![An improved classification of B[e]-type stars](http://s1.studyres.com/store/data/015293756_1-5784ffaa4d7d33ad2633e3151daf904c-300x300.png)
An improved classification of B[e]-type stars
... ionization species, e.g. He ii λ4686, [O iii] λ5007, but this is not a defining characteristic. These spectroscopic criteria were defined for the optical spectrum and should not automatically be extended to other wavelength regions. For instance, the ISO − SW S spectrum of many luminous supergiants ...
... ionization species, e.g. He ii λ4686, [O iii] λ5007, but this is not a defining characteristic. These spectroscopic criteria were defined for the optical spectrum and should not automatically be extended to other wavelength regions. For instance, the ISO − SW S spectrum of many luminous supergiants ...
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... entrance pupil and adjusted at the telescope. Another requirement is high-accuracy pointing. Unlike stellar photometry, in general not all of the light from our emission region falls within the diaphragm. Thus interpretation of the observations requires accurate knowledge of the diaphragm's position ...
... entrance pupil and adjusted at the telescope. Another requirement is high-accuracy pointing. Unlike stellar photometry, in general not all of the light from our emission region falls within the diaphragm. Thus interpretation of the observations requires accurate knowledge of the diaphragm's position ...
Astronomy Astrophysics - Max Planck Institut für Radioastronomie
... 1. Introduction Accretion disks around young stellar objects (YSOs) are at the focus of astronomical research, not only because they play an essential role in the star-formation process, but also because they provide the stage where planet formation takes place. Historically, these disks were discov ...
... 1. Introduction Accretion disks around young stellar objects (YSOs) are at the focus of astronomical research, not only because they play an essential role in the star-formation process, but also because they provide the stage where planet formation takes place. Historically, these disks were discov ...
Evolution and fate of very massive stars
... LMC and SMC metallicities, which covers the initial mass range from 120 to 500 M . Both rotating and non-rotating models were calculated using the Geneva stellar evolution code and evolved until at least the end of helium burning and for most models until oxygen burning. Since very massive stars ha ...
... LMC and SMC metallicities, which covers the initial mass range from 120 to 500 M . Both rotating and non-rotating models were calculated using the Geneva stellar evolution code and evolved until at least the end of helium burning and for most models until oxygen burning. Since very massive stars ha ...
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... Low-mass stars (0.1 . M . 1 M ) in OB associations are key to addressing some of the most fundamental problems in star formation. The low-mass stellar populations of OB associations provide a snapshot of the fossil star-formation record of giant molecular cloud complexes. Large scale surveys have i ...
... Low-mass stars (0.1 . M . 1 M ) in OB associations are key to addressing some of the most fundamental problems in star formation. The low-mass stellar populations of OB associations provide a snapshot of the fossil star-formation record of giant molecular cloud complexes. Large scale surveys have i ...
Neutron stars: the densest state of condensed matter
... lie inside a supernova remnant in the Large Magellanic Cloud (N49) thus suggesting that it might be a young isolated neutron star. But it was difficult at that time to explain the origin of the bursts. ...
... lie inside a supernova remnant in the Large Magellanic Cloud (N49) thus suggesting that it might be a young isolated neutron star. But it was difficult at that time to explain the origin of the bursts. ...
$^{13} $ CO/C $^{18} $ O Gradients Across the Disks of Nearby
... whole EMPIRE or ALMA area for each target. We observe widespread 13 CO(1-0) from each galaxy while C18 O(1-0) is fainter, requiring substantial averaging to achieve good signal to noise. After averaging, we detect C18 O at good significance for six targets in EMPIRE. The other two, NGC 2903 and NGC ...
... whole EMPIRE or ALMA area for each target. We observe widespread 13 CO(1-0) from each galaxy while C18 O(1-0) is fainter, requiring substantial averaging to achieve good signal to noise. After averaging, we detect C18 O at good significance for six targets in EMPIRE. The other two, NGC 2903 and NGC ...
Determination of the position angle of stellar spin axes
... determine the stellar position angle directly within 10◦ with a signal-to-noise ratio of the order of 6. Under less favourable conditions, i.e. larger plate scale or smaller stellar diameter, the cross-correlation method yields comparable results. Conclusions. We show that with the currently existin ...
... determine the stellar position angle directly within 10◦ with a signal-to-noise ratio of the order of 6. Under less favourable conditions, i.e. larger plate scale or smaller stellar diameter, the cross-correlation method yields comparable results. Conclusions. We show that with the currently existin ...
Rapid neutral–neutral reactions at low temperatures
... et al. (1994) and Bettens, Lee & Herbst (1995), the latter referring to their network as the ‘new neutral–neutral model (nnnm)’. In these networks, the small number of low-temperature studies then extant was generalized based on the chemical intuition of the authors. In general, the models failed to ...
... et al. (1994) and Bettens, Lee & Herbst (1995), the latter referring to their network as the ‘new neutral–neutral model (nnnm)’. In these networks, the small number of low-temperature studies then extant was generalized based on the chemical intuition of the authors. In general, the models failed to ...
![The P Cygni supergiant [OMN2000] LS1](http://s1.studyres.com/store/data/014882705_1-5f78b60dc5267f0c5ad35fc8d810ae0e-300x300.png)
The P Cygni supergiant [OMN2000] LS1
... of nearby galaxies reveal that such clusters form in larger complexes (e.g. M51; Bastian et al. 2005). Unfortunately, the process(es) that converts giant molecular clouds (GMCs) into such complexes and the timescale for their formation currently remain opaque. This in part is a consequence of the re ...
... of nearby galaxies reveal that such clusters form in larger complexes (e.g. M51; Bastian et al. 2005). Unfortunately, the process(es) that converts giant molecular clouds (GMCs) into such complexes and the timescale for their formation currently remain opaque. This in part is a consequence of the re ...
THE NEW GALAXY: Signatures of Its Formation
... who noted that Galactic globular clusters have a wide range of metal abundances essentially independent of radius from the Galactic Center. They suggested that this could be explained by a halo built up over an extended period from independent fragments with masses of ∼108 M¯ . In contrast, in the E ...
... who noted that Galactic globular clusters have a wide range of metal abundances essentially independent of radius from the Galactic Center. They suggested that this could be explained by a halo built up over an extended period from independent fragments with masses of ∼108 M¯ . In contrast, in the E ...
Modelling the observed properties of carbon-enhanced metal
... CEMP stars have enhanced abundances of s-process elements (CEMP-s stars), and some of these are also enriched in r-process elements (CEMP-s/r stars). In one formation scenario proposed for CEMP stars, the observed carbon excess is explained by invoking wind mass transfer in the past from a more mass ...
... CEMP stars have enhanced abundances of s-process elements (CEMP-s stars), and some of these are also enriched in r-process elements (CEMP-s/r stars). In one formation scenario proposed for CEMP stars, the observed carbon excess is explained by invoking wind mass transfer in the past from a more mass ...
Empirical properties of Very Massive Stars
... Spectrally, massive stars appear as O and early B (i.e. earlier than B3) stars on the main sequence. Once they evolve, they become supergiants of all sorts: blue supergiants (spectral type O, B and A), yellow supergiants (spectral type F and G) and red supergiants (spectral type K and M). The most m ...
... Spectrally, massive stars appear as O and early B (i.e. earlier than B3) stars on the main sequence. Once they evolve, they become supergiants of all sorts: blue supergiants (spectral type O, B and A), yellow supergiants (spectral type F and G) and red supergiants (spectral type K and M). The most m ...
Cosmic Extremes
... When a cosmic ray enters the Earth’s atmosphere, it eventually smashes into a nitrogen or oxygen atom in the air. This collision causes a chain reaction in which the broken bits of the atom move on to break apart other atoms and so on. The result is an air shower of particles in the atmosphere. Most ...
... When a cosmic ray enters the Earth’s atmosphere, it eventually smashes into a nitrogen or oxygen atom in the air. This collision causes a chain reaction in which the broken bits of the atom move on to break apart other atoms and so on. The result is an air shower of particles in the atmosphere. Most ...
mass transfer in close, rapidly accreting protobinaries
... R50 L4 yr, where L4 is the star’s KH GM12 /(R1 L1 ) 6200M10 luminosity in units of 104 L . This describes the time required for the star to adjust thermally to mass loss. The most important point to take from this calculation is that KH is by far the largest timescale in the problem, so tha ...
... R50 L4 yr, where L4 is the star’s KH GM12 /(R1 L1 ) 6200M10 luminosity in units of 104 L . This describes the time required for the star to adjust thermally to mass loss. The most important point to take from this calculation is that KH is by far the largest timescale in the problem, so tha ...
ASTROPHYSICAL PARAMETERS OF LS 2883 AND IMPLICATIONS FOR THE Y egueruela ,
... Only a few binary systems with compact objects display TeV emission. The physical properties of the companion stars represent basic input for understanding the physical mechanisms behind the particle acceleration, emission, and absorption processes in these so-called gamma-ray binaries. Here we pres ...
... Only a few binary systems with compact objects display TeV emission. The physical properties of the companion stars represent basic input for understanding the physical mechanisms behind the particle acceleration, emission, and absorption processes in these so-called gamma-ray binaries. Here we pres ...
The observed distribution of spectroscopic binaries from the Anglo
... the precise form of the age–activity relationship, along with the possibility of flux contamination from the secondary, a number of isochronal mass/age/metallicity points can equally account for a star’s colour and magnitude. In fact, an offset is found between ages derived from the activity indices ...
... the precise form of the age–activity relationship, along with the possibility of flux contamination from the secondary, a number of isochronal mass/age/metallicity points can equally account for a star’s colour and magnitude. In fact, an offset is found between ages derived from the activity indices ...
L95 IRON-RICH EJECTA IN THE SUPERNOVA
... mainly through the decay of radioactive 56Ni. The nuclear decay of this material powers the SN light curve, thereby providing a constraint on the quantity of material ejected in individual SN events. Although variation in the amount and distribution of radioactive ejecta likely accounts for the mode ...
... mainly through the decay of radioactive 56Ni. The nuclear decay of this material powers the SN light curve, thereby providing a constraint on the quantity of material ejected in individual SN events. Although variation in the amount and distribution of radioactive ejecta likely accounts for the mode ...
Metallicities of Planet Hosting Stars: A Sample of Giants and Subgiants
... the lower boundary of the main sequence and has Mbol > 2.82 ; the 17 stars which have Mbol < 2.82 are classified as giants (represented as blue squares in Figure 2). This boundary transition between the main-sequence and the subgiant branch is somewhat uncertain and for two stars in particular we ad ...
... the lower boundary of the main sequence and has Mbol > 2.82 ; the 17 stars which have Mbol < 2.82 are classified as giants (represented as blue squares in Figure 2). This boundary transition between the main-sequence and the subgiant branch is somewhat uncertain and for two stars in particular we ad ...
The star formation history of galaxies in 3D: CALIFA perspective
... 2.1. Hubble sequence: stellar population properties of galaxies in the tuning-fork diagram One step to understand how galaxies form and evolve is classifying galaxies and studying their properties. Most of the massive galaxies in the near Universe are E, S0 and spirals (Blanton & Moustakas 2009), fo ...
... 2.1. Hubble sequence: stellar population properties of galaxies in the tuning-fork diagram One step to understand how galaxies form and evolve is classifying galaxies and studying their properties. Most of the massive galaxies in the near Universe are E, S0 and spirals (Blanton & Moustakas 2009), fo ...
Progenitor systems of Type Ia Supernovae: mergers of white dwarfs
... are known nor the explosion mechanism of type Ia supernovae is understood. The goal of this thesis is to shed some light on both. There are two different progenitor scenarios that have been proposed for type Ia supernovae. Using two different approaches, we address both using partially the same meth ...
... are known nor the explosion mechanism of type Ia supernovae is understood. The goal of this thesis is to shed some light on both. There are two different progenitor scenarios that have been proposed for type Ia supernovae. Using two different approaches, we address both using partially the same meth ...
an approach to effective temperature and surface gravity in post
... SDSS gri photometric systems for main sequence stars. These transformations provide absolute magnitude and distance determinations which can be used in space density evaluations at short distances where some or all of the gri magnitudes are saturated. These authors also showed that those formulae we ...
... SDSS gri photometric systems for main sequence stars. These transformations provide absolute magnitude and distance determinations which can be used in space density evaluations at short distances where some or all of the gri magnitudes are saturated. These authors also showed that those formulae we ...
The stellar populations in the low-luminosity, early
... many luminous ETGs that have been the subject of stellar population analysis. Therefore, results for LLEs may be more susceptible to the well-known age–metallicity degeneracies that plague such analysis. It is for this reason that we wished to check our results for the most extreme LLEs, using new d ...
... many luminous ETGs that have been the subject of stellar population analysis. Therefore, results for LLEs may be more susceptible to the well-known age–metallicity degeneracies that plague such analysis. It is for this reason that we wished to check our results for the most extreme LLEs, using new d ...
PRESPEC – towards gamma-ray spectroscopy of exotic nuclei at FAIR
... How does the nuclear force depend on varying proton‐to‐neutron ratios? What is the isospin dependence of the spin‐orbit force? How does shell structure change far away from stability? ...
... How does the nuclear force depend on varying proton‐to‐neutron ratios? What is the isospin dependence of the spin‐orbit force? How does shell structure change far away from stability? ...
Nucleosynthesis
Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons, primarily protons and neutrons. The first nuclei were formed about three minutes after the Big Bang, through the process called Big Bang nucleosynthesis. It was then that hydrogen and helium formed to become the content of the first stars, and this primeval process is responsible for the present hydrogen/helium ratio of the cosmos.With the formation of stars, heavier nuclei were created from hydrogen and helium by stellar nucleosynthesis, a process that continues today. Some of these elements, particularly those lighter than iron, continue to be delivered to the interstellar medium when low mass stars eject their outer envelope before they collapse to form white dwarfs. The remains of their ejected mass form the planetary nebulae observable throughout our galaxy.Supernova nucleosynthesis within exploding stars by fusing carbon and oxygen is responsible for the abundances of elements between magnesium (atomic number 12) and nickel (atomic number 28). Supernova nucleosynthesis is also thought to be responsible for the creation of rarer elements heavier than iron and nickel, in the last few seconds of a type II supernova event. The synthesis of these heavier elements absorbs energy (endothermic) as they are created, from the energy produced during the supernova explosion. Some of those elements are created from the absorption of multiple neutrons (the R process) in the period of a few seconds during the explosion. The elements formed in supernovas include the heaviest elements known, such as the long-lived elements uranium and thorium.Cosmic ray spallation, caused when cosmic rays impact the interstellar medium and fragment larger atomic species, is a significant source of the lighter nuclei, particularly 3He, 9Be and 10,11B, that are not created by stellar nucleosynthesis.In addition to the fusion processes responsible for the growing abundances of elements in the universe, a few minor natural processes continue to produce very small numbers of new nuclides on Earth. These nuclides contribute little to their abundances, but may account for the presence of specific new nuclei. These nuclides are produced via radiogenesis (decay) of long-lived, heavy, primordial radionuclides such as uranium and thorium. Cosmic ray bombardment of elements on Earth also contribute to the presence of rare, short-lived atomic species called cosmogenic nuclides.