star. Sirius, a hot blue star, is type B3. Why do some stars have strong lines of hydrogen, others strong lines of calcium? The answer was not composition (all stars are 95% hydrogen) but rather surface temp ...
... Between the classes there were 10 subdivisions numbered 0 to 9. For example, our Sun is a G2 star. Sirius, a hot blue star, is type B3. Why do some stars have strong lines of hydrogen, others strong lines of calcium? The answer was not composition (all stars are 95% hydrogen) but rather surface temp ...
Thermodynamic properties of nuclear" pasta" in neutron star crusts
... a way as to reproduce nuclear masses and radii of β stable nuclei are replaced by the following values that are generally accepted among recent literature: w0 = 16.0 MeV, k0 = 1.36 fm−1 , K = 230 MeV and s = 30.0 MeV. We remark in passing that such a replacement makes no significant difference in th ...
... a way as to reproduce nuclear masses and radii of β stable nuclei are replaced by the following values that are generally accepted among recent literature: w0 = 16.0 MeV, k0 = 1.36 fm−1 , K = 230 MeV and s = 30.0 MeV. We remark in passing that such a replacement makes no significant difference in th ...
Spectroscopy – Lecture 1
... If in a region of the star the opacity changes, then the star can block energy (photons) which can be subsequently released in a later phase of the pulsation. Helium and and Hydrogen ionization zones of the star are normally where this works. Consider the Helium ionization zone in the interior of a ...
... If in a region of the star the opacity changes, then the star can block energy (photons) which can be subsequently released in a later phase of the pulsation. Helium and and Hydrogen ionization zones of the star are normally where this works. Consider the Helium ionization zone in the interior of a ...
Zinc and chromium abundances in a third
... A detailed description of the procedures used in acquiring and reducing the data can be found in Pettini et al. (1994). Briefly, we used a 1200 grooves mm−1 grating, blazed near 4100 Å, and a thinned 1024 × 1024 pixel Tektronix CCD to record a ≈400 Å wide portion of the spectrum centred at 4121 Å ...
... A detailed description of the procedures used in acquiring and reducing the data can be found in Pettini et al. (1994). Briefly, we used a 1200 grooves mm−1 grating, blazed near 4100 Å, and a thinned 1024 × 1024 pixel Tektronix CCD to record a ≈400 Å wide portion of the spectrum centred at 4121 Å ...
Chemical composition of halo and disk stars with
... whereas Teff = 5800 K gives b = 0.023 ± 0.006. In both cases σ([Fe/H]) ' 0.04 dex. From this we find the effective temperature of CD−57 1633 to be close to 5950 K. Using a similar technique the microturbulent velocity, ξ, can be determined from the slope of [Fe/H] vs. equivalent width. Here, only li ...
... whereas Teff = 5800 K gives b = 0.023 ± 0.006. In both cases σ([Fe/H]) ' 0.04 dex. From this we find the effective temperature of CD−57 1633 to be close to 5950 K. Using a similar technique the microturbulent velocity, ξ, can be determined from the slope of [Fe/H] vs. equivalent width. Here, only li ...
page proofs
... Albert Einstein published his General Theory of Relativity in 1915, which provided a new way of understanding gravity. Until then, scientists had used Isaac Newton’s theory of gravity, which essentially stated that masses exert an attractive force on each other. Einstein’s theory was that mass curve ...
... Albert Einstein published his General Theory of Relativity in 1915, which provided a new way of understanding gravity. Until then, scientists had used Isaac Newton’s theory of gravity, which essentially stated that masses exert an attractive force on each other. Einstein’s theory was that mass curve ...
age of the universe.
... In the first few minutes after the Big Bang, a) the universe cooled and formed neutral matter. b) the cosmic microwave background radiation was released. c) electrons recombined with protons. d) hydrogen fused into deuterium and then helium. e) the universe was governed by one unified superforce. Ex ...
... In the first few minutes after the Big Bang, a) the universe cooled and formed neutral matter. b) the cosmic microwave background radiation was released. c) electrons recombined with protons. d) hydrogen fused into deuterium and then helium. e) the universe was governed by one unified superforce. Ex ...
Complete quantum teleportation using nuclear magnetic resonance
... source consisting of freshly synthesized r-process material with FIPordered preferential acceleration (``rp-®p'' in Fig. 2). Although an rprocess enhancement might be expected in supernova ejecta, no detailed model has been proposed which gives such an enhancement only for Z . 60. However, there is ...
... source consisting of freshly synthesized r-process material with FIPordered preferential acceleration (``rp-®p'' in Fig. 2). Although an rprocess enhancement might be expected in supernova ejecta, no detailed model has been proposed which gives such an enhancement only for Z . 60. However, there is ...
Test 4 Review
... appears to be going more and more slowly as it approaches the event horizon. This is called a gravitational redshift – it is not due to motion, but to the large gravitational ...
... appears to be going more and more slowly as it approaches the event horizon. This is called a gravitational redshift – it is not due to motion, but to the large gravitational ...
Eclipsing binary stars
... total stellar population, but higher is the number of stars in system, lower is the number of known systems [2]. Double stars, or in a shorter term binaries, are important because they are numerous and we can compare them among themselves. They are also the main source of our knowledge on basic char ...
... total stellar population, but higher is the number of stars in system, lower is the number of known systems [2]. Double stars, or in a shorter term binaries, are important because they are numerous and we can compare them among themselves. They are also the main source of our knowledge on basic char ...
Nucleosynthesis
Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons, primarily protons and neutrons. The first nuclei were formed about three minutes after the Big Bang, through the process called Big Bang nucleosynthesis. It was then that hydrogen and helium formed to become the content of the first stars, and this primeval process is responsible for the present hydrogen/helium ratio of the cosmos.With the formation of stars, heavier nuclei were created from hydrogen and helium by stellar nucleosynthesis, a process that continues today. Some of these elements, particularly those lighter than iron, continue to be delivered to the interstellar medium when low mass stars eject their outer envelope before they collapse to form white dwarfs. The remains of their ejected mass form the planetary nebulae observable throughout our galaxy.Supernova nucleosynthesis within exploding stars by fusing carbon and oxygen is responsible for the abundances of elements between magnesium (atomic number 12) and nickel (atomic number 28). Supernova nucleosynthesis is also thought to be responsible for the creation of rarer elements heavier than iron and nickel, in the last few seconds of a type II supernova event. The synthesis of these heavier elements absorbs energy (endothermic) as they are created, from the energy produced during the supernova explosion. Some of those elements are created from the absorption of multiple neutrons (the R process) in the period of a few seconds during the explosion. The elements formed in supernovas include the heaviest elements known, such as the long-lived elements uranium and thorium.Cosmic ray spallation, caused when cosmic rays impact the interstellar medium and fragment larger atomic species, is a significant source of the lighter nuclei, particularly 3He, 9Be and 10,11B, that are not created by stellar nucleosynthesis.In addition to the fusion processes responsible for the growing abundances of elements in the universe, a few minor natural processes continue to produce very small numbers of new nuclides on Earth. These nuclides contribute little to their abundances, but may account for the presence of specific new nuclei. These nuclides are produced via radiogenesis (decay) of long-lived, heavy, primordial radionuclides such as uranium and thorium. Cosmic ray bombardment of elements on Earth also contribute to the presence of rare, short-lived atomic species called cosmogenic nuclides.