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Can Neutron Star Mergers Alone Explain the r-process Enrichment of the Milky Way?
(2023-01-30)
Comparing Galactic chemical evolution models to the observed elemental abundances in the Milky Way, we show that neutron star mergers can be a leading r-process site only if at low metallicities such mergers have very short ...
Ultracool dwarfs in Gaia DR3
(2023-01-26)
Context. Previous Gaia data releases offered the opportunity to uncover ultracool dwarfs (UCDs) through astrometric, rather than purely photometric, selection. The most recent, the third data release (DR3), offers in ...
Deep Narrowband Photometry of the M101 Group: Strong-line Abundances of 720 H ii Regions
(2022-12-22)
We present deep, narrowband imaging of the nearby spiral galaxy M101 and its satellites to analyze the oxygen abundances of their H ii regions. Using Case Western Reserve University’s Burrell Schmidt telescope, we add to ...
The X–shooter/ALMA Sample of Quasars in the Epoch of Reionization. II. Black Hole Masses, Eddington Ratios, and the Formation of the First Quasars
(2022-12-20)
We present measurements of black hole masses and Eddington ratios (λ Edd) for a sample of 38 bright (M 1450 < −24.4 mag) quasars at 5.8 ≲ z ≲ 7.5, derived from Very Large Telescope/X-shooter near-IR spectroscopy of their ...
Extragalactic Peaked-Spectrum Radio Sources at Low-Frequencies are Young Radio Galaxies
(2022-12-20)
We present a sample of 373 peaked-spectrum (PS) sources with spectral peaks around 150 MHz, selected using a subset of the two LOw Frequency ARray (LOFAR) all-sky surveys, the LOFAR Two Meter Sky Survey and the LOFAR LBA ...
Central Star Formation in Early-type Galaxy I Zw 81 in the Bootes Void
(2022-12-16)
The origin of star formation in customarily passively evolving early-type massive galaxies is poorly understood. We present a case study of a massive galaxy, I Zw 81, inside the Bootes void. The void galaxy is known to ...
The Origin of High-energy Emission in the Young Radio Source PKS 1718–649
(2022-12-12)
We present a model for the broadband radio-to-γ-ray spectral energy distribution of the compact radio source PKS 1718 − 649. Because of its young age (≃100 yr) and proximity (z = 0.014), PKS 1718 − 649 offers a unique ...
The survey of planetary nebulae in Andromeda (M31). IV. Radial oxygen and argon abundance gradients of the thin and thicker disc
(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, ...
Possible discovery of Calvera's supernova remnant
(2022-11-01)
We report the discovery of a ring of low surface brightness radio emission around the Calvera pulsar, a high Galactic latitude, isolated neutron star, in the LOFAR Two-metre Sky Survey (LoTSS). It is centered at α = ...
Transient obscuration event captured in NGC 3227 III. Photoionization modeling of the X-ray obscuration event in 2019
(2022-09-12)
Context. A growing number of transient X-ray obscuration events in type I active galactic nuclei suggest that our line of sight to the central engine is not always free. Multiple X-ray obscuration events were reported in ...