The isotopic mixture of barium in the metal-poor
... et al. (2000) by the Unsöld approximation, our abundance estimate would increase by 0.04 dex. Next, we fit the profile of the Ba II 4554 Å line by changing the barium abundance, and f odd . Our ultra-high resolution spectra can easily distinguish the effects of the two parameters; at the metallici ...
... et al. (2000) by the Unsöld approximation, our abundance estimate would increase by 0.04 dex. Next, we fit the profile of the Ba II 4554 Å line by changing the barium abundance, and f odd . Our ultra-high resolution spectra can easily distinguish the effects of the two parameters; at the metallici ...
Statistical properties of a sample of periodically variable B-type supergiants ⋆
... These 31 targets (for spectral types, see Table 6 and discussion in Sect. 7) were added to the long-term spectroscopic monitoring programme of periodic B stars conducted at Leuven University (Aerts et al. 1999). The spectra of the stars were gathered with the CES spectrograph attached to the CAT tel ...
... These 31 targets (for spectral types, see Table 6 and discussion in Sect. 7) were added to the long-term spectroscopic monitoring programme of periodic B stars conducted at Leuven University (Aerts et al. 1999). The spectra of the stars were gathered with the CES spectrograph attached to the CAT tel ...
Towards the understanding of the deepest layers of solar
... I would like to start by thanking both my supervisors, Dra. Margarida Cunha and Prof. Dr. Jørgen Christensen-Dalsgaard, without whom the realization of this thesis would not have been possible. I would like to give a very special thank to Prof. Dr. Jørgen ChristensenDalsgaard for his hospitality and ...
... I would like to start by thanking both my supervisors, Dra. Margarida Cunha and Prof. Dr. Jørgen Christensen-Dalsgaard, without whom the realization of this thesis would not have been possible. I would like to give a very special thank to Prof. Dr. Jørgen ChristensenDalsgaard for his hospitality and ...
Here
... of stellar evolution through the differences between decanters for port and claret to the intricacies of English grammar (though I’m still struggling with the latter, apparently). I may not have been the model student but Chris has been the ideal supervisor. He has been there when I have needed him ...
... of stellar evolution through the differences between decanters for port and claret to the intricacies of English grammar (though I’m still struggling with the latter, apparently). I may not have been the model student but Chris has been the ideal supervisor. He has been there when I have needed him ...
Stellar Structure and Evolution
... our Galaxy, depends on stellar evolution calculations. Furthermore, since the synthesis of almost all chemical elements is supposed to take place inside stars, an understanding of the chemical history of the Universe (and of our own origins) requires that one understands stellar evolution. However, ...
... our Galaxy, depends on stellar evolution calculations. Furthermore, since the synthesis of almost all chemical elements is supposed to take place inside stars, an understanding of the chemical history of the Universe (and of our own origins) requires that one understands stellar evolution. However, ...
Luminosities and mass-loss rates of SMC and LMC AGB stars and
... describing these programs, and considering our radiative transfer models (see Sect. 3). Excluded sources include those with very poor S/N IRS data, sources where the SED and spectrum did not match at all (indicating that the IRS peak-up was on a source other than the intended target), sources with a ...
... describing these programs, and considering our radiative transfer models (see Sect. 3). Excluded sources include those with very poor S/N IRS data, sources where the SED and spectrum did not match at all (indicating that the IRS peak-up was on a source other than the intended target), sources with a ...
bode elert johann
... Note that Harris is mentioned on the southern map only. In the literature a publication date of 1721 is often given for both maps. This is impossible, for Harris was only 17 at that time. A few sources give 1728 for the southern map, which fits much better. Harris may well have got in contact with H ...
... Note that Harris is mentioned on the southern map only. In the literature a publication date of 1721 is often given for both maps. This is impossible, for Harris was only 17 at that time. A few sources give 1728 for the southern map, which fits much better. Harris may well have got in contact with H ...
A Spitzer mid-infrared spectral survey of mass
... mass-loss: the so-called superwind phase. After this final burst of activity, the star remains as a hot, compact white dwarf of mass 0.6– 1.4 M . The expanding ejecta surrounding the star become ionized and form a planetary nebula, before dispersing into the interstellar medium (ISM). The superwind ...
... mass-loss: the so-called superwind phase. After this final burst of activity, the star remains as a hot, compact white dwarf of mass 0.6– 1.4 M . The expanding ejecta surrounding the star become ionized and form a planetary nebula, before dispersing into the interstellar medium (ISM). The superwind ...
Starspots: A Key to the Stellar Dynamo | SpringerLink
... sunspots, plages, network, etc. They further expand into the outer atmosphere and exhibit themselves as highly dynamic coronal loops. Thus, a detailed study of solar activity phenomena reveals the structure of underlying magnetic fields and provides valuable constraints for solar dynamo theory. Thes ...
... sunspots, plages, network, etc. They further expand into the outer atmosphere and exhibit themselves as highly dynamic coronal loops. Thus, a detailed study of solar activity phenomena reveals the structure of underlying magnetic fields and provides valuable constraints for solar dynamo theory. Thes ...
Article PDF - IOPscience
... updated version of the local population defined by Holberg et al. (2002, 2008). As mentioned earlier, significant additions to this initial sample have been made by Kawka et al. (2004), Kawka & Vennes (2006), and Subasavage et al. (2007, 2008), with some contributions from other studies (see referen ...
... updated version of the local population defined by Holberg et al. (2002, 2008). As mentioned earlier, significant additions to this initial sample have been made by Kawka et al. (2004), Kawka & Vennes (2006), and Subasavage et al. (2007, 2008), with some contributions from other studies (see referen ...
The Ages of Stars
... • We could better understand the behavior and future of our Sun if we could create a true cohort based on mass, composition, and age. At present, comparisons of the Sun to other stars often rely on the very stellar properties (such as activity, rotation, or lithium abundance) that one is trying to u ...
... • We could better understand the behavior and future of our Sun if we could create a true cohort based on mass, composition, and age. At present, comparisons of the Sun to other stars often rely on the very stellar properties (such as activity, rotation, or lithium abundance) that one is trying to u ...
preprint, pdf version - LESIA
... ideal in the case of TNOs. In contrast to Pluto occultations, for TNOs we obtain good contrast in the light curves using very modest instruments for stars as faint as R = 18.0, as verified in the recent successfully recorded TNO occultations reported here. This is due to the TNO magnitudes being muc ...
... ideal in the case of TNOs. In contrast to Pluto occultations, for TNOs we obtain good contrast in the light curves using very modest instruments for stars as faint as R = 18.0, as verified in the recent successfully recorded TNO occultations reported here. This is due to the TNO magnitudes being muc ...
The Stars - Springer
... some basic astrophysics, and it will be basic! From this point on, we will be mentioning such topics as luminosity, spectral classification, and so on, so let’s begin by explaining in detail what is meant. It is no use, and indeed pointless, if certain details about a star are given without an expla ...
... some basic astrophysics, and it will be basic! From this point on, we will be mentioning such topics as luminosity, spectral classification, and so on, so let’s begin by explaining in detail what is meant. It is no use, and indeed pointless, if certain details about a star are given without an expla ...
Classification of Variable Stars
... QZ. This system (the letter J is omitted) can accommodate 334 names. There are so many variables in some constellations in the Milky Way, however, that additional nomenclature is necessary. After QZ, variables are named V335, V336, and so on. The letters representing stars are then combined with the ...
... QZ. This system (the letter J is omitted) can accommodate 334 names. There are so many variables in some constellations in the Milky Way, however, that additional nomenclature is necessary. After QZ, variables are named V335, V336, and so on. The letters representing stars are then combined with 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.