as a PDF - Research Database
... at the ESO 3.5 m NTT at La Silla, Chile, was used on 24 December 1998 and on 15 and 16 January 2000, to obtain low-resolution (R ∼ 500) long-slit spectra between ∼0.61 and 1.04 µm with grism #4 and a 1.5 slit width. Integration times ranged between 5 and 30 min. ...
... at the ESO 3.5 m NTT at La Silla, Chile, was used on 24 December 1998 and on 15 and 16 January 2000, to obtain low-resolution (R ∼ 500) long-slit spectra between ∼0.61 and 1.04 µm with grism #4 and a 1.5 slit width. Integration times ranged between 5 and 30 min. ...
Confronting Dark Matter Powered Stars with Recent Results from
... In 1933 it was noted for the rst time by Zwicky (1933), that there seemed to be more matter in the Coma cluster, than could be seen by visible observations. Additional astrophysical evidence for a non luminous mass component in the Universe, called Dark Matter (DM), has been provided over the follo ...
... In 1933 it was noted for the rst time by Zwicky (1933), that there seemed to be more matter in the Coma cluster, than could be seen by visible observations. Additional astrophysical evidence for a non luminous mass component in the Universe, called Dark Matter (DM), has been provided over the follo ...
17 The Atomic Nature of Matter
... atoms in the known universe are hydrogen. Helium, the second-lightest element, makes up most of the remaining atoms in the universe, although it is rare on Earth. The heavier atoms that we find about us were manufactured by fusion reactions in the hot, highpressure environments of stars. ...
... atoms in the known universe are hydrogen. Helium, the second-lightest element, makes up most of the remaining atoms in the universe, although it is rare on Earth. The heavier atoms that we find about us were manufactured by fusion reactions in the hot, highpressure environments of stars. ...
17 The Atomic Nature of Matter
... atoms in the known universe are hydrogen. Helium, the second-lightest element, makes up most of the remaining atoms in the universe, although it is rare on Earth. The heavier atoms that we find about us were manufactured by fusion reactions in the hot, highpressure environments of stars. ...
... atoms in the known universe are hydrogen. Helium, the second-lightest element, makes up most of the remaining atoms in the universe, although it is rare on Earth. The heavier atoms that we find about us were manufactured by fusion reactions in the hot, highpressure environments of stars. ...
Bright 22 μm excess candidates from the wise all-sky
... from Kepler and WISE and concluded that the excesses in the Kepler field are mainly due to high background levels. Lawler & Gladman (2012) studied the dust emission around more than 900 Kepler exoplanet candidates using WISE data and they found 8 candidates with excess IR. Morales et al. (2012) stud ...
... from Kepler and WISE and concluded that the excesses in the Kepler field are mainly due to high background levels. Lawler & Gladman (2012) studied the dust emission around more than 900 Kepler exoplanet candidates using WISE data and they found 8 candidates with excess IR. Morales et al. (2012) stud ...
EXPLORING STELLAR EVOLUTION MODELS OF sdB STARS
... up-to-date physics modules, including several MLT convection options, and is capable of evolving stars through the He-flash, a crucial part of the evolutionary path to sdB stars. The latter is modeled as a quasi-static process, with MLT mixing, as a substitute for the full dynamical process. Because ...
... up-to-date physics modules, including several MLT convection options, and is capable of evolving stars through the He-flash, a crucial part of the evolutionary path to sdB stars. The latter is modeled as a quasi-static process, with MLT mixing, as a substitute for the full dynamical process. Because ...
Entropy Production of Stars
... variational principles proves to be important both for the foundation of nonequilibrium physics and for calculations: from heat-conduction problems to the solution of the Boltzmann equation [1–4]. It should be noted that the quantity of entropy production is convenient from the standpoint of theory ...
... variational principles proves to be important both for the foundation of nonequilibrium physics and for calculations: from heat-conduction problems to the solution of the Boltzmann equation [1–4]. It should be noted that the quantity of entropy production is convenient from the standpoint of theory ...
Slide 1
... emitting any kind of radiation) in the universe adds up to much less than the critical density. • Gravitational lensing shows that some clusters contain 10 times as much mass as is directly visible. Big Bang, Black Early Times & Fate of The Universe Holes, No Math Topic 2: Dark Matter ...
... emitting any kind of radiation) in the universe adds up to much less than the critical density. • Gravitational lensing shows that some clusters contain 10 times as much mass as is directly visible. Big Bang, Black Early Times & Fate of The Universe Holes, No Math Topic 2: Dark Matter ...
Session 1: Stellar winds, diagnostics across the electromagnetic
... concentrate on the thermal and non-thermal continuum emission from early-type stars. The thermal radio emission is due to free-free interactions in the ionized stellar wind material. Early ideas that this would lead to an easy and straightforward way of measuring the mass-loss rates were thwarted by ...
... concentrate on the thermal and non-thermal continuum emission from early-type stars. The thermal radio emission is due to free-free interactions in the ionized stellar wind material. Early ideas that this would lead to an easy and straightforward way of measuring the mass-loss rates were thwarted by ...
The Primeval Populations of the Ultra
... [Fe/H]= −2.3; blue curve) and the low extreme of the metallicity distribution in these UFDs ([Fe/H]= −3.2; green curve). It is clear from the comparison that the luminosity of the MS turnoff and SGB in each galaxy is consistent with ancient metal-poor stars. The few stars immediately brighter and bl ...
... [Fe/H]= −2.3; blue curve) and the low extreme of the metallicity distribution in these UFDs ([Fe/H]= −3.2; green curve). It is clear from the comparison that the luminosity of the MS turnoff and SGB in each galaxy is consistent with ancient metal-poor stars. The few stars immediately brighter and bl ...
Debris discs around M stars: non-existence versus non
... Motivated by the reported dearth of debris discs around M stars, we use survival models to study the occurrence of planetesimal discs around them. These survival models describe a planetesimal disc with a small number of parameters, determine if it may survive a series of dynamical processes and com ...
... Motivated by the reported dearth of debris discs around M stars, we use survival models to study the occurrence of planetesimal discs around them. These survival models describe a planetesimal disc with a small number of parameters, determine if it may survive a series of dynamical processes and com ...
Atoms are the building blocks of most matter.
... The lightest element of all is hydrogen. Over 90% of the atoms in the known universe are hydrogen. Helium, the second-lightest element, makes up most of the remaining atoms in the universe, although it is rare on Earth. The heavier atoms that we find about us were manufactured by fusion reactions in ...
... The lightest element of all is hydrogen. Over 90% of the atoms in the known universe are hydrogen. Helium, the second-lightest element, makes up most of the remaining atoms in the universe, although it is rare on Earth. The heavier atoms that we find about us were manufactured by fusion reactions in ...
Cluster formation in molecular clouds – I. Stellar populations, star
... luminosity of a cluster can be determined from its mass via an averaged IMF (Murray, Quataert & Thompson 2010). This simplified approach misses key aspects of the star formation process. As an attempt to bridge the gap between these two types of simulations, we present a model which can be used to r ...
... luminosity of a cluster can be determined from its mass via an averaged IMF (Murray, Quataert & Thompson 2010). This simplified approach misses key aspects of the star formation process. As an attempt to bridge the gap between these two types of simulations, we present a model which can be used to r ...
ON THE ORIGIN OF THE SALPETER SLOPE FOR THE INITIAL
... This yields a simple power-law IMF having γ = 2 (see also Bonnell et al. 2007; Hsu et al. 2010). Thus γ = 2 is a value that is intuitive, with simple and reasonable physical bases from both the parent ICMF equipartition arguments and buildup from simple accretion. So then why is the Salpeter slope o ...
... This yields a simple power-law IMF having γ = 2 (see also Bonnell et al. 2007; Hsu et al. 2010). Thus γ = 2 is a value that is intuitive, with simple and reasonable physical bases from both the parent ICMF equipartition arguments and buildup from simple accretion. So then why is the Salpeter slope o ...
stellar diameters and temperatures. iii. main-sequence a, f, g
... linear diameter compensates for their relatively large distance from the observer, and main-sequence stars, whose linear size remains non-inflated from stellar evolution and therefore must reside in the observer’s close vicinity. It is these nearby stars with known parallaxes and interferometrically ...
... linear diameter compensates for their relatively large distance from the observer, and main-sequence stars, whose linear size remains non-inflated from stellar evolution and therefore must reside in the observer’s close vicinity. It is these nearby stars with known parallaxes and interferometrically ...
Astronomy Astrophysics
... of this series we presented the photometric observations and determined the existence of starspot cycles and their correlation with the global stellar properties. In the present paper we investigate the surface differential rotation (SDR). The periodogram analysis of the photometric data time series ...
... of this series we presented the photometric observations and determined the existence of starspot cycles and their correlation with the global stellar properties. In the present paper we investigate the surface differential rotation (SDR). The periodogram analysis of the photometric data time series ...
Binary progenitor models of type IIb supernovae
... Massive stars that lose their hydrogen-rich envelope down to a few tenths of a solar mass explode as extended type IIb supernovae, an intriguing subtype that links the hydrogen-rich type II supernovae with the hydrogen-poor type Ib and Ic. The progenitors may be very massive single stars that lose t ...
... Massive stars that lose their hydrogen-rich envelope down to a few tenths of a solar mass explode as extended type IIb supernovae, an intriguing subtype that links the hydrogen-rich type II supernovae with the hydrogen-poor type Ib and Ic. The progenitors may be very massive single stars that lose t ...
The occurrence of nitrogen-enhanced metal
... (Lucatello et al. 2005b). A widely accepted formation scenario for this group involves pollution by mass transfer in a binary system from a more massive asymptotic giant branch (AGB) companion, which has since become a white dwarf. Of the CEMP ...
... (Lucatello et al. 2005b). A widely accepted formation scenario for this group involves pollution by mass transfer in a binary system from a more massive asymptotic giant branch (AGB) companion, which has since become a white dwarf. Of the CEMP ...
Pioneering Women in the Spectral Classification of Stars
... Fig. 4, did Fleming report finding B-type stars. This is the first time – in 1897 – that open clusters of stars could be separated into two major categories, those in which either A-type or F-type stars predominated, now called Pleiades or Hyades types, respectively. In 1867 Secchi discovered that his ...
... Fig. 4, did Fleming report finding B-type stars. This is the first time – in 1897 – that open clusters of stars could be separated into two major categories, those in which either A-type or F-type stars predominated, now called Pleiades or Hyades types, respectively. In 1867 Secchi discovered that his ...
properties and evolution of disks around pre-main
... HAeBe stars cover a large range of spectral types and luminosities; this variety has implications for their environments, which, by the time a star becomes optically visible, are very different in early B stars (HBe; M多 ⲏ 5 M䉺 ) and in stars of later spectral types (HAe; M多 ⱗ 5 M䉺 ). A variety of re ...
... HAeBe stars cover a large range of spectral types and luminosities; this variety has implications for their environments, which, by the time a star becomes optically visible, are very different in early B stars (HBe; M多 ⲏ 5 M䉺 ) and in stars of later spectral types (HAe; M多 ⱗ 5 M䉺 ). A variety of re ...
A Dozen Colliding-Wind X-Ray Binaries in the Star - UvA-DARE
... Large Magellanic Cloud. The image contains 20 X-ray point sources with luminosities between 5 1032 and 2 1035 ergs s1 (0.2–3.5 keV). A dozen sources have bright WN Wolf-Rayet or spectral type O stars as optical counterparts. Nine of these are within 3.4 pc of R136, the central star cluster of ...
... Large Magellanic Cloud. The image contains 20 X-ray point sources with luminosities between 5 1032 and 2 1035 ergs s1 (0.2–3.5 keV). A dozen sources have bright WN Wolf-Rayet or spectral type O stars as optical counterparts. Nine of these are within 3.4 pc of R136, the central star cluster of ...
Interstellar neutral oxygen in a two-shock
... al, 1995). Recently Frisch (1994) has demonstrated how oxygen measurements could be used in conjunction with carbon data to infer the interstellar electron density in the LISM. However, filtration of neutral oxygen and neutral carbon at the interface should be taken into account to obtain a more pre ...
... al, 1995). Recently Frisch (1994) has demonstrated how oxygen measurements could be used in conjunction with carbon data to infer the interstellar electron density in the LISM. However, filtration of neutral oxygen and neutral carbon at the interface should be taken into account to obtain a more pre ...
Angular momentum and the formation of stars and
... rotating magnetospheric region. More than 99% of the initial angular momentum of the gas from which each star forms must therefore be removed during the formation process. Where does this angular momentum go, and how is it transported? In standard models for isolated star formation (Shu et al 1987, ...
... rotating magnetospheric region. More than 99% of the initial angular momentum of the gas from which each star forms must therefore be removed during the formation process. Where does this angular momentum go, and how is it transported? In standard models for isolated star formation (Shu et al 1987, ...
First detection of helium emissions in RR Lyrae⋆
... shock wave occurs during the rising light. Its intensity and velocity increase as the shock propagates outward in the atmosphere. During the Blazhko cycle, the critical level of shock formation moves up and down in the atmosphere. In addition to the now well known emission occurring just before the ...
... shock wave occurs during the rising light. Its intensity and velocity increase as the shock propagates outward in the atmosphere. During the Blazhko cycle, the critical level of shock formation moves up and down in the atmosphere. In addition to the now well known emission occurring just before the ...
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.