Article
Astronomy & Astrophysics
Adam M. Dillamore, Vasily Belokurov, Andreea S. Font, Ian G. McCarthy
Summary: By using high-resolution cosmological simulations, this study investigates various dynamical transformations of Milky Way-like galaxies during mergers, including the pathways of star clusters, changes in dark matter haloes, shifts in angular momentum axes, and the origin of in situ retrograde stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Gigi Y. C. Leung, Ryan Leaman, Giuseppina Battaglia, Glenn van de Ven, Alyson M. Brooks, Jorge Penarrubia, Kim A. Venn
Summary: This study presents multitracer dynamical models of the dwarf irregular galaxy WLM to constrain the dark matter halo density profile and stellar orbital anisotropy. The results show a reduction in uncertainties on the inner slope of the dark matter halo and suggest that the cored and prolate DM halo may pose a challenge for self-interacting dark matter models. Additionally, the radial profile of stellar anisotropy in WLM follows a trend similar to other dwarf galaxies, raising questions about its formation and evolutionary pathways.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
M. Khademi, Y. Yang, F. Hammer, S. Nasiri
Summary: The study investigates the origin of the strong asymmetry of the rotation curve of WLM and suggests that an m=1 perturbation in the halo potential could be a mechanism creating such kinematical asymmetry. The results show that a lopsided halo potential model can reasonably explain the asymmetry in the kinematic data of WLM. Additionally, the kinematical classification of WLM indicates that its velocity field is significantly perturbed due to its asymmetrical rotation curve and peculiar velocity dispersion map.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Hyunmi Song, Clotilde Laigle, Ho Seong Hwang, Julien Devriendt, Yohan Dubois, Katarina Kraljic, Christophe Pichon, Adrianne Slyz, Rory Smith
Summary: The study shows that the dependency of galaxy properties on large-scale environment is mainly influenced by the host halo mass. Proximity to cosmic filaments enhances the build-up of stellar mass, but at the edge of filaments, star formation is suppressed and the stellar distribution becomes compact.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Hyunmi Song, Clotilde Laigle, Ho Seong Hwang, Julien Devriendt, Yohan Dubois, Katarina Kraljic, Christophe Pichon, Adrianne Slyz, Rory Smith
Summary: The study finds that the dependency of galaxy properties on large-scale environment is mostly inherited from the host halo mass, while proximity to cosmic filaments enhances the build-up of stellar mass. However, star formation is suppressed at the edge of filaments, and there are indications of compaction of the stellar distribution at close proximity to filaments.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Ryan Hausen, Brant E. E. Robertson, Hanjue Zhu, Nickolay Y. Y. Gnedin, Piero Madau, Evan E. E. Schneider, Bruno Villasenor, Nicole E. E. Drakos
Summary: By using Explainable Boosting Machines (EBMs), a machine-learning method, we have discovered the connections between galaxy stellar mass, star formation rate, and dark matter halo mass in the theory of galaxy formation. The most dominant contribution comes from the peak circular velocity of the galaxy, while environmental properties have a lesser impact on the simulated galaxies.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Sanjib Sharma, Joss Bland-Hawthorn, Joseph Silk, Celine Boehm
Summary: By studying the radial motion of stars in the stellar halo of the galaxy, we can constrain the rate of change of mass in the galaxy, including dark matter decay. Most stellar haloes have small radial motions, which can be further reduced by removing substructures. This research is important for determining dark matter decay parameters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Yifan Mai, Sam P. Vaughan, Scott M. Croom, Jesse van de Sande, Stefania Barsanti, Joss Bland-Hawthorn, Sarah Brough, Julia J. Bryant, Matthew Colless, Michael Goodwin, Brent Groves, Iraklis S. Konstantopoulos, Jon S. Lawrence, Nuria P. F. Lorente, Samuel N. Richards
Summary: Using data from the SAMI Galaxy Survey, the study explores the correlation between the rotation of SAMI galaxies and the motion of neighboring galaxies. The results show that there is a significant coherence signal within 1 Mpc, which increases with distance up to 2 Mpc but becomes consistent with zero or negative beyond 3 Mpc. The study suggests that the coherence signals within 2 Mpc might be influenced by the variance of large-scale structure.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Danny Horta, Ricardo P. Schiavon, J. Ted Mackereth, Joel Pfeffer, Andrew C. Mason, Shobhit Kisku, Francesca Fragkoudi, Carlos Allende Prieto, Katia Cunha, Sten Hasselquist, Jon Holtzman, Steven R. Majewski, David Nataf, Robert W. O'Connell, Mathias Schultheis, Verne V. Smith
Summary: Evidence from APOGEE suggests the presence of a new metal-poor stellar structure near the Galactic Center, possibly associated with an accretion event in the early Milky Way. This structure, termed the Inner Galaxy Structure (IGS), displays chemical composition similarities to low-mass Milky Way satellites and is dynamically detached from more metal-rich populations in the inner Galaxy. Comparisons with cosmological simulations indicate a progenitor system for the IGS with a stellar mass approximately double that of the Gaia-Enceladus/Sausage system. The ratio of accreted to in situ stars within the metal-poor bulge sample is estimated to be between 1:3 and 1:2, in line with predictions from various cosmological numerical simulations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Tommaso Marchetti
Summary: The European Space Agency satellite Gaia's latest data release provides coordinates, parallaxes, and proper motions for nearly 1.47 billion sources in the Milky Way. Through precise measurements and calculations, possible hyper-runaway star candidates were identified, requiring follow-up with ground-based telescopes for confirmation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Adam M. Dillamore, Vasily Belokurov, N. Wyn Evans, Adrian M. Price-Whelan
Summary: This study investigates the effects of the Sagittarius dwarf spheroidal galaxy (Sgr) on stellar streams. It is found that Sgr can disrupt streams formed more than 3 billion years ago, resulting in asymmetry. However, many streams survive unaffected.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Yutaka Hirai, Timothy C. Beers, Masashi Chiba, Wako Aoki, Derek Shank, Takayuki R. Saitoh, Takashi Okamoto, Junichiro Makino
Summary: Research suggests that most highly r-process-enhanced (RPE) stars are formed in low-mass dwarf galaxies, while stars with higher metallicity may be formed in situ. These findings contribute to our understanding of the assembly history of the Milky Way and the nucleosynthesis of heavy elements.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
T. K. Chan, Dusan Keres, Alexander B. Gurvich, Philip F. Hopkins, Cameron Trapp, Suoqing Ji, Claude-Andre Faucher-Giguere
Summary: This study investigates the impact of CRs on the gas dynamics in late-type galaxies, revealing that CRs can influence gas flow and properties, accelerating warm gas and reducing the scale height of hot gas, making the disc-halo interface the most dominant warm-hot phase.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
James Binney, Eugene Vasiliev
Summary: A new class of models of stellar discs is introduced to construct a self-consistent model of our Galaxy. The model includes parameters that define the action-based distribution functions (DFs) of various components, such as stellar discs, bulge, and dark haloes. By incorporating observational constraints and solving for the densities and potentials, the model predicts the density and kinematics of stars and dark matter throughout the Galaxy. The code used to create this model is available on github.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Adam M. Dillamore, Vasily Belokurov, N. Wyn Evans, Elliot Y. Davies
Summary: Using Gaia satellite data, researchers discover a new and stable feature in the phase-space distribution of halo stars, confirming the influence of the rotating bar on the stellar halo. Test particle simulations show similar structures generated from particles trapped at resonances with the bar, resulting in a mild, net spin of the inner stellar halo in the direction of the bar's rotation. The observed variation in rotational velocity matches the behavior of metal-poor stars in the APOGEE survey.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Scott J. Kenyon, Benjamin C. Bromley
Summary: Based on numerical calculations, the long-term evolution of circumbinary debris from the Pluto-Charon giant impact is studied. Most solids are ejected from the system due to dynamical interactions with Pluto and Charon over timescales of 100-1000 yr. The resulting circumbinary disk in the Pluto-Charon orbital plane is more extended compared to narrow rings produced from other collision debris, but may be less suitable for producing small circumbinary satellites.
ASTRONOMICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Benjamin C. Bromley, Austin Leonard, Amanda Quintanilla, Austin J. King, Chris Mann, Scott J. Kenyon
Summary: This study revisits the problem of identifying faint echoes in postflare light curves, focusing on circumstellar dust detection. By applying algorithms to light curves from over 2100 stars observed by NASA's Kepler mission and grouping stars according to IR excess, researchers found that the average mass of dust around the stars cannot exceed certain limits. Stars with strong IR excess showed greater mass limits, suggesting that echoes may be more easily detected in these cases.
ASTRONOMICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Andrew Swan, Scott J. Kenyon, Jay Farihi, Erik Dennihy, Boris T. Gansicke, J. J. Hermes, Carl Melis, Ted von Hippel
Summary: WD0145+234 is a white dwarf accreting metals from a circumstellar disc, with a significant increase in 3-5 μm flux since 2018 that began to decrease by late 2019. Stochastic brightening events during the decline suggest liberation of dust during collisional evolution of circumstellar solids. Emission lines from circumstellar gas support the idea of white dwarf debris discs as sites of collisional gas and dust production.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Joan R. Najita, Scott J. Kenyon, Benjamin C. Bromley
Summary: This study explores the potential connection between protoplanetary disk rings, planets, and debris disks through new calculations, which suggest that solid rings with high initial masses and modest planetesimal formation efficiencies may evolve into known cold debris disks. These findings support the possibility that large protoplanetary disk rings evolve into cold debris disks.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Laura Flagg, Christopher M. Johns-Krull, Kevin France, Gregory Herczeg, Joan Najita, John M. Carpenter, Scott J. Kenyon
Summary: Using HST-COS far-UV spectra, warm molecular hydrogen has been discovered in the TWA 7 system, indicating that TWA 7 may be accreting at very low levels and retaining a reservoir of gas in the near circumstellar environment.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Scott J. Kenyon, Benjamin C. Bromley
Summary: The study discusses 500 numerical n-body calculations aimed at constraining the masses and bulk densities of four Pluto's moons. Comparisons favor methods based on the theory of Lee & Peale and suggest that Styx and Kerberos may have bulk densities comparable with water ice.
ASTRONOMICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Laura Flagg, Christopher M. Johns-Krull, Kevin France, Gregory Herczeg, Joan Najita, Allison Youngblood, Adolfo Carvalho, John Carptenter, Scott J. Kenyon, Elisabeth Newton, Keighley Rockcliffe
Summary: Molecular hydrogen, which is abundant in the galaxy, plays vital roles in planets, their circumstellar environments, and host stars. In this study, the presence of molecular hydrogen in the AU Mic system is confirmed through high-resolution FUV spectra. The gas temperature is estimated to be 1000-2000K, and the emission is likely produced in the star instead of the disk or the planet.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Benjamin C. Bromley, Scott J. Kenyon
Summary: The magnetic field of a host star can affect the orbit of its stellar partner, planet, or asteroid if the orbiting body is magnetic or electrically conducting. When an orbiting permanent magnet is close to the stellar host, it will be drawn towards it due to the dipole-dipole interaction. Although the observed magnetic fields in systems are generally too weak to cause a merger event, they may be strong enough in some compact binaries to result in measurable orbital precession. When the orbiting body is a conductor, the stellar field induces a time-varying magnetic dipole moment, which can lead to eccentricity pumping and resonance trapping. The challenge is that the orbiting body must be close to the star, competing with tidal forces and intense stellar radiation.
ASTRONOMICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Joan R. Najita, Scott J. Kenyon
Summary: The formation of terrestrial planets like Earth through late-stage giant impacts may not produce the anticipated visible signpost of warm dusty debris due to transport mechanisms that can erase the debris signature. The regeneration of a tenuous gas disk or the powerful stellar wind can effectively remove the warm debris. This suggests that terrestrial planets may quietly assemble without attracting much attention or undergo early formation without late-stage giant impacts.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Benjamin C. Bromley, Scott J. Kenyon
Summary: The method allows fast and approximate characterization of satellite orbits around a central binary, distinguish free eccentricity from oscillatory modes driven by the central binary's gravitational potential. By applying the method to numerical simulations of various systems, it resolves relative speeds between small bodies slow enough to promote mergers and growth.
ASTRONOMICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Scott J. Kenyon, Benjamin C. Bromley
PLANETARY SCIENCE JOURNAL
(2020)
Article
Astronomy & Astrophysics
Benjamin C. Bromley, Scott J. Kenyon
ASTRONOMICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
Warren R. Brown, Mukremin Kilic, Alekzander Kosakowski, Jeff J. Andrews, Craig O. Heinke, Marcel A. Agueros, Fernando Camilo, A. Gianninas, J. J. Hermes, Scott J. Kenyon
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
Scott J. Kenyon, Benjamin C. Bromley
ASTRONOMICAL JOURNAL
(2019)
Article
Astronomy & Astrophysics
Scott J. Kenyon, Benjamin C. Bromley
ASTRONOMICAL JOURNAL
(2019)
