Chapter 8 Formation of Stars
... ρJ = 10−22 g cm−3. On the other hand, a molecular hydrogen cloud at the same temperature but containing only 1 solar mass has a Jeans density that is 6 orders of magnitude larger. • The Jeans criterion is simple because it is a static condition that says nothing about gas dynamics and it neglects po ...
... ρJ = 10−22 g cm−3. On the other hand, a molecular hydrogen cloud at the same temperature but containing only 1 solar mass has a Jeans density that is 6 orders of magnitude larger. • The Jeans criterion is simple because it is a static condition that says nothing about gas dynamics and it neglects po ...
ppt - Institute for Astronomy
... • The study of young binaries began with Joy & van Biesbrock (1944) who found 5 visual binaries among the newly recognized T Tauri stars. • In 1962, George Herbig added another 24 T Tauri binaries, demonstrating that binaries among young stars are not uncommon. • Observations of young binaries remai ...
... • The study of young binaries began with Joy & van Biesbrock (1944) who found 5 visual binaries among the newly recognized T Tauri stars. • In 1962, George Herbig added another 24 T Tauri binaries, demonstrating that binaries among young stars are not uncommon. • Observations of young binaries remai ...
The evolution of stars - School of Physics
... underlying physical link between these properties. What is this link? For example, consider an alien scientist constructing a similar diagram ...
... underlying physical link between these properties. What is this link? For example, consider an alien scientist constructing a similar diagram ...
Red Dwarf Stars: Ages, Rotation, Magnetic
... tionary age. Two recent independent age determinations for the 40 Eri B are essentially identical, yielding an age of 5.1±0.7 Gyr (Ballouz et al. 2010; Zhao et al. 2011). We used this WD age to calibrate the measured Ca ii HK and coronal X-ray luminosity (LX ) of the K1 V and M4.5 V stars. We have b ...
... tionary age. Two recent independent age determinations for the 40 Eri B are essentially identical, yielding an age of 5.1±0.7 Gyr (Ballouz et al. 2010; Zhao et al. 2011). We used this WD age to calibrate the measured Ca ii HK and coronal X-ray luminosity (LX ) of the K1 V and M4.5 V stars. We have b ...
PDF format
... the masses of the stars and the sizes of their orbits. Why is this so valuable to know? a) We can predict how long an orbit will take. b) This is the main way we determine the masses of stars. c) This lets us know if two stars that look close together in the sky really orbit one another. ...
... the masses of the stars and the sizes of their orbits. Why is this so valuable to know? a) We can predict how long an orbit will take. b) This is the main way we determine the masses of stars. c) This lets us know if two stars that look close together in the sky really orbit one another. ...
Spatial distribution of stars in the Milky Way
... •This may seem anomalous because they are later type than F •But the sample is dominated by giants, which can be observed to (on average) large distances in the disk Note that the faintest stars, M dwarfs, are restricted to the inner 20 pc or so, while progressively brighter stars are seen fill prog ...
... •This may seem anomalous because they are later type than F •But the sample is dominated by giants, which can be observed to (on average) large distances in the disk Note that the faintest stars, M dwarfs, are restricted to the inner 20 pc or so, while progressively brighter stars are seen fill prog ...
File
... A star’s spectral type (OBAFGKM) tells us its surface temperature, because different sets of lines form more easily at different temperatures. Color can also be used as a rough measure of surface temperature; for example, a blue star is hotter than a red star. ...
... A star’s spectral type (OBAFGKM) tells us its surface temperature, because different sets of lines form more easily at different temperatures. Color can also be used as a rough measure of surface temperature; for example, a blue star is hotter than a red star. ...
– 1 – 1. Chemical Evolution 1.1.
... She calculates the delay time between the initial formation of the stars and the SNIa explosion. This is the crucial delay between SNIa and SNII (core-collapse SN, which for massive stars occurs almost instantaneously as their lifetimes as so short). Novae are similar to SNIa, in that they too invol ...
... She calculates the delay time between the initial formation of the stars and the SNIa explosion. This is the crucial delay between SNIa and SNII (core-collapse SN, which for massive stars occurs almost instantaneously as their lifetimes as so short). Novae are similar to SNIa, in that they too invol ...
Hertzsprung Rusell Diagram KLT
... dwarf. Describe some of the characteristics of a white dwarf. [2 marks] Explain why, in its evolution, the star is brightest when at its coolest. [2 marks] ...
... dwarf. Describe some of the characteristics of a white dwarf. [2 marks] Explain why, in its evolution, the star is brightest when at its coolest. [2 marks] ...
Document
... – two stars in a binary system can be close enough to transfer mass from one to the other – gaining or losing mass will change the life path of a star ...
... – two stars in a binary system can be close enough to transfer mass from one to the other – gaining or losing mass will change the life path of a star ...
Magnitudes and Colours of Stars - Lincoln
... 3. When both mv and the distance are known, the absolute visual magnitude Mv is calculated. ...
... 3. When both mv and the distance are known, the absolute visual magnitude Mv is calculated. ...
The University of Sydney Page
... Very low mass stars Very low mass stars (mass less than about 0.4 solar masses) are different in one important respect from heavier stars: their interiors are fully convective. The fused helium is stirred through the whole star, so it has the whole of its hydrogen mass to prolong its stay on the ma ...
... Very low mass stars Very low mass stars (mass less than about 0.4 solar masses) are different in one important respect from heavier stars: their interiors are fully convective. The fused helium is stirred through the whole star, so it has the whole of its hydrogen mass to prolong its stay on the ma ...
Introduction - Cambridge University Press
... energy sources that fuel them, what they do during their lifetimes, and what happens when their fuel runs out. It is assumed that you already have a general, qualitative idea of some events in the life cycles of stars. This book is intended to take you beyond a description of events to an understand ...
... energy sources that fuel them, what they do during their lifetimes, and what happens when their fuel runs out. It is assumed that you already have a general, qualitative idea of some events in the life cycles of stars. This book is intended to take you beyond a description of events to an understand ...
on the mass distribution of stars in the solar neighbourhood
... the solar neighbourhood there are evolved stars (say, red giants and white dwarfs) and, also, the nearby stars are of different chemical composition. Nevertheless, the situation in the solar neighbourhood is especially important. For example Rana (1987) found a mass function for the solar neighbourh ...
... the solar neighbourhood there are evolved stars (say, red giants and white dwarfs) and, also, the nearby stars are of different chemical composition. Nevertheless, the situation in the solar neighbourhood is especially important. For example Rana (1987) found a mass function for the solar neighbourh ...
2. The Anatomy of Stellar Life and Death
... Over the last 4.5 billion years the Sun has grown hotter and slightly larger, and is now more luminous in response to this effect; the same is true for more massive stars. As the fuel is consumed the luminosity slowly increases. The effect is quite subtle in comparison to later changes, but over the ...
... Over the last 4.5 billion years the Sun has grown hotter and slightly larger, and is now more luminous in response to this effect; the same is true for more massive stars. As the fuel is consumed the luminosity slowly increases. The effect is quite subtle in comparison to later changes, but over the ...
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.