Formation of millisecond pulsars with CO white dwarf companions–I
... corresponding to a maximum accretion rate of ∼10−8 M yr−1 , depending on the exact chemical composition of the accreted material and the geometry of its flow. It has been suggested that the possibility of hypercritical accretion on to the neutron star during the spiral-in phase leads to a significa ...
... corresponding to a maximum accretion rate of ∼10−8 M yr−1 , depending on the exact chemical composition of the accreted material and the geometry of its flow. It has been suggested that the possibility of hypercritical accretion on to the neutron star during the spiral-in phase leads to a significa ...
Atmospheric Chemistry of Venus-like Exoplanets
... for 3 hypothetical Venus-like exoplanets. The initial parameters of these models were chosen from intersections of different CO2 and H2O buffers. These intersections determine the total pressure of CO2 and the temperature. The parameters (T, P, XH2O, XHCl, XHF) for each model and the buffers used ar ...
... for 3 hypothetical Venus-like exoplanets. The initial parameters of these models were chosen from intersections of different CO2 and H2O buffers. These intersections determine the total pressure of CO2 and the temperature. The parameters (T, P, XH2O, XHCl, XHF) for each model and the buffers used ar ...
Blue horizontal branch stars in the Sloan Digital Sky Survey:
... template and wavelength shift that give the best match is automatically measured. The stars in the present sample were almost all best-fit with spectral types between B6 and A0. The radial velocities are corrected to the heliocentric standard of rest, and throughout this paper are denoted vr . ...
... template and wavelength shift that give the best match is automatically measured. The stars in the present sample were almost all best-fit with spectral types between B6 and A0. The radial velocities are corrected to the heliocentric standard of rest, and throughout this paper are denoted vr . ...
The ionized gas in the central region of NGC 5253
... spirals, this option seems unlikely. However, it could not be rejected a priori in our previous work. Here, we present the natural continuation of the work in Paper I. To overcome the aforementioned drawbacks, we obtained new FLAMES observations that allowed missing physical properties, such as elec ...
... spirals, this option seems unlikely. However, it could not be rejected a priori in our previous work. Here, we present the natural continuation of the work in Paper I. To overcome the aforementioned drawbacks, we obtained new FLAMES observations that allowed missing physical properties, such as elec ...
the mass-loss return from evolved stars to the large
... hot dust, are hampered by the high extinction along lines of sight through the disk of the Milky Way (e.g., see Schultheis ...
... hot dust, are hampered by the high extinction along lines of sight through the disk of the Milky Way (e.g., see Schultheis ...
The Massive Star Population of Cygnus OB2
... it is likely that there still remain a number of undiscovered binary companions in this sample. For objects with known companions it is possible to correct for the light of the secondary when using the observed photometry as long as the spectral type of both stars is known. This is relatively simple ...
... it is likely that there still remain a number of undiscovered binary companions in this sample. For objects with known companions it is possible to correct for the light of the secondary when using the observed photometry as long as the spectral type of both stars is known. This is relatively simple ...
Chapter 5 - Leiden Observatory
... Pakmor et al., 2010, 2012; Shen et al., 2012]. Although in the SD channel the models for the explosion process need to be fine-tuned to reproduce the observed spectra and light curves, an SNIa like event is more easily reproduced in the simulations of the explosion process. One problem with the SD sc ...
... Pakmor et al., 2010, 2012; Shen et al., 2012]. Although in the SD channel the models for the explosion process need to be fine-tuned to reproduce the observed spectra and light curves, an SNIa like event is more easily reproduced in the simulations of the explosion process. One problem with the SD sc ...
Core-Halo Age Gradients and Star Formation in the Orion Nebula
... While considerable insights have been gained regarding the formation of stars on small scales, the formation of rich stellar clusters dominated by OB stars is quite uncertain. Debate has waged for decades over the relative importance of rapid ‘top-down’ fragmentation or a slower ‘bottom-up’ process ...
... While considerable insights have been gained regarding the formation of stars on small scales, the formation of rich stellar clusters dominated by OB stars is quite uncertain. Debate has waged for decades over the relative importance of rapid ‘top-down’ fragmentation or a slower ‘bottom-up’ process ...
Dust input from AGB stars in the Large Magellanic Cloud
... Riebel et al. 2012). This can be used to test and constrain models of dust evolution at the present time. For our galaxy, such a global study is complicated by the high extinction in the galactic disk. With the integrated DPR from IR observations of evolved stars and an assumed galactic value for th ...
... Riebel et al. 2012). This can be used to test and constrain models of dust evolution at the present time. For our galaxy, such a global study is complicated by the high extinction in the galactic disk. With the integrated DPR from IR observations of evolved stars and an assumed galactic value for th ...
A" Light," Centrally-Concentrated Milky Way Halo?
... halo was selected to have a quiet merger history, and the high resolution region was resampled with 13 million dark matter particles and an equal number of gas particles, for a mass resolution of mDM = 9.8 × 104 M⊙ and mSPH = 2 × 104 M⊙ , and a gravitational softening of 120 pc (physical). Star part ...
... halo was selected to have a quiet merger history, and the high resolution region was resampled with 13 million dark matter particles and an equal number of gas particles, for a mass resolution of mDM = 9.8 × 104 M⊙ and mSPH = 2 × 104 M⊙ , and a gravitational softening of 120 pc (physical). Star part ...
Radial velocity planet detection biases at the stellar rotational period
... (GJ 581, GJ 667, and Kapteyn’s star; Udry et al. 2007; AngladaEscudé et al. 2012, 2014) are likely the result of low-amplitude stellar RV variability (Robertson et al. 2014; Robertson & Mahadevan 2014; Robertson et al. 2015). These studies used measurements of spectroscopic activity indicators (in ...
... (GJ 581, GJ 667, and Kapteyn’s star; Udry et al. 2007; AngladaEscudé et al. 2012, 2014) are likely the result of low-amplitude stellar RV variability (Robertson et al. 2014; Robertson & Mahadevan 2014; Robertson et al. 2015). These studies used measurements of spectroscopic activity indicators (in ...
ongoing massive star formation in the bulge of m511 hjglm lamers,2
... e.g., Millard et al. 1999). The galaxy was observed through the broadband Ðlters F255W and F336W in 1994 and through the broadband Ðlters F439W, F555W, F675W, and F814W in 1995. We will refer to these Ðlters as the UV, U, B, V , R, and I Ðlters. The observations in the UV, U, and B Ðlters were split ...
... e.g., Millard et al. 1999). The galaxy was observed through the broadband Ðlters F255W and F336W in 1994 and through the broadband Ðlters F439W, F555W, F675W, and F814W in 1995. We will refer to these Ðlters as the UV, U, B, V , R, and I Ðlters. The observations in the UV, U, and B Ðlters were split ...
O stars with weak winds: the Galactic case - Max-Planck
... In spite of these encouraging results, the behaviour of the wind properties of O stars with relatively low luminosity seems to be a little more complicated. Martins et al. (2002b, 2004, hereafter paper I) have shown that the stellar components of the star forming region N81 of the SMC are O dwarfs w ...
... In spite of these encouraging results, the behaviour of the wind properties of O stars with relatively low luminosity seems to be a little more complicated. Martins et al. (2002b, 2004, hereafter paper I) have shown that the stellar components of the star forming region N81 of the SMC are O dwarfs w ...
Frontiers in Neutrino Astrophysics
... Understanding supernovae is crucial for astrophysics: How do supernovae work and what do they do? What is the history of stellar birth and death? Detecting neutrinos is crucial for supernovae: What is the neutrino emission per supernova? How are neutron stars and black holes formed? ...
... Understanding supernovae is crucial for astrophysics: How do supernovae work and what do they do? What is the history of stellar birth and death? Detecting neutrinos is crucial for supernovae: What is the neutrino emission per supernova? How are neutron stars and black holes formed? ...
Gamma-ray burst investigation via polarimetry and spectroscopy
... measure GRBs from the death of these first stars and probe the universe up to the highest redshifts after matter-photon decoupling. Redshift determination via resonance absorption The observational use of nuclear resonance absorption for GRB redshift determination depends on two critical questions: ...
... measure GRBs from the death of these first stars and probe the universe up to the highest redshifts after matter-photon decoupling. Redshift determination via resonance absorption The observational use of nuclear resonance absorption for GRB redshift determination depends on two critical questions: ...
Chapter: The Evolution of Binary Systems
... One particularly important concept in studying the evolution of binary systems is the Roche lobe. Considering the so-called restricted three-body problem, where one follows the motion of a mass-less test particle in the gravitational field of two orbiting masses M1 and M2 , one can define an effecti ...
... One particularly important concept in studying the evolution of binary systems is the Roche lobe. Considering the so-called restricted three-body problem, where one follows the motion of a mass-less test particle in the gravitational field of two orbiting masses M1 and M2 , one can define an effecti ...
The occurrence of nitrogen-enhanced metal
... CEMP-rs stars in the literature). Radial velocity monitoring suggests that probably all CEMP-s stars are binaries (Lucatello et al. 2005b). A widely accepted formation scenario for this group involves pollution by mass transfer in a binary system from a more massive asymptotic giant branch (AGB) com ...
... CEMP-rs stars in the literature). Radial velocity monitoring suggests that probably all CEMP-s stars are binaries (Lucatello et al. 2005b). A widely accepted formation scenario for this group involves pollution by mass transfer in a binary system from a more massive asymptotic giant branch (AGB) com ...
Decoding Galaxy Evolution with Gas
... PCAA to a sample of local disk dwarfs yields a nearly identical PC1, suggesting broadly similar α-enrichment histories. However, the disk PC2 is dominated by a Y–Ba correlation, likely indicating a contribution of s-process enrichment from long-lived asymptotic giant branch stars that is absent from ...
... PCAA to a sample of local disk dwarfs yields a nearly identical PC1, suggesting broadly similar α-enrichment histories. However, the disk PC2 is dominated by a Y–Ba correlation, likely indicating a contribution of s-process enrichment from long-lived asymptotic giant branch stars that is absent from ...
Non-spherical core collapse supernovae-I. Neutrino
... neutrino heating, neutrino-driven convection, explosive nucleosynthesis, the growth of Rayleigh-Taylor instabilities, and the propagation of newly formed metal clumps through the exploding star. A simulation of a type II explosion in a 15 M blue supergiant progenitor is presented, that confirms our ...
... neutrino heating, neutrino-driven convection, explosive nucleosynthesis, the growth of Rayleigh-Taylor instabilities, and the propagation of newly formed metal clumps through the exploding star. A simulation of a type II explosion in a 15 M blue supergiant progenitor is presented, that confirms our ...
Galactic Evolution - Harvard-Smithsonian Center for Astrophysics
... gravitationally trapping H gas, which is then further concentrated by dissipative interactions and angularmomentum conservation into flattened, spinning disks where most star formation has occurred during the past ~10 Gy. Both Pop-II and Pop-III stars likely formed before most galaxies had developed ...
... gravitationally trapping H gas, which is then further concentrated by dissipative interactions and angularmomentum conservation into flattened, spinning disks where most star formation has occurred during the past ~10 Gy. Both Pop-II and Pop-III stars likely formed before most galaxies had developed ...
Maximum Mass Restraint of Neutron Stars
... A rational starting point to begin looking at neutron stars is their birth. The most common scenario is for a neutron star to be born in a core-collapse type II supernovae explosion. In this case the pre-supernovae star is several solar masses and as it nears the end of its main-phase life it begins ...
... A rational starting point to begin looking at neutron stars is their birth. The most common scenario is for a neutron star to be born in a core-collapse type II supernovae explosion. In this case the pre-supernovae star is several solar masses and as it nears the end of its main-phase life it begins ...
Stellar Population Effects on the Inferred Photon Density at
... for the initial mass function (IMF) in our standard models, with a slope of -1.3 between 0.1 and 0.5 M and -2.35 at masses above this, extending to 100 M for the models used in this study. The shallow slope below a stellar mass of 0.5 M biases our models towards the more massive stellar populatio ...
... for the initial mass function (IMF) in our standard models, with a slope of -1.3 between 0.1 and 0.5 M and -2.35 at masses above this, extending to 100 M for the models used in this study. The shallow slope below a stellar mass of 0.5 M biases our models towards the more massive stellar populatio ...
Optical and Infrared Colors of Stars Observed by the
... errors ([10%) in both surveys, we present optical and infrared color-magnitude and color-color diagrams. We use optical (SDSS) colors to identify the stellar spectral sequence and show that stars of different spectral types can have similar infrared colors, thus making the classiÐcation of stars bas ...
... errors ([10%) in both surveys, we present optical and infrared color-magnitude and color-color diagrams. We use optical (SDSS) colors to identify the stellar spectral sequence and show that stars of different spectral types can have similar infrared colors, thus making the classiÐcation of stars bas ...
Explosion and Systematics for Core
... exact mechanism of the explosion and the crucial ingredients of this physically appealing scenario are still uncertain and controversial. If the shock wave is strong enough not only to stop the collapse, but also to explode the outer burning shells of the star, one speaks about the ‘‘prompt mechanis ...
... exact mechanism of the explosion and the crucial ingredients of this physically appealing scenario are still uncertain and controversial. If the shock wave is strong enough not only to stop the collapse, but also to explode the outer burning shells of the star, one speaks about the ‘‘prompt mechanis ...
Absolute Magnitudes of Turnoff Stars in Globular Clusters Palomar
... bound group of hundreds of thousands of stars originally formed from one cloud of gas and dust. However, using high accuracy Hubble Space Telescope data, Piotto et al. (2012) recently showed that many globular clusters have more than one stellar population, visible from a broad subgiant branch (SBG) ...
... bound group of hundreds of thousands of stars originally formed from one cloud of gas and dust. However, using high accuracy Hubble Space Telescope data, Piotto et al. (2012) recently showed that many globular clusters have more than one stellar population, visible from a broad subgiant branch (SBG) ...
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.