Browsing by Author "Kobayashi, Chiaki"

Now showing items 41-60 of 102

    • Galactic 26Al traces metal loss through hot chimneys 

      Krause, Martin G. H.; Rodgers-Lee, Donna; Dale, James E.; Diehl, Roland; Kobayashi, Chiaki (2021-02-01)
      Radioactive 26Al is an excellent tracer for metal ejection in the Milky Way, and can provide a direct constraint on the modelling of supernova feedback in galaxy evolution. Gamma-ray observations of the 26Al decay line ...

    • Galactic Simulations of r-process Elemental Abundances 

      Haynes, Christopher; Kobayashi, Chiaki (2019-03-01)
      We present the distributions of elemental abundance ratios using chemodynamical simulations that include four different neutron capture processes: magnetorotational supernovae, neutron star mergers, neutrino-driven winds, ...

    • The GALAH Survey: Chemical tagging and chrono-chemodynamics of accreted halo stars with GALAH+ DR3 and $Gaia$ eDR3 

      Buder, Sven; Lind, Karin; Ness, Melissa K.; Feuillet, Diane K.; Horta, Danny; Monty, Stephanie; Buck, Tobias; Nordlander, Thomas; Bland-Hawthorn, Joss; Casey, Andrew R.; Silva, Gayandhi M. De; D'Orazi, Valentina; Freeman, Ken C.; Hayden, Michael R.; Kos, Janez; Martell, Sarah L.; Lewis, Geraint F.; Lin, Jane; Schlesinger, Katharine J.; Sharma, Sanjib; Simpson, Jeffrey D.; Stello, Dennis; Zucker, Daniel B.; Zwitter, Tomaz; Ciuca, Ioana; Horner, Jonathan; Kobayashi, Chiaki; Ting, Yuan-Sen; Wyse, Rosemary F. G.; Collaboration, The GALAH (2022-02-01)
      Since the advent of $Gaia$ astrometry, it is possible to identify massive accreted systems within the Galaxy through their unique dynamical signatures. One such system, $Gaia$-Sausage-Enceladus (GSE), appears to be an early ...

    • The GALAH+ Survey : Third Data Release 

      Buder, Sven; Sharma, Sanjib; Kos, Janez; Amarsi, Anish M.; Nordlander, Thomas; Lind, Karin; Martell, Sarah L.; Asplund, Martin; Bland-Hawthorn, Joss; Casey, Andrew R.; Silva, Gayandhi M. De; D'Orazi, Valentina; Freeman, Ken C.; Hayden, Michael R.; Lewis, Geraint F.; Lin, Jane; Schlesinger, Katharine J.; Simpson, Jeffrey D.; Stello, Dennis; Zucker, Daniel B.; Zwitter, Tomaz; Beeson, Kevin L.; Buck, Tobias; Casagrande, Luca; Clark, Jake T.; Cotar, Klemen; Costa, Gary S. Da; Grijs, Richard de; Feuillet, Diane; Horner, Jonathan; Kafle, Prajwal R.; Khanna, Shourya; Kobayashi, Chiaki; Liu, Fan; Montet, Benjamin T.; Nandakumar, Govind; Nataf, David M.; Ness, Melissa K.; Spina, Lorenzo; Tepper-Garcia, Thor; Ting, Yuan-Sen; Traven, Gregor; Vogrincic, Rok; Wittenmyer, Robert A.; Wyse, Rosemary F. G.; Zerjal, Marusa; collaboration, the GALAH (2021-05-06)
      The ensemble of chemical element abundance measurements for stars, along with precision distances and orbit properties, provides high-dimensional data to study the evolution of the Milky Way. With this third data release ...

    • Gradients of absorption-line strengths in elliptical galaxies 

      Arimoto, N; Kobayashi, Chiaki (1999-12-20)
      We have restudied line-strength gradients of 80 elliptical galaxies. Typical metallicity gradients of elliptical galaxies are Delta[Fe/H]/Delta log r similar or equal to -0.3, which is flatter than the gradients predicted ...

    • He abundances in disc galaxies. I. Predictions from cosmological chemodynamical simulations 

      Vincenzo, Fiorenzo; Miglio, Andrea; Kobayashi, Chiaki; Mackereth, J. Ted; Montalban, Josefina (2019-10-01)
      We investigate how the stellar and gas-phase He abundances evolve as a function of time within simulated star-forming disc galaxies with different star formation histories. We make use of a cosmological chemodynamical ...

    • The history of the cosmic supernova rate derived from the evolution of the host galaxies 

      Kobayashi, C; Tsujimoto, T; Nomoto, K; Kobayashi, Chiaki (2000-08-10)
      Ne make a prediction of the cosmic supernova rate history as a composite of the supernova rates in spiral and elliptical galaxies. Ne include the metallicity effect on the evolution of Type Ia supernova (SN Ia) progenitors ...

    • The impact of metallicity on nova populations 

      Kemp, Alex J.; Karakas, Amanda I.; Casey, Andrew R.; Kobayashi, Chiaki; Izzard, Robert G. (2022-01-01)
      The metallicity of a star affects its evolution in a variety of ways, changing stellar radii, luminosities, lifetimes, and remnant properties. In this work, we use the population synthesis code binary_c to study how ...

    • The impact of supernova feedback on the mass-metallicity relations 

      Ibrahim, Dyna; Kobayashi, Chiaki (2024-01-01)
      Metallicity is a fundamental physical property that strongly constrains galaxy formation and evolution. The formation of stars in galaxies is suppressed by the energy released from supernova explosions and can be enhanced ...

    • Inhomogeneous Enrichment of Radioactive Nuclei in the Galaxy: Deposition of Live 53 Mn, 60 Fe, 182 Hf, and 244 Pu into Deep-sea Archives. Surfing the Wave? 

      Wehmeyer, Benjamin; López, Andrés Yagüe; Côté, Benoit; K. Pető, Maria; Kobayashi, Chiaki; Lugaro, Maria (2023-02-16)
      While modeling the galactic chemical evolution (GCE) of stable elements provides insights to the formation history of the Galaxy and the relative contributions of nucleosynthesis sites, modeling the evolution of short-lived ...

    • The Initial mass function of the first stars inferred from extremely metal-poor stars 

      Ishigaki, Miho N.; Tominaga, Nozomu; Kobayashi, Chiaki; Nomoto, Ken'ichi (2018-04-11)
      We compare the elemental abundance patterns of ~200 extremely metal-poor (EMP; [Fe/H] < −3) stars to the supernova yields of metal-free stars, in order to obtain insights into the characteristic masses of the first (Population ...

    • Iron-Group Abundances in the Metal-Poor Main Sequence Turnoff Star HD~84937 

      Sneden, Christopher; Cowan, John J.; Kobayashi, Chiaki; Pignatari, Marco; Lawler, James E.; Hartog, Elizabeth A. Den; Wood, Michael P. (2016-01-20)
      We have derived new very accurate abundances of the Fe-group elements Sc through Zn (Z = 21-30) in the bright main-sequence turnoff star HD 84937, based on high-resolution spectra covering the visible and ultraviolet ...

    • The K2 Galactic Archaeology Program Data Release 3: Age-abundance Patterns in C1–C8 and C10–C18 

      Zinn, Joel C.; Stello, Dennis; Elsworth, Yvonne; García, Rafael A.; Kallinger, Thomas; Mathur, Savita; Mosser, Benoît; Hon, Marc; Bugnet, Lisa; Jones, Caitlin; Reyes, Claudia; Sharma, Sanjib; Schönrich, Ralph; Warfield, Jack T.; Luger, Rodrigo; Vanderburg, Andrew; Kobayashi, Chiaki; Pinsonneault, Marc H.; Johnson, Jennifer A.; Huber, Daniel; Buder, Sven; Joyce, Meridith; Bland-Hawthorn, Joss; Casagrande, Luca; Lewis, Geraint F.; Miglio, Andrea; Nordlander, Thomas; Davies, Guy R.; Silva, Gayandhi De; Chaplin, William J.; Silva Aguirre, Victor (2022-02-24)
      Abstract: We present the third and final data release of the K2 Galactic Archaeology Program (K2 GAP) for Campaigns C1–C8 and C10–C18. We provide asteroseismic radius and mass coefficients, κ R and κ M , for ∼19,000 red ...

    • The KLEVER survey: nitrogen abundances at z ∼ 2 and probing the existence of a fundamental nitrogen relation 

      Hayden-Pawson, Connor; Curti, Mirko; Maiolino, Roberto; Cirasuolo, Michele; Belfiore, Francesco; Cappellari, Michele; Concas, Alice; Cresci, Giovanni; Cullen, Fergus; Kobayashi, Chiaki; Mannucci, Filippo; Marconi, Alessandro; Meneghetti, Massimo; Mercurio, Amata; Peng, Yingjie; Swinbank, Mark; Vincenzo, Fiorenzo (2022-05-30)
      We present a comparison of the nitrogen-to-oxygen ratio (N/O) in 37 high-redshift galaxies at z ∼2 taken from the KMOS Lensed Emission Lines and VElocity Review (KLEVER) Survey with a comparison sample of local galaxies, ...

    • Light, Alpha, and Fe-Peak Element Abundances in the Galactic Bulge 

      Johnson, Christian I.; Rich, R. Michael; Kobayashi, Chiaki; Kunder, Andrea; Koch, Andreas (2014-09-09)
      We present radial velocities and chemical abundances of O, Na, Mg, Al, Si, Ca, Cr, Fe, Co, Ni, and Cu for a sample of 156 red giant branch stars in two Galactic bulge fields centered near (l,b)=(+5.25,-3.02) and (0,-12). ...

    • Locations of Peculiar Supernovae as a Diagnostic of Their Origins 

      Yuan, Fang; Kobayashi, Chiaki; Schmidt, Brian P.; Podsiadlowski, Philipp; Sim, Stuart A.; Scalzo, Richard A. (2013-06-21)
      We put constraints on the properties of the progenitors of peculiar calcium-rich transients using the distribution of locations within their host galaxies. We confirm that this class of transients do not follow the galaxy ...

    • Low-metallicity inhibition of type Ia supernovae and galactic and cosmic chemical evolution 

      Kobayashi, Chiaki; Tsujimoto, T; Nomoto, K; Hachisu, I; Kato, M (1998-08-20)
      We introduce a metallicity dependence of the Type Ia supernova (SN Ia) rate into the Galactic and cosmic chemical evolution models. In our SN Ia progenitor scenario, the accreting white dwarf (WD) blows a strong wind to ...

    • The Metallicity and Elemental Abundance Gradients of Simulated Galaxies, and their Environmental Dependence 

      Taylor, Philip; Kobayashi, Chiaki (2017-11-11)
      The internal distribution of heavy elements, in particular the radial metallicity gradient, offers insight into the merging history of galaxies. Using our cosmological, chemodynamical simulations that include both detailed ...

    • The metallicity and elemental abundance maps of kinematically atypical galaxies for constraining minor merger and accretion histories 

      Taylor, Philip; Kobayashi, Chiaki; Federrath, Christoph (2019-03-06)
      Explaining the internal distribution and motions of stars and gas in galaxies is a key aspect in understanding their evolution. In previous work we identified five well-resolved galaxies with atypical kinematics from a ...

    • Metallicity distributions of elliptical galaxies and globular cluster systems - Absorption line strength gradients in elliptical galaxies 

      Arimoto, N; Kobayashi, Chiaki (1999)
      Gradients of absorption line indices are studied and mean stellar metallicities are estimated for 46 elliptical galaxies. The mean stellar metallicities range from [[Fe/H]] similar or equal to -0.8 to +0.2 and ellipticals ...