The slow-neutron capture process at low metallicity
... • No 13C pocket needed for production of s-process elements due to proton ingestion during first few thermal pulses • Neutrons released in these conditions produce lower [Pb/ls] ratios than when released in 13C pockets ...
... • No 13C pocket needed for production of s-process elements due to proton ingestion during first few thermal pulses • Neutrons released in these conditions produce lower [Pb/ls] ratios than when released in 13C pockets ...
IDENTIFICATION OF MAIN-SEQUENCE STARS WITH MID
... main sequence is not well understood (Meyer & Beckwith 2000). Lack of observational evidence of an evolutionary disk sequence is a major hindrance in the understanding of planetary formation. The reason for this lack of evidence is that only the nearest stars have been probed for circumstellar disks ...
... main sequence is not well understood (Meyer & Beckwith 2000). Lack of observational evidence of an evolutionary disk sequence is a major hindrance in the understanding of planetary formation. The reason for this lack of evidence is that only the nearest stars have been probed for circumstellar disks ...
Fulltext
... clever way to distinguish between the two scenarios can be found. On the other hand, scalar fields, or composites of Lorentz scalar in nature, are indispensible building blocks of matter, which may explain why building blocks of matter acquire masses at the fundamental level. In the present-day part ...
... clever way to distinguish between the two scenarios can be found. On the other hand, scalar fields, or composites of Lorentz scalar in nature, are indispensible building blocks of matter, which may explain why building blocks of matter acquire masses at the fundamental level. In the present-day part ...
Astronomy 100—Exam 3
... 24. Astronomers believe a massive black hole exists in the nucleus of the Galaxy. The evidence they provide: A. large amount of X-ray is observed from the nucleus B. if there were not a black hole there, all stars in the Galaxy would just drift into space. C. motions of stars near the center suggest ...
... 24. Astronomers believe a massive black hole exists in the nucleus of the Galaxy. The evidence they provide: A. large amount of X-ray is observed from the nucleus B. if there were not a black hole there, all stars in the Galaxy would just drift into space. C. motions of stars near the center suggest ...
Transport of angular momentum in massive stars
... survey was started to obtain rotation rates, radial radiation variation for binaries and surface abundances for a large sample of O and B stars to progress the understanding of massive star evolution. The tool of observation was the VLT and most measurements where spectral analysis of the stars. Her ...
... survey was started to obtain rotation rates, radial radiation variation for binaries and surface abundances for a large sample of O and B stars to progress the understanding of massive star evolution. The tool of observation was the VLT and most measurements where spectral analysis of the stars. Her ...
The IMF of intermediate-mass stars in young star clusters
... for a total of 53 measurements; excluding 4 deviant points, we get 2.35 ± 0.24. For the full mass range 1-80M , we get a value of 2.32 ± 0.3. Reliable MF slope and cluster age for a number of young star clusters and associations located in LMCs have been determined using both ground-based telescope ...
... for a total of 53 measurements; excluding 4 deviant points, we get 2.35 ± 0.24. For the full mass range 1-80M , we get a value of 2.32 ± 0.3. Reliable MF slope and cluster age for a number of young star clusters and associations located in LMCs have been determined using both ground-based telescope ...
Distances to the Hyades Cluster
... position of a star across our line of sight, measured in arc seconds per year. For stars visible to the naked eye, the average proper motion is around 0.1 arcsec per year (remember how small an arc second is? A tennis ball 8 miles away is an arcsecond in diameter). The largest proper motion award go ...
... position of a star across our line of sight, measured in arc seconds per year. For stars visible to the naked eye, the average proper motion is around 0.1 arcsec per year (remember how small an arc second is? A tennis ball 8 miles away is an arcsecond in diameter). The largest proper motion award go ...
plato
... • Complete statistical study of exoplanetary systems • Identification and characterisation of planetary systems - including planets of all masses and sizes on various orbits - around stars of all types and ages - including seismic characterization of planet host stars - in particular rocky planets i ...
... • Complete statistical study of exoplanetary systems • Identification and characterisation of planetary systems - including planets of all masses and sizes on various orbits - around stars of all types and ages - including seismic characterization of planet host stars - in particular rocky planets i ...
Neutron Degeneracy Pressure
... for example, of non-Hydrogen like atoms. This idea of energy state filling becomes crucial when discussing degeneracy pressure. The Pauli Exclusion Principle can also be applied to further our understanding of stars, black holes, supernovae, and many other celestial objects and phenomena studied in ...
... for example, of non-Hydrogen like atoms. This idea of energy state filling becomes crucial when discussing degeneracy pressure. The Pauli Exclusion Principle can also be applied to further our understanding of stars, black holes, supernovae, and many other celestial objects and phenomena studied in ...
The California Planet Survey II. A Saturn
... Henry et al. (1995b) show many examples of active stars with low-amplitude starspot variability. Queloz et al. (2001) and Paulson et al. (2004) show several examples of stellar spots masquerading as planets. In the case of Gl 649 described here, the photometric observations reveal variability timesc ...
... Henry et al. (1995b) show many examples of active stars with low-amplitude starspot variability. Queloz et al. (2001) and Paulson et al. (2004) show several examples of stellar spots masquerading as planets. In the case of Gl 649 described here, the photometric observations reveal variability timesc ...
The X-ray Bursters Problem and its Implications to the Equation of
... unstable and lead to thermonuclear ashes. This would be caused by unstable burning of a several meters thick layer of accreted hydrogen and helium on the surface of neutron stars from the binary companion. The group noted that the energy of these ashes could produce variable X-ray emission from th ...
... unstable and lead to thermonuclear ashes. This would be caused by unstable burning of a several meters thick layer of accreted hydrogen and helium on the surface of neutron stars from the binary companion. The group noted that the energy of these ashes could produce variable X-ray emission from th ...
P-process nucleosynthesis in detonating white dwarfs in the light of
... type Ia Supernovae owing to the more credible evolutionary track leading to the ignition of the detonation and their relatively high estimated frequency of about 0.01 y−1 (Iben & Tutukov 1991). Nevertheless the resulting spectrum of the explosions near maximum light does not agree so well with obser ...
... type Ia Supernovae owing to the more credible evolutionary track leading to the ignition of the detonation and their relatively high estimated frequency of about 0.01 y−1 (Iben & Tutukov 1991). Nevertheless the resulting spectrum of the explosions near maximum light does not agree so well with obser ...
Carbon Enhanced Stars in the Sloan Digital Sky Survey ( SDSS )
... SDSS DR4 has about 102,714 stars at a resolution R= 1800 from 3800Å to 9000Å Already about 500 Faint high latitute carbon stars have been identified by Morgan et al. 2002 and Downes et al. 2004. from SDSS DR1 The propermotions indicate that most of them are near by dwarfs. ==> Young population which ...
... SDSS DR4 has about 102,714 stars at a resolution R= 1800 from 3800Å to 9000Å Already about 500 Faint high latitute carbon stars have been identified by Morgan et al. 2002 and Downes et al. 2004. from SDSS DR1 The propermotions indicate that most of them are near by dwarfs. ==> Young population which ...
Chapter 9 Early stages of evolution and the main sequence phase
... The process of star formation constitutes one of the main problems of modern astrophysics. Compared to our understanding of what happens after stars have formed out of the interstellar medium – that is, stellar evolution – star formation is a very ill-understood problem. No predictive theory of star ...
... The process of star formation constitutes one of the main problems of modern astrophysics. Compared to our understanding of what happens after stars have formed out of the interstellar medium – that is, stellar evolution – star formation is a very ill-understood problem. No predictive theory of star ...
Planet formation around M-dwarfs: the moving snow line and super
... 2–3 AU, and 1–2M⊕ planets at 3–4 AU. If we simply adapt the collisional history of Earth formation to a planetesimal disk around a 0.25M star, mergers of ∼10 oligarchs should yield planets with masses ∼1–2M⊕ at 1 AU and ∼3–5M⊕ at 2.5 AU. To consider whether oligarchs can merge into superEarths on r ...
... 2–3 AU, and 1–2M⊕ planets at 3–4 AU. If we simply adapt the collisional history of Earth formation to a planetesimal disk around a 0.25M star, mergers of ∼10 oligarchs should yield planets with masses ∼1–2M⊕ at 1 AU and ∼3–5M⊕ at 2.5 AU. To consider whether oligarchs can merge into superEarths on r ...
The Sun's Crowded Delivery Room July 6, 2007
... The 60Fe cannot have come from a source too far from the infant Sun. If too far away it would decay before arriving or be so diluted that we could not measure it. The exploding star had to be in the Sun's general vicinity. It was a cluster mate of the Sun. One type of massive star is called a Wolf-R ...
... The 60Fe cannot have come from a source too far from the infant Sun. If too far away it would decay before arriving or be so diluted that we could not measure it. The exploding star had to be in the Sun's general vicinity. It was a cluster mate of the Sun. One type of massive star is called a Wolf-R ...
Expected Coalescence Rate of NS/NS Binaries for Laser Beam
... NS : fraction of massive binaries that remain bounded after the second supernova P( ): probability for a newly formed NS/NS to coalesce in a timescale 0 : minimum coalescence time * : mean timescale required for the newly formed massive system to evolve into two NSs ...
... NS : fraction of massive binaries that remain bounded after the second supernova P( ): probability for a newly formed NS/NS to coalesce in a timescale 0 : minimum coalescence time * : mean timescale required for the newly formed massive system to evolve into two NSs ...
The white dwarf cooling sequence of 47 Tucanae
... Synthetic main-sequence stars are randomly drawn according to the initial mass function of Kroupa et al. (1993). The selected range of masses is that necessary to produce the white dwarf progenitors of 47 Tuc. In particular, a lower limit of M > 0.5 M guarantees that enough white dwarfs are produce ...
... Synthetic main-sequence stars are randomly drawn according to the initial mass function of Kroupa et al. (1993). The selected range of masses is that necessary to produce the white dwarf progenitors of 47 Tuc. In particular, a lower limit of M > 0.5 M guarantees that enough white dwarfs are produce ...
The Sagittarius dwarf irregular galaxy: Metallicity and stellar
... New measurements of the O and N abundance in the Hii regions of SagDIG are presented in a companion paper (Saviane et al. 2001). The new estimate, 12 + log(O/H) = 7.23 ± 0.20, is by 0.2 dex more metal-poor than found by Skillman et al. (1989b). The photometric properties of the Hii regions were inve ...
... New measurements of the O and N abundance in the Hii regions of SagDIG are presented in a companion paper (Saviane et al. 2001). The new estimate, 12 + log(O/H) = 7.23 ± 0.20, is by 0.2 dex more metal-poor than found by Skillman et al. (1989b). The photometric properties of the Hii regions were inve ...
The Sagittarius dwarf irregular galaxy: Metallicity and stellar
... New measurements of the O and N abundance in the Hii regions of SagDIG are presented in a companion paper (Saviane et al. 2001). The new estimate, 12 + log(O/H) = 7.23 ± 0.20, is by 0.2 dex more metal-poor than found by Skillman et al. (1989b). The photometric properties of the Hii regions were inve ...
... New measurements of the O and N abundance in the Hii regions of SagDIG are presented in a companion paper (Saviane et al. 2001). The new estimate, 12 + log(O/H) = 7.23 ± 0.20, is by 0.2 dex more metal-poor than found by Skillman et al. (1989b). The photometric properties of the Hii regions were inve ...
The Sagittarius dwarf irregular galaxy
... New measurements of the O and N abundance in the Hii regions of SagDIG are presented in a companion paper (Saviane et al. 2001). The new estimate, 12 + log(O/H) = 7.23 ± 0.20, is by 0.2 dex more metal-poor than found by Skillman et al. (1989b). The photometric properties of the Hii regions were inve ...
... New measurements of the O and N abundance in the Hii regions of SagDIG are presented in a companion paper (Saviane et al. 2001). The new estimate, 12 + log(O/H) = 7.23 ± 0.20, is by 0.2 dex more metal-poor than found by Skillman et al. (1989b). The photometric properties of the Hii regions were inve ...
Poster - unist
... We explore the possibility that globular clusters (GCs) form within UV radiation fields. To simulate the formation of GCs under UV radiation, we solve gas and dark matter dynamics in spherical symmetry, consistently incorporating the radiative transfer of UV photons and non-equilibrium chemical reac ...
... We explore the possibility that globular clusters (GCs) form within UV radiation fields. To simulate the formation of GCs under UV radiation, we solve gas and dark matter dynamics in spherical symmetry, consistently incorporating the radiative transfer of UV photons and non-equilibrium chemical reac ...
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.