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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 ...
3D Selection of 167 Substellar Companions to Nearby Stars
(2022-08-26)
We analyze 5108 AFGKM stars with at least five high-precision radial velocity points, as well as Gaia and Hipparcos astrometric data, utilizing a novel pipeline developed in previous work. We find 914 radial velocity signals ...
UGPS J194310+183851 : an Unusual Optical and X-ray Faint Cataclysmic Variable?
(2022-08-01)
The growing number of multi-epoch optical and infrared sky surveys are uncovering unprecedented numbers of new variable stars, of an increasing number of types. The short interval between observations in adjacent near-infrared ...