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Gamma Cas Stars as Be+White Dwarf Binary Systems
Gies, Douglas R.; Wang, Luqian; Klement, Robert
The origin of the bright and hard X-ray emission flux among the γ Cas subgroup of B-emission line (Be) stars may be caused by gas accretion onto an orbiting white dwarf (WD) companion. Such Be+WD binaries are the predicted outcome of a second stage of mass transfer from a helium star mass donor to a rapidly rotating mass gainer star. The stripped …
Revisiting Galactic Disk and Spiral Arms Using Open Clusters
Joshi, Yogesh C.; Malhotra, Sagar
We use the largest catalog of open clusters in the post-Gaia era to provide an observational view of the Galactic disk. By compiling physical parameters such as age, distance, and kinematic information, we investigate the spatial distribution of open clusters and revisit the spiral arms and other asymmetries in the Galactic disk. Using young open …
The Green Bank North Celestial Cap Survey. VII. 12 New Pulsar Timing Solutions
Ransom, S. M.; Kaplan, D. L.; McLaughlin, M. A. +22 more
We present timing solutions for 12 pulsars discovered in the Green Bank North Celestial Cap 350 MHz pulsar survey, including six millisecond pulsars (MSPs), a double neutron star (DNS) system, and a pulsar orbiting a massive white dwarf companion. Timing solutions presented here include 350 and 820 MHz Green Bank Telescope data from initial confir…
A new resonance-like feature in the outer disc of the Milky Way
Fouesneau, M.; Andrae, R.; Castro-Ginard, A. +18 more
Modern astrometric and spectroscopic surveys have revealed a wealth of structure in the phase space of stars in the Milky Way, with evidence of resonance features and non-equilibrium processes. Using the third Gaia data release, we present evidence of a new resonance-like feature in the outer disc of the Milky Way. The feature is most evident in t…
An environmental analysis of the fast transient AT2018cow and implications for its progenitor and late-time brightness
Sun, Ning-Chen; Shao, Yali; Maund, Justyn R. +1 more
The nature of the newly discovered fast blue optical transients (FBOTs) is still puzzling astronomers. In this paper, we carry out a comprehensive analysis of the molecular gas, ionized gas, and stellar populations in the environment of the nearby FBOT AT2018cow based on ALMA, VLT/MUSE, and HST/WFC3 observations. A prominent molecular concentratio…
On the gravitational lensing interpretation of three gravitational wave detections in the mass gap by LIGO and Virgo
Richard, Johan; Smith, Graham P.; Massey, Richard +7 more
We search for gravitational wave (GW) events from LIGO-Virgo's third run that may have been affected by gravitational lensing. Gravitational lensing delays the arrival of GWs, and alters their amplitude - thus biasing the inferred progenitor masses. This would provide a physically well-understood interpretation of GW detections in the 'mass gap' b…
CECILIA: The Faint Emission Line Spectrum of z 2-3 Star-forming Galaxies
Maseda, Michael V.; Steidel, Charles C.; Law, David R. +7 more
We present the first results from Chemical Evolution Constrained Using Ionized Lines in Interstellar Aurorae (CECILIA), a Cycle 1 JWST NIRSpec/MSA program that uses ultra-deep ~30 hr G235M/F170LP observations to target multiple electron temperature-sensitive auroral lines in the spectra of 33 galaxies at z ~ 1-3. Using a subset of 23 galaxies, we …
X-Ray Detection of the Galaxy's Missing Baryons in the Circumgalactic Medium of L* Galaxies
Bianchi, S.; Piconcelli, E.; Nicastro, Fabrizio +10 more
The number of baryons hosted in the disks of galaxies is lower than expected based on the mass of their dark matter halos and the fraction of baryon-to-total matter in the Universe, giving rise to the so-called galaxy missing-baryon problem. The presence of cool circumgalactic matter gravitationally bound to its galaxy's halo up to distances of at…
A super-Earth and a mini-Neptune near the 2:1 MMR straddling the radius valley around the nearby mid-M dwarf TOI-2096
Gabor, P.; Alonso, R.; Queloz, D. +72 more
Context. Several planetary formation models have been proposed to explain the observed abundance and variety of compositions of super-Earths and mini-Neptunes. In this context, multitransiting systems orbiting low-mass stars whose planets are close to the radius valley are benchmark systems, which help to elucidate which formation model dominates.…
Possible origin of the non-detection of metastable He I in the upper atmosphere of the hot Jupiter WASP-80b
Fossati, L.; Bonfanti, A.; Borsa, F. +5 more
Aims: We aim to constrain the origin of the non-detection of the metastable He I triplet at ≈10 830 Å obtained for the hot Jupiter WASP-80b.
Methods: We measure the X-ray flux of WASP-80 from archival observations and use it as input to scaling relations accounting for the coronal [Fe/O] abundance ratio in order to infer the extreme-ultr…