my dissertation (PhD. Thesis) - Argelander
... Moreover they are the sites of the formation of stars such as our Sun. Therefore knowledge about their morphology and evolutionary history is of utmost importance for the understanding of the structure formation process in the universe and hence the process which in the end leads to the birth of sta ...
... Moreover they are the sites of the formation of stars such as our Sun. Therefore knowledge about their morphology and evolutionary history is of utmost importance for the understanding of the structure formation process in the universe and hence the process which in the end leads to the birth of sta ...
Communications in Asteroseismology
... David Evans, and the rest is history!” Mike was impressed particularly with Stoy, who was then the director of the observatory. He found, as he puts it, “Dick Stoy put students at the telescope!” And that lesson stuck. Mike Breger throughout his career with the many students he has supervised “puts ...
... David Evans, and the rest is history!” Mike was impressed particularly with Stoy, who was then the director of the observatory. He found, as he puts it, “Dick Stoy put students at the telescope!” And that lesson stuck. Mike Breger throughout his career with the many students he has supervised “puts ...
Understanding Variable Stars - Central Florida Astronomical Society
... Understanding Variable Stars Variable stars are those that change brightness. Their variability may be due to geometric processes such as rotation, or eclipse by a companion star, or physical processes such as vibration, flares, or cataclysmic explosions. In each case, variable stars provide unique ...
... Understanding Variable Stars Variable stars are those that change brightness. Their variability may be due to geometric processes such as rotation, or eclipse by a companion star, or physical processes such as vibration, flares, or cataclysmic explosions. In each case, variable stars provide unique ...
A spectroscopic study of detached binary systems using precise radial velocities
... A complete understanding of a binary system’s orbital characteristics, as well as the measurement of the all-important stellar masses, is almost always only achieved after the binary system has been studied using two or more complementary observing techniques. Two of the suitable techniques are astr ...
... A complete understanding of a binary system’s orbital characteristics, as well as the measurement of the all-important stellar masses, is almost always only achieved after the binary system has been studied using two or more complementary observing techniques. Two of the suitable techniques are astr ...
Differential rotation in Sun-like stars from surface variability and
... very early phases of stellar evolution is still poorly understood. This is in part because the only available indicator of the AM of a star is its surface rotation rate. For PMS stars this is measured by either spectroscopic v sin i (Vogel and Kuhi 1981, Hartmann et al. 1986, see also Appendix C) or ...
... very early phases of stellar evolution is still poorly understood. This is in part because the only available indicator of the AM of a star is its surface rotation rate. For PMS stars this is measured by either spectroscopic v sin i (Vogel and Kuhi 1981, Hartmann et al. 1986, see also Appendix C) or ...
The evolution of low-metallicity massive stars - Argelander
... hydrogen and helium – in other words, low-metallicity environments – is responsible for some of the most intriguing and energetic cosmic phenomena, including supernovae, gamma-ray bursts and gravitational waves. This thesis aims to investigate the life and death of metal-poor massive stars, using th ...
... hydrogen and helium – in other words, low-metallicity environments – is responsible for some of the most intriguing and energetic cosmic phenomena, including supernovae, gamma-ray bursts and gravitational waves. This thesis aims to investigate the life and death of metal-poor massive stars, using th ...
Carbon, nitrogen and oxygen abundances in
... is somewhat lower than the solar one; this small but stable carbon deficiency is confirmed by other authors. One may suggest two possibilities to explain the observed C deficiency. First, current non-LTE computations of C II lines are still partially inadequate. In this case the C deficiency is inva ...
... is somewhat lower than the solar one; this small but stable carbon deficiency is confirmed by other authors. One may suggest two possibilities to explain the observed C deficiency. First, current non-LTE computations of C II lines are still partially inadequate. In this case the C deficiency is inva ...
Spectroscopic Atlas for Amateur Astronomers
... on Linux with a command-oriented interface. The installation for non Linux users, and also the operation are demanding. So this is probably a realistic option for very few amateurs only. This atlas is primarily intended to be used as a tool for the line identification – as a supplement to my " Spect ...
... on Linux with a command-oriented interface. The installation for non Linux users, and also the operation are demanding. So this is probably a realistic option for very few amateurs only. This atlas is primarily intended to be used as a tool for the line identification – as a supplement to my " Spect ...
Full Text - Departement Natuurkunde en Sterrenkunde
... Stars seem to be a constant factor in our nightly skies. People often do not realise that stars evolve and change, and that one day, they will die and fade, some very quietly, some explosively. We do not have to wait an evolutionary long time to see stellar changes, however. One can detect stellar v ...
... Stars seem to be a constant factor in our nightly skies. People often do not realise that stars evolve and change, and that one day, they will die and fade, some very quietly, some explosively. We do not have to wait an evolutionary long time to see stellar changes, however. One can detect stellar v ...
Astronomy Astrophysics Gaia-ESO Survey: The analysis of high-resolution The
... available. Exactly the same analysis strategy that we applied to iDR2 is being applied to iDR3. For completeness, we also present the analysis of iDR1 in an Appendix. There, we discuss the main differences between the analysis implementation for these two iDRs. The first Gaia-ESO science verification ...
... available. Exactly the same analysis strategy that we applied to iDR2 is being applied to iDR3. For completeness, we also present the analysis of iDR1 in an Appendix. There, we discuss the main differences between the analysis implementation for these two iDRs. The first Gaia-ESO science verification ...
Multiplicity in Early Stellar Evolution - Astronomy Group
... be represented by a binary graph; the figure describes all possible multiples up to an octuple system. The position of each subsystem is coded by levels indicated in the circles. The nomenclature follows the IAU recommendation. ...
... be represented by a binary graph; the figure describes all possible multiples up to an octuple system. The position of each subsystem is coded by levels indicated in the circles. The nomenclature follows the IAU recommendation. ...
A Variability Study of the Typical Red Supergiant Antares A
... the exception of the bright M-class supergiant Betelgeuse (α Orionis, M2 Iab). Betelgeuse has been well studied both observationally and theoretically, and has many features that are well described by models of convection. It was these studies of Betelgeuse that provided the main motivation for this ...
... the exception of the bright M-class supergiant Betelgeuse (α Orionis, M2 Iab). Betelgeuse has been well studied both observationally and theoretically, and has many features that are well described by models of convection. It was these studies of Betelgeuse that provided the main motivation for this ...
Multiplicity in Early Stellar Evolution
... Bonnell et al., 2008; Bate, 2009a,b; Attwood et al., 2009). 3D HD SPH calculations by Bate (2009a) made predictions of the frequency of single, binary, triple and quadruple star systems formed during the collapse of a highly unstable cloud with an initial mass of 500 M⊙ , a Jeans mass of 1 M⊙ , and ...
... Bonnell et al., 2008; Bate, 2009a,b; Attwood et al., 2009). 3D HD SPH calculations by Bate (2009a) made predictions of the frequency of single, binary, triple and quadruple star systems formed during the collapse of a highly unstable cloud with an initial mass of 500 M⊙ , a Jeans mass of 1 M⊙ , and ...
abstracts book - Instituto de Astrofísica e Ciências do Espaço
... has secured major advances in the understanding of the physics of the stellar interiors and has allowed us to build and prepare the tools to look at other stars. Several ground facilities and space missions have completed the picture by adding the necessary data to study stars across the HR diagram ...
... has secured major advances in the understanding of the physics of the stellar interiors and has allowed us to build and prepare the tools to look at other stars. Several ground facilities and space missions have completed the picture by adding the necessary data to study stars across the HR diagram ...
the PDF program book
... There are five meeting rooms in UKK (rooms K1 – K4, K6) that may be used for meetings or telecons. The rooms are located on level 3 and seat between 12 and 24 people. If you want to hold a small meeting, you can either speak to the LOC representative at the registration desk or reserve a meeting roo ...
... There are five meeting rooms in UKK (rooms K1 – K4, K6) that may be used for meetings or telecons. The rooms are located on level 3 and seat between 12 and 24 people. If you want to hold a small meeting, you can either speak to the LOC representative at the registration desk or reserve a meeting roo ...
WILLIAM HERSCHEL AND THE `GARNET` STARS: μ CEPHEI AND
... Abstract: Although William Herschel‘s ‗Garnet Star‘ (µ Cephei) is a prominent object, the story of the discovery of this famous red star is not well documented. Prior to and after Herschel, the identification of this star was the subject of confusion in various catalogues and atlases. The case is co ...
... Abstract: Although William Herschel‘s ‗Garnet Star‘ (µ Cephei) is a prominent object, the story of the discovery of this famous red star is not well documented. Prior to and after Herschel, the identification of this star was the subject of confusion in various catalogues and atlases. The case is co ...
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.