The impact of mass-loss on the evolution and pre
... Context. The post main-sequence evolution of massive stars is very sensitive to many parameters of the stellar models. Key parameters ...
... Context. The post main-sequence evolution of massive stars is very sensitive to many parameters of the stellar models. Key parameters ...
Galaxies Astronomy 1 — Elementary Astronomy LA Mission College Spring F2015
... What is the fate of a 5 solar mass remnant core after a Type II supernova has occurred? ...
... What is the fate of a 5 solar mass remnant core after a Type II supernova has occurred? ...
Observation of Circumstellar Disks: Dust and Gas Components
... Observations show that the mass accretion rate (and the mass ejection rate) decreases from the protostars to the Class III phases by several orders of magnitude (Hartmann et al., 1998; Boss, 2004). Despite the uncertainties resulting from the various observational methods and tracers used for measur ...
... Observations show that the mass accretion rate (and the mass ejection rate) decreases from the protostars to the Class III phases by several orders of magnitude (Hartmann et al., 1998; Boss, 2004). Despite the uncertainties resulting from the various observational methods and tracers used for measur ...
Photospheric activity, rotation, and star
... drifts present in individual channels, we sum up the flux in the red, green, and blue channels to obtain a light curve in a spectral range extending from 300 to 1100 nm. The observations and data processing are described by Fridlund et al. (2010), to whom we refer the reader for details. The reducti ...
... drifts present in individual channels, we sum up the flux in the red, green, and blue channels to obtain a light curve in a spectral range extending from 300 to 1100 nm. The observations and data processing are described by Fridlund et al. (2010), to whom we refer the reader for details. The reducti ...
Stellar activity in exoplanet hosts Enrique Herrero Casas
... Most of the efforts on the search and characterization of Earth-like exoplanets are currently focused on low mass stars. These represent the vast majority of the population in our galaxy (about 75% of the stars have a lower mass than the Sun) and their interest lies in the fact that the photometric a ...
... Most of the efforts on the search and characterization of Earth-like exoplanets are currently focused on low mass stars. These represent the vast majority of the population in our galaxy (about 75% of the stars have a lower mass than the Sun) and their interest lies in the fact that the photometric a ...
ABSTRACT Exoplanet Habitability and an Analysis of Gliese 436 b
... and nitrogen with nitrogen most likely being the most important of the three due to its presence in DNA and proteins.11 Remember that without the presence of water though, these building blocks will not lead to the development of life. Along with water and these building blocks, UV radiation and gre ...
... and nitrogen with nitrogen most likely being the most important of the three due to its presence in DNA and proteins.11 Remember that without the presence of water though, these building blocks will not lead to the development of life. Along with water and these building blocks, UV radiation and gre ...
Presolar History Recorded in Extraterrestrial Materials
... the Universe. But, the very source of energy that powers exhausted, stars of less than ~8 solar mass (M ) evolve stars also leads to their undoing: once the fuel is exhausted, to the asymptotic giant branch (AGB) phase where stars die gradually as red giants or in spectacular fashion H-burning and ...
... the Universe. But, the very source of energy that powers exhausted, stars of less than ~8 solar mass (M ) evolve stars also leads to their undoing: once the fuel is exhausted, to the asymptotic giant branch (AGB) phase where stars die gradually as red giants or in spectacular fashion H-burning and ...
Downloaded - Royal Society Open Science
... flashes’. This value of 2.0 M represents a key transition mass; the duration and character of the mass loss changes markedly when crossing this threshold. After the core helium is exhausted, a heliumburning shell is formed. At this point, the star is said to have begun evolving on the ‘asymptotic g ...
... flashes’. This value of 2.0 M represents a key transition mass; the duration and character of the mass loss changes markedly when crossing this threshold. After the core helium is exhausted, a heliumburning shell is formed. At this point, the star is said to have begun evolving on the ‘asymptotic g ...
The VLT LEGA-C Spectroscopic Survey: The Physics of Galaxies at
... causes this and how quickly this happens, and whether it is preceded by a burst of star formation is widely discussed, but remains an unsettled problem. AGN feedback, owing to large available energies and evidence for AGN driven outflows and bubbles (e.g., McNamara & Nulsen 2007; Nesvadba et al. 200 ...
... causes this and how quickly this happens, and whether it is preceded by a burst of star formation is widely discussed, but remains an unsettled problem. AGN feedback, owing to large available energies and evidence for AGN driven outflows and bubbles (e.g., McNamara & Nulsen 2007; Nesvadba et al. 200 ...
Differential rotation of main sequence F stars
... most rigid rotation law. Note also that for fast rotation all lines are practically horizontal, i.e. there is no radial shear, while the model with a rotation period of 27 d shows a substantial decrease of the rotation rate with increasing radius at high latitudes. This change of the rotation patter ...
... most rigid rotation law. Note also that for fast rotation all lines are practically horizontal, i.e. there is no radial shear, while the model with a rotation period of 27 d shows a substantial decrease of the rotation rate with increasing radius at high latitudes. This change of the rotation patter ...
Global structure and kinematics of stellar haloes in cosmological
... (Ferland et al. 1998) that contain cooling rates as a function of density, temperature, and redshift and that account for the presence of the cosmic microwave background and photoionisation from a Haardt & Madau (2001) ionising UV/X-Ray background (see Wiersma et al. 2009a). This background is switc ...
... (Ferland et al. 1998) that contain cooling rates as a function of density, temperature, and redshift and that account for the presence of the cosmic microwave background and photoionisation from a Haardt & Madau (2001) ionising UV/X-Ray background (see Wiersma et al. 2009a). This background is switc ...
![Detection of [Ne ii] Emission from Young Circumstellar Disks](http://s1.studyres.com/store/data/014394769_1-fdf9c6283148d488005c87b005dab353-300x300.png)
What Gaia can reveal about the matter distribution in the Milky Way
... In this master’s thesis, it is investigated to what extent the Galactic matter distribution can be determined using data coming from the astrometric satellite Gaia. This is done through a direct application of the Jeans equations on simulated data. The Galactic matter distribution Formation and evol ...
... In this master’s thesis, it is investigated to what extent the Galactic matter distribution can be determined using data coming from the astrometric satellite Gaia. This is done through a direct application of the Jeans equations on simulated data. The Galactic matter distribution Formation and evol ...
Lithium abundances in nearby FGK dwarf and subgiant stars
... dwarf and subgiant stars. The catalog is constructed using also data from the literature, but RAL’s stellar parameters and the lithium abundances derived here are used to normalize all data sets to a common scale. Given the nature of the RAL work, our sample is suited to study systematic differences ...
... dwarf and subgiant stars. The catalog is constructed using also data from the literature, but RAL’s stellar parameters and the lithium abundances derived here are used to normalize all data sets to a common scale. Given the nature of the RAL work, our sample is suited to study systematic differences ...
The ROSAT galactic plane survey: ASTRONOMY AND
... sources is far beyond the nowadays possibilities. Accordingly, we used three different paths for exploring this unprecedented amount of new sources. The first and easiest step was the cross correlation of RGPS source positions with astronomical catalogues, mostly extracted from the SIMBAD database. ...
... sources is far beyond the nowadays possibilities. Accordingly, we used three different paths for exploring this unprecedented amount of new sources. The first and easiest step was the cross correlation of RGPS source positions with astronomical catalogues, mostly extracted from the SIMBAD database. ...
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.