An Optical Study of Young Stellar Clusters
... since their evolution towards the main–sequence is extremely slow and can last for many tens of Myr. Moreover, young (few Myr old) clusters are usually not dynamically evolved nor have had time to disperse; thus the mass distribution of their members reflects that at the time of formation, i.e., thei ...
... since their evolution towards the main–sequence is extremely slow and can last for many tens of Myr. Moreover, young (few Myr old) clusters are usually not dynamically evolved nor have had time to disperse; thus the mass distribution of their members reflects that at the time of formation, i.e., thei ...
Modelling the observed properties of carbon-enhanced metal
... adopt slightly different criteria, e.g. [Ba/Fe] > +1 and/or [Ba/Eu] > +0.5 (Beers & Christlieb 2005; Jonsell et al. 2006; Masseron et al. 2010). – CEMP-s/r stars2 are CEMP-s stars that also enriched in europium and r-elements, [Eu/Fe] > +1. – CEMP-r stars are a rare CEMP subclass enriched in element ...
... adopt slightly different criteria, e.g. [Ba/Fe] > +1 and/or [Ba/Eu] > +0.5 (Beers & Christlieb 2005; Jonsell et al. 2006; Masseron et al. 2010). – CEMP-s/r stars2 are CEMP-s stars that also enriched in europium and r-elements, [Eu/Fe] > +1. – CEMP-r stars are a rare CEMP subclass enriched in element ...
Formation of low-mass helium white dwarfs
... globular clusters. ELM WDs are most likely the result of binary evolution as they cannot be formed from single stars within a Hubble time. Indeed, over 80% of the observed ELM WDs are found in binary systems, most commonly around a more massive CO WD. The new wealth of data raises questions regardin ...
... globular clusters. ELM WDs are most likely the result of binary evolution as they cannot be formed from single stars within a Hubble time. Indeed, over 80% of the observed ELM WDs are found in binary systems, most commonly around a more massive CO WD. The new wealth of data raises questions regardin ...
spatially resolved star formation history of milky way satellites
... satellites there is another galaxy similar in size than the Milky Way, called Andromeda or Messier 31 (M31), which, as the Milky Way, has its own satellites. These two big galaxies and their own satellites form a self-gravitating association called the Local Group, and hence, the satellite galaxies ...
... satellites there is another galaxy similar in size than the Milky Way, called Andromeda or Messier 31 (M31), which, as the Milky Way, has its own satellites. These two big galaxies and their own satellites form a self-gravitating association called the Local Group, and hence, the satellite galaxies ...
Thermohaline mixing and the photospheric composition of low
... Denissenkov & Merryfield 2011; Stancliffe 2010). The thermohaline mixing has therefore been studied by means of numerical simulations either by considering it as an isolated process or by combining it with other mechanisms that might contribute to the turbulence of the material (e.g., rotation, inte ...
... Denissenkov & Merryfield 2011; Stancliffe 2010). The thermohaline mixing has therefore been studied by means of numerical simulations either by considering it as an isolated process or by combining it with other mechanisms that might contribute to the turbulence of the material (e.g., rotation, inte ...
The age of elliptical galaxies and bulges in a merger model The age
... predict that bright elliptical galaxies in low-density environments are formed by much more recent merging events than cluster ellipticals and consequently contain younger stars. The colours of field ellipticals are bluer on average and show more scatter. The models also predict that the ages of spi ...
... predict that bright elliptical galaxies in low-density environments are formed by much more recent merging events than cluster ellipticals and consequently contain younger stars. The colours of field ellipticals are bluer on average and show more scatter. The models also predict that the ages of spi ...
A STRONGLY MAGNETIZED PULSAR WITHIN THE GRASP OF THE MILKY... SUPERMASSIVE BLACK HOLE Rea ,
... a short X-ray burst was observed from the direction of the Galactic center. With a series of observations with the Chandra and the Swift satellites, we pinpoint the associated magnetar at an angular distance of 2.4 ± 0.3 arcsec from Sgr A∗ , and refine the source spin period and its derivative (P = ...
... a short X-ray burst was observed from the direction of the Galactic center. With a series of observations with the Chandra and the Swift satellites, we pinpoint the associated magnetar at an angular distance of 2.4 ± 0.3 arcsec from Sgr A∗ , and refine the source spin period and its derivative (P = ...
Harikane
... • Galactic outflows powered by starformation activities or AGNs have been reported. + SN and AGN • Galactic outflows play a significant role in feedback galaxy formation and evolution. – Chemical enrichment of IGM – Regulating star formation Courtesy: Darren Croton ...
... • Galactic outflows powered by starformation activities or AGNs have been reported. + SN and AGN • Galactic outflows play a significant role in feedback galaxy formation and evolution. – Chemical enrichment of IGM – Regulating star formation Courtesy: Darren Croton ...
Power Point
... telescope (nearby this not the case – one has to target individual galaxies in clusters one by one) • around a cluster there are many more galaxies that lie within a single telescope pointing than for a typical field pointing ...
... telescope (nearby this not the case – one has to target individual galaxies in clusters one by one) • around a cluster there are many more galaxies that lie within a single telescope pointing than for a typical field pointing ...
the origin of binary stars - Institut d`Astronomie et d`Astrophysique
... toward stellar densities. This leads to the formation of a central protostar embedded within an infalling envelope of dust and gas. A disk almost always surrounds the embedded protostar, reflecting the fact that molecular cloud cores are almost always rotating. The protostar accretes matter, largely ...
... toward stellar densities. This leads to the formation of a central protostar embedded within an infalling envelope of dust and gas. A disk almost always surrounds the embedded protostar, reflecting the fact that molecular cloud cores are almost always rotating. The protostar accretes matter, largely ...
WSokolov-PROTVINO
... FIG. 1.— The L_iso luminosity-redshift distribution of 119 Swift GRBs, as we determine from the (updated) Butler et al. (2007) catalog. Squares represent the 63 GRBs used in Y¨uksel et al. (2008), with 56 found subsequently: before (grey circles) and after (red circles) the start of Fermi. Three Fer ...
... FIG. 1.— The L_iso luminosity-redshift distribution of 119 Swift GRBs, as we determine from the (updated) Butler et al. (2007) catalog. Squares represent the 63 GRBs used in Y¨uksel et al. (2008), with 56 found subsequently: before (grey circles) and after (red circles) the start of Fermi. Three Fer ...
SUPERNOVA REMNANT SHOCKS IN AN INHOMOGENEOUS
... (McKee and Ostriker 1977). Although fh is high in the local ISM, its value at a typical point in the galactic disk remains controversial (Cox 1987). It is quite likely that fh depends on both the nature of the galaxy and the location within it. In principle, observations of SNRs could provide the me ...
... (McKee and Ostriker 1977). Although fh is high in the local ISM, its value at a typical point in the galactic disk remains controversial (Cox 1987). It is quite likely that fh depends on both the nature of the galaxy and the location within it. In principle, observations of SNRs could provide the me ...
Luminous Blue Variables are Antisocial: Their Isolation Implies that
... However, several lines of evidence now point to an explosive mechanism driving LBV giant eruptions, instead of (or in addition to) a wind (Smith 2008, 2013; Smith et al. 2003a). Moreover, spectra of the light echoes from η Car’s 19th century Great Eruption seem inconsistent with a wind pseudophotosp ...
... However, several lines of evidence now point to an explosive mechanism driving LBV giant eruptions, instead of (or in addition to) a wind (Smith 2008, 2013; Smith et al. 2003a). Moreover, spectra of the light echoes from η Car’s 19th century Great Eruption seem inconsistent with a wind pseudophotosp ...
Galactic Evolution of Silicon Isotopes: Applications to
... cross sections, and because of the large 33S(n, a)30Si cross section (Bao & Kappeler 1987 ; Brown & Clayton 1992). This forces one to reach deeper for a satisfactory explanation, perhaps even casting some doubt on the hypothesis of a carbon star origin. The puzzle drove (Brown & Clayton (1992) to p ...
... cross sections, and because of the large 33S(n, a)30Si cross section (Bao & Kappeler 1987 ; Brown & Clayton 1992). This forces one to reach deeper for a satisfactory explanation, perhaps even casting some doubt on the hypothesis of a carbon star origin. The puzzle drove (Brown & Clayton (1992) to p ...
THE FUTURE IS NOW: THE FORMATION OF SINGLE LOW
... The Ohio State University, Department of Astronomy, Columbus, OH 43210; [email protected], [email protected], p[email protected] Received 2007 June 21; accepted 2007 August 2 ...
... The Ohio State University, Department of Astronomy, Columbus, OH 43210; [email protected], [email protected], p[email protected] Received 2007 June 21; accepted 2007 August 2 ...
Munshi_washington_0250E_12611
... mass ratio as a function of halo mass for a new sample of simulated field galaxies using fully cosmological, LCDM, high resolution SPH + N-Body simulations carried to the present time. I find there is extremely good agreement between the simulations and predictions from the statistical Halo Occupati ...
... mass ratio as a function of halo mass for a new sample of simulated field galaxies using fully cosmological, LCDM, high resolution SPH + N-Body simulations carried to the present time. I find there is extremely good agreement between the simulations and predictions from the statistical Halo Occupati ...
Astronomy Astrophysics Spectral energy distributions of an AKARI-SDSS-GALEX sample of galaxies
... Results. Our galaxy sample is primarily selected in far-IR and mostly constituted of massive, actively star-forming galaxies. There is some evidence for a dust attenuation law that is slightly steeper than that used for starburst galaxies but we are unable to constrain the presence or not of a bump ...
... Results. Our galaxy sample is primarily selected in far-IR and mostly constituted of massive, actively star-forming galaxies. There is some evidence for a dust attenuation law that is slightly steeper than that used for starburst galaxies but we are unable to constrain the presence or not of a bump ...
EVIDENCE FOR IMF VARIATIONS WITH GALACTIC ENVIRONMENT
... simultaneously fit for the binary fraction, finding fbinary = 0.47+0.16 −0.14 for Hercules, and 0.47−0.17 for Leo IV. The UFD binary fractions are consistent with that inferred for Milky Way stars in the same mass range, despite very different metallicities. In contrast, the IMF slopes in the UFDs a ...
... simultaneously fit for the binary fraction, finding fbinary = 0.47+0.16 −0.14 for Hercules, and 0.47−0.17 for Leo IV. The UFD binary fractions are consistent with that inferred for Milky Way stars in the same mass range, despite very different metallicities. In contrast, the IMF slopes in the UFDs a ...
LOOKING INTO THE HORSEHEAD Marc W. Pound Bo Reipurth and
... Horsehead got the name B33 by which it is known today. The first indication that the IC 434 and Horsehead region could be related to young stars came with the discovery of H emission line stars in the general area by Haro & Moreno (1953), followed by the detection of variable stars in the same regio ...
... Horsehead got the name B33 by which it is known today. The first indication that the IC 434 and Horsehead region could be related to young stars came with the discovery of H emission line stars in the general area by Haro & Moreno (1953), followed by the detection of variable stars in the same regio ...
Giant molecular clouds in the dwarf galaxy NGC 1569
... However, Maloney (1990) has argued that this MV T –LCO correlation is simply a result of the observed size-linewidth relation and would exist whether or not the GMCs were in virial equilibrium. In the end, the fact that conversion factors derived with this method generally agree with those derived f ...
... However, Maloney (1990) has argued that this MV T –LCO correlation is simply a result of the observed size-linewidth relation and would exist whether or not the GMCs were in virial equilibrium. In the end, the fact that conversion factors derived with this method generally agree with those derived f ...
γ Doradus pulsation in two pre-main sequence stars discovered by
... pulsators are of δ Scuti-type. γ Doradus-type pulsation in young stars has been predicted by theory, but lack observational evidence. Aims. We present the investigation of variability caused by rotation and (γ Doradus-type) pulsation in two pre-main sequence members of the young open cluster NGC 226 ...
... pulsators are of δ Scuti-type. γ Doradus-type pulsation in young stars has been predicted by theory, but lack observational evidence. Aims. We present the investigation of variability caused by rotation and (γ Doradus-type) pulsation in two pre-main sequence members of the young open cluster NGC 226 ...
The evolution of massive stars and their spectra
... Massive stars are essential constituents of stellar populations and galaxies in the near and far Universe. They are among the most important sources of ionizing photons, energy, and some chemical species, which are ejected into the interstellar medium through powerful stellar winds and during their ...
... Massive stars are essential constituents of stellar populations and galaxies in the near and far Universe. They are among the most important sources of ionizing photons, energy, and some chemical species, which are ejected into the interstellar medium through powerful stellar winds and during their ...
Post Common Envelope Binaries from SDSS. I: 101 white dwarf
... and Eisenstein et al. (2006), as well as a set of WDMS independently found in the SDSS data by our team. This search resulted in a sample of 130 WDMS with two to seven SDSS spectra. Among those WDMS, 101 systems have a clearly pronounced Na I λλ 8183.27,8194.81 absorption doublet and/or Hα emission ...
... and Eisenstein et al. (2006), as well as a set of WDMS independently found in the SDSS data by our team. This search resulted in a sample of 130 WDMS with two to seven SDSS spectra. Among those WDMS, 101 systems have a clearly pronounced Na I λλ 8183.27,8194.81 absorption doublet and/or Hα emission ...
Evolution of Stars and Stellar Populations
... The theory of stellar evolution is by now well established, after more than half a century of continuous development, and its main predictions confirmed by various empirical tests. As a consequence, we can now use its results with some confidence, and obtain vital information about the structure and ...
... The theory of stellar evolution is by now well established, after more than half a century of continuous development, and its main predictions confirmed by various empirical tests. As a consequence, we can now use its results with some confidence, and obtain vital information about the structure and ...
Planetary nebula
A planetary nebula, often abbreviated as PN or plural PNe, is a kind of emission nebula consisting of an expanding glowing shell of ionized gas ejected from old red giant stars late in their lives. The word ""nebula"" is Latin for mist or cloud and the term ""planetary nebula"" is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.A mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red giant phase, the outer layers of the star are expelled by strong stellar winds. Eventually, after most of the red giant's atmosphere is dissipated, the exposed hot, luminous core emits ultraviolet radiation to ionize the ejected outer layers of the star. Absorbed ultraviolet light energises the shell of nebulous gas around the central star, appearing as a bright coloured planetary nebula at several discrete visible wavelengths.Planetary nebulae may play a crucial role in the chemical evolution of the Milky Way, returning material to the interstellar medium from stars where elements, the products of nucleosynthesis (such as carbon, nitrogen, oxygen and neon), have been created. Planetary nebulae are also observed in more distant galaxies, yielding useful information about their chemical abundances.In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. About one-fifth are roughly spherical, but the majority are not spherically symmetric. The mechanisms which produce such a wide variety of shapes and features are not yet well understood, but binary central stars, stellar winds and magnetic fields may play a role.