HD 140283: A Star in the Solar Neighborhood that Formed Shortly
... the distance estimates using ground-based spectroscopy and photometry of the six reference stars (whose V magnitudes range from 11.9 to 16.6). Due to space limitations, the details of this process will be published elsewhere, but we summarize here. For spectral classification, we obtained digital sp ...
... the distance estimates using ground-based spectroscopy and photometry of the six reference stars (whose V magnitudes range from 11.9 to 16.6). Due to space limitations, the details of this process will be published elsewhere, but we summarize here. For spectral classification, we obtained digital sp ...
Presentation - Relativity Group
... • temperature dictates the types of ions or molecules which exist • this, in turn, determines the number and relative strengths of absorption lines in the star’s spectrum • this fact was discovered by Cecilia Payne-Gaposchkin in 1925 ...
... • temperature dictates the types of ions or molecules which exist • this, in turn, determines the number and relative strengths of absorption lines in the star’s spectrum • this fact was discovered by Cecilia Payne-Gaposchkin in 1925 ...
Chapter 4 Galactic Chemical Evolution
... The material we find around us in the Universe today contains significant quantities of heavy elements, although these are still only minor contributors to the total mass of baryonic matter (most is hydrogen). These heavy elements have been synthesised in nuclear reactions in stars, a process known ...
... The material we find around us in the Universe today contains significant quantities of heavy elements, although these are still only minor contributors to the total mass of baryonic matter (most is hydrogen). These heavy elements have been synthesised in nuclear reactions in stars, a process known ...
Life and Death of Stars - UM Research Repository
... massed stars from Red giant stage turns to Planetary Nebula when outer parts drifted off into space and cool down. They are not able to fuse carbon or heavier elements into their cores and ended their lives by expelling their outer layers and leaving behind a White Dwarf; or a carbon star. For massi ...
... massed stars from Red giant stage turns to Planetary Nebula when outer parts drifted off into space and cool down. They are not able to fuse carbon or heavier elements into their cores and ended their lives by expelling their outer layers and leaving behind a White Dwarf; or a carbon star. For massi ...
PDF file - Memorie della SAIt
... a fossil record of the nucleosynthesis that occurred several Gyr ago in halo AGB stars. They are dwarfs or giants, whose surface composition was polluted by the wind of an AGB companion. Then, the C and s-element enhancements are ashes of the nucleosynthesis occurred in the He-rich inter-shell of a ...
... a fossil record of the nucleosynthesis that occurred several Gyr ago in halo AGB stars. They are dwarfs or giants, whose surface composition was polluted by the wind of an AGB companion. Then, the C and s-element enhancements are ashes of the nucleosynthesis occurred in the He-rich inter-shell of a ...
Review 3 (11-18-10)
... •Young stars near clouds of gas and dust •Contraction and heating of clouds • Hydrogen fusion stops collapse II. Leaving the Main Sequence: Hydrogen fusion stops 1. Low mass stars (M < 0.4 solar masses) Not enough mass to ever fuse any element heavier than Hydrogen → white dwarf 2.Intermediate mass ...
... •Young stars near clouds of gas and dust •Contraction and heating of clouds • Hydrogen fusion stops collapse II. Leaving the Main Sequence: Hydrogen fusion stops 1. Low mass stars (M < 0.4 solar masses) Not enough mass to ever fuse any element heavier than Hydrogen → white dwarf 2.Intermediate mass ...
*Studying Complex Star-Forming Fields: Rosette Nebula and Monoceros Loop by Chris Hathaway and Anthony Kuchera
... physical parameters indicated that the stellar content of the possible subgroups is similar. At the same time, the photometric diagrams related to stellar distance further supported the notion of subgroups at different distances. This finding of subgroups within the clusters, however, requires furth ...
... physical parameters indicated that the stellar content of the possible subgroups is similar. At the same time, the photometric diagrams related to stellar distance further supported the notion of subgroups at different distances. This finding of subgroups within the clusters, however, requires furth ...
Document
... thus, at a certain point, the newly forming object becomes visible. At this stage the large luminous body is called a protostar. The other half of its gravitational energy remains within the protostar as heat. As contraction continues, the internal temperature of the protostar keeps rising, and when ...
... thus, at a certain point, the newly forming object becomes visible. At this stage the large luminous body is called a protostar. The other half of its gravitational energy remains within the protostar as heat. As contraction continues, the internal temperature of the protostar keeps rising, and when ...
Dancing with Stars 3 Dancing with Stars Binary Stellar Evolution 1
... must do so to conserve the linear momentum, to keep the net momentum constant and equal to zero. If they moved in the same direction, the momentum would be first directed in one direction and later in another in violation of the principle of conservation of momentum. Nature does not allow such beha ...
... must do so to conserve the linear momentum, to keep the net momentum constant and equal to zero. If they moved in the same direction, the momentum would be first directed in one direction and later in another in violation of the principle of conservation of momentum. Nature does not allow such beha ...
AST1100 Lecture Notes
... high that a quantum mechanical effect sets in: there is no more space in the core for more electrons. Quantum physics sets an upper limit on the number of electrons within a certain volume with a certain momentum. This is called electron degeneracy. The core has become electron degenerate. In the n ...
... high that a quantum mechanical effect sets in: there is no more space in the core for more electrons. Quantum physics sets an upper limit on the number of electrons within a certain volume with a certain momentum. This is called electron degeneracy. The core has become electron degenerate. In the n ...
Chapter 15 Surveying the Stars
... • How do we measure stellar luminosities? – If we measure a star’s apparent brightness and distance, we can compute its luminosity with the inverse square law for light. – Parallax tells us distances to the nearest stars. ...
... • How do we measure stellar luminosities? – If we measure a star’s apparent brightness and distance, we can compute its luminosity with the inverse square law for light. – Parallax tells us distances to the nearest stars. ...
E3 – Stellar distances
... • At distances greater than Mpc, neither parallax nor spectroscopic parallax can be relied upon to measure the distance to a star. • When we observe another galaxy, all of the stars in that galaxy are approximately the same distance away from the earth. What we really need is a light source of known ...
... • At distances greater than Mpc, neither parallax nor spectroscopic parallax can be relied upon to measure the distance to a star. • When we observe another galaxy, all of the stars in that galaxy are approximately the same distance away from the earth. What we really need is a light source of known ...
Fate of Stars
... • In WD, gravity is balanced by pressure due to degenerate electrons • A heavier WD will have smaller radius • if Mass(WD) > 1.4 M(Sun) electrons can not resist gravity ! called Chandrasekhar limit and no WD has a mass greater than this • If WD can acquire mass from companion star and goes over ...
... • In WD, gravity is balanced by pressure due to degenerate electrons • A heavier WD will have smaller radius • if Mass(WD) > 1.4 M(Sun) electrons can not resist gravity ! called Chandrasekhar limit and no WD has a mass greater than this • If WD can acquire mass from companion star and goes over ...
PSF - ESO
... The program starts off by considering the first input list as a "master" list. Taking each star in turn from the second input list, it applies the provisional transformations derived to determine the star's position in the coordinate system of the master list. It then goes through the master list, l ...
... The program starts off by considering the first input list as a "master" list. Taking each star in turn from the second input list, it applies the provisional transformations derived to determine the star's position in the coordinate system of the master list. It then goes through the master list, l ...
20_LectureOutline
... Mass Loss from Giant Stars All stars lose mass via some form of stellar wind. The most massive stars have the strongest winds; O- and Btype stars can lose a tenth of their total mass this way in only a million years. These stellar winds hollow out cavities in the interstellar medium surrounding gian ...
... Mass Loss from Giant Stars All stars lose mass via some form of stellar wind. The most massive stars have the strongest winds; O- and Btype stars can lose a tenth of their total mass this way in only a million years. These stellar winds hollow out cavities in the interstellar medium surrounding gian ...
Stellar Evolution
... Learning Astronomy from History Sirius is the brightest star in the northern sky and has been recorded throughout history But there is a mystery! All sightings recorded between about 100 BCE and 200 CE describe it as being red It is now blue-white. Why? Could there have been an intervening dust clo ...
... Learning Astronomy from History Sirius is the brightest star in the northern sky and has been recorded throughout history But there is a mystery! All sightings recorded between about 100 BCE and 200 CE describe it as being red It is now blue-white. Why? Could there have been an intervening dust clo ...
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.