K. C. Freeman
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View article: Turbulent Gas-rich Disks at High Redshift: Origin of Thick Stellar Disks Through 3D “Baryon Sloshing”
Turbulent Gas-rich Disks at High Redshift: Origin of Thick Stellar Disks Through 3D “Baryon Sloshing” Open
In response to recent observations from JWST and Atacama Large Millimeter Array, we explore a new class of dynamically self-consistent models that mimics a plausible progenitor of the Milky Way over a wide range of disk gas fractions, f ga…
View article: The GALAH survey: Improving chemical abundances using star clusters
The GALAH survey: Improving chemical abundances using star clusters Open
Large spectroscopic surveys aim to consistently compute stellar parameters of very diverse stars, while minimizing systematic errors. We explore the use of stellar clusters as benchmarks to verify the precision of spectroscopic parameters …
View article: The GECKOS survey: Identifying kinematic sub-structures in edge-on galaxies
The GECKOS survey: Identifying kinematic sub-structures in edge-on galaxies Open
The vertical evolution of galactic discs is governed by the sub-structures within them. Several of these features, including bulges and kinematically distinct discs, are best studied in edge-on galaxies, as the viewing angle allows the eas…
View article: The emergence of galactic thin and thick discs across cosmic history
The emergence of galactic thin and thick discs across cosmic history Open
Present-day disc galaxies often exhibit distinct thin and thick discs. The formation mechanisms of the two discs and the timing of their onset remain open questions. To address these questions, we select edge-on galaxies from flagship JWST…
View article: An integral field spectroscopy study of thin and thick discs in IC 2531
An integral field spectroscopy study of thin and thick discs in IC 2531 Open
Thin and thick discs are prominent components in the Milky Way and other spiral galaxies, but their formation histories are not yet understood, which is particularly true for thick discs. This is partially due to the fact that we lack suff…
View article: Cryoscope: A Cryogenic Infrared Survey Telescope in Antarctica
Cryoscope: A Cryogenic Infrared Survey Telescope in Antarctica Open
We present Cryoscope, a new 50 deg 2 field-of-view, 1.2 m aperture, K dark survey telescope to be located at Dome C, Antarctica. Cryoscope has an innovative optical–thermal design wherein the entire telescope is cryogenically cooled. Cryos…
View article: On the origin of the Hercules group: II. The Trojan quasi-periodic identity on the orbital level
On the origin of the Hercules group: II. The Trojan quasi-periodic identity on the orbital level Open
The Hercules kinematic group is a stellar anomaly structure observed in the solar neighbourhood (SNd). In the previous paper, we analysed chemical signatures and related the origin of this stellar population to the outer bar. Next to consi…
View article: On the origin of the Hercules group – I. Chemical signatures indicating the outer bar origin
On the origin of the Hercules group – I. Chemical signatures indicating the outer bar origin Open
The Hercules kinematic group is a kinematic anomaly of stars observed in the solar neighbourhood (SNd). In this series of papers, we present a comprehensive study of this structure. This paper focuses on its chemical signatures over severa…
View article: Cryoscope: A Cryogenic Infrared Survey Telescope in Antarctica
Cryoscope: A Cryogenic Infrared Survey Telescope in Antarctica Open
We present Cryoscope--a new 50 deg$^2$ field-of-view, 1.2 m aperture, $K_{dark}$ survey telescope to be located at Dome C, Antarctica. Cryoscope has an innovative optical-thermal design wherein the entire telescope is cryogenically cooled.…
View article: Turbulent gas-rich discs at high redshift: origin of thick stellar discs through 3D 'baryon sloshing'
Turbulent gas-rich discs at high redshift: origin of thick stellar discs through 3D 'baryon sloshing' Open
In response to recent observations from JWST and ALMA, we explore a new class of dynamically self-consistent models using our AGAMA/Ramses hydrodynamic N-body framework (Nexus) that mimics a plausible progenitor of the Milky Way over a wid…
View article: The GALAH Survey: Stellar parameters and abundances for 800 000 <i>Gaia</i> RVS spectra using GALAH DR4 and <i>The Cannon</i>
The GALAH Survey: Stellar parameters and abundances for 800 000 <i>Gaia</i> RVS spectra using GALAH DR4 and <i>The Cannon</i> Open
Analysing stellar parameters and abundances from nearly one million Gaia Data Release 3 (DR3) Radial Velocity Spectrometer (RVS) spectra poses challenges due to the limited spectral coverage (restricted to the infrared Ca ii triplet) and v…
View article: The GALAH survey: Improving chemical abundances using star clusters
The GALAH survey: Improving chemical abundances using star clusters Open
Large spectroscopic surveys aim to consistently compute stellar parameters of very diverse stars while minimizing systematic errors. We explore the use of stellar clusters as benchmarks to verify the precision of spectroscopic parameters i…
View article: The GALAH survey: Data release 4
The GALAH survey: Data release 4 Open
The stars of the Milky Way carry the chemical history of our Galaxy in their atmospheres as they journey through its vast expanse. Like barcodes, we can extract the chemical fingerprints of stars from high-resolution spectroscopy. The four…
View article: On the origin of the Hercules group: I. chemical signatures indicating the outer bar origin
On the origin of the Hercules group: I. chemical signatures indicating the outer bar origin Open
The Hercules kinematic group is a kinematic anomaly of stars observed in the solar neighbourhood (SNd). In this series of papers, we present a comprehensive study of this structure. This paper focuses on its chemical signatures over severa…
View article: On the origin of the Hercules group: II. the Trojan quasi-periodic identity on the orbital level
On the origin of the Hercules group: II. the Trojan quasi-periodic identity on the orbital level Open
The Hercules kinematic group is a stellar anomaly structure observed in the solar neighbourhood (SNd). In the previous paper, we analysed chemical signatures and related the origin of this stellar population to the outer bar. Next to consi…
View article: The GECKOS Survey: Identifying kinematic sub-structures in edge-on galaxies
The GECKOS Survey: Identifying kinematic sub-structures in edge-on galaxies Open
The vertical evolution of galactic discs is governed by the sub-structures within them. We examine the diversity of kinematic sub-structure present in the first 12 galaxies observed from the GECKOS survey, a VLT/MUSE large programme provid…
View article: There is no place like home – finding birth radii of stars in the Milky Way
There is no place like home – finding birth radii of stars in the Milky Way Open
Stars move away from their birthplaces over time via a process known as radial migration, which blurs chemo–kinematic relations used for reconstructing the Milky Way (MW) formation history. To understand the true time evolution of the MW, …
View article: The GALAH Survey: Stellar parameters and abundances for 800,000 Gaia RVS spectra using GALAH DR4 and The Cannon
The GALAH Survey: Stellar parameters and abundances for 800,000 Gaia RVS spectra using GALAH DR4 and The Cannon Open
Analysing stellar parameters and abundances from nearly one million Gaia Data Release 3 (DR3) Radial Velocity Spectrometer (RVS) spectra poses challenges due to the limited spectral coverage (restricted to the infrared Ca II triplet) and v…
View article: The emergence of galactic thin and thick discs across cosmic history
The emergence of galactic thin and thick discs across cosmic history Open
Present-day disc galaxies often exhibit distinct thin and thick discs. The formation mechanisms of the two discs and the timing of their onset remain open questions. To address these questions, we select edge-on galaxies from flagship JWST…
View article: The GALAH survey: tracing the Milky Way’s formation and evolution through RR Lyrae stars
The GALAH survey: tracing the Milky Way’s formation and evolution through RR Lyrae stars Open
Stellar mergers and accretion events have been crucial in shaping the evolution of the Milky Way (MW). These events have been dynamically identified and chemically characterized using red giants and main-sequence stars. RR Lyrae (RRL) vari…
View article: The Gasing Pangkah Collaboration. I. Asteroseismic Identification and Characterization of a Rapidly Rotating Engulfment Candidate*
The Gasing Pangkah Collaboration. I. Asteroseismic Identification and Characterization of a Rapidly Rotating Engulfment Candidate* Open
We report the discovery and characterization of TIC 350842552 (“Zvrk”), an apparently isolated, rapidly rotating ( P rot ∼ 99 days) red giant observed by TESS in its southern Continuous Viewing Zone. The star’s fast surface rotation is ind…
View article: The Gasing Pangkah Collaboration: I. Asteroseismic Identification and Characterisation of a Rapidly-Rotating Engulfment Candidate
The Gasing Pangkah Collaboration: I. Asteroseismic Identification and Characterisation of a Rapidly-Rotating Engulfment Candidate Open
We report the discovery and characterisation of TIC 350842552 ("Zvrk"), an apparently isolated, rapidly-rotating ($P_\text{rot} \sim 99\ \mathrm{d}$) red giant observed by TESS in its Southern Continuous Viewing Zone. The star's fast surfa…
View article: WiFeS observations of nearby southern Type Ia supernova host galaxies
WiFeS observations of nearby southern Type Ia supernova host galaxies Open
We present high-resolution observations of nearby ($z\lesssim 0.1$) galaxies that have hosted Type Ia supernovae to measure systemic spectroscopic redshifts using the Wide Field Spectrograph (WiFeS) instrument on the Australian National Un…
View article: The GALAH survey: elemental abundances in open clusters using joint effective temperature and surface gravity photometric priors
The GALAH survey: elemental abundances in open clusters using joint effective temperature and surface gravity photometric priors Open
The ability to measure precise and accurate stellar effective temperatures (Teff) and surface gravities (log (g)) is essential in determining accurate and precise abundances of chemical elements in stars. Measuring log (g) from isochrones …
View article: The GALAH survey: Elemental abundances in open clusters using joint effective temperature and surface gravity photometric priors
The GALAH survey: Elemental abundances in open clusters using joint effective temperature and surface gravity photometric priors Open
The ability to measure precise and accurate stellar effective temperatures ($T_{\rm{eff}}$) and surface gravities ($\log(g)$) is essential in determining accurate and precise abundances of chemical elements in stars. Measuring $\log(g)$ fr…
View article: WiFeS observations of nearby southern Type Ia supernova host galaxies
WiFeS observations of nearby southern Type Ia supernova host galaxies Open
We present high-resolution observations of nearby ( $z\lesssim0.1$ ) galaxies that have hosted Type Ia supernovae to measure systemic spectroscopic redshifts using the wide field spectrograph (WiFeS) instrument on the Australian National U…
View article: The Magellanic stream, high velocity clouds, and the sculptor group
The Magellanic stream, high velocity clouds, and the sculptor group Open
The Magellanic Stream is a 100deg×10deg filament of gas that lies within the Galactic halo and contains ~2×108 Msolar of neutral hydrogen. In this paper we present data from the H I Parkes All Sky Survey (HIPASS) in the first complete surv…
View article: The survey for ionization in neutral gas galaxies. II. The star formation rate density of the local universe
The survey for ionization in neutral gas galaxies. II. The star formation rate density of the local universe Open
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View article: Planetary nebulae populations in the haloes of nearby massive early-type galaxies
Planetary nebulae populations in the haloes of nearby massive early-type galaxies Open
Planetary nebulae (PNe) are excellent tracers of the metal-poor haloes of nearby early-type galaxies. They are commonly used to trace spatial distribution and kinematics of the halo and intracluster light at distances of up to 100 Mpcs. Th…