Roche accretion of stars close to massive black holes
... to be circular and equatorial, and shrinks due to gravitational radiation. New fitting formulae are presented for the inspiral time and the radiation reaction torque in the relativistic regime. If the inspiralling star fills its Roche lobe outside the innermost stable circular orbit of the hole, gas ...
... to be circular and equatorial, and shrinks due to gravitational radiation. New fitting formulae are presented for the inspiral time and the radiation reaction torque in the relativistic regime. If the inspiralling star fills its Roche lobe outside the innermost stable circular orbit of the hole, gas ...
Chapter 8 – Continuous Absorption
... contribute to opacity • Bound-Bound Transitions – absorption or emission of radiation from electrons moving between bound energy levels. • Bound-Free Transitions – the energy of the higher level electron state lies in the continuum or is unbound. • Free-Free Transitions – change the motion of an ele ...
... contribute to opacity • Bound-Bound Transitions – absorption or emission of radiation from electrons moving between bound energy levels. • Bound-Free Transitions – the energy of the higher level electron state lies in the continuum or is unbound. • Free-Free Transitions – change the motion of an ele ...
Kinetic equilibrium of iron in the atmospheres of cool stars
... of absolute f values. It is important to recognize that the typical abundance scatter obtained from solar spectral analysis of Fe lines is considerably higher than warranted by both observational error and differences in theoretical models. There are essentially two explanations for this result: eith ...
... of absolute f values. It is important to recognize that the typical abundance scatter obtained from solar spectral analysis of Fe lines is considerably higher than warranted by both observational error and differences in theoretical models. There are essentially two explanations for this result: eith ...
Spinar Paradigm
... balance of centrifugal and gravitational forces and whose evolution is determined by its magnetic field. The spinar quasi equilibrium model recently discussed as the course for extralong X-ray plateu in GRB (Lipunov & Gorbovskoy, 2007). We propose a simple non stationary three-parameter collapse mod ...
... balance of centrifugal and gravitational forces and whose evolution is determined by its magnetic field. The spinar quasi equilibrium model recently discussed as the course for extralong X-ray plateu in GRB (Lipunov & Gorbovskoy, 2007). We propose a simple non stationary three-parameter collapse mod ...
Indications for an influence of Hot Jupiters
... Gyr) from Micela et al. (1997). We use the median X-ray luminosities and standard deviations from those authors; if no standard deviation is given, we fit the measured luminosities with a log-normal distribution to derive the median and the standard deviation. The literature gives values for the chr ...
... Gyr) from Micela et al. (1997). We use the median X-ray luminosities and standard deviations from those authors; if no standard deviation is given, we fit the measured luminosities with a log-normal distribution to derive the median and the standard deviation. The literature gives values for the chr ...
LAB #5 - GEOCITIES.ws
... the physical reason for these differences in spectra were not understood until the 1930’s and 1940’s. Then it was realized that, while there were some chemical differences among stars, the main thing that determined the spectral type of a star was its surface temperature. Stars with strong lines of ...
... the physical reason for these differences in spectra were not understood until the 1930’s and 1940’s. Then it was realized that, while there were some chemical differences among stars, the main thing that determined the spectral type of a star was its surface temperature. Stars with strong lines of ...
Weakened magnetic braking as the origin of anomalously
... composition2,14; the observed saturation of magnetic braking in rapid rotators; and the sharp transition from slow to rapid rotation that occurs in hot stars (of greater than 6,250 K) because of their thinning convective envelopes14. Under traditional prescriptions, stars undergo braking throughout ...
... composition2,14; the observed saturation of magnetic braking in rapid rotators; and the sharp transition from slow to rapid rotation that occurs in hot stars (of greater than 6,250 K) because of their thinning convective envelopes14. Under traditional prescriptions, stars undergo braking throughout ...
Black Hole Accretion
... and NS radii (1.6 -- 4 Schw. radii, i.e., 6.5 -- 16 km), for three choices of the core temperature ...
... and NS radii (1.6 -- 4 Schw. radii, i.e., 6.5 -- 16 km), for three choices of the core temperature ...
If neutron star is born with a strong magnetic field
... take place in the degenerate interior of a neutron star. The flux tubes would become buoyant (Parker 1979) and rise rapidly on the time ~1s until they reach the crust. • Muslimov & Tsygan (1985) assumed that the protons in the interior of the neutron star form a Type II superconductor. They then arg ...
... take place in the degenerate interior of a neutron star. The flux tubes would become buoyant (Parker 1979) and rise rapidly on the time ~1s until they reach the crust. • Muslimov & Tsygan (1985) assumed that the protons in the interior of the neutron star form a Type II superconductor. They then arg ...
The HERMES GALAH survey: overview
... remnants of the early days of the Galaxy, not only in the halo but throughout the major luminous components of the Galaxy. The goal of these studies in Galactic archaeology is to reconstruct as much as possible of the early Galactic history by using the stellar relics of ancient star formation event ...
... remnants of the early days of the Galaxy, not only in the halo but throughout the major luminous components of the Galaxy. The goal of these studies in Galactic archaeology is to reconstruct as much as possible of the early Galactic history by using the stellar relics of ancient star formation event ...
Star Gauging (Star Counting)
... Sun, the core of the broader, "traditional" stream may be shifted closer to Earth¡|s orbit, resulting in a stronger-thanaverage annual shower. In fact, Lyytinen and Van Flandern suspect that the Perseids tend to put on stronger-thanaverage displays at 12-year intervals (12 years being Jupiter's orbi ...
... Sun, the core of the broader, "traditional" stream may be shifted closer to Earth¡|s orbit, resulting in a stronger-thanaverage annual shower. In fact, Lyytinen and Van Flandern suspect that the Perseids tend to put on stronger-thanaverage displays at 12-year intervals (12 years being Jupiter's orbi ...
CONTINUING GALACTIC FORMATION
... emanating from the galactic nucleus due to a continual influx of cosmic dust. In the neighborhood of the nucleus the problem is treated as a fluid flow and a simple solution is given using conservation of momentum. When rotational dynamics are included the spinning arm system is the result. This sol ...
... emanating from the galactic nucleus due to a continual influx of cosmic dust. In the neighborhood of the nucleus the problem is treated as a fluid flow and a simple solution is given using conservation of momentum. When rotational dynamics are included the spinning arm system is the result. This sol ...
Energy rate density as a complexity metric and evolutionary driver
... mass M" # 2 3 1033 g, making Fm # 2 erg/s/g, as listed in Table 1 (where the dot-circled subscript denotes solar values). This is the average rate of the Sun’s energy release per unit mass of cosmic baryons, which fuse !10% of their H in 1 Hubble time (10 Gy). It is energy flowing effectively throug ...
... mass M" # 2 3 1033 g, making Fm # 2 erg/s/g, as listed in Table 1 (where the dot-circled subscript denotes solar values). This is the average rate of the Sun’s energy release per unit mass of cosmic baryons, which fuse !10% of their H in 1 Hubble time (10 Gy). It is energy flowing effectively throug ...
PH109 Exploring the Universe, Test#4, Spring 2005 Please indicate
... c) bright galaxies, and only later found to be radio sources d) the only type of radio source within our galaxy 17. Which type of galaxy contains the least amount of interstellar material? a) Ellipticals, b) spirals, c) barred spirals, d) irregulars 18. A primary difference between spiral and ellipt ...
... c) bright galaxies, and only later found to be radio sources d) the only type of radio source within our galaxy 17. Which type of galaxy contains the least amount of interstellar material? a) Ellipticals, b) spirals, c) barred spirals, d) irregulars 18. A primary difference between spiral and ellipt ...
Announcements
... Disk has young stars with orbits nearly in plane Initially gravity pulled in matter from all directions. Stars formed during this stage have random orbits passing close to center Later, rotation made any remaining gas flatten into disk. Stars forming after this have orbits in disk. ...
... Disk has young stars with orbits nearly in plane Initially gravity pulled in matter from all directions. Stars formed during this stage have random orbits passing close to center Later, rotation made any remaining gas flatten into disk. Stars forming after this have orbits in disk. ...
here - NASA/IPAC Extragalactic Database
... the relative number of evolved massive stars of various kinds, such as the relative number of Wolf-Rayet stars to red supergiants, or the relative number of WC- and WN-type WRs. Secondly, these massive stars affect the overall evolution and properties of the galaxies themselves, through three “feedb ...
... the relative number of evolved massive stars of various kinds, such as the relative number of Wolf-Rayet stars to red supergiants, or the relative number of WC- and WN-type WRs. Secondly, these massive stars affect the overall evolution and properties of the galaxies themselves, through three “feedb ...
The Big Bang and Stellar Evolution
... to 15 billion years ago, and stars were formed 5 billion years later. They only allow about 2½ billion years for it to clump together into stars! Their dating problem has been caused by the discovery of supposedly faraway quasars (which we will discuss later), some of which are dated at 15 billion l ...
... to 15 billion years ago, and stars were formed 5 billion years later. They only allow about 2½ billion years for it to clump together into stars! Their dating problem has been caused by the discovery of supposedly faraway quasars (which we will discuss later), some of which are dated at 15 billion l ...
Nuclear astrophysics: the unfinished quest for the origin of the
... assemble in a suite of different nuclear configurations. The masses of such bound nuclei are actually smaller than the sum of the masses of the free individual nucleons. The difference is a measure of the nuclear binding energy that holds the nucleus together, according to Einstein’s famous equation ...
... assemble in a suite of different nuclear configurations. The masses of such bound nuclei are actually smaller than the sum of the masses of the free individual nucleons. The difference is a measure of the nuclear binding energy that holds the nucleus together, according to Einstein’s famous equation ...
Astronomy Astrophysics
... 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 ...
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.