IAC_L5_bulge_GALAH
... To study the bar/bulge, we want to reduce contamination by foreground and background stars, so photometric or spectroscopic distances are important. Ideally use stars for which reasonably accurate distances can be derived. Bright giants are not ideal. Clump giants are good: they have narrow range o ...
... To study the bar/bulge, we want to reduce contamination by foreground and background stars, so photometric or spectroscopic distances are important. Ideally use stars for which reasonably accurate distances can be derived. Bright giants are not ideal. Clump giants are good: they have narrow range o ...
ppt - A century of cosmology
... • Exhaustive spectroscopic and imaging follow-up supports hypothesis that many of lensed Lya emitters are at z~10 but additional follow-up still required. Final confirmation is especially difficult at z>7! • Implied densities of z~9 LAEs still very uncertain, but if correct, would require increase i ...
... • Exhaustive spectroscopic and imaging follow-up supports hypothesis that many of lensed Lya emitters are at z~10 but additional follow-up still required. Final confirmation is especially difficult at z>7! • Implied densities of z~9 LAEs still very uncertain, but if correct, would require increase i ...
Dust Formation in a Galaxy with Primitive Abundances REPORTS
... The stable CO molecule will form until either C or O is exhausted. Solids form from the remainder, resulting in either oxygen-rich dust dominated by silicates or carbonaceous dust. Both observations (10, 11) and theory (12) show that the fraction of AGB stars that become carbonrich increases in more ...
... The stable CO molecule will form until either C or O is exhausted. Solids form from the remainder, resulting in either oxygen-rich dust dominated by silicates or carbonaceous dust. Both observations (10, 11) and theory (12) show that the fraction of AGB stars that become carbonrich increases in more ...
Accretion
... rs = 2GM/c2 = 3km x M/Mo (Schwarzschild radius) rs = 30 km for 10 Mo BH From studying equation of motion of matter around a black hole in General Relativity one finds that radius of last stable orbit is 3rs ---> this is the “radius” of a black hole relevant for accretion since inside this radius mat ...
... rs = 2GM/c2 = 3km x M/Mo (Schwarzschild radius) rs = 30 km for 10 Mo BH From studying equation of motion of matter around a black hole in General Relativity one finds that radius of last stable orbit is 3rs ---> this is the “radius” of a black hole relevant for accretion since inside this radius mat ...
Astronomy Astrophysics
... Furthermore, and perhaps even more importantly, individual age determinations are possible for these stars using long-lived radioactive isotopes, such as 232 Th (half-life 14.05 Gyr) or 238 U (4.468 Gyr). By comparing the abundance ratio of these elements relative to a stable r-process element of si ...
... Furthermore, and perhaps even more importantly, individual age determinations are possible for these stars using long-lived radioactive isotopes, such as 232 Th (half-life 14.05 Gyr) or 238 U (4.468 Gyr). By comparing the abundance ratio of these elements relative to a stable r-process element of si ...
The Hamburg/ESO R-process Enhanced Star survey (HERES)
... Furthermore, and perhaps even more importantly, individual age determinations are possible for these stars using long-lived radioactive isotopes, such as 232 Th (half-life 14.05 Gyr) or 238 U (4.468 Gyr). By comparing the abundance ratio of these elements relative to a stable r-process element of si ...
... Furthermore, and perhaps even more importantly, individual age determinations are possible for these stars using long-lived radioactive isotopes, such as 232 Th (half-life 14.05 Gyr) or 238 U (4.468 Gyr). By comparing the abundance ratio of these elements relative to a stable r-process element of si ...
Pulsar slow glitches in a solid quark star model
... A series of five slow glitches are shown in Fig.1. Fig. 1(a) shows the frequency derivative ν̇. The peaks of ν̇ are enveloped in a parabolic curve, that may indicate that all the slow glitches could be the components of one process. This process could be triggered by the small glitch (∆ν/ν ∼ 8 × 10− ...
... A series of five slow glitches are shown in Fig.1. Fig. 1(a) shows the frequency derivative ν̇. The peaks of ν̇ are enveloped in a parabolic curve, that may indicate that all the slow glitches could be the components of one process. This process could be triggered by the small glitch (∆ν/ν ∼ 8 × 10− ...
L21 THE NONSPHERICAL SHAPE OF BETELGEUSE IN THE
... as a source of opacity (Ohnaka 2004; Tsuji 2006), but it is difficult for current models to generate lines broad enough to agree with no significant structure being seen in the spectra at ISI wavelengths (Weiner et al. 2003; Verhoelst et al. 2006). Furthermore, temperatures are high enough near the ...
... as a source of opacity (Ohnaka 2004; Tsuji 2006), but it is difficult for current models to generate lines broad enough to agree with no significant structure being seen in the spectra at ISI wavelengths (Weiner et al. 2003; Verhoelst et al. 2006). Furthermore, temperatures are high enough near the ...
Quantitative evidence of an intrinsic luminosity spread in the Orion
... Treasury Program observations of the ONC utilizing the cluster distance estimated by Menten and collaborators. We investigate whether there is an intrinsic age spread in the region and whether the age depends on the spatial distribution. Methods. We estimate the extinction and accretion luminosity t ...
... Treasury Program observations of the ONC utilizing the cluster distance estimated by Menten and collaborators. We investigate whether there is an intrinsic age spread in the region and whether the age depends on the spatial distribution. Methods. We estimate the extinction and accretion luminosity t ...
C, N, O abundances and carbon isotope ratios in evolved stars of
... (Mikolaitis et al. 2010, 2011a,b), the atlas models with overshooting (Kurucz 1993) and a computing code by Gratton (1988) were used for the analysis of the spectra. The analysis was differential to the Sun. The main atmospheric parameters for the observed stars in Cr 261 have been determined spectr ...
... (Mikolaitis et al. 2010, 2011a,b), the atlas models with overshooting (Kurucz 1993) and a computing code by Gratton (1988) were used for the analysis of the spectra. The analysis was differential to the Sun. The main atmospheric parameters for the observed stars in Cr 261 have been determined spectr ...
The Milky Way as a Galaxy, Galaxy Classification
... – van den Bergh hypothesizes that all disk galaxies are formed as normal spirals, but gradually consume gas (or lose gas) and evolve to anemic and eventually S0 galaxies, while retaining roughly constant bulge/disk ratio ...
... – van den Bergh hypothesizes that all disk galaxies are formed as normal spirals, but gradually consume gas (or lose gas) and evolve to anemic and eventually S0 galaxies, while retaining roughly constant bulge/disk ratio ...
Nucleosynthesis, the r-Process, Abundances and Jim Truran
... r-process elements observed in very metal-poor (old) halo stars – they are ubiquitous Implies that r-process sites, earliest stellar generations rapidly evolving: live and die, eject r-process material into ISM prior to formation of halo stars exact site still unknown Elements (even s-process ones l ...
... r-process elements observed in very metal-poor (old) halo stars – they are ubiquitous Implies that r-process sites, earliest stellar generations rapidly evolving: live and die, eject r-process material into ISM prior to formation of halo stars exact site still unknown Elements (even s-process ones l ...
JCMT Sciences on Debris Disks and other brief
... revised goal of 1.4), although ~1/3 of the sample (34 stars) are higher than 1.4 • Detection rate: 48 out of 100 stars (48%) have detected peaks at or near the star (the offset ones could be background objects…) • Publications: First-look paper has been published (Panić et al., 2013) with many more ...
... revised goal of 1.4), although ~1/3 of the sample (34 stars) are higher than 1.4 • Detection rate: 48 out of 100 stars (48%) have detected peaks at or near the star (the offset ones could be background objects…) • Publications: First-look paper has been published (Panić et al., 2013) with many more ...
low surface brightness galaxies
... However, the data also seem to indicate that only a small fraction of the mass is involved in such episodes. ...
... However, the data also seem to indicate that only a small fraction of the mass is involved in such episodes. ...
A massive hypergiant star as the progenitor of the supernova SN
... shells4,28, along with very luminous optical displays, during which the luminosity of the star may increase by an order of magnitude or more. These events (sometimes called supernova impostors26) can therefore be confused with genuine supernova explosions. b, Collisions between a faster massive ejec ...
... shells4,28, along with very luminous optical displays, during which the luminosity of the star may increase by an order of magnitude or more. These events (sometimes called supernova impostors26) can therefore be confused with genuine supernova explosions. b, Collisions between a faster massive ejec ...
Document
... The large fraction of matter in the universe is dark (nonluminous) matter. The need to postulate dark matter was given by Fritz-Zwicky, who observed that galaxies in the coma cluster seemed to be moving to rapidly to be held together by the gravitational attraction of the visible matter. The matter ...
... The large fraction of matter in the universe is dark (nonluminous) matter. The need to postulate dark matter was given by Fritz-Zwicky, who observed that galaxies in the coma cluster seemed to be moving to rapidly to be held together by the gravitational attraction of the visible matter. The matter ...
X-ray Emission Line Profile Diagnostics of Hot Star Winds
... z Ori and d Ori: similar situation, very little wind absorption; but wind-shock parameters are otherwise ...
... z Ori and d Ori: similar situation, very little wind absorption; but wind-shock parameters are otherwise ...
A Test of Pre-Main-Sequence Lithium Depletion Models
... age of a PMS star whose distance is unknown, e.g. a young field star. In order to do this, we need to understand PMS lithium depletion very well. Most of the work comparing lithium depletion to HR diagram ages has been done in open clusters, focusing on comparing the cluster age derived from the lit ...
... age of a PMS star whose distance is unknown, e.g. a young field star. In order to do this, we need to understand PMS lithium depletion very well. Most of the work comparing lithium depletion to HR diagram ages has been done in open clusters, focusing on comparing the cluster age derived from the lit ...
San Diego Astronomy Association CONTENTS
... 1.4 solar masses, with a diameter about that of Earth. Above 1.4 solar masses the WD will collapse into a neutron star about 10 km in diameter. Neutron star binaries are X-ray emitters, while ordinary WD have surface temperatures as high as 60,000 K and emit white-hot light of spectral class O. Whit ...
... 1.4 solar masses, with a diameter about that of Earth. Above 1.4 solar masses the WD will collapse into a neutron star about 10 km in diameter. Neutron star binaries are X-ray emitters, while ordinary WD have surface temperatures as high as 60,000 K and emit white-hot light of spectral class O. Whit ...
RESOLVING INFORMATION ON ALGOL SYSTEMS Edwin Budding
... 1.2.4 The mass ratio versus period diagram Potentially significant implications on the mass loss/transfer theory of Algols also come from the form of the mass ratio (q) versus period (P) distribution, as has been noted in various previous compilations (cf. Giuricin et al., 1983). The general trend o ...
... 1.2.4 The mass ratio versus period diagram Potentially significant implications on the mass loss/transfer theory of Algols also come from the form of the mass ratio (q) versus period (P) distribution, as has been noted in various previous compilations (cf. Giuricin et al., 1983). The general trend o ...
Nature paper - University of Southampton
... binaries, contains neutron stars that accrete material from a more massive companion star5. The two subpopulations are most probably associated with the two distinct types of neutron-starforming supernova, with electron-capture supernovae preferentially producing systems with short spin periods, sho ...
... binaries, contains neutron stars that accrete material from a more massive companion star5. The two subpopulations are most probably associated with the two distinct types of neutron-starforming supernova, with electron-capture supernovae preferentially producing systems with short spin periods, sho ...
the Launching of Be-Star Disks
... propelled in the direction of rotation gains suÆcient velocity to achieve circumstellar orbit, while material ejected in other directions simply falls back in a reaccretion onto the stellar surface. In Kroll's simulations, the exploding material is arbitrarily given an initial velocity V 100-200 ...
... propelled in the direction of rotation gains suÆcient velocity to achieve circumstellar orbit, while material ejected in other directions simply falls back in a reaccretion onto the stellar surface. In Kroll's simulations, the exploding material is arbitrarily given an initial velocity V 100-200 ...
FLARESTARSINTHEORIONN EBULAREGION SUMARIO Durante
... 4. Further Comments and Summary From what has been said before, in the Orion Nebula region there are at least four different kinds of flare stars: a) typical T Tauri stars in which, during long periods, the strong emission lines of H, CaII and some other bright lines, plus a rather strong ultraviol ...
... 4. Further Comments and Summary From what has been said before, in the Orion Nebula region there are at least four different kinds of flare stars: a) typical T Tauri stars in which, during long periods, the strong emission lines of H, CaII and some other bright lines, plus a rather strong ultraviol ...
Astron 104 Laboratory #5 Colors of Stars
... 16. In the daytime, we can see the rock because it reflects sunlight. Based on your explanations with the PhET simulator, explain what conditions are required for you to be able to see an object by the light of its thermal spectrum if the object is placed in darkness. ...
... 16. In the daytime, we can see the rock because it reflects sunlight. Based on your explanations with the PhET simulator, explain what conditions are required for you to be able to see an object by the light of its thermal spectrum if the object is placed in darkness. ...
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.