Search Publications
Did Sgr cause the vertical waves in the solar neighbourhood?
Bovy, Jo; Bennett, Morgan
The vertical distribution of stars in the solar neighbourhood is not in equilibrium but contains a wave signature in both density and velocity space originating from a perturbation. With the discovery of the phase-space spiral in Gaia data release (DR) 2, determining the origin of this perturbation has become even more urgent. We develop and test …
The orbit and stellar masses of the archetype colliding-wind binary WR 140
Corcoran, Michael F.; Couperus, Andrew; Moffat, Anthony F. J. +33 more
We present updated orbital elements for the Wolf-Rayet (WR) binary WR 140 (HD 193793; WC7pd + O5.5fc). The new orbital elements were derived using previously published measurements along with 160 new radial velocity measurements across the 2016 periastron passage of WR 140. Additionally, four new measurements of the orbital astrometry were collect…
Velocity Dispersion of the GD-1 Stellar Stream
Naidu, Rohan P.; Bonaca, Ana; Gialluca, Megan T.
Tidally dissolved globular clusters form thin stellar streams that preserve a historical record of their past evolution. We report a radial velocity dispersion of 2.1 ± 0.3 km s-1 in the GD-1 stellar stream using a sample of 43 spectroscopically confirmed members. The GD-1 velocity dispersion is constant over the surveyed ≈15° span of t…
3D spectroscopic analysis of helium-line white dwarfs
Ludwig, Hans-Günter; Bergeron, Pierre; Tremblay, Pier-Emmanuel +3 more
In this paper, we present corrections to the spectroscopic parameters of DB and DBA white dwarfs with -10.0 ≤ log (H/He) ≤ -2.0, 7.5 ≤ log g ≤ 9.0, and $12\, 000$ ≲ Teff $\lesssim 34\, 000\,\mathrm{ K}$ , based on 282 3D atmospheric models calculated with the CO5BOLD radiation-hydrodynamics code. These corrections arise due t…
The Most Metal-poor Stars in the Magellanic Clouds Are r-process Enhanced
Casey, Andrew R.; Simon, Joshua D.; Ji, Alexander P. +2 more
The chemical abundances of a galaxy's metal-poor stellar population can be used to investigate the earliest stages of its formation and chemical evolution. The Magellanic Clouds are the most massive of the Milky Way's satellite galaxies and are thought to have evolved in isolation until their recent accretion by the Milky Way. Unlike the Milky Way…
Galactic bar resonances inferred from kinematically hot stars in Gaia EDR3
Cropper, Mark; Ciucă, Ioana; Seabroke, George +5 more
Using a numerical simulation of an isolated barred disc galaxy, we first demonstrate that the resonances of the inner bar structure induce more prominent features in the action space distribution for the kinematically hotter stars, which are less sensitive to the local perturbation, such as the transient spiral arms. Then, we analyse the action di…
Molecules with ALMA at Planet-forming Scales (MAPS). XVI. Characterizing the Impact of the Molecular Wind on the Evolution of the HD 163296 System
Zhang, Ke; Wilner, David J.; Ménard, François +27 more
During the main phase of evolution of a protoplanetary disk, accretion regulates the inner-disk properties, such as the temperature and mass distribution, and in turn, the physical conditions associated with planet formation. The driving mechanism behind accretion remains uncertain; however, one promising mechanism is the removal of a fraction of …
Abundance Patterns of α and Neutron-capture Elements in the Helmi Stream
Chiappini, Cristina; Limberg, Guilherme; Rossi, Silvia +6 more
We identified eight additional stars as members of the Helmi stream (HStr) in the combined GALAH+ DR3 and Gaia EDR3 catalog. By consistently reevaluating claimed members from the literature, we consolidate a sample of 22 HStr stars with parameters determined from high-resolution spectroscopy and spanning a considerably wider (by ∼0.5 dex) metallic…
Alfvénic Perturbations in a Sunspot Chromosphere Linked to Fractionated Plasma in the Corona
Stangalini, Marco; Brooks, David H.; Baker, Deborah +7 more
In this study, we investigate the spatial distribution of highly varying plasma composition around one of the largest sunspots of solar cycle 24. Observations of the photosphere, chromosphere, and corona are brought together with magnetic field modeling of the sunspot in order to probe the conditions that regulate the degree of plasma fractionatio…
CoBiToM project - I. Contact binaries towards merging
Hakala, P.; Liakos, A.; Zola, S. +6 more
Binary and multiple stellar systems are numerous in our solar neighbourhood with 80 per cent of the solar-type stars being members of systems with high order multiplicity. The Contact Binaries Towards Merging (CoBiToM) Project is a programme that focuses on contact binaries and multiple stellar systems, as a key for understanding stellar nature. T…