Heating and Cooling of Neutron Star Crusts
... A theoretical crust model was developed in this work to follow the evolution of the quiescent luminosity of a transiently accreting neutron star, and its results were compared with observations of two transient neutron stars: KS 1731-260 and MXB 1659-298. The comparison shows that the calculations f ...
... A theoretical crust model was developed in this work to follow the evolution of the quiescent luminosity of a transiently accreting neutron star, and its results were compared with observations of two transient neutron stars: KS 1731-260 and MXB 1659-298. The comparison shows that the calculations f ...
2 Statistical properties of a sample of periodically variable B-type supergiants
... a sample of 32 B- to G-type supergiants and derived an empirical semi-period-luminositycolour (PLC) relation (see his Eq. 5), from which he suggested the variability to be caused by oscillations rather than mass loss. Lovy et al. (1984) indeed managed to come up with a theoretical PLC relation in ag ...
... a sample of 32 B- to G-type supergiants and derived an empirical semi-period-luminositycolour (PLC) relation (see his Eq. 5), from which he suggested the variability to be caused by oscillations rather than mass loss. Lovy et al. (1984) indeed managed to come up with a theoretical PLC relation in ag ...
The Celestial Sphere CHAPTER 1
... motion was a good approximation. Furthermore, since a geocentric model maintains circular motion, it was very difficult to make any observational distinction between geocentric and heliocentric universes. (Parallax effects are far too small to be noticeable with the naked eye.) ...
... motion was a good approximation. Furthermore, since a geocentric model maintains circular motion, it was very difficult to make any observational distinction between geocentric and heliocentric universes. (Parallax effects are far too small to be noticeable with the naked eye.) ...
multimessenger astronomy: modeling
... Modeling Gravitational and Electromagnetic Radiations from a Stellar Binary System Kevin Kern ABSTRACT The Sun is one of roughly 100 billion other stars that make up the Milky Way galaxy. Two-thirds of all stars are paired off with a gravitational bond between the two stars. Such systems are known a ...
... Modeling Gravitational and Electromagnetic Radiations from a Stellar Binary System Kevin Kern ABSTRACT The Sun is one of roughly 100 billion other stars that make up the Milky Way galaxy. Two-thirds of all stars are paired off with a gravitational bond between the two stars. Such systems are known a ...
The Spitzer/GLIMPSE Surveys - UW-Madison Astronomy
... highest degree of deuteration reported to date in the interstellar medium. Since deuteration only occurs in very cold environments, these data confirm that IRDCs are cold (typically ≤20 K). Rathborne et al. (2006) found from 1.2 mm continuum emission that the 38 IRDCs they observed have core masses ...
... highest degree of deuteration reported to date in the interstellar medium. Since deuteration only occurs in very cold environments, these data confirm that IRDCs are cold (typically ≤20 K). Rathborne et al. (2006) found from 1.2 mm continuum emission that the 38 IRDCs they observed have core masses ...
Luminosity, Flux and Magnitudes Outline
... Fluxes and Magnitudes Flux is the power per unit area received from an object, e.g. fsun = 1 kW/m2 If two stars, A and B, have fluxes, fA and fB, their magnitudes are related by ...
... Fluxes and Magnitudes Flux is the power per unit area received from an object, e.g. fsun = 1 kW/m2 If two stars, A and B, have fluxes, fA and fB, their magnitudes are related by ...
L101 DETECTION OF A LARGE ARC OF IONIZED HYDROGEN
... side (l p 132⬚–134⬚, b p ⫹14⬚– ⫹ 20⬚), where the Ha velocity is about ⫺62 km s⫺1, there is a corresponding H i “filament” offset approximately 2⬚ to lower longitude (i.e., to the outside of the loop) on the ⫺62.5 to ⫺55 km s⫺1 velocity interval maps of the Dwingeloo 21 cm survey (Hartmann 1994). Thi ...
... side (l p 132⬚–134⬚, b p ⫹14⬚– ⫹ 20⬚), where the Ha velocity is about ⫺62 km s⫺1, there is a corresponding H i “filament” offset approximately 2⬚ to lower longitude (i.e., to the outside of the loop) on the ⫺62.5 to ⫺55 km s⫺1 velocity interval maps of the Dwingeloo 21 cm survey (Hartmann 1994). Thi ...
Towards a deterministic model of planetary formation. III. Mass
... Although in the present paper, we will propose a scenario that type II migration of a Neptunemass planet occurs without significant gas accretion onto the planet around an M star, there are several other potential scenarios for the origins of dynamically-isolated, close-in Neptune-mass planets. Boss ...
... Although in the present paper, we will propose a scenario that type II migration of a Neptunemass planet occurs without significant gas accretion onto the planet around an M star, there are several other potential scenarios for the origins of dynamically-isolated, close-in Neptune-mass planets. Boss ...
Heliacal Rising of Canopus in Indian Astronomy
... significance, lies in its becoming circumpolar for different latitudes during different periods, usually in intervals of thousands of years. In this paper, we show how star Canopus which became circumpolar for an extreme North Indian latitude, attained some status after a couple of thousands of year ...
... significance, lies in its becoming circumpolar for different latitudes during different periods, usually in intervals of thousands of years. In this paper, we show how star Canopus which became circumpolar for an extreme North Indian latitude, attained some status after a couple of thousands of year ...
Forming Jupiter, Saturn, Uranus and Neptune in Few Million Years
... 1980; Pollack et al. 1996). When a solid embryo has grown to few thousandths of the Earth mass, a gaseous envelope in hydrostatic equilibrium begins to bind to it. This equilibrium is achieved by the balance between the heating due to the energy released by the incoming planetesimals and the gravity ...
... 1980; Pollack et al. 1996). When a solid embryo has grown to few thousandths of the Earth mass, a gaseous envelope in hydrostatic equilibrium begins to bind to it. This equilibrium is achieved by the balance between the heating due to the energy released by the incoming planetesimals and the gravity ...
Carbon-enhanced metal-poor stars: a window on AGB
... giant branch (AGB) phase of its evolution. We investigate the mechanism of mass transfer and the process of nucleosynthesis in low-metallicity AGB stars by modelling the binary systems in which the observed CEMP-s stars were formed. For this purpose we compare a sample of 67 CEMP-s stars with a grid ...
... giant branch (AGB) phase of its evolution. We investigate the mechanism of mass transfer and the process of nucleosynthesis in low-metallicity AGB stars by modelling the binary systems in which the observed CEMP-s stars were formed. For this purpose we compare a sample of 67 CEMP-s stars with a grid ...
Quiescent and flaring X-ray emission from the nearby M/T dwarf
... Spectrometer) detectors is rather weak; while we clearly see a few photons from prominent emission lines, e.g. O viii at 19 Å and O vii at 21.6–22.1 Å, the RGS spectra are not suitable for a quantitative analysis. Thus we considered only X-ray data taken with the EPIC (European Photon Imaging Camera ...
... Spectrometer) detectors is rather weak; while we clearly see a few photons from prominent emission lines, e.g. O viii at 19 Å and O vii at 21.6–22.1 Å, the RGS spectra are not suitable for a quantitative analysis. Thus we considered only X-ray data taken with the EPIC (European Photon Imaging Camera ...
Stars: Stellar Evol & “death” Galaxies Astronomy 1 — Elementary Astronomy
... Astronomy 1 — Elementary Astronomy LA Mission College Spring F2015 ...
... Astronomy 1 — Elementary Astronomy LA Mission College Spring F2015 ...
Edmund C. Stoner and the discovery of the maximum mass of white
... exclusion principle could be applied to solve a major puzzle, the origin of the extreme high density of white dwarfs ix x, which could not be explained by classical physics. Eddington expressed this puzzle as follows: `` I do not see how a star which has once got into this compressed state is ever g ...
... exclusion principle could be applied to solve a major puzzle, the origin of the extreme high density of white dwarfs ix x, which could not be explained by classical physics. Eddington expressed this puzzle as follows: `` I do not see how a star which has once got into this compressed state is ever g ...
Metal-Like Gravity and Its Cosmological Applications
... fields [9]-[12]. While such theories successfully explain much of cosmological dynamics within the realm of GR, they failed to explain the source of such a field. In this paper, such a field is presented by modification of gravitational interaction of two types of mass—one is DM particles and the ot ...
... fields [9]-[12]. While such theories successfully explain much of cosmological dynamics within the realm of GR, they failed to explain the source of such a field. In this paper, such a field is presented by modification of gravitational interaction of two types of mass—one is DM particles and the ot ...
Morphology and kinematics of the gas envelope of the variable AGB
... and an orbital period of over 6200 years (Mayer et al. 2014). Its large scale environment has been recently observed by Mayer et al. (2014) at 70 µm and 160 µm using Herschel/PACS images and interferometric observations from the VLTI/AMBER archive. They observe an arc east of the star at a projectio ...
... and an orbital period of over 6200 years (Mayer et al. 2014). Its large scale environment has been recently observed by Mayer et al. (2014) at 70 µm and 160 µm using Herschel/PACS images and interferometric observations from the VLTI/AMBER archive. They observe an arc east of the star at a projectio ...
Star formation rates and efficiencies in the Galactic Centre
... most importantly and urgently, by their dependence on ill-constrained free parameters. The lack of empirical constraints on these parameters therefore represents a key challenge in the further verification or falsification of current star formation theories. Key words: stars: formation−ISM: clouds−I ...
... most importantly and urgently, by their dependence on ill-constrained free parameters. The lack of empirical constraints on these parameters therefore represents a key challenge in the further verification or falsification of current star formation theories. Key words: stars: formation−ISM: clouds−I ...
Krypton in presolar mainstream SiC grains from AGB stars
... and the light noble gases (Lewis et al. 1990, 1994) and also with analysis of the xenon implantation energy in the grains (Verchovsky et al. 2004). In this paper we want to analyse the Kr−G component in mainstream SiC grains. For a detailed description of the s−process in AGB stars see Gallino et al ...
... and the light noble gases (Lewis et al. 1990, 1994) and also with analysis of the xenon implantation energy in the grains (Verchovsky et al. 2004). In this paper we want to analyse the Kr−G component in mainstream SiC grains. For a detailed description of the s−process in AGB stars see Gallino et al ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.