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 ...
1. INTRODUCTION 2. THE MODEL
... C. Hayashi prescribed a ““ minimum-mass solar nebula,ÏÏ which contained just enough material to make the planets. This prescription, which has been widely used in constructing scenarios for planet formation, proposed that ice will condense when the temperature falls below 170 K (the ““ snow line ÏÏ) ...
... C. Hayashi prescribed a ““ minimum-mass solar nebula,ÏÏ which contained just enough material to make the planets. This prescription, which has been widely used in constructing scenarios for planet formation, proposed that ice will condense when the temperature falls below 170 K (the ““ snow line ÏÏ) ...
page proofs
... others the universe would expand for a time and then collapse back on itself. It is interesting to note that this theoretical work was established before Hubble measured the recession of the galaxies. Georges Lemaitre (1894–1966) was both a Catholic priest and professor of physics. He was fascinated ...
... others the universe would expand for a time and then collapse back on itself. It is interesting to note that this theoretical work was established before Hubble measured the recession of the galaxies. Georges Lemaitre (1894–1966) was both a Catholic priest and professor of physics. He was fascinated ...
Galactic Stellar and Substellar Initial Mass Function Invited Review Gilles Chabrier
... early star formation conditions. The disk IMF for single objects has a characteristic mass around mc ∼ 0.08 M, and a variance in logarithmic mass j ∼ 0.7 , whereas the IMF for multiple systems has mc ∼ 0.2 M, and j ∼ 0.6. The extension of the single MF into the brown dwarf regime is in good agreemen ...
... early star formation conditions. The disk IMF for single objects has a characteristic mass around mc ∼ 0.08 M, and a variance in logarithmic mass j ∼ 0.7 , whereas the IMF for multiple systems has mc ∼ 0.2 M, and j ∼ 0.6. The extension of the single MF into the brown dwarf regime is in good agreemen ...
Herschel far-infrared observations of the Carina Nebula complex⋆
... Most stars in our Galaxy form in giant molecular clouds, as parts of rich stellar clusters or associations, containing highmass (M > 20 M ) stars. Recent investigations have shown that also our solar system formed close to massive stars, which had important influences on the early evolution of the ...
... Most stars in our Galaxy form in giant molecular clouds, as parts of rich stellar clusters or associations, containing highmass (M > 20 M ) stars. Recent investigations have shown that also our solar system formed close to massive stars, which had important influences on the early evolution of the ...
Kinematic signature of an intermediate
... They found less compelling evidence for a central black hole, but more importantly, they found a location for the center that differs from previous measurements. Both G1 and ω Centauri have been suggested to be stripped nuclei of dwarf galaxies (Freeman 1993; Meylan et al. 2001) and therefore may no ...
... They found less compelling evidence for a central black hole, but more importantly, they found a location for the center that differs from previous measurements. Both G1 and ω Centauri have been suggested to be stripped nuclei of dwarf galaxies (Freeman 1993; Meylan et al. 2001) and therefore may no ...
THE MONTHLY SKY GUIDE, SIXTH EDITION
... All stars are suns, blazing balls of gas like our own Sun, but so far away that they appear as mere points of light in even the most powerful telescopes. At the centre of each star is an immense natural nuclear reactor, which produces the energy that makes the star shine. Stars can shine uninterrupt ...
... All stars are suns, blazing balls of gas like our own Sun, but so far away that they appear as mere points of light in even the most powerful telescopes. At the centre of each star is an immense natural nuclear reactor, which produces the energy that makes the star shine. Stars can shine uninterrupt ...
Direct Imaging discovery of a second planet candidate
... first very young (< 10 Myr) L – T type planet bound to a star, i.e. appearing bluer than expected due to a decreasing cloud opacity at low effective temperatures. All except a planetary spectral model are inconsistent with the spectroscopy, and we deduce a best mass of 4 - 5 Jupiter masses (total ra ...
... first very young (< 10 Myr) L – T type planet bound to a star, i.e. appearing bluer than expected due to a decreasing cloud opacity at low effective temperatures. All except a planetary spectral model are inconsistent with the spectroscopy, and we deduce a best mass of 4 - 5 Jupiter masses (total ra ...
chemical compositions of rv tauri stars and related objects
... and exhibit strong CN and CH bands at light minimum. RVCs have weak metal lines in their spectra and have high radial velocities (Joy 1952). The CN and CH bands are weaker or absent at all phases. They are genuinely metal-poor objects. As suggested by Wallerstein (2002) and van Winckel (2003) in the ...
... and exhibit strong CN and CH bands at light minimum. RVCs have weak metal lines in their spectra and have high radial velocities (Joy 1952). The CN and CH bands are weaker or absent at all phases. They are genuinely metal-poor objects. As suggested by Wallerstein (2002) and van Winckel (2003) in the ...
Ch. 22
... • Our Galactic halo should contain baryonic matter which is dark: • low-mass M dwarfs, brown dwarfs, and Jovian-sized planets • they are too faint to be seen at large distances • they have been called “MAssive Compact Halo Objects” or MACHOs ...
... • Our Galactic halo should contain baryonic matter which is dark: • low-mass M dwarfs, brown dwarfs, and Jovian-sized planets • they are too faint to be seen at large distances • they have been called “MAssive Compact Halo Objects” or MACHOs ...
Magnitude-range brightness variations of overactive K giants
... 2012). In a recent investigation of the previous three solar cycles, Fröhlich (2013) showed that the long-term solar variability requires a global solar temperature change, likely originating from the changing strength of its magnetic activity. The solar effective temperature appears lower during l ...
... 2012). In a recent investigation of the previous three solar cycles, Fröhlich (2013) showed that the long-term solar variability requires a global solar temperature change, likely originating from the changing strength of its magnetic activity. The solar effective temperature appears lower during l ...
L53 He I 1.083 mm EMISSION AND ABSORPTION IN DG TAURI
... coincide with a high-velocity component of the [Fe ii] 1.257 mm emission, which arises from a jet within an arcsecond of the star. The presence of such a high-excitation line (with an excitation energy of ∼20 eV) within the jet supports the scenario of shock heating. The bright He i component does n ...
... coincide with a high-velocity component of the [Fe ii] 1.257 mm emission, which arises from a jet within an arcsecond of the star. The presence of such a high-excitation line (with an excitation energy of ∼20 eV) within the jet supports the scenario of shock heating. The bright He i component does n ...
Chapter 2 Observing the Electromagnetic Spectrum
... Dusty, dark nebulae (e.g. the Horsehead Nebula in Orion) exist at temperatures between 10-100 K enabling molecular hydrogen (H2 ), carbon monoxide (CO), hydrogen cyanide (HCN) and water (H2 O) to exist in molecular clouds. Dust grains emit at a characteristic temperature between 20-100 K and are fou ...
... Dusty, dark nebulae (e.g. the Horsehead Nebula in Orion) exist at temperatures between 10-100 K enabling molecular hydrogen (H2 ), carbon monoxide (CO), hydrogen cyanide (HCN) and water (H2 O) to exist in molecular clouds. Dust grains emit at a characteristic temperature between 20-100 K and are fou ...
MHD seismology as a tool to diagnose the coronae of X
... corona during the solar and stellar flaring processes. The stellar loops are filled with denser and hot plasma that is observed in form of soft X-ray stellar flares during the transient plasma processes in the stellar coronae (e.g., Pandey & Singh 2008). Fig. 1 shows the X-ray active stars detected ...
... corona during the solar and stellar flaring processes. The stellar loops are filled with denser and hot plasma that is observed in form of soft X-ray stellar flares during the transient plasma processes in the stellar coronae (e.g., Pandey & Singh 2008). Fig. 1 shows the X-ray active stars detected ...
![On the trend of [Mg/Fe] among giant elliptical galaxies](http://s1.studyres.com/store/data/024377891_1-9ed25030908d9b00f4379170c2bcef77-300x300.png)
On the trend of [Mg/Fe] among giant elliptical galaxies
... galaxies which develop a wind later than the less massive ones. All of this is valid under the assumption that after the onset of a galactic wind star formation should stop or should be negligible, which is a reasonable assumption for elliptical galaxies. Faber et al. (1992) proposed alternative sce ...
... galaxies which develop a wind later than the less massive ones. All of this is valid under the assumption that after the onset of a galactic wind star formation should stop or should be negligible, which is a reasonable assumption for elliptical galaxies. Faber et al. (1992) proposed alternative sce ...
The occurrence of nitrogen-enhanced metal
... stars are produced in binary systems with AGB primaries of 3.5–6 M . From an assumed CEMP-no/CEMP-s ratio of at least 1/3, consistent with observations available to them, they find consistency with both the CEMP-s fraction (10–25%) and the CEMP-no/CEMP-s ratio for a top-heavy IMF, with a median mas ...
... stars are produced in binary systems with AGB primaries of 3.5–6 M . From an assumed CEMP-no/CEMP-s ratio of at least 1/3, consistent with observations available to them, they find consistency with both the CEMP-s fraction (10–25%) and the CEMP-no/CEMP-s ratio for a top-heavy IMF, with a median mas ...
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.