Word version - White dwarf stars and the Chandrasekhar limit
... radiate, to a fair approximation, like black bodies, with temperatures well correlated with color, the dimness of Sirius B could not be explained as low surface brightness. Although some suggested that it might be reflected light from Sirius, Adams pointed out that a similar star had been found with ...
... radiate, to a fair approximation, like black bodies, with temperatures well correlated with color, the dimness of Sirius B could not be explained as low surface brightness. Although some suggested that it might be reflected light from Sirius, Adams pointed out that a similar star had been found with ...
Stellar evolution - Statistical Physics Group
... Typically evolutionary time scales are between loe and 10lo years. Despite this, studies of stellar evolution have progressed considerably. On the observational side, it has been realized that, although the classification of stars into groups with similar properties is very useful, these groups are ...
... Typically evolutionary time scales are between loe and 10lo years. Despite this, studies of stellar evolution have progressed considerably. On the observational side, it has been realized that, although the classification of stars into groups with similar properties is very useful, these groups are ...
Nucleosynthesis and Chemical Evolution of Oxygen
... depleted (Figure 1). Nevertheless, if the CNO cycling is not complete or the burning happens at a lower temperature, the matter may be enriched in 17O and depleted in 16,18O, as is the case in Figure 1B at a time of 106 years. This is typically the case in the envelopes of stars that have experience ...
... depleted (Figure 1). Nevertheless, if the CNO cycling is not complete or the burning happens at a lower temperature, the matter may be enriched in 17O and depleted in 16,18O, as is the case in Figure 1B at a time of 106 years. This is typically the case in the envelopes of stars that have experience ...
Do We Know of Any Maunder Minimum Stars?
... galaxy, searches for extrasolar planets, and studies of the Sun as a star often benefit from the ability to determine the age of sun-like stars. But, because stars change very little during their lifetime on the main sequence, determining their age is difficult. An important tool for making that det ...
... galaxy, searches for extrasolar planets, and studies of the Sun as a star often benefit from the ability to determine the age of sun-like stars. But, because stars change very little during their lifetime on the main sequence, determining their age is difficult. An important tool for making that det ...
structure and evolution of white dwarfs and their
... ideas remain unchanged. However, importantly, they have also hardly been tested by direct observation. Theoretical and observational study of stellar evolution has placed white dwarfs as one possible end point of the process. In general terms, all stars with masses below about eight times that of th ...
... ideas remain unchanged. However, importantly, they have also hardly been tested by direct observation. Theoretical and observational study of stellar evolution has placed white dwarfs as one possible end point of the process. In general terms, all stars with masses below about eight times that of th ...
Isotopic composition of Hg and Pt in 5 slowly rotating HgMn stars *
... taken from Kalus et al. (1998). Terrestrial isotopic abun- The wavelength ranges that were observed contain a numdances were taken from Anders & Grevesse (1989), while ber of spectral lines of other elements. In the process of the hyperne intensities were obtained from Engleman's computing the synt ...
... taken from Kalus et al. (1998). Terrestrial isotopic abun- The wavelength ranges that were observed contain a numdances were taken from Anders & Grevesse (1989), while ber of spectral lines of other elements. In the process of the hyperne intensities were obtained from Engleman's computing the synt ...
Chapter 12
... larger and brighter than our Sun. They look dim to us only because they are so far away—several light-years (trillions of miles) to even the nearest. Such remoteness creates tremendous difficulties for astronomers trying to understand the nature of stars. We cannot physically travel to the stars, bu ...
... larger and brighter than our Sun. They look dim to us only because they are so far away—several light-years (trillions of miles) to even the nearest. Such remoteness creates tremendous difficulties for astronomers trying to understand the nature of stars. We cannot physically travel to the stars, bu ...
High-precision abundances of elements in solar twin stars: Trends
... (EWs) of spectral lines by Gaussian fitting relative to pseudocontinuum regions lying within 3 Å from the line measured. These regions do not necessarily represent the true continuum, but care was taken to use the same continuum windows in all stars, so that differences in EW between stars are preci ...
... (EWs) of spectral lines by Gaussian fitting relative to pseudocontinuum regions lying within 3 Å from the line measured. These regions do not necessarily represent the true continuum, but care was taken to use the same continuum windows in all stars, so that differences in EW between stars are preci ...
Lives of Stars - Astronomy Outreach
... small and massive, the gravitational force was incredibly strong. PAGE: So, the core and shells must have been even hotter this time? SOL: Yes, it’s amazing how the core changes in such short time. But its fusion days were limited. The hydrogen shell dumped helium ash onto the helium fusion shell. T ...
... small and massive, the gravitational force was incredibly strong. PAGE: So, the core and shells must have been even hotter this time? SOL: Yes, it’s amazing how the core changes in such short time. But its fusion days were limited. The hydrogen shell dumped helium ash onto the helium fusion shell. T ...
Test Ch. 27 Multiple Choice Identify the choice that best completes
... 25. In the last stage of stellar evolution following a supernova, stars too massive to form neutron stars may form a A. black dwarf. B. red supergiant. C. white dwarf. D. black hole. 26. In which stage of stellar evolution does combined hydrogen fusion and helium fusion cause a star’s outer shell to ...
... 25. In the last stage of stellar evolution following a supernova, stars too massive to form neutron stars may form a A. black dwarf. B. red supergiant. C. white dwarf. D. black hole. 26. In which stage of stellar evolution does combined hydrogen fusion and helium fusion cause a star’s outer shell to ...
The ages of pre-main-sequence stars
... does not lend itself well to the one-dimensional models normally employed in stellar evolution. On the other hand, we can model the hydrostatic inner regions using the methods normally employed in stellar evolution and so, with appropriate boundary conditions, approximate a forming star. Indeed, thi ...
... does not lend itself well to the one-dimensional models normally employed in stellar evolution. On the other hand, we can model the hydrostatic inner regions using the methods normally employed in stellar evolution and so, with appropriate boundary conditions, approximate a forming star. Indeed, thi ...
Lives of Stars - McDonald Observatory
... SOL: Yes, it’s amazing how the core changes in such short time. But its fusion days were limited. The hydrogen shell dumped helium ash onto the helium fusion shell. Then the helium shell dumped its carbon ash into the carbon core. This core continued to contract, which shrank the outer shells. And t ...
... SOL: Yes, it’s amazing how the core changes in such short time. But its fusion days were limited. The hydrogen shell dumped helium ash onto the helium fusion shell. Then the helium shell dumped its carbon ash into the carbon core. This core continued to contract, which shrank the outer shells. And t ...
Life Histories Of Some Stars
... graph? Where do newborn babies cluster? Children? Or is there no clustering at all? Describe the shape of the graph? Is it a straight line? A curve? 5. Give each group the list of stars attached and the HR diagram attached. Instead of height and weight, the information is in Luminosity (compared to ...
... graph? Where do newborn babies cluster? Children? Or is there no clustering at all? Describe the shape of the graph? Is it a straight line? A curve? 5. Give each group the list of stars attached and the HR diagram attached. Instead of height and weight, the information is in Luminosity (compared to ...
WHAT MAKES A STAR SO SPECIAL Abstract
... 1. The teacher introduces the physical characteristics of stars and the spectral classification to the students (you can use the information from the Introduction section as a supplement to the lesson about Star characteristics in the textbook you are using). 2. The teacher gives every student an en ...
... 1. The teacher introduces the physical characteristics of stars and the spectral classification to the students (you can use the information from the Introduction section as a supplement to the lesson about Star characteristics in the textbook you are using). 2. The teacher gives every student an en ...
Star
A star is a luminous sphere of plasma held together by its own gravity. The nearest star to Earth is the Sun. Other stars are visible from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, and the brightest stars gained proper names. Extensive catalogues of stars have been assembled by astronomers, which provide standardized star designations.For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space. Once the hydrogen in the core of a star is nearly exhausted, almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star's lifetime and, for some stars, by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, luminosity, and spectrum respectively. The total mass of a star is the principal determinant of its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star's environment affects its rotation and movement. A plot of the temperature of many stars against their luminosities, known as a Hertzsprung–Russell diagram (H–R diagram), allows the age and evolutionary state of a star to be determined.A star's life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Once the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, releasing energy in the process. The remainder of the star's interior carries energy away from the core through a combination of radiative and convective processes. The star's internal pressure prevents it from collapsing further under its own gravity. Once the hydrogen fuel at the core is exhausted, a star with at least 0.4 times the mass of the Sun expands to become a red giant, in some cases fusing heavier elements at the core or in shells around the core. The star then evolves into a degenerate form, recycling a portion of its matter into the interstellar environment, where it will contribute to the formation of a new generation of stars with a higher proportion of heavy elements. Meanwhile, the core becomes a stellar remnant: a white dwarf, a neutron star, or (if it is sufficiently massive) a black hole.Binary and multi-star systems consist of two or more stars that are gravitationally bound, and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy.