Farthest Neighbor: The Distant Milky Way Satellite Eridanus II
... We observed EriII with the IMACS spectrograph (Dressler et al. 2006) on the Magellan Baade telescope on the nights of 2015October16–17 and 2015November18–19. The observing conditions on both runs were clear, with seeing that varied from 0 6 to 0 9. The observing procedure and instrument setup a ...
... We observed EriII with the IMACS spectrograph (Dressler et al. 2006) on the Magellan Baade telescope on the nights of 2015October16–17 and 2015November18–19. The observing conditions on both runs were clear, with seeing that varied from 0 6 to 0 9. The observing procedure and instrument setup a ...
Formation of Molecular Clouds and Global Conditions for Star
... or the H2 to 13 CO abundance ratio, both of which can vary within and between clouds in response to local conditions of UV irradiance, density, temperature, and metallicity (Bolatto et al. 2013; Ripple et al. 2013). Millimeter wave interferometers can resolve large GMC complexes in nearby galaxies b ...
... or the H2 to 13 CO abundance ratio, both of which can vary within and between clouds in response to local conditions of UV irradiance, density, temperature, and metallicity (Bolatto et al. 2013; Ripple et al. 2013). Millimeter wave interferometers can resolve large GMC complexes in nearby galaxies b ...
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... magnetic forces and winds from recently formed protostars. The dense gas structure is highly filamentary and rapidly changing due to the initial clump turbulence and to subsequent shocks. The clump forms low-mass and massive protostars. For the massive protostars, much of the accretion flow is along ...
... magnetic forces and winds from recently formed protostars. The dense gas structure is highly filamentary and rapidly changing due to the initial clump turbulence and to subsequent shocks. The clump forms low-mass and massive protostars. For the massive protostars, much of the accretion flow is along ...
Models for circumstellar nebulae around red and blue supergiants
... capable of ionizing the H II regions. The hot ionized gas of the H II region, or diffuse nebula, can expand into the cold surrounding neutral gas, decreasing the density of the nebula and increasing the volume of ionized gas. During their lives, stars interact with the surrounding interstellar mediu ...
... capable of ionizing the H II regions. The hot ionized gas of the H II region, or diffuse nebula, can expand into the cold surrounding neutral gas, decreasing the density of the nebula and increasing the volume of ionized gas. During their lives, stars interact with the surrounding interstellar mediu ...
Cold dark matter heats up
... galaxies ‘in the field’ (that is, away from the influence of larger galaxies). In the innermost regions (of radius less than about half a kiloparsec) the baryonic contribution to the potential is comparable to that of the dark matter and must be subtracted12,48. Consequently, inferring the dark matt ...
... galaxies ‘in the field’ (that is, away from the influence of larger galaxies). In the innermost regions (of radius less than about half a kiloparsec) the baryonic contribution to the potential is comparable to that of the dark matter and must be subtracted12,48. Consequently, inferring the dark matt ...
The Rainbows of Gravity
... whenever locally a large quantity of matter and energy collapses under the force of its own gravity. This later situation will be effectively realized in the gravitational collapse of massive stars in the universe, which collapse and shrink catastrophically under their self-gravity, when the star ha ...
... whenever locally a large quantity of matter and energy collapses under the force of its own gravity. This later situation will be effectively realized in the gravitational collapse of massive stars in the universe, which collapse and shrink catastrophically under their self-gravity, when the star ha ...
Red giants rotational splittings
... to another. However, if it is still possible to select correctly the original triplets (as done in [6]), the first order approach could be used for a first guess of the core rotation, but non-perturbative modeling is required for a precise determination, particularly because of avoided crossings und ...
... to another. However, if it is still possible to select correctly the original triplets (as done in [6]), the first order approach could be used for a first guess of the core rotation, but non-perturbative modeling is required for a precise determination, particularly because of avoided crossings und ...
17 April 2013 When Galaxies Collide Professor Carolin Crawford
... The characteristics of current active star formation are not just the bright open clusters of the massive blue stars - each cluster having collapsed from the same original interstellar cloud - but also include the pink-coloured nebulae that surround them. The energy emitted by the young stars excite ...
... The characteristics of current active star formation are not just the bright open clusters of the massive blue stars - each cluster having collapsed from the same original interstellar cloud - but also include the pink-coloured nebulae that surround them. The energy emitted by the young stars excite ...
Astronomy Astrophysics
... envelope of the companion, the hydrogen reach layers are removed, and a 2–2.5 M Wolf-Rayet like star remains with P = 0.2 d. A system containing a black hole and an He core burning star is also favored by Ergma & van den Heuvel (1998). In addition, Cygnus X-3 undergoes giant radio bursts and there ...
... envelope of the companion, the hydrogen reach layers are removed, and a 2–2.5 M Wolf-Rayet like star remains with P = 0.2 d. A system containing a black hole and an He core burning star is also favored by Ergma & van den Heuvel (1998). In addition, Cygnus X-3 undergoes giant radio bursts and there ...
The Relation between Interstellar Turbulence and Star Formation
... of the Milky Way. These are clouds of dust and Stars are important. They are the primary source gas that block the light from stars further away. of radiation, with competition only from the 3K Since about a century ago we know that these black body radiation of the cosmic microwave clouds are assoc ...
... of the Milky Way. These are clouds of dust and Stars are important. They are the primary source gas that block the light from stars further away. of radiation, with competition only from the 3K Since about a century ago we know that these black body radiation of the cosmic microwave clouds are assoc ...
The white dwarf luminosity function
... a typical white dwarf of 0.58 M⊙ , oxygen represents 62% of the total mass, while its concentration in the central layers of the white dwarf can be as high as 85% (Wood, 1992; Salaris et al., 1997). In all cases, the core is surrounded by a thin layer of pure helium with a mass ranging from 10−2 to ...
... a typical white dwarf of 0.58 M⊙ , oxygen represents 62% of the total mass, while its concentration in the central layers of the white dwarf can be as high as 85% (Wood, 1992; Salaris et al., 1997). In all cases, the core is surrounded by a thin layer of pure helium with a mass ranging from 10−2 to ...
Astronomy Astrophysics Spectral energy distributions of an AKARI-SDSS-GALEX sample of galaxies
... this distribution. Models are generated with a stellar population synthesis code, assuming a particular star formation history and dust attenuation scenario. The energetic balance between dustenshrouded stellar emission and re-emission in the IR is carefully conserved by combining the UV-optical and ...
... this distribution. Models are generated with a stellar population synthesis code, assuming a particular star formation history and dust attenuation scenario. The energetic balance between dustenshrouded stellar emission and re-emission in the IR is carefully conserved by combining the UV-optical and ...
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.