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Composite Bulges. III. A Study of Nuclear Star Clusters in Nearby Spiral Galaxies
Beckman, John E.; Bender, Ralf; Drory, Niv +17 more
We present photometric and morphological analyses of nuclear star clusters (NSCs)-very dense, massive star clusters present in the central regions of most galaxies-in a sample of 33 massive disk galaxies within 20 Mpc, part of the "Composite Bulges Survey." We use data from the Hubble Space Telescope including optical (F475W and F814W) and near-IR…
Searching for Gravitational-wave Counterparts Using the Transiting Exoplanet Survey Satellite
Jayaraman, Rahul; Ricker, George R.; Vanderspek, Roland +3 more
In 2017, the LIGO and Virgo gravitational-wave (GW) detectors, in conjunction with electromagnetic (EM) astronomers, observed the first GW multimessenger astrophysical event, the binary neutron star (BNS) merger GW170817. This marked the beginning of a new era in multimessenger astrophysics. To discover further GW multimessenger events, we explore…
ALMA Reveals Hidden Morphologies in the Molecular Envelope of VY Canis Majoris
Humphreys, R. M.; Decin, L.; Richards, A. M. S. +2 more
The J = 2 → 1 transition of CO near 230 GHz and the J = 3 → 2 line of HCN at 265 GHz have been imaged in the envelope of the red hypergiant star, VY Canis Majoris (VY CMa), using the Atacama Large Millimeter Array (ALMA) with angular resolutions 0.″2-1.″5; single-dish data were added to provide sensitivity up to 30″. These images reveal a far more…
The Hα Luminosity Function of Galaxies at z 4.5
Illingworth, Garth D.; Labbé, Ivo; Bouwens, Rychard J. +5 more
We present the Hα luminosity function (LF) derived from a large sample of Lyman break galaxies at z ~ 4.5 over the GOODS-South and North fields. This study makes use of the new, full-depth Spitzer/IRAC [3.6] and [4.5] imaging from the GOODS Re-ionization Era wide-Area Treasury from the Spitzer program. The Hα flux is derived from the offset betwee…
Center-to-limb Variation of Transition-region Doppler Shifts in Active Regions
Tripathi, Durgesh; Kashyap, Vinay L.; Ghosh, Avyarthana +2 more
Studying Doppler shifts provides deep insights into the flow of mass and energy in the solar atmosphere. We perform a comprehensive measurement of Doppler shifts in the transition region and its center-to-limb variation (CLV) in the strong-field regions (∣ B ∣ ≥ 50 G) of 50 active regions (ARs), using the Si IV 1394 Å line recorded by the Interfac…
White-light Superflare and Long-term Activity of the Nearby M7-type Binary EI Cnc Observed with GWAC System
Wang, Jing; Liang, En-Wei; Wang, Xiang-Gao +14 more
Stellar white-light flares are believed to play an essential role in the physical and chemical properties of the atmosphere of the surrounding exoplanets. Here we report an optical monitoring campaign on the nearby flaring system EI Cnc carried out by the Ground-based Wide Angle Camera (GWAC) and its dedicated follow-up telescope. A superflare, co…
Unusual Hard X-Ray Flares Caught in NICER Monitoring of the Binary Supermassive Black Hole Candidate AT2019cuk/Tick Tock/SDSS J1430+2303
Fabian, Andrew C.; Remillard, Ronald A.; Arzoumanian, Zaven +17 more
The nuclear transient AT2019cuk/Tick Tock/SDSS J1430+2303 has been suggested to harbor a supermassive black hole (SMBH) binary near coalescence. We report results from high-cadence NICER X-ray monitoring with multiple visits per day from 2022 January to August, as well as continued optical monitoring during the same time period. We find no evidenc…
A Large Double-ring Disk Around the Taurus M Dwarf J04124068+2438157
Herczeg, Gregory J.; Wilner, David J.; Ren, Bin B. +23 more
Planet formation imprints signatures on the physical structures of disks. In this paper, we present high-resolution (~50 mas, 8 au) Atacama Large Millimeter/submillimeter Array observations of 1.3 mm dust continuum and CO line emission toward the disk around the M3.5 star 2MASS J04124068+2438157. The dust disk consists of only two narrow rings at …
A Reemerging Bright Soft X-Ray State of the Changing-look Active Galactic Nucleus 1ES 1927+654: A Multiwavelength View
Cenko, S. Bradley; Meyer, Eileen; Lusso, Elisabeta +24 more
1ES1927+654 is a nearby active galactic nucleus (AGN) that has shown an enigmatic outburst in optical/UV followed by X-rays, exhibiting strange variability patterns at timescales of months to years. Here we report the unusual X-ray, UV, and radio variability of the source in its postflare state (2022 January-2023 May). First, we detect an increase…
On the 3D Curvature and Dynamics of the Musca Filament
Coudé, Simon; Arzoumanian, Doris; Kaminsky, Aidan +1 more
Filaments are ubiquitous in the interstellar medium, yet their formation and evolution remain the topic of intense debate. In order to obtain a more comprehensive view of the 3D morphology and evolution of the Musca filament, we model the C18O(2-1) emission along the filament crest with several large-scale velocity field structures. Thi…