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Ram pressure stripping candidates in the coma cluster: evidence for enhanced star formation
Parker, Laura C.; Roberts, Ian D.
The Coma cluster is the nearest massive (M ≳ 1015 M⊙) galaxy cluster, making it an excellent laboratory to probe the influence of the cluster environment on galaxy star formation. Here, we present a sample of 41 galaxies with disturbed morphologies consistent with ram pressure stripping. These galaxies are identified visually using high…
Exploring Solar Wind Origins and Connecting Plasma Flows from the Parker Solar Probe to 1 au: Nonspherical Source Surface and Alfvénic Fluctuations
D'Amicis, Raffaella; Réville, Victor; Velli, Marco +18 more
The magnetic field measurements of the FIELDS instrument on the Parker Solar Probe (PSP) have shown intensities, throughout its first solar encounter, that require a very low source surface (SS) height ( ${R}_{\mathrm{SS}}\leqslant 1.8\,{R}_{\odot }$ ) to be reconciled with magnetic field measurements at the Sun via potential field extrapolation (…
The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary
Duev, Dmitry A.; Riddle, Reed; Szkody, Paula +29 more
We report the discovery of the first short-period binary in which a hot subdwarf star (sdOB) filled its Roche lobe and started mass transfer to its companion. The object was discovered as part of a dedicated high-cadence survey of the Galactic plane named the Zwicky Transient Facility and exhibits a period of P = 39.3401(1) minutes, making it the …
How many components? Quantifying the complexity of the metallicity distribution in the Milky Way bulge with APOGEE
Monachesi, Antonela; Cohen, Roger E.; Cunha, Katia +16 more
We use data of ∼13-=000 stars from the Sloan Digital Sky Survey/Apache Point Observatory Galactic Evolution Experiment survey to study the shape of the bulge metallicity distribution function (MDF) within the region |ℓ| ≤ 11° and |b| ≤ 13°, and spatially constrained to RGC ≤ 3.5 kpc. We apply Gaussian mixture modelling and non-negative …
Birds of a Feather? Magellan/IMACS Spectroscopy of the Ultra-faint Satellites Grus II, Tucana IV, and Tucana V
Bechtol, K.; Smith, M.; Lidman, C. +55 more
We present Magellan/IMACS spectroscopy of three recently discovered ultra-faint Milky Way satellites, Grus II, Tucana IV, and Tucana V. We measure systemic velocities of Vhel = 110.0 ± 0.5 km s-1, Vhel = 15.9-1.7+1.8 km s-1, and Vhel=-36.2-2.2+2.5 km…
Constraining the Milky Way Mass Profile with Phase-space Distribution of Satellite Galaxies
Li, Ting S.; Wang, Wenting; Han, Jiaxin +3 more
We estimate the Milky Way (MW) halo properties using satellite kinematic data including the latest measurements from Gaia DR2. With a simulation-based 6D phase-space distribution function (DF) of satellite kinematics, we can infer halo properties efficiently and without bias, and handle the selection function and measurement errors rigorously in t…
On the activity of comets: understanding the gas and dust emission from comet 67/Churyumov-Gerasimenko's south-pole region during perihelion
Blum, J.; Fulle, M.; Gundlach, B.
When comets approach the Sun, their surface is heated and the volatile species start to sublimate. Due to the increasing gas pressure, dust is ejected off the surface, which can be observed as cometary coma, dust tail, and trail. However, the underlying physical processes are not fully understood. Using state-of-the-art results for the transport o…
The GALAH survey: chemodynamics of the solar neighbourhood
Ting, Yuan-Sen; Buder, Sven; Bland-Hawthorn, Joss +15 more
We present the chemodynamic structure of the solar neighbourhood using 55 652 stars within a 500 pc volume around the Sun observed by GALAH and with astrometric parameters from Gaia DR2. We measure the velocity dispersion for all three components (vertical, radial, and tangential) and find that it varies smoothly with [Fe/H] and [α/Fe] for each co…
The messy merger of a large satellite and a Milky Way-like galaxy
Helmi, Amina; Koppelman, Helmer H.; Bos, Roy O. Y.
Aims: About 10 billion years ago the Milky Way merged with a massive satellite, Gaia-Enceladus. To gain insight into the properties of its debris we analyse in detail a suite of simulations that includes an experiment that produces a good match to the kinematics of nearby halo stars inferred from Gaia data.
Methods: We compare the kinema…
The Pristine survey - IX. CFHT ESPaDOnS spectroscopic analysis of 115 bright metal-poor candidate stars
Sestito, Federico; Navarro, Julio F.; Martin, Nicolas +18 more
A chemo-dynamical analysis of 115 metal-poor candidate stars selected from the narrow-band Pristine photometric survey is presented based on CFHT high-resolution ESPaDOnS spectroscopy. We have discovered 28 new bright (V < 15) stars with [Fe/H] < -2.5 and 5 with [Fe/H] < -3.0 for success rates of 40 (28/70) and 19 per cent (5/27), respect…