Finding high-redshift dark stars with the James Webb Space
... fusion processes eventually take over as the dominant power source if the dark matter is not replenished. At this point, the dark star will essentially transform into a conventional population III star, albeit more massive because the increased duration of the formation phase has allowed it to accre ...
... fusion processes eventually take over as the dominant power source if the dark matter is not replenished. At this point, the dark star will essentially transform into a conventional population III star, albeit more massive because the increased duration of the formation phase has allowed it to accre ...
Astrophysical Quark Matter
... neutron stars, in a CC-process? This idea is attractive since more energy and radiation (, ) are released … Note: quark stars formed in this way should be bare! “Astrophysical QM” ...
... neutron stars, in a CC-process? This idea is attractive since more energy and radiation (, ) are released … Note: quark stars formed in this way should be bare! “Astrophysical QM” ...
REVIEW Numerical Star-Formation Studies— A Status Report
... Stars and their parental clouds are connected via a number of In the past, progress has only been achievable by dividing the problem into smaller bits and pieces and by focusing on few feedback loops. Stars of all ages radiate and will thus heat up physical processes or single scales only. Today, ho ...
... Stars and their parental clouds are connected via a number of In the past, progress has only been achievable by dividing the problem into smaller bits and pieces and by focusing on few feedback loops. Stars of all ages radiate and will thus heat up physical processes or single scales only. Today, ho ...
The white dwarf binary pathways survey – I. A sample of FGK stars
... and explain the lack of hydrogen and helium lines in most SN Ia spectra (Branch et al. 1995). Moreover, there is both theoretical and observational evidence for a large population of close double white dwarf binaries (Yungelson et al. 1994; Nelemans & Tout 2005; Napiwotzki et al. 2001). However, the ...
... and explain the lack of hydrogen and helium lines in most SN Ia spectra (Branch et al. 1995). Moreover, there is both theoretical and observational evidence for a large population of close double white dwarf binaries (Yungelson et al. 1994; Nelemans & Tout 2005; Napiwotzki et al. 2001). However, the ...
Grosdidier et al. 1998
... Composition is a window into galaxy formation and chemical/dynamical evolution • Type II supernovae are produced by massive stars (>8 M) on very short (107 to 108 yr) timescales. • Type I supernovae produce Fe-peak elements on longer ~109 yr timescales. ...
... Composition is a window into galaxy formation and chemical/dynamical evolution • Type II supernovae are produced by massive stars (>8 M) on very short (107 to 108 yr) timescales. • Type I supernovae produce Fe-peak elements on longer ~109 yr timescales. ...
arXiv:1604.01613v2 [astro-ph.SR] 23 Aug 2016
... and explain the lack of hydrogen and helium lines in most SN Ia spectra (Branch et al. 1995). Moreover, there is both theoretical and observational evidence for a large population of close double white dwarf binaries (Yungelson et al. 1994; Nelemans & Tout 2005; Napiwotzki et al. 2001). However, the ...
... and explain the lack of hydrogen and helium lines in most SN Ia spectra (Branch et al. 1995). Moreover, there is both theoretical and observational evidence for a large population of close double white dwarf binaries (Yungelson et al. 1994; Nelemans & Tout 2005; Napiwotzki et al. 2001). However, the ...
IV Interstellar Dust
... We will be covering all of these topics with greater or lesser degrees of detail. Many are very active areas of research, and so only an introduction to the observational problem and the current state of understanding (or not) will be discussed. How important is dust? In our Galaxy the gas-to-dust r ...
... We will be covering all of these topics with greater or lesser degrees of detail. Many are very active areas of research, and so only an introduction to the observational problem and the current state of understanding (or not) will be discussed. How important is dust? In our Galaxy the gas-to-dust r ...
Str\" omgren uvby photometry of the peculiar globular cluster NGC
... clusters (see Frank 2014, for a recent review). In contrast to ω Cen (NGC 5139) or M54, which are thought to be remnant nuclei of accreted satellites and which have broad metallicity distributions (ωCen: [Fe/H]=−1.75 to −0.75 dex, Johnson & Pilachowski 2010; M54: intrinsic r.m.s. scatter in [Fe/H]∼ ...
... clusters (see Frank 2014, for a recent review). In contrast to ω Cen (NGC 5139) or M54, which are thought to be remnant nuclei of accreted satellites and which have broad metallicity distributions (ωCen: [Fe/H]=−1.75 to −0.75 dex, Johnson & Pilachowski 2010; M54: intrinsic r.m.s. scatter in [Fe/H]∼ ...
on the absolute age of the metal-rich globular m71
... We investigated the absolute age of the Galactic globular cluster M71 (NGC 6838) using optical ground-based images (u¢ , g¢ , r ¢ , i¢ , z ¢) collected with the MegaCam camera at the Canada–France–Hawaii Telescope (CFHT). We performed a robust selection of field and cluster stars by applying a new me ...
... We investigated the absolute age of the Galactic globular cluster M71 (NGC 6838) using optical ground-based images (u¢ , g¢ , r ¢ , i¢ , z ¢) collected with the MegaCam camera at the Canada–France–Hawaii Telescope (CFHT). We performed a robust selection of field and cluster stars by applying a new me ...
m82 as a galaxy: morphology and stellar content of the disk and halo
... morphological class assigned to M82. The amorphous appearance seen on the ground based images of M82, breaks down at the resolution of HST/ACS images (Mutchler et al. 2007), especially in the F814 (I) band as can be seen in the bottom-right panel of Figure 1. At mid infrared wavelengths, Spitzer ima ...
... morphological class assigned to M82. The amorphous appearance seen on the ground based images of M82, breaks down at the resolution of HST/ACS images (Mutchler et al. 2007), especially in the F814 (I) band as can be seen in the bottom-right panel of Figure 1. At mid infrared wavelengths, Spitzer ima ...
Z - STScI
... Late time tail powered by radioactive 56Ni 56Ni explosively created from Si burning after corecollapse Direct probe of the explosion How Is it related to progenitor mass ? ...
... Late time tail powered by radioactive 56Ni 56Ni explosively created from Si burning after corecollapse Direct probe of the explosion How Is it related to progenitor mass ? ...
Massive Star Formation in the Galactic Center
... are extraordinarily dense (n > 104 cm−3 ) and warm (T ∼ 70 K) with respect to those found in the disk of the Galaxy. Stark et al. (1989) argue that the density and internal velocities of clouds in the GC are a direct result of the strong tidal fields in the region, i.e. only the dense survive. Seraby ...
... are extraordinarily dense (n > 104 cm−3 ) and warm (T ∼ 70 K) with respect to those found in the disk of the Galaxy. Stark et al. (1989) argue that the density and internal velocities of clouds in the GC are a direct result of the strong tidal fields in the region, i.e. only the dense survive. Seraby ...
Polaris B, an optical companion of the Polaris (αUMi) system
... 43 and 83 arcsec, respectively), are also potential members of the multiple system (Fernie 1966), although recent observations refute that suggestion (Evans et al. 2007). It would therefore be interesting to establish the atmospheric parameters and chemical composition of component B for comparison ...
... 43 and 83 arcsec, respectively), are also potential members of the multiple system (Fernie 1966), although recent observations refute that suggestion (Evans et al. 2007). It would therefore be interesting to establish the atmospheric parameters and chemical composition of component B for comparison ...
The Spitzer/GLIMPSE Surveys - UW-Madison Astronomy
... crash into the ambient interstellar medium and excite NIR line emission. NIR H2 narrow-band images and ISO spectra show that the extended 4.5 μm emission of the massive DR21 outflow is due to shocked H2 (Davis et al. 2007; Smith et al. 2006, and references therein); Smith et al. (2006) do not detect ...
... crash into the ambient interstellar medium and excite NIR line emission. NIR H2 narrow-band images and ISO spectra show that the extended 4.5 μm emission of the massive DR21 outflow is due to shocked H2 (Davis et al. 2007; Smith et al. 2006, and references therein); Smith et al. (2006) do not detect ...
SN 2011dh and the progenitors of Type IIb supernovae Mattias Ergon
... The 20th of January 2005, the Hubble Space Telescope (HST) is slewed to the nearby galaxy M51, and images covering the location where supernova (SN) 2011dh would later occur are obtained. Examining the position of the SN reveals an anonymous yellow star, seemingly similar to millions of other stars ...
... The 20th of January 2005, the Hubble Space Telescope (HST) is slewed to the nearby galaxy M51, and images covering the location where supernova (SN) 2011dh would later occur are obtained. Examining the position of the SN reveals an anonymous yellow star, seemingly similar to millions of other stars ...
Sources of Stellar Energy and the Theory of the Internal Constitution
... The results obtained, taken altogether, permit calculation of the physical conditions in the internal constitution of stars, proceeding from their observational characteristics L, M , and R. For instance, the temperature obtained for the centre of the Sun is about 6 million degrees. This is not enou ...
... The results obtained, taken altogether, permit calculation of the physical conditions in the internal constitution of stars, proceeding from their observational characteristics L, M , and R. For instance, the temperature obtained for the centre of the Sun is about 6 million degrees. This is not enou ...
Nuclear forces and their impact on neutron-rich
... In the following, we discuss results for the neutron-rich oxygen isotopes and neighboring nuclei based on chiral EFT interactions. In particular, the softening of nuclear forces by RG transformations (11, 12) enabled many new calculations of nuclei with a range of many-body methods. The results with ...
... In the following, we discuss results for the neutron-rich oxygen isotopes and neighboring nuclei based on chiral EFT interactions. In particular, the softening of nuclear forces by RG transformations (11, 12) enabled many new calculations of nuclei with a range of many-body methods. The results with ...
Pre-main sequence stars, emission stars and recent star formation in
... Cygnus region, located between 70◦ < l < 80◦ is a region of recent star formation activity in the Milky Way and is rich in massive early type stars concentrated in OB associations. The presence of nebulosity and massive stars indicate that the stars have been forming till very recently and the young ...
... Cygnus region, located between 70◦ < l < 80◦ is a region of recent star formation activity in the Milky Way and is rich in massive early type stars concentrated in OB associations. The presence of nebulosity and massive stars indicate that the stars have been forming till very recently and the young ...
Symbiotic Stars as Laboratories for the Study of
... to occur every few years to decades. In some symbiotics, material that is transferred from the red giant to the WD forms a disk around the WD. Thus, symbiotic stars are a bit like overgrown cataclysmic variables (CVs), but with less violent eruptions. Symbiotic stars are not as well understood as CV ...
... to occur every few years to decades. In some symbiotics, material that is transferred from the red giant to the WD forms a disk around the WD. Thus, symbiotic stars are a bit like overgrown cataclysmic variables (CVs), but with less violent eruptions. Symbiotic stars are not as well understood as CV ...
The role of tidal interactions in star formation
... 2001). Even in the context of standard accretion disc models, a binary companion may play an important role by limiting the growth in radius of the disc and thus preventing the accretion time from becoming too long (Calvet et al. 2000); in this case most of the angular momentum of the system must go ...
... 2001). Even in the context of standard accretion disc models, a binary companion may play an important role by limiting the growth in radius of the disc and thus preventing the accretion time from becoming too long (Calvet et al. 2000); in this case most of the angular momentum of the system must go ...
Thermohaline mixing and the photospheric composition of low
... process to be enough to reproduce the surface abundances observed, others consider this mechanism to be insufficient and propose the interaction of more than one process to explain the observations. Surely a realistic scenario should consider all possible physical processes present and study how the ...
... process to be enough to reproduce the surface abundances observed, others consider this mechanism to be insufficient and propose the interaction of more than one process to explain the observations. Surely a realistic scenario should consider all possible physical processes present and study how the ...
CHEMICAL ABUNDANCE DISTRIBUTIONS OF GALACTIC HALOS
... King model (King 1962), whose extent is set by the observed trend of core radius with luminosity for Local Group dwarfs. With all possible freedom in the model now constrained, it additionally produces the observed stellar mass–circular velocity (M-vcirc) relation for Local Group dwarfs (both the a ...
... King model (King 1962), whose extent is set by the observed trend of core radius with luminosity for Local Group dwarfs. With all possible freedom in the model now constrained, it additionally produces the observed stellar mass–circular velocity (M-vcirc) relation for Local Group dwarfs (both the a ...
Effects of color superconductivity on the nucleation of quark matter in
... Aims. We study the nucleation of quark matter drops at the center of cold deleptonized neutron stars. These drops can be made up of unpaired quark matter or of color-superconducting quark matter, depending on the details of the equations of state for quark and hadronic matter. The nature of the nucl ...
... Aims. We study the nucleation of quark matter drops at the center of cold deleptonized neutron stars. These drops can be made up of unpaired quark matter or of color-superconducting quark matter, depending on the details of the equations of state for quark and hadronic matter. The nature of the nucl ...
The Recent Star Formation Histories of M81 Group Dwarf Irregular
... find only minor differences in SF characteristics among the M81 Group dIs despite a wide range of physical properties. We extend our comparison to select dIs in the Local Group (LG), with similar quality photometry, and again find only minor differences in SF parameters. The lack of a clear trend in ...
... find only minor differences in SF characteristics among the M81 Group dIs despite a wide range of physical properties. We extend our comparison to select dIs in the Local Group (LG), with similar quality photometry, and again find only minor differences in SF parameters. The lack of a clear trend in ...
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.