Evolutionary properties of galaxies and mass assembly up
... While the higher fraction of bright galaxies in over-dense regions seen locally is already present at z ~ 1.2, the environmental dependency of the LF shape at high redshift appears to be different from what is seen at low redshift. Is this difference due to an increase with cosmic time of the number ...
... While the higher fraction of bright galaxies in over-dense regions seen locally is already present at z ~ 1.2, the environmental dependency of the LF shape at high redshift appears to be different from what is seen at low redshift. Is this difference due to an increase with cosmic time of the number ...
The Historical X-ray Transient KY TrA in quiescence
... hence it can be used to derive a dynamical mass for the compact object (e.g. Charles & Coe 2006). The distribution of black hole masses can only be determined from the study of X-ray binaries (e.g. Casares 2007) and it is intricately related to the population and evolution of massive stars, the ener ...
... hence it can be used to derive a dynamical mass for the compact object (e.g. Charles & Coe 2006). The distribution of black hole masses can only be determined from the study of X-ray binaries (e.g. Casares 2007) and it is intricately related to the population and evolution of massive stars, the ener ...
The star-forming content of the W3 giant molecular cloud
... variations in the stellar IMF (Massey 2003). Turbulent fragmentation models of star formation (e.g. Padoan & Nordlund 2002) predict that complete Salpeterlike mass functions of gravitationally bound dense clumps will form spontanously in molecular clouds with driven turbulence. Such models also sugg ...
... variations in the stellar IMF (Massey 2003). Turbulent fragmentation models of star formation (e.g. Padoan & Nordlund 2002) predict that complete Salpeterlike mass functions of gravitationally bound dense clumps will form spontanously in molecular clouds with driven turbulence. Such models also sugg ...
The rebirth of Supernova 1987A a study of the ejecta-ring collision
... At this mass, electron degeneracy pressure can no longer withstand the gravitational forces and, as a consequence, the iron core starts to contract. Due to electron captures in the iron core, e− + p → n + νe , the number of electrons decreases and the pressure reduces accordingly. Furthermore, energ ...
... At this mass, electron degeneracy pressure can no longer withstand the gravitational forces and, as a consequence, the iron core starts to contract. Due to electron captures in the iron core, e− + p → n + νe , the number of electrons decreases and the pressure reduces accordingly. Furthermore, energ ...
Lu_Ye
... The tidal disruption of a solar type star by an IMBH with a mass of 2104Msoalr is proposed for the special event of GRB 060614, which is nearby long burst but is not associated with a supernova ...
... The tidal disruption of a solar type star by an IMBH with a mass of 2104Msoalr is proposed for the special event of GRB 060614, which is nearby long burst but is not associated with a supernova ...
Spectroscopic Variability of Supergiant Star HD14134, B3Ia
... In addition, some of the results of measurements in the spectra of HD14134 presented on a time scale in Fig. 4 and Fig. 5. It has been revealed that the variability of radial velocity, equivalent widths, depths and half-widths of Hβ line, as well as HeIλ5875.72Å and averaged CII (λ6578.05Å, λ6582. ...
... In addition, some of the results of measurements in the spectra of HD14134 presented on a time scale in Fig. 4 and Fig. 5. It has been revealed that the variability of radial velocity, equivalent widths, depths and half-widths of Hβ line, as well as HeIλ5875.72Å and averaged CII (λ6578.05Å, λ6582. ...
The electron temperature of the inner halo of the Planetary Nebula
... spectral type [WC 8]. The P Cygni profiles of, for example, C iv and N iv in its spectrum indicate a terminal wind velocity of V (∞) = 2150 km s−1 (Castor et al. 1981). The chemical abundances in NGC 6543 are likely to be position dependent (Hyung et al. 2000). Its distance is not well known; values ...
... spectral type [WC 8]. The P Cygni profiles of, for example, C iv and N iv in its spectrum indicate a terminal wind velocity of V (∞) = 2150 km s−1 (Castor et al. 1981). The chemical abundances in NGC 6543 are likely to be position dependent (Hyung et al. 2000). Its distance is not well known; values ...
microlensing binaries with candidate brown dwarf companions
... Then, brown dwarf candidates can be sorted out based on the first-order criterion of small mass ratios. Second, the majority of binary-lensing events involve caustic crossings (Schneider & Weiß 1986; Mao & Paczyński 1991). The caustics represent the positions on the source plane at which the lensin ...
... Then, brown dwarf candidates can be sorted out based on the first-order criterion of small mass ratios. Second, the majority of binary-lensing events involve caustic crossings (Schneider & Weiß 1986; Mao & Paczyński 1991). The caustics represent the positions on the source plane at which the lensin ...
Stars & Galaxies - newmanlib.ibri.org
... Lifespan of a G Star • When it uses up the H in its core, it expands to form a red giant, burning H in an outer shell & He in the core. • When the He is gone, the star collapses to form a white dwarf. • The dwarf gradually cools till it ceases to shine, becoming a black dwarf. ...
... Lifespan of a G Star • When it uses up the H in its core, it expands to form a red giant, burning H in an outer shell & He in the core. • When the He is gone, the star collapses to form a white dwarf. • The dwarf gradually cools till it ceases to shine, becoming a black dwarf. ...
Survey of Astrophysics A110 The Milky Way Galaxy
... 3. Found in the Galactic disk. 4. Spectral analysis shows that they have chemical compositions like the Sun (Population I type stars). – 5. They have long main sequences on the HR diagram which indicate that they are young (e.g., many contain young hot O and B type Population I stars). ...
... 3. Found in the Galactic disk. 4. Spectral analysis shows that they have chemical compositions like the Sun (Population I type stars). – 5. They have long main sequences on the HR diagram which indicate that they are young (e.g., many contain young hot O and B type Population I stars). ...
Is there a Supermassive Black Hole at the Center of the Milky Way?
... density is 4 × 109 M⊙ pc−3 . Were one to place 4 × 107 stars inside a radius of 0.13 parsecs, the system would be dynamically unstable with less massive stars being expelled (“evaporated”) and more massive stars sinking to the center, colliding and possibly forming a black hole. The timescale for th ...
... density is 4 × 109 M⊙ pc−3 . Were one to place 4 × 107 stars inside a radius of 0.13 parsecs, the system would be dynamically unstable with less massive stars being expelled (“evaporated”) and more massive stars sinking to the center, colliding and possibly forming a black hole. The timescale for th ...
on the pms star hbc 498 and its associated nebulous stars1
... similar to ours. The comparison spectra were normalized prior to the confrontation with the problem spectra. We expect the accuracy in the resulting MK classification to be of ±1 sub-class. The three brightest objects, namely HBC 498, HBC 495 and DL Ori/G2 have Li Iλ6708 Å strong in absorption (see ...
... similar to ours. The comparison spectra were normalized prior to the confrontation with the problem spectra. We expect the accuracy in the resulting MK classification to be of ±1 sub-class. The three brightest objects, namely HBC 498, HBC 495 and DL Ori/G2 have Li Iλ6708 Å strong in absorption (see ...
K through 8
... The constellation Cygnus, is beyond Cepheus. Facing Polaris, pass through the righthand pair of stars forming the trapezoid of Cepheus for about the same distance as Cepheus was from Polaris, reaching Deneb, the brightest star which is at the top of the Northern Cross. Thus, the Big Dipper, Polaris, ...
... The constellation Cygnus, is beyond Cepheus. Facing Polaris, pass through the righthand pair of stars forming the trapezoid of Cepheus for about the same distance as Cepheus was from Polaris, reaching Deneb, the brightest star which is at the top of the Northern Cross. Thus, the Big Dipper, Polaris, ...
An Unbiased Near-infrared Interferometric Survey for Hot
... all the way down to the sublimation distance of the dust from the Sun, which corresponds to a few Solar radii. The dust temperatures range from about 100 K to about 2000 K, depending on the distance from the Sun. In the innermost regions it forms the Fraunhofer corona (F-corona) of the Sun, a region ...
... all the way down to the sublimation distance of the dust from the Sun, which corresponds to a few Solar radii. The dust temperatures range from about 100 K to about 2000 K, depending on the distance from the Sun. In the innermost regions it forms the Fraunhofer corona (F-corona) of the Sun, a region ...
Red supergiants around the obscured open cluster Stephenson 2
... supergiants. Amongst these clusters, Stephenson 2, with a core grouping of 26 red supergiants, is a strong candidate to be the most massive cluster in the Galaxy. Aims. Stephenson 2 is located close to a region where a strong over-density of red supergiants had been found. We explore the actual clus ...
... supergiants. Amongst these clusters, Stephenson 2, with a core grouping of 26 red supergiants, is a strong candidate to be the most massive cluster in the Galaxy. Aims. Stephenson 2 is located close to a region where a strong over-density of red supergiants had been found. We explore the actual clus ...
Document
... • While magnetic stress virtually dies out in the dead zone, Reynolds stress gets transmitted (albeit at low levels) into this zone maintaining some transport there. • Accretion rate is not constant in the dead zone long term steady state is not possible ...
... • While magnetic stress virtually dies out in the dead zone, Reynolds stress gets transmitted (albeit at low levels) into this zone maintaining some transport there. • Accretion rate is not constant in the dead zone long term steady state is not possible ...
Telescope Bernard Lyot/Narval The Observatory of Stellar Magnetism
... - Micro-structures in the ISM (~0.1-10 pc), by monitoring absorption line profile Evolution in bright stars Ca II (3933Å), Na I (5889, 5895Å) and K I (7698Å) at different epochs (Smoker et al., 2007) in the direction of star clusters or North ...
... - Micro-structures in the ISM (~0.1-10 pc), by monitoring absorption line profile Evolution in bright stars Ca II (3933Å), Na I (5889, 5895Å) and K I (7698Å) at different epochs (Smoker et al., 2007) in the direction of star clusters or North ...
Hunting for Substructure in the Milky Way
... i.e stars in the thin disk show a certain trend, which in general differs from stars in the thick disk. The halo and bulge also contain stars with characteristic properties. Therefore, when stars which formed in the thin disk are analysed, they are likely to show spectral and dynamical properties ty ...
... i.e stars in the thin disk show a certain trend, which in general differs from stars in the thick disk. The halo and bulge also contain stars with characteristic properties. Therefore, when stars which formed in the thin disk are analysed, they are likely to show spectral and dynamical properties ty ...
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.