Browsing by Author "Freeman, Kenneth C."

Now showing items 1-7 of 7

    • The Andromeda Galaxy’s Last Major Merger: Constraints from the survey of Planetary Nebulae 

      Bhattacharya, Souradeep; Arnaboldi, Magda; Gerhard, Ortwin; Caldwell, Nelson; Kobayashi, Chiaki; Hammer, Francois; Yang, Yanbin; Freeman, Kenneth C.; Hartke, Johanna; McConnachie, Alan (The International Astronomical Union, 2023-05-04)
      The Andromeda galaxy (M 31) has experienced a tumultuous merger history as evidenced by the many substructures present in its inner halo. We use planetary nebulae (PNe) as chemodynamic tracers to shed light on the recent ...

    • The COMBS Survey -- III. The Chemodynamical Origins of Metal-Poor Bulge Stars 

      Lucey, Madeline; Hawkins, Keith; Ness, Melissa; Nelson, Tyler; Debattista, Victor P.; Luna, Alice; Bensby, Thomas; Freeman, Kenneth C.; Kobayashi, Chiaki (2022-01-01)
      The characteristics of the stellar populations in the Galactic Bulge inform and constrain the Milky Way's formation and evolution. The metal-poor population is particularly important in light of cosmological simulations, ...

    • The COMBS survey I : Chemical Origins of Metal-Poor Stars in the Galactic Bulge 

      Lucey, Madeline; Hawkins, Keith; Ness, Melissa; Asplund, Martin; Bensby, Thomas; Casagrande, Luca; Feltzing, Sofia; Freeman, Kenneth C.; Kobayashi, Chiaki; Marino, Anna F. (2019-09-01)
      Chemistry and kinematic studies can determine the origins of stellar population across the Milky Way. The metallicity distribution function of the bulge indicates that it comprises multiple populations, the more metal-poor ...

    • The COMBS Survey II: Distinguishing the Metal-Poor Bulge from the Halo Interlopers 

      Lucey, Madeline; Hawkins, Keith; Ness, Melissa; Debattista, Victor P.; Luna, Alice; Asplund, Martin; Bensby, Thomas; Casagrande, Luca; Feltzing, Sofia; Freeman, Kenneth C.; Kobayashi, Chiaki; Marino, Anna F. (2021-03-01)
      The metal-poor stars in the bulge are important relics of the Milky Way's formation history, as simulations predict that they are some of the oldest stars in the Galaxy. In order to determine if they are truly ancient ...

    • Principal component analysis on chemical abundances spaces 

      Ting, Y. S.; Freeman, Kenneth C.; Kobayashi, C.; De Silva, G. M.; Bland-Hawthorn, J. (2012-04)
      In preparation for the High Efficiency and Resolution Multi-Element Spectrograph (HERMES) chemical tagging survey of about a million Galactic FGK stars, we estimate the number of independent dimensions of the space defined ...

    • The survey of planetary nebulae in Andromeda (M 31) V. Chemical enrichment of the thin and thicker discs of Andromeda. Oxygen to argon abundance ratios for planetary nebulae and H II regions 

      Arnaboldi, Magda; Bhattacharya, Souradeep; Gerhard, Ortwin; Kobayashi, Chiaki; Freeman, Kenneth C.; Caldwell, Nelson; Hartke, Johanna; McConnachie, Alan; Guhathakurta, Puragra (2022-10-13)
      We use oxygen and argon abundances for planetary nebulae (PNe) with low internal extinction (progenitor ages of (>4.5 Gyr) and high extinction (progenitor ages

    • The survey of planetary nebulae in Andromeda (M31). IV. Radial oxygen and argon abundance gradients of the thin and thicker disc 

      Bhattacharya, Souradeep; Arnaboldi, Magda; Caldwell, Nelson; Gerhard, Ortwin; Kobayashi, Chiaki; Hartke, Johanna; Freeman, Kenneth C.; McConnachie, Alan W.; Guhathakurta, Puragra (2022-12-01)
      We obtain a magnitude-limited sample of Andromeda (M 31) disc PNe with chemical abundance estimated through the direct detection of the [O III] 4363 Å line. This leads to 205 and 200 PNe with oxygen and argon abundances, ...