Radiative hydrodynamics simulations of red supergiant stars. III
... 5.6 ≤ V ≤ 20. These data along with multi-band and multiepoch photometric and spectrocopic data will allow to reconstruct the formation history, structure, and evolution of the Galaxy. Among all the objects that will be observed, late-type stars present granulation-related variability that is consid ...
... 5.6 ≤ V ≤ 20. These data along with multi-band and multiepoch photometric and spectrocopic data will allow to reconstruct the formation history, structure, and evolution of the Galaxy. Among all the objects that will be observed, late-type stars present granulation-related variability that is consid ...
Orion the Hunter
... Hunter. Its brightest stars form one of the best known celestial shapes, which is visible even from cities. The plane of the Milky Way clips the northeast corner of the constellation and manifests itself as a featureless, hazy band through the neighboring constellations of Gemini and Monoceros. Or ...
... Hunter. Its brightest stars form one of the best known celestial shapes, which is visible even from cities. The plane of the Milky Way clips the northeast corner of the constellation and manifests itself as a featureless, hazy band through the neighboring constellations of Gemini and Monoceros. Or ...
A novel study in relation between the mass and gravity
... at the centre, tensile pressure at the surface (although much less than Centrum), is not zero, and this small imbalance would be as enough to make impossible, the existence of any star, or planet with its hot core. As a matter of fact, the only thing that a huge amount of particles can present, is o ...
... at the centre, tensile pressure at the surface (although much less than Centrum), is not zero, and this small imbalance would be as enough to make impossible, the existence of any star, or planet with its hot core. As a matter of fact, the only thing that a huge amount of particles can present, is o ...
Star-Galaxy Classification in Multi
... the data set, they generally show improved probabilistic performance over simpler approaches, while requiring no additional knowledge outside the observed data and the template SEDs. Functionally, hierarchical approaches consist of parameterizing the prior probability distributions (for example, wit ...
... the data set, they generally show improved probabilistic performance over simpler approaches, while requiring no additional knowledge outside the observed data and the template SEDs. Functionally, hierarchical approaches consist of parameterizing the prior probability distributions (for example, wit ...
X-Ray Properties of Young Stars and Stellar Clusters
... Star and planet formation is generally viewed as a hydrodynamic process involving gravitational collapse of interstellar material at low temperatures, 10–100 K in molecular cloud cores and 100–1500 K in protoplanetary disks. If thermodynamical equilibrium holds, this material should be neutral excep ...
... Star and planet formation is generally viewed as a hydrodynamic process involving gravitational collapse of interstellar material at low temperatures, 10–100 K in molecular cloud cores and 100–1500 K in protoplanetary disks. If thermodynamical equilibrium holds, this material should be neutral excep ...
Stellar contents and star formation in the young open cluster Stock 8
... SFRs (such as ρ Oph, IC 348, Trapezium) although there is a large difference in stellar densities. On the other hand Hillenbrand (1997) found a few SFRs with unusual IMFs. The lack of strong evidence for IMF variations suggests that its fundamental form may be universal. Consequently, local conditio ...
... SFRs (such as ρ Oph, IC 348, Trapezium) although there is a large difference in stellar densities. On the other hand Hillenbrand (1997) found a few SFRs with unusual IMFs. The lack of strong evidence for IMF variations suggests that its fundamental form may be universal. Consequently, local conditio ...
The role of black holes in galaxy formation and evolution
... In the first type of clusters, the gas has a high central density and radiates its thermal energy on a timescale tcool~ 3/2 kT / n2Λ that is usually less than a gigayear over much of the cluster cores. These clusters are called “cool core” clusters because T decreases toward the centre. However, “c ...
... In the first type of clusters, the gas has a high central density and radiates its thermal energy on a timescale tcool~ 3/2 kT / n2Λ that is usually less than a gigayear over much of the cluster cores. These clusters are called “cool core” clusters because T decreases toward the centre. However, “c ...
mass and temperature of the twa 7 debris disk
... of temperatures according to distance. We discuss this disk in the context of known disks in the TWA and around lowmass stars; a comparison of masses of disks in the TWA reveals no trend in mass or evolutionary state (gas-rich vs. debris) as a function of spectral type. Subject headingg s: circumste ...
... of temperatures according to distance. We discuss this disk in the context of known disks in the TWA and around lowmass stars; a comparison of masses of disks in the TWA reveals no trend in mass or evolutionary state (gas-rich vs. debris) as a function of spectral type. Subject headingg s: circumste ...
EL CVn-type binaries - Discovery of 17 helium white dwarf
... mass and composition of the star (Nelson et al. 2004), but is typically 0.001 – 0.005M⊙ , much greater than for typical white dwarfs (hydrogen layer mass < 10−4 M⊙ ). The preHe-WD then evolves at nearly constant luminosity towards higher effective temperatures as a result of the gradual reduction in ...
... mass and composition of the star (Nelson et al. 2004), but is typically 0.001 – 0.005M⊙ , much greater than for typical white dwarfs (hydrogen layer mass < 10−4 M⊙ ). The preHe-WD then evolves at nearly constant luminosity towards higher effective temperatures as a result of the gradual reduction in ...
Galactic Evolution of Silicon Isotopes: Applications to
... isotopes. Typically, the matter ejected contains about 10 times as many atoms as a given heavy element as did the initial matter of the massive star. Type Ia supernovae can a†ect the evolution of the silicon isotopes by several percent. AGB stars may also inject small, but interesting, amounts of si ...
... isotopes. Typically, the matter ejected contains about 10 times as many atoms as a given heavy element as did the initial matter of the massive star. Type Ia supernovae can a†ect the evolution of the silicon isotopes by several percent. AGB stars may also inject small, but interesting, amounts of si ...
m82 as a galaxy: morphology and stellar content of the disk and halo
... profiles at RG > 6000 can be very well fitted by an exponential function, with the scale-lengths systematically increasing at shorter wavelengths — again a property characteristic of dusty disks (Evans 1994). The shortest scale-length is reached in the K-band, where the observed scale-length (4700 = ...
... profiles at RG > 6000 can be very well fitted by an exponential function, with the scale-lengths systematically increasing at shorter wavelengths — again a property characteristic of dusty disks (Evans 1994). The shortest scale-length is reached in the K-band, where the observed scale-length (4700 = ...
Radiatively driven Rayleigh-Taylor instability candidates around a
... these features represent details of previously known morphology (Fujiyoshi et al. 2001). The 8−12 μm spectro-polarimetric studies have been used to show that the emission in this region is composed of both absorptive and emissive polarized components (Fujiyoshi et al. 2001). Also, significant line e ...
... these features represent details of previously known morphology (Fujiyoshi et al. 2001). The 8−12 μm spectro-polarimetric studies have been used to show that the emission in this region is composed of both absorptive and emissive polarized components (Fujiyoshi et al. 2001). Also, significant line e ...
H 2 O, OH, SiO, NH 3 and CH 3 OH
... [proh-toh-stahr] an early stage in the evolution of a star, after the beginning of the collapse of the gas cloud from which it is formed, but before sufficient contraction has occurred to permit initiation of nuclear reactions at its core. ...
... [proh-toh-stahr] an early stage in the evolution of a star, after the beginning of the collapse of the gas cloud from which it is formed, but before sufficient contraction has occurred to permit initiation of nuclear reactions at its core. ...
Galactic Evolution of Silicon Isotopes: Application to Presolar SiC
... including the silicon isotopes. Typically, the matter ejected contains about 10 times as many atoms of a given heavy element than did the initial matter of the massive star. Type Ia supernovae can a ect the evolution of the silicon isotopes by several percent. AGB stars may also inject small, but in ...
... including the silicon isotopes. Typically, the matter ejected contains about 10 times as many atoms of a given heavy element than did the initial matter of the massive star. Type Ia supernovae can a ect the evolution of the silicon isotopes by several percent. AGB stars may also inject small, but in ...
observations and theory of star cluster formation
... Vogelaar and Wakker 1994). This power law structure includes both gas that is self-gravitating and gas that is non-self-gravitating, so the origin is not purely gravitational fragmentation. The most likely source is some combination of turbulence (see review in Falgarone and Phillips 1991), agglomer ...
... Vogelaar and Wakker 1994). This power law structure includes both gas that is self-gravitating and gas that is non-self-gravitating, so the origin is not purely gravitational fragmentation. The most likely source is some combination of turbulence (see review in Falgarone and Phillips 1991), agglomer ...
Non-conservative mass transfers in Algols
... Rensbergen et al. 2010, 2011; Deschamps et al. 2013). Many physical mechanisms (conservative and non-conservative mass transfer, torques, tidal effects, disc accretion, magnetic braking, etc.) were taken into account for modelling Algol evolutions. However, it appears that more accurate and detailed ...
... Rensbergen et al. 2010, 2011; Deschamps et al. 2013). Many physical mechanisms (conservative and non-conservative mass transfer, torques, tidal effects, disc accretion, magnetic braking, etc.) were taken into account for modelling Algol evolutions. However, it appears that more accurate and detailed ...
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.