Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian
... in Harmanec et al 2002a), although some have been in the past and underwent spinup (see, e.g., de Mink et al 2013, for the physics involved). No classical Be star has yet been found to have a Roche lobe filling companion, and given Sects. 3 to 5, any such star would have to be discussed in a differe ...
... in Harmanec et al 2002a), although some have been in the past and underwent spinup (see, e.g., de Mink et al 2013, for the physics involved). No classical Be star has yet been found to have a Roche lobe filling companion, and given Sects. 3 to 5, any such star would have to be discussed in a differe ...
The binary fractions in the massive young Large Magellanic Cloud
... yield high detection efficiency, since it only depends on a single set of observations. In principle, one does not need to adopt many physical assumptions either; the approach is only based on our understanding of stellar evolution. This also allows us to simulate artificial observations for compari ...
... yield high detection efficiency, since it only depends on a single set of observations. In principle, one does not need to adopt many physical assumptions either; the approach is only based on our understanding of stellar evolution. This also allows us to simulate artificial observations for compari ...
The X-shooter Spectral Library (XSL): I. DR1. Near
... Gustafsson et al. (2008), and Allard et al. (2011). Theoretical libraries have the advantage of (nearly) unlimited resolution and selectable abundance patterns, which include not only scaledsolar abundances but also non-solar patterns. Unfortunately, theoretical libraries suffer from systematic unce ...
... Gustafsson et al. (2008), and Allard et al. (2011). Theoretical libraries have the advantage of (nearly) unlimited resolution and selectable abundance patterns, which include not only scaledsolar abundances but also non-solar patterns. Unfortunately, theoretical libraries suffer from systematic unce ...
Stellar Mass Loss in Globular - Jodrell Bank Centre for Astrophysics
... supervisor, Jacco van Loon (JvL), who gave backing to my findings, and who assisted with both scientific theory and practise. Similarly, thanks to my colleagues at Keele for all the minutiae: from shell scripting to coffee making, and allowing me to indulge in other fields of research in my supposed ‘fr ...
... supervisor, Jacco van Loon (JvL), who gave backing to my findings, and who assisted with both scientific theory and practise. Similarly, thanks to my colleagues at Keele for all the minutiae: from shell scripting to coffee making, and allowing me to indulge in other fields of research in my supposed ‘fr ...
Extragalactic Astronomical Masers I
... Maser (Microwave Amplification by Stimulated Emission of Radiation) is a radio wave equivalent of laser at optical wavelength. Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser is an artificial light and it is very different from other lights in that a laser ligh ...
... Maser (Microwave Amplification by Stimulated Emission of Radiation) is a radio wave equivalent of laser at optical wavelength. Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser is an artificial light and it is very different from other lights in that a laser ligh ...
History
... microkelvins by the adiabatic demagnetization of copper nuclei. It has other peculiar properties. Helium is the only liquid that cannot be solidified by lowering the temperature. It remains liquid down to absolute zero at ordinary pressures, but it can readily be solidified by increasing the pressur ...
... microkelvins by the adiabatic demagnetization of copper nuclei. It has other peculiar properties. Helium is the only liquid that cannot be solidified by lowering the temperature. It remains liquid down to absolute zero at ordinary pressures, but it can readily be solidified by increasing the pressur ...
The evolution of massive stars and their spectra
... and galaxies in the near and far Universe. They are among the most important sources of ionizing photons, energy, and some chemical species, which are ejected into the interstellar medium through powerful stellar winds and during their extraordinary deaths as supernovae (SN) and long gamma-ray burst ...
... and galaxies in the near and far Universe. They are among the most important sources of ionizing photons, energy, and some chemical species, which are ejected into the interstellar medium through powerful stellar winds and during their extraordinary deaths as supernovae (SN) and long gamma-ray burst ...
Hot and Dense Matter in Compact Stars – From Nuclei to Quarks
... matter behaves at nuclear and higher densities, providing insights about the physics of nuclear matter and possibly even of new states of matter.” “How Were the Elements from Iron to Uranium Made? While we have a relatively complete understanding of the origin of elements lighter than iron, importan ...
... matter behaves at nuclear and higher densities, providing insights about the physics of nuclear matter and possibly even of new states of matter.” “How Were the Elements from Iron to Uranium Made? While we have a relatively complete understanding of the origin of elements lighter than iron, importan ...
An Optical Study of Young Stellar Clusters
... The star formation process determines the conversion of gas to stars, and the outcome are stars with a range of masses. The distribution of the stellar masses in a given volume of space in a stellar system at the time of their formation is known as the Initial Mass Function (IMF) of the system (Salp ...
... The star formation process determines the conversion of gas to stars, and the outcome are stars with a range of masses. The distribution of the stellar masses in a given volume of space in a stellar system at the time of their formation is known as the Initial Mass Function (IMF) of the system (Salp ...
SN 2006gy: DISCOVERY OF THE MOST LUMINOUS
... O-type stars and WR stars have shown that their winds are highly clumped, requiring that their mass-loss rates through line-driven winds on the main sequence could be an order of magnitude lower than previously believed (Fullerton et al. 2006; Bouret et al. 2005). In that case, for stars with initia ...
... O-type stars and WR stars have shown that their winds are highly clumped, requiring that their mass-loss rates through line-driven winds on the main sequence could be an order of magnitude lower than previously believed (Fullerton et al. 2006; Bouret et al. 2005). In that case, for stars with initia ...
a0041_Spectral Analysis and Classification of Herbig A
... correlation coefficient obtained for each feature is shown in column (5) of Table 1. The width of the bands typically range from 6 to 30 Å. Once the optimum widths and central wavelengths for each band (RCB, BCB, and FB) were fixed by the best correlation coefficient, we fitted straight lines to th ...
... correlation coefficient obtained for each feature is shown in column (5) of Table 1. The width of the bands typically range from 6 to 30 Å. Once the optimum widths and central wavelengths for each band (RCB, BCB, and FB) were fixed by the best correlation coefficient, we fitted straight lines to th ...
Luminous Blue Variables are Antisocial: Their Isolation Implies that
... winds, and this wind mass loss propels the evolution that converts the most massive H-rich main-sequence stars to become H-free WR stars. This is the co-called “Conti scenario” (Conti 1976). LBVs are crucial to this picture because of the recent downward revisions of O-star mass-loss rates, as noted ...
... winds, and this wind mass loss propels the evolution that converts the most massive H-rich main-sequence stars to become H-free WR stars. This is the co-called “Conti scenario” (Conti 1976). LBVs are crucial to this picture because of the recent downward revisions of O-star mass-loss rates, as noted ...
A Herschel/HIFI study of Water in Two Intermediate
... of life. An investigation into the physical and chemical properties of a star forming environment may assist not only an investigation into the beginning of life, but possibly also where to look for it. The picture for low-mass (0.02-2 M⊙ ) star formation is far more developed than that of high-mass ...
... of life. An investigation into the physical and chemical properties of a star forming environment may assist not only an investigation into the beginning of life, but possibly also where to look for it. The picture for low-mass (0.02-2 M⊙ ) star formation is far more developed than that of high-mass ...
Equations of state and structure of neutron stars
... This thesis represents the results of work that was done during Ph.D. studies at the Institute of physics at Silesian university in Opava. New results were found and are concentrated in two connected fields related to structure of the neutron (strange) stars and their external gravitational field. T ...
... This thesis represents the results of work that was done during Ph.D. studies at the Institute of physics at Silesian university in Opava. New results were found and are concentrated in two connected fields related to structure of the neutron (strange) stars and their external gravitational field. T ...
Applications of Photospheric Spot Temperature Models ... Stellar Angular Momentum Evolution
... disk-locking models of young stars ascribe spot temperatures hotter than the photosphere to active accretion from a circumstellar disk. If accretion acts to brake stellar rotation, spot temperatures hotter than the photosphere should be more prevalent among slow rotators. From the variability amplit ...
... disk-locking models of young stars ascribe spot temperatures hotter than the photosphere to active accretion from a circumstellar disk. If accretion acts to brake stellar rotation, spot temperatures hotter than the photosphere should be more prevalent among slow rotators. From the variability amplit ...
γ Doradus pulsation in two pre-main sequence stars discovered by
... The young open cluster NGC 2264 (α2000 = 6h 41m , δ2000 = +9◦ 53 ) has been studied frequently in all wavelength regimes in the past. It is located in the Monoceros OB1 association about 30 pc above the galactic plane and has a diameter of ∼39 arcmin. Sung et al. (1997) reported a cluster distance ...
... The young open cluster NGC 2264 (α2000 = 6h 41m , δ2000 = +9◦ 53 ) has been studied frequently in all wavelength regimes in the past. It is located in the Monoceros OB1 association about 30 pc above the galactic plane and has a diameter of ∼39 arcmin. Sung et al. (1997) reported a cluster distance ...
REVIEW Early star-forming galaxies and the reionization of the Universe
... being intercepted by clouds of dust and hydrogen within galaxies. Astronomers desire accurate measurements of the abundance of early galaxies and the distribution of their luminosities to quantify the number of sources producing energetic photons, as well as a determination of the mixture of stars, ...
... being intercepted by clouds of dust and hydrogen within galaxies. Astronomers desire accurate measurements of the abundance of early galaxies and the distribution of their luminosities to quantify the number of sources producing energetic photons, as well as a determination of the mixture of stars, ...
Stellar activity in exoplanet hosts Enrique Herrero Casas
... Most of the efforts on the search and characterization of Earth-like exoplanets are currently focused on low mass stars. These represent the vast majority of the population in our galaxy (about 75% of the stars have a lower mass than the Sun) and their interest lies in the fact that the photometric a ...
... Most of the efforts on the search and characterization of Earth-like exoplanets are currently focused on low mass stars. These represent the vast majority of the population in our galaxy (about 75% of the stars have a lower mass than the Sun) and their interest lies in the fact that the photometric a ...
APS Neutrino Study
... nearly a million times LARGER than produced by Fermilab or LHC at CERN. But how are they made and where do they come from? We do not know at present and the mystery is only deepening. Detection of neutrinos from astrophysical sources would provide insight on the longstanding question of the origin o ...
... nearly a million times LARGER than produced by Fermilab or LHC at CERN. But how are they made and where do they come from? We do not know at present and the mystery is only deepening. Detection of neutrinos from astrophysical sources would provide insight on the longstanding question of the origin o ...
Envelope inflation in massive stars near the Eddington limit
... ∼ 100 − 140 M ) for relatively lighter oxygen cores, only a fraction of the envelope might be ejected, which is called pulsational pair-instability (Woosley et al. 2007). Stars with even higher initial masses (& 250 M ) are believed to collapse directly to a black hole after the pair-instability p ...
... ∼ 100 − 140 M ) for relatively lighter oxygen cores, only a fraction of the envelope might be ejected, which is called pulsational pair-instability (Woosley et al. 2007). Stars with even higher initial masses (& 250 M ) are believed to collapse directly to a black hole after the pair-instability p ...
THE GREAT AGN DEBATE `AGN VS STARBURST
... astronomers use the term QSO for this object reserving 'quasar' for radio-loud objects, while others use the terminology radio-quiet and radio-loud quasars. QSO host galaxies can be spirals, irregulars or ellipticals: there is a correlation between the quasar's luminosity and the mass of its host ga ...
... astronomers use the term QSO for this object reserving 'quasar' for radio-loud objects, while others use the terminology radio-quiet and radio-loud quasars. QSO host galaxies can be spirals, irregulars or ellipticals: there is a correlation between the quasar's luminosity and the mass of its host ga ...
THE FUTURE IS NOW: THE FORMATION OF SINGLE LOW
... higher mass (2 M ) primary with a low-mass companion and as large as 1.5 AU for a lower mass (1 M ) primary with a higher mass companion. We adopt 1 AU as an average value. For the Duquennoy & Mayor (1991) period distribution, 12% of binaries have orbital periods less than 1 AU. For a 50% binary ...
... higher mass (2 M ) primary with a low-mass companion and as large as 1.5 AU for a lower mass (1 M ) primary with a higher mass companion. We adopt 1 AU as an average value. For the Duquennoy & Mayor (1991) period distribution, 12% of binaries have orbital periods less than 1 AU. For a 50% binary ...
Modelling galaxy spectra in presence of interstellar dust – II. From
... ultraviolet–optical (UV–optical) light and re-emitting it in the infrared. The models contain three main components: (i) the diffuse interstellar medium (ISM) composed of gas and dust, (ii) the large complexes of molecular clouds (MCs) in which new stars are formed and (iii) the stars of any age and ...
... ultraviolet–optical (UV–optical) light and re-emitting it in the infrared. The models contain three main components: (i) the diffuse interstellar medium (ISM) composed of gas and dust, (ii) the large complexes of molecular clouds (MCs) in which new stars are formed and (iii) the stars of any age and ...
A Rotational and Variability Study of a Large Sample of... in NGC 2264 M. H. Lamm , C. A. L. Bailer-Jones
... Nebular cluster (ONC). They found that the period distribution for higher mass stars (i. e. M ≥ 0.25M ) is bimodal with peaks at 2 and 8 days. The bimodality is interpreted as an effect of disk-star interactions in PMS stars: Slow rotators have been magnetically locked to their disks which prevent ...
... Nebular cluster (ONC). They found that the period distribution for higher mass stars (i. e. M ≥ 0.25M ) is bimodal with peaks at 2 and 8 days. The bimodality is interpreted as an effect of disk-star interactions in PMS stars: Slow rotators have been magnetically locked to their disks which prevent ...
Physical Processes in the Interstellar Medium
... density and also freezes out on dust grains at very high densities, other tracers such as HCN or N2 H+ need to be used to study conditions within high density regions such as prestellar cores. We discuss the microphysics of the interaction between radiation and matter and the various heating and coo ...
... density and also freezes out on dust grains at very high densities, other tracers such as HCN or N2 H+ need to be used to study conditions within high density regions such as prestellar cores. We discuss the microphysics of the interaction between radiation and matter and the various heating and coo ...
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.