Analysis of Stellar Activity and Orbital Dynamics in Extrasolar
... Nearly four centuries later, as- age can be estimated based on short26 tronomers are much closer to finding lived, extinct radionuclides like Al and ...
... Nearly four centuries later, as- age can be estimated based on short26 tronomers are much closer to finding lived, extinct radionuclides like Al and ...
LACEwING: A New Moving Group Analysis Code
... members of each group at the α and δ of the input star, and compares them directly to the measured observable quantities. Producing a membership probability from the goodness-offit value is a complex task, because most of the NYMGs considered here (particularly those under 100 Myr) are found within a ...
... members of each group at the α and δ of the input star, and compares them directly to the measured observable quantities. Producing a membership probability from the goodness-offit value is a complex task, because most of the NYMGs considered here (particularly those under 100 Myr) are found within a ...
NUMERICAL SIMULATIONS OF SOLAR AND STELLAR CONVECTION AND OSCILLATIONS By Dali Giorgobiani
... to thank my thesis advisor, Professor Robert Stein, for his support and assistance, for everything I have learned from him, for always being there for me when I needed help. I thank Prof. Stein for allowing me to use his 3D (M)HD code, which is the basis of my research and which represents one of th ...
... to thank my thesis advisor, Professor Robert Stein, for his support and assistance, for everything I have learned from him, for always being there for me when I needed help. I thank Prof. Stein for allowing me to use his 3D (M)HD code, which is the basis of my research and which represents one of th ...
Type Ia Supernovae
... after Tycho made his paradigm changing discovery using SN 1572, and some 60 years after supernovae had been identified as distant dying stars, two teams changed the view of the world again using supernovae. The found that the Universe was accelerating in its expansion, a conclusion that could most e ...
... after Tycho made his paradigm changing discovery using SN 1572, and some 60 years after supernovae had been identified as distant dying stars, two teams changed the view of the world again using supernovae. The found that the Universe was accelerating in its expansion, a conclusion that could most e ...
Chemical Evolution of Galactic Systems
... previously published or written by another author, except where due reference is made in the text of the thesis. All work presented is primarily that of the candidate. Brad Gibson was involved in the planning and direction of much of this thesis. The co-authors on the following list of publications ...
... previously published or written by another author, except where due reference is made in the text of the thesis. All work presented is primarily that of the candidate. Brad Gibson was involved in the planning and direction of much of this thesis. The co-authors on the following list of publications ...
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 ...
Cool Stars in the Galaxy — A ROSAT and ASCA View.
... the Einstein Imaging Proportional Counter (IPC) th a t the field of stellar X-ray astronomy truly came into its own with the discovery of over 1000 coronal sources. Prior to this point it was expected th at only the very nearest of stars could be detected in X-rays. By scaling the solar X-ray flux a ...
... the Einstein Imaging Proportional Counter (IPC) th a t the field of stellar X-ray astronomy truly came into its own with the discovery of over 1000 coronal sources. Prior to this point it was expected th at only the very nearest of stars could be detected in X-rays. By scaling the solar X-ray flux a ...
Clusters: age scales for stellar physics
... energy emission rate of the Sun was therefore not sustainable. Therefore, some new mechanism laid behind. What physicists did not know was that complete new branch of physics was at hand: relativity and quantum mechanics. Eventually the nuclear reactions were identified as the culprit (Bethe 1939). ...
... energy emission rate of the Sun was therefore not sustainable. Therefore, some new mechanism laid behind. What physicists did not know was that complete new branch of physics was at hand: relativity and quantum mechanics. Eventually the nuclear reactions were identified as the culprit (Bethe 1939). ...
Present-day cosmic abundances - Dr. Karl Remeis
... An ideal alternative to find a reference for the chemical composition of cosmic matter are normal unevolved early B-type stars of ∼8-18 M⊙ , which can provide simultaneously temporal (present-day) and local (birth place) information on chemical abundances. They can be observed not only in the solar ...
... An ideal alternative to find a reference for the chemical composition of cosmic matter are normal unevolved early B-type stars of ∼8-18 M⊙ , which can provide simultaneously temporal (present-day) and local (birth place) information on chemical abundances. They can be observed not only in the solar ...
- National Optical Astronomy Observatory
... limit of the telescope at 5 microns is ~0.8 arcseconds. Spatially sampling at ~0.4 arcseconds would then be about right under good seeing.) ! Input scan parameters (number of steps, number of spectral frames, integration time, etc.) ! Start the scan sequence and simultaneously begin stepping the tra ...
... limit of the telescope at 5 microns is ~0.8 arcseconds. Spatially sampling at ~0.4 arcseconds would then be about right under good seeing.) ! Input scan parameters (number of steps, number of spectral frames, integration time, etc.) ! Start the scan sequence and simultaneously begin stepping the tra ...
The Alpha Centauri binary system
... damping theory (Barklem et al. 1998 and references therein), which allowed them to fit accurate damping constants to the profile of strong lines, turning these into reliable abundances indicators, an approach normally avoided in abundance analysis. They found [Fe/H]=0.12 ± 0.06 for the iron abundanc ...
... damping theory (Barklem et al. 1998 and references therein), which allowed them to fit accurate damping constants to the profile of strong lines, turning these into reliable abundances indicators, an approach normally avoided in abundance analysis. They found [Fe/H]=0.12 ± 0.06 for the iron abundanc ...
PhD thesis - Hamburger Sternwarte
... In this PhD thesis, the fully automatic data reduction pipeline of the Hamburg Robotic Telescope (HRT), first observations and the first analyses of stellar activity are presented. The first part of this thesis deals with the data reduction pipeline. It is based on the IDL reduction package REDUCE, ...
... In this PhD thesis, the fully automatic data reduction pipeline of the Hamburg Robotic Telescope (HRT), first observations and the first analyses of stellar activity are presented. The first part of this thesis deals with the data reduction pipeline. It is based on the IDL reduction package REDUCE, ...
abstracts book - Instituto de Astrofísica e Ciências do Espaço
... across the HR diagram with a level of detail that was in no way foreseen in 1985. In spite of the great science successes, astero- and helioseismic data still contain many secrets waiting to be uncovered. The opportunity to use the existing data and tools to clarify major questions of stellar physic ...
... across the HR diagram with a level of detail that was in no way foreseen in 1985. In spite of the great science successes, astero- and helioseismic data still contain many secrets waiting to be uncovered. The opportunity to use the existing data and tools to clarify major questions of stellar physic ...
variation in the pre-transit balmer line signal around
... when interpreting transmission spectra of lines produced in stellar active regions. Evidence for pre-transit material has now been observed in a handful of hot planet systems, namely, WASP-12 b (Fossati et al. 2010), HD 189733 b (Ben-Jaffel & Ballester 2013; Bourrier et al. 2013; Cauley et al. 2015) ...
... when interpreting transmission spectra of lines produced in stellar active regions. Evidence for pre-transit material has now been observed in a handful of hot planet systems, namely, WASP-12 b (Fossati et al. 2010), HD 189733 b (Ben-Jaffel & Ballester 2013; Bourrier et al. 2013; Cauley et al. 2015) ...
The Stars - Springer
... and analyzed. The end result is something called a spectrum. Basically, a spectrum is a map of the light coming from the star. It consists of all of the light from the star, spread out according to wavelength (color) so that the different amounts of light at different wavelengths can be measured. Re ...
... and analyzed. The end result is something called a spectrum. Basically, a spectrum is a map of the light coming from the star. It consists of all of the light from the star, spread out according to wavelength (color) so that the different amounts of light at different wavelengths can be measured. Re ...
An Atlas of Stellar Spectra
... The Atlas of Stellar Spectra and the accompanying outline have been prepared from the viewpoint of the practical stellar astronomer. Problems connected with the astrophysical interpretation of the spectral sequence are not touched on; as a consequence, emphasis is placed on ``ordinary'' stars. These ...
... The Atlas of Stellar Spectra and the accompanying outline have been prepared from the viewpoint of the practical stellar astronomer. Problems connected with the astrophysical interpretation of the spectral sequence are not touched on; as a consequence, emphasis is placed on ``ordinary'' stars. These ...
Chandra Characterization of X-ray Emission in the Young F
... spectra than their lower mass brethren. For example, HD 100453 and the similarly aged 51 Eri (F0V) have coronal temperatures of about 0.2 keV as opposed to 1-2 keV for similarly aged GKM stars (Collins et al. 2009, Feigelson et al. 2006). Finally, the “FIP-effect” in which elements with first ioniza ...
... spectra than their lower mass brethren. For example, HD 100453 and the similarly aged 51 Eri (F0V) have coronal temperatures of about 0.2 keV as opposed to 1-2 keV for similarly aged GKM stars (Collins et al. 2009, Feigelson et al. 2006). Finally, the “FIP-effect” in which elements with first ioniza ...
The SMC as a probe of dust in the early Universe
... fundamentally different dust chemistries in high-redshift galaxies, showing emission from polycyclic aromatic hydrocarbons (PAHs) at z = 3.0 (Huang et al. 2007), amorphous silicate emission at z = 2.3 (Teplitz et al. 2006), crystalline silicates out to z = 0.3 (Spoon et al. 2006), and even the possi ...
... fundamentally different dust chemistries in high-redshift galaxies, showing emission from polycyclic aromatic hydrocarbons (PAHs) at z = 3.0 (Huang et al. 2007), amorphous silicate emission at z = 2.3 (Teplitz et al. 2006), crystalline silicates out to z = 0.3 (Spoon et al. 2006), and even the possi ...
ancient cultures 114 - Stellenbosch University
... mundane and inappropriate as domestic lighting when viewed from a distance). In true astronomical terms, however, a star is a giant ball of gas, constantly undergoing nuclear processes, and as such constantly emitting electromagnetic waves. The light waves produced from these reactions are particula ...
... mundane and inappropriate as domestic lighting when viewed from a distance). In true astronomical terms, however, a star is a giant ball of gas, constantly undergoing nuclear processes, and as such constantly emitting electromagnetic waves. The light waves produced from these reactions are particula ...
DUSTiNGS III: Distribution of Intermediate
... candidates from the larger DUSTiNGS sample. The variable AGB star candidates are a powerful tracer of stars at greater radii in the galaxies as the identification of the variable AGB stars is independent of photometric contamination. Thus, membership of an individual point source to the galaxy is mo ...
... candidates from the larger DUSTiNGS sample. The variable AGB star candidates are a powerful tracer of stars at greater radii in the galaxies as the identification of the variable AGB stars is independent of photometric contamination. Thus, membership of an individual point source to the galaxy is mo ...
Development of Iodine Cells for the Subaru HDS and the Okayama
... its asymmetry introduces apparent Doppler shifts in the stellar absorption lines. In fact, the precision of our radial velocity measurement was limited to 20 m s−1 or so without such corrections (Takeda et al. 2002). Butler et al. (1996) first outlined such a modeling technique that a star + I2 spec ...
... its asymmetry introduces apparent Doppler shifts in the stellar absorption lines. In fact, the precision of our radial velocity measurement was limited to 20 m s−1 or so without such corrections (Takeda et al. 2002). Butler et al. (1996) first outlined such a modeling technique that a star + I2 spec ...
The chemical composition of solar-type stars and its impact on the
... Planet search is usually conducted using two different methods, the radial velocity method and the transit one. In the radial velocity method, displacements of a star’s spectral lines are observed. This effect is caused by the star’s motion around the common center of mass of the star-planet system ...
... Planet search is usually conducted using two different methods, the radial velocity method and the transit one. In the radial velocity method, displacements of a star’s spectral lines are observed. This effect is caused by the star’s motion around the common center of mass of the star-planet system ...
azu_etd_13224_sip1_m
... structure, and host star abundances play in the different stages of planet formation? In this thesis, beginning with a brief literature review in Chapter 2, I trace oxygen and carbon species through these stages to inform how, when, and where planets form. In Chapter 3 I describe a study of the mole ...
... structure, and host star abundances play in the different stages of planet formation? In this thesis, beginning with a brief literature review in Chapter 2, I trace oxygen and carbon species through these stages to inform how, when, and where planets form. In Chapter 3 I describe a study of the mole ...
Carbon, nitrogen and oxygen abundances in
... for 22 B-type stars with distances d ≤ 600 pc and slow rotation (v sin i ≤ 66 km s−1 ). The stars are selected according to their effective temperatures Teff and surface gravities log g, namely: Teff is between 15 300 and 24 100 K and log g is mostly greater than 3.75; therefore, stars with medium m ...
... for 22 B-type stars with distances d ≤ 600 pc and slow rotation (v sin i ≤ 66 km s−1 ). The stars are selected according to their effective temperatures Teff and surface gravities log g, namely: Teff is between 15 300 and 24 100 K and log g is mostly greater than 3.75; therefore, stars with medium m ...
Altair -- the ``hottest`` magnetically active star in X-rays
... the range of 7–13 h for both observations separately, resulting in a minimum of ten time bin pairs per period and observation. We then calculated the variation of the folded light curve, weighted with the mean deviation, for each period. As shown in the upper panel of Fig. 2, a minimum, particularly ...
... the range of 7–13 h for both observations separately, resulting in a minimum of ten time bin pairs per period and observation. We then calculated the variation of the folded light curve, weighted with the mean deviation, for each period. As shown in the upper panel of Fig. 2, a minimum, particularly ...
Stellar classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Light from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines. Each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere. The spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photosphere's temperature and density.Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest (e.g. A8, A9, F0, F1 form a sequence from hotter to cooler). The sequence has been expanded with classes for other stars and star-like objects that do not fit in the classical system, such class D for white dwarfs and class C for carbon stars.In the MK system a luminosity class is added to the spectral class using Roman numerals. This is based on the width of certain absorption lines in the star's spectrum which vary with the density of the atmosphere and so distinguish giant stars from dwarfs. Luminosity class 0 or Ia+ stars for hypergiants, class I stars for supergiants, class II for bright giants, class III for regular giants, class IV for sub-giants, class V for main-sequence stars, class sd for sub-dwarfs, and class D for white dwarfs. The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800K.