The chemical composition of two supergiants in the dwarf
... similar stars in NGC 6822 and the SMC). The absolute Mg abundance, [Mg/H] = −0.62 is high relative to what is expected from the nebulae though, where two independent spectroscopic analyses of the H II regions in WLM yield [O/H] = −0.89. Intriguingly, the oxygen abundance determined from the O I λ615 ...
... similar stars in NGC 6822 and the SMC). The absolute Mg abundance, [Mg/H] = −0.62 is high relative to what is expected from the nebulae though, where two independent spectroscopic analyses of the H II regions in WLM yield [O/H] = −0.89. Intriguingly, the oxygen abundance determined from the O I λ615 ...
BD−21 3873: another yellow-symbiotic barium star
... to the binary barium and CH stars which are also s-process enriched. These binary systems, which exhibit overabundances of the heavy elements, owe their abundance peculiarities to mass transfer from thermally-pulsing asymptotic giant branch stars, which have since evolved to become white-dwarf compa ...
... to the binary barium and CH stars which are also s-process enriched. These binary systems, which exhibit overabundances of the heavy elements, owe their abundance peculiarities to mass transfer from thermally-pulsing asymptotic giant branch stars, which have since evolved to become white-dwarf compa ...
Formation of low-mass helium white dwarfs
... Astronomy is as old as mankind although the concepts tremendously evolved and changed with time. The last 100 years represents a huge step forward in scientific and technological development. For astronomy, the availability of more telescopes, bigger telescopes, space missions and ever increasing co ...
... Astronomy is as old as mankind although the concepts tremendously evolved and changed with time. The last 100 years represents a huge step forward in scientific and technological development. For astronomy, the availability of more telescopes, bigger telescopes, space missions and ever increasing co ...
SN 2011dh and the progenitors of Type IIb supernovae Mattias Ergon
... 2011dh would later occur are obtained. Examining the position of the SN reveals an anonymous yellow star, seemingly similar to millions of other stars in this galaxy. However, beneath the surface, in the interior of the star, the situation is quite different, and a furious struggle between gravity a ...
... 2011dh would later occur are obtained. Examining the position of the SN reveals an anonymous yellow star, seemingly similar to millions of other stars in this galaxy. However, beneath the surface, in the interior of the star, the situation is quite different, and a furious struggle between gravity a ...
Whole Earth Telescope observations of BPM 37093: A
... In 1996 and 1997, observations of BPM 37093 were obtained from the 0.9 m telescope at CTIO and the 1.6 m telescope at Observatório Pico dos Dias (OPD, Brazil) respectively. The two initial goals of these observations were: 1) to identify as many pulsation modes as possible, to help constrain asteros ...
... In 1996 and 1997, observations of BPM 37093 were obtained from the 0.9 m telescope at CTIO and the 1.6 m telescope at Observatório Pico dos Dias (OPD, Brazil) respectively. The two initial goals of these observations were: 1) to identify as many pulsation modes as possible, to help constrain asteros ...
Post-Common-Envelope Binaries from the Sloan Digital Sky Survey
... I deeply thank Dr. Boris Gänsicke for his excellent guidance through my PhD, for his help and suggestions, and most importantly for making it possible for me to develop my qualities as a researcher. I am also deeply thankful for his trust in me in this and other projects. Without him this thesis wo ...
... I deeply thank Dr. Boris Gänsicke for his excellent guidance through my PhD, for his help and suggestions, and most importantly for making it possible for me to develop my qualities as a researcher. I am also deeply thankful for his trust in me in this and other projects. Without him this thesis wo ...
spatially resolved star formation history of milky way satellites
... galaxies and their own satellites form a self-gravitating association called the Local Group, and hence, the satellite galaxies that reside in it are called local dwarf galaxies. Local dwarf galaxies are crutial for understanding several key aspects of modern astrophysics (Mateo, 1998; Tolstoy et al ...
... galaxies and their own satellites form a self-gravitating association called the Local Group, and hence, the satellite galaxies that reside in it are called local dwarf galaxies. Local dwarf galaxies are crutial for understanding several key aspects of modern astrophysics (Mateo, 1998; Tolstoy et al ...
New Evidence for Mass-Loss from δ Cephei from H i 21
... pattern in the VLA images caused by large-scale Galactic emission diminishes near VLSR = 13.8 km s−1 . Furthermore, that same channel exhibits an extended H i emission region centered near the position of δ Cephei. Looking toward higher velocities, we find a series of 15 contiguous channels where spa ...
... pattern in the VLA images caused by large-scale Galactic emission diminishes near VLSR = 13.8 km s−1 . Furthermore, that same channel exhibits an extended H i emission region centered near the position of δ Cephei. Looking toward higher velocities, we find a series of 15 contiguous channels where spa ...
H 2 O, OH, SiO, NH 3 and CH 3 OH
... Problems with scaling low mass star formation up: 1. Radiation pressure is too great (spherically symmetric) high mass star on the main sequence while still trying to accrete matter Incredibly high accretion rates required 2. No clear cases of isolated high mass star formation 3. Fragmentation r ...
... Problems with scaling low mass star formation up: 1. Radiation pressure is too great (spherically symmetric) high mass star on the main sequence while still trying to accrete matter Incredibly high accretion rates required 2. No clear cases of isolated high mass star formation 3. Fragmentation r ...
Astronomy 112: The Physics of Stars Class 1 Notes
... nearest star to us is Proxima Centauri, which has a parallax of 0.88” – to put this in perspective, this corresponds to the size of a quarter at a distance of half a kilometer. As a result of this difficulty, the first successful use of parallax to measure the distance to a star outside the solar sy ...
... nearest star to us is Proxima Centauri, which has a parallax of 0.88” – to put this in perspective, this corresponds to the size of a quarter at a distance of half a kilometer. As a result of this difficulty, the first successful use of parallax to measure the distance to a star outside the solar sy ...
Confronting Dark Matter Powered Stars with Recent Results from
... Matter powered star (Dark Star). The properties of such a Dark Star (DS) may be altered in comparison to a normal Pop III star. Dark Stars are predicted to be cooler, larger, more massive and potentially longer lived, due to their additional energy source. Using the PHOENIX atmospheric code, stellar ...
... Matter powered star (Dark Star). The properties of such a Dark Star (DS) may be altered in comparison to a normal Pop III star. Dark Stars are predicted to be cooler, larger, more massive and potentially longer lived, due to their additional energy source. Using the PHOENIX atmospheric code, stellar ...
Giant molecular clouds in the dwarf galaxy NGC 1569
... 4 to 9 km s−1 . The (2-1)/(1-0) line ratios range from 0.64 ± 0.30 to 1.31 ± 0.60 in the different clouds. The lower line ratios are similar to those seen in typical Galactic GMCs, while values higher than unity are often seen in interacting or starburst galaxies. We use the virial theorem to derive ...
... 4 to 9 km s−1 . The (2-1)/(1-0) line ratios range from 0.64 ± 0.30 to 1.31 ± 0.60 in the different clouds. The lower line ratios are similar to those seen in typical Galactic GMCs, while values higher than unity are often seen in interacting or starburst galaxies. We use the virial theorem to derive ...
EL CVn-type binaries - Discovery of 17 helium white dwarf
... is eclipsed by a 0.945M⊙ star with an effective temperature Teff = 9370 K. The eclipsing binary star AW UMa may also contain a pre-He-WD, although the interpretation of this system is complicated by an equatorial belt of material that makes the lightcurve of this binary look like that of a W UMa-typ ...
... is eclipsed by a 0.945M⊙ star with an effective temperature Teff = 9370 K. The eclipsing binary star AW UMa may also contain a pre-He-WD, although the interpretation of this system is complicated by an equatorial belt of material that makes the lightcurve of this binary look like that of a W UMa-typ ...
A numerical study of recent tidal interactions between dwarf galaxies
... These simulations demonstrated that the presence of a Milky Way-like dark matter halo has an influence on the evolution of the dwarf galaxies. In all studies tidal stripping and tidal tails were observed. These interactions also led to star formation bursts in the dwarf galaxies. And there was stat ...
... These simulations demonstrated that the presence of a Milky Way-like dark matter halo has an influence on the evolution of the dwarf galaxies. In all studies tidal stripping and tidal tails were observed. These interactions also led to star formation bursts in the dwarf galaxies. And there was stat ...
The physics of neutron stars
... the mass M ∼ M⊙ have the radius R ∼ 104 km, which is comparable to Earth’s radius but almost 1000 times greater than the radius of a neutron star [3]. Therefore, the matter density in their interiors is less than one-thousandth of ρ0 . On the other hand, according to theoretical models, quark stars ...
... the mass M ∼ M⊙ have the radius R ∼ 104 km, which is comparable to Earth’s radius but almost 1000 times greater than the radius of a neutron star [3]. Therefore, the matter density in their interiors is less than one-thousandth of ρ0 . On the other hand, according to theoretical models, quark stars ...
CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR
... of low-mass KOIs. The spectrum confirmed that it is a dwarf and not a giant based on the shallowness of the CO absorption band, and we reported an effective temperature of 3200 ± 50 K and an overall metallicity ([M/H]) of −0.33 ± 0.12 using the spectroscopic indices and calibrations of Rojas-Ayala e ...
... of low-mass KOIs. The spectrum confirmed that it is a dwarf and not a giant based on the shallowness of the CO absorption band, and we reported an effective temperature of 3200 ± 50 K and an overall metallicity ([M/H]) of −0.33 ± 0.12 using the spectroscopic indices and calibrations of Rojas-Ayala e ...
O stars with weak winds: the Galactic case - Max-Planck
... Leitherer 1993), or on the analysis of UV and optical emission or P-Cygni lines (e.g. Leitherer 1988, Haser 1995, Puls et al. 1996). The results confirmed the prediction of the theory that the mass loss rate should scale mainly as a power law of luminosity (e.g. Howarth & Prinja 1989) and that the t ...
... Leitherer 1993), or on the analysis of UV and optical emission or P-Cygni lines (e.g. Leitherer 1988, Haser 1995, Puls et al. 1996). The results confirmed the prediction of the theory that the mass loss rate should scale mainly as a power law of luminosity (e.g. Howarth & Prinja 1989) and that the t ...
STELLAR STRUCTURE AND EVOLUTION
... courses on stellar astrophysics (e.g. the Utrecht first-year course Introduction to stellar structure and evolution by F. Verbunt). The goal of this course on stellar evolution can be formulated as follows: to understand the structure and evolution of stars, and their observational properties, using ...
... courses on stellar astrophysics (e.g. the Utrecht first-year course Introduction to stellar structure and evolution by F. Verbunt). The goal of this course on stellar evolution can be formulated as follows: to understand the structure and evolution of stars, and their observational properties, using ...
Z - STScI
... Linked to the formation of long duration GRBs Are the ideas of SNe progenitor stars correct ? Are SNe explosion and lightcurve models ...
... Linked to the formation of long duration GRBs Are the ideas of SNe progenitor stars correct ? Are SNe explosion and lightcurve models ...
The Recent Star Formation Histories of M81 Group Dwarf Irregular
... and for IC 2574, an ACS field from the HST Archive was supplemented by two additional fields. The ninth galaxy, the Garland, was also added from the HST archive. Both of these galaxies were observed in the same filter combination for comparable integration times. All observations were CR-split to re ...
... and for IC 2574, an ACS field from the HST Archive was supplemented by two additional fields. The ninth galaxy, the Garland, was also added from the HST archive. Both of these galaxies were observed in the same filter combination for comparable integration times. All observations were CR-split to re ...
Characterizing the Cool KOIs III. KOI
... In this paper we present measurements of the stellar parameters of KOI 961 by direct comparison to a well-studied low-mass star: Barnard’s Star, or Gl 699. Barnard’s Star is the second nearest main-sequence star system to the Sun at a distance of 1.824 ± 0.005 pc (van Leeuwen 2007). Discovered by Ba ...
... In this paper we present measurements of the stellar parameters of KOI 961 by direct comparison to a well-studied low-mass star: Barnard’s Star, or Gl 699. Barnard’s Star is the second nearest main-sequence star system to the Sun at a distance of 1.824 ± 0.005 pc (van Leeuwen 2007). Discovered by Ba ...
Boron Abundances Across the" Li
... rather than disappearing by nondestructive diffusion which would have brought up Li atoms from the radiative zone.) Deliyannis et al. (1998) and Boesgaard et al. (2001) have shown that Li and Be abundances are correlated in F field stars on the cool side of the Li-Be dip (Teff = 5900 - 6650 K). Boes ...
... rather than disappearing by nondestructive diffusion which would have brought up Li atoms from the radiative zone.) Deliyannis et al. (1998) and Boesgaard et al. (2001) have shown that Li and Be abundances are correlated in F field stars on the cool side of the Li-Be dip (Teff = 5900 - 6650 K). Boes ...
THE DEARTH OF UV-BRIGHT STARS IN M32
... theoretical predictions. In contrast, the rapid evolution of these stars means few of them are found in Galactic globular clusters (the traditional testing ground for stellar evolution), while distance and reddening uncertainties hamper their study in the Galactic field population. In an elliptical ...
... theoretical predictions. In contrast, the rapid evolution of these stars means few of them are found in Galactic globular clusters (the traditional testing ground for stellar evolution), while distance and reddening uncertainties hamper their study in the Galactic field population. In an elliptical ...
Masses, Radii, and Equation of State of Neutron Stars
... We now know precise masses for ∼ 35 neutron stars spanning the range from 1.17 to 2.0 M⊙ and can pin down the radii of more than a dozen to the 9.9−11.2 km range. The combination of the heaviest known neutron star mass with the existing radius measurements already places significant constraints on t ...
... We now know precise masses for ∼ 35 neutron stars spanning the range from 1.17 to 2.0 M⊙ and can pin down the radii of more than a dozen to the 9.9−11.2 km range. The combination of the heaviest known neutron star mass with the existing radius measurements already places significant constraints on t ...
THE FUTURE IS NOW: THE FORMATION OF SINGLE LOW
... WDs with TeA > 25;000 K that were used to estimate the formation rate without applying an incompleteness correction. We would expect two double degenerate systems, five close binary companions, and 3.5 distant binary companions. Three systems are known to have degenerate companions, and we find sign ...
... WDs with TeA > 25;000 K that were used to estimate the formation rate without applying an incompleteness correction. We would expect two double degenerate systems, five close binary companions, and 3.5 distant binary companions. Three systems are known to have degenerate companions, and we find sign ...