The Hamburg/ESO R-process Enhanced Star survey (HERES)
... Furthermore, and perhaps even more importantly, individual age determinations are possible for these stars using long-lived radioactive isotopes, such as 232 Th (half-life 14.05 Gyr) or 238 U (4.468 Gyr). By comparing the abundance ratio of these elements relative to a stable r-process element of si ...
... Furthermore, and perhaps even more importantly, individual age determinations are possible for these stars using long-lived radioactive isotopes, such as 232 Th (half-life 14.05 Gyr) or 238 U (4.468 Gyr). By comparing the abundance ratio of these elements relative to a stable r-process element of si ...
Reprint
... to carbon, supernovae (12 C) and evolved stars (12 C and 13 C), including red giants, supergiants, and asymptotic giant branch (AGB) stars. Stellar yields from such objects result in an average galactic C/O ratio of 0.7 (Carigi et al. 2005). Hence, in most stars, C < O. The exceptions are AGB stars, ...
... to carbon, supernovae (12 C) and evolved stars (12 C and 13 C), including red giants, supergiants, and asymptotic giant branch (AGB) stars. Stellar yields from such objects result in an average galactic C/O ratio of 0.7 (Carigi et al. 2005). Hence, in most stars, C < O. The exceptions are AGB stars, ...
a kiloparsec-scale nuclear stellar disk in the milky way
... (2014) showed that the nuclear disk that it forms is qualitatively similar to those in external galaxies. The simulation was evolved with the N-body+smoothed particle hydrodynamics code GASOLINE (Wadsley et al. 2004). The galaxy forms out of gas cooling off a hot corona in pressure equilibrium withi ...
... (2014) showed that the nuclear disk that it forms is qualitatively similar to those in external galaxies. The simulation was evolved with the N-body+smoothed particle hydrodynamics code GASOLINE (Wadsley et al. 2004). The galaxy forms out of gas cooling off a hot corona in pressure equilibrium withi ...
Document
... condition fulfilled between magic numbers of neutrons A~140 sudden drops observed at neutron magic numbers ...
... condition fulfilled between magic numbers of neutrons A~140 sudden drops observed at neutron magic numbers ...
Document
... In 2003, theorists conclude that these young stars indeed could have migrated into the center in a few million years, but only if they remained bound in a compact, very heavy cluster of stars that rapidly sank toward the center of the Galaxy. If it were only a star cluster, then it would have been t ...
... In 2003, theorists conclude that these young stars indeed could have migrated into the center in a few million years, but only if they remained bound in a compact, very heavy cluster of stars that rapidly sank toward the center of the Galaxy. If it were only a star cluster, then it would have been t ...
14stardeath
... Matter falling toward a neutron star forms an accretion disk, just as in a white dwarf binary. © 2010 Pearson Education, Inc. ...
... Matter falling toward a neutron star forms an accretion disk, just as in a white dwarf binary. © 2010 Pearson Education, Inc. ...
the magellanic clouds newsletter - Keele University Astrophysics
... much as 30 kpc and 75 km s−1 . Furthermore, we show that the gravitational pull of the LMC and response of the Milky Way are likely to significantly affect the orbit and phase space distribution of tidal debris from the Sagittarius dwarf galaxy (Sgr). Such effects are larger than previous estimates ...
... much as 30 kpc and 75 km s−1 . Furthermore, we show that the gravitational pull of the LMC and response of the Milky Way are likely to significantly affect the orbit and phase space distribution of tidal debris from the Sagittarius dwarf galaxy (Sgr). Such effects are larger than previous estimates ...
UCLA 2004
... Stellar nucleosynthesis products ejected by an evolved star and enter the Solar System material shortly before, or soon after, Solar System formation: AGB star Contaminates Sun’s molecular cloud (Wasserburg et al. 1994) ...
... Stellar nucleosynthesis products ejected by an evolved star and enter the Solar System material shortly before, or soon after, Solar System formation: AGB star Contaminates Sun’s molecular cloud (Wasserburg et al. 1994) ...
Lecture 12: Evolution of the Galaxy
... • New stars which form therefore have higher values of heavy element mass fraction, Z, at the time of their birth. The youngest stars are therefore the most heavy-element rich, and the oldest ones (Population II stars) are the most deficient in heavy elements relative to the Sun. • Halo Population I ...
... • New stars which form therefore have higher values of heavy element mass fraction, Z, at the time of their birth. The youngest stars are therefore the most heavy-element rich, and the oldest ones (Population II stars) are the most deficient in heavy elements relative to the Sun. • Halo Population I ...
Book: Introduction to Matter (in
... 8. If two stars had identical apparent magnitudes, but Star A had an absolute magnitude of -2.8 and Star B had an absolute magnitude of 3.1, which star is further away and why? 9. Describe how color indicates the temperature of a star. What is the class order from hottest to coolest? ...
... 8. If two stars had identical apparent magnitudes, but Star A had an absolute magnitude of -2.8 and Star B had an absolute magnitude of 3.1, which star is further away and why? 9. Describe how color indicates the temperature of a star. What is the class order from hottest to coolest? ...
Evolution of stars
... d. produces the energy responsible for bipolar flows. e. combines four hydrogen nuclei to form one helium nucleus, which produces energy. What causes the outward pressure that balances the inward pull of gravity in a star? a. The outward flow of energy. b. The opacity of the gas. c. The temperature ...
... d. produces the energy responsible for bipolar flows. e. combines four hydrogen nuclei to form one helium nucleus, which produces energy. What causes the outward pressure that balances the inward pull of gravity in a star? a. The outward flow of energy. b. The opacity of the gas. c. The temperature ...
VY Canis Majoris: The Astrophysical Basis of Its Luminosity
... fluxes have shown only small variability. Most of the star’s radiation is reprocessed by the dust in its extensive circumstellar ejecta. I therefore used the total fluxes integrated over the entire nebula for Figure 1. Its energy distribution rises rapidly in the infrared and has a broad maximum bet ...
... fluxes have shown only small variability. Most of the star’s radiation is reprocessed by the dust in its extensive circumstellar ejecta. I therefore used the total fluxes integrated over the entire nebula for Figure 1. Its energy distribution rises rapidly in the infrared and has a broad maximum bet ...
a new planet around an m dwarf: revealing a correlation between
... leverage can be gained by measuring the planet occurrence rate around higher mass F- and A-type stars (1:3 M M P 3:0 M ). Unfortunately, intermediate-mass, main-sequence stars are poor precision Doppler targets. Stars with spectral types earlier than F8 tend to have rotationally broadened absor ...
... leverage can be gained by measuring the planet occurrence rate around higher mass F- and A-type stars (1:3 M M P 3:0 M ). Unfortunately, intermediate-mass, main-sequence stars are poor precision Doppler targets. Stars with spectral types earlier than F8 tend to have rotationally broadened absor ...
Document
... • New observations and good practical theories of dense matter • Individual sources and statistical analysis ...
... • New observations and good practical theories of dense matter • Individual sources and statistical analysis ...
![arXiv:1705.00964v1 [astro-ph.GA] 2 May 2017](http://s1.studyres.com/store/data/013011793_1-8f89fb3e8b5cd5cf78613aebb3c8e2a5-300x300.png)
arXiv:1705.00964v1 [astro-ph.GA] 2 May 2017
... we are drawing randomly from amongst all such local stars, and we can use the Hipparcos catalogue to estimate the chances of two random coincidences that are at least as close as the associations we have identified. We define “local”, here, to mean stars within 60 pc. We assume that the position and ...
... we are drawing randomly from amongst all such local stars, and we can use the Hipparcos catalogue to estimate the chances of two random coincidences that are at least as close as the associations we have identified. We define “local”, here, to mean stars within 60 pc. We assume that the position and ...
Constellation Classification Cards*
... brightness is used. In the second set, B, more advanced students are introduced to the additional term, magnitude. In addition, several stars are what are called binaries (a star system with two stars orbiting around their center of mass). In Set B both stars are shown, along with their combined bri ...
... brightness is used. In the second set, B, more advanced students are introduced to the additional term, magnitude. In addition, several stars are what are called binaries (a star system with two stars orbiting around their center of mass). In Set B both stars are shown, along with their combined bri ...
The Hipparcos Star Globe Booklet - Cosmos
... gathered data for four years. The satellite span slowly, controlled in such a way as to gradually shift the axis of rotation so that over time the telescope could repeatedly scan the entire celestial sphere. A simultaneous onboard experiment named Tycho was also to provide astrometric and two-colour ...
... gathered data for four years. The satellite span slowly, controlled in such a way as to gradually shift the axis of rotation so that over time the telescope could repeatedly scan the entire celestial sphere. A simultaneous onboard experiment named Tycho was also to provide astrometric and two-colour ...
Galactic Encounters: The Dynamics of Mergers and Satellite Accretion
... galaxies merge, direct hits of stars are very unlikely. This shouldn’t be surprising, considering how small the fraction of the area filled by stars in a galaxy is. For the solar neighbourhood we typically have 20 stars/pc3 and the radius of each star is about 0.2Rsun on average. So the fractional a ...
... galaxies merge, direct hits of stars are very unlikely. This shouldn’t be surprising, considering how small the fraction of the area filled by stars in a galaxy is. For the solar neighbourhood we typically have 20 stars/pc3 and the radius of each star is about 0.2Rsun on average. So the fractional a ...
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.