Search Publications
Exploring the Mpc Environment of the Quasar ULAS J1342+0928 at z = 7.54
Finkelstein, Steven L.; Willott, Chris J.; Brammer, Gabriel +10 more
Theoretical models predict that z ≳ 6 quasars are hosted in the most massive halos of the underlying dark matter distribution and thus would be immersed in protoclusters of galaxies. However, observations report inconclusive results. We investigate the 1.1 proper-Mpc2 environment of the z = 7.54 luminous quasar ULAS J1342+0928. We searc…
Spectroscopic Survey of Faint Planetary-nebula Nuclei. IV. The A35-type Central Star of Pa 27
Bond, Howard E.; Zeimann, Gregory R.
We present optical spectroscopy of the 12th-magnitude central star of the planetary nebula (PN) Patchick 27 (Pa 27), obtained during a survey of faint PN nuclei (PNNs) with the Low-Resolution Spectrograph of the Hobby–Eberly Telescope. The optical spectrum of Pa 27 is that of a K0 III red giant with rotationally broadened lines. However, the star …
Detection of Accretion Shelves Out to the Virial Radius of a Low-mass Galaxy with JWST
van Dokkum, Pieter; Conroy, Charlie; Johnson, Benjamin D. +8 more
We report the serendipitous discovery of an extended stellar halo surrounding the low-mass galaxy Ark 227 (M * = 5 × 109 M ⊙; d = 35 Mpc) in deep JWST NIRCam imaging from the Blue Jay Survey. The F200W–F444W color provides robust star–galaxy separation, enabling the identification of stars at very low density. By c…
Inferring Fundamental Properties of the Flare Current Sheet Using Flare Ribbons: Oscillations in the Reconnection Flux Rates
Kazachenko, Maria D.; Lynch, Benjamin J.; Corchado Albelo, Marcel F.
Magnetic reconnection is understood to be the main physical process that facilitates the transformation of magnetic energy into heat, motion, and particle acceleration during solar eruptions. Yet, observational constraints on reconnection region properties and dynamics are limited due to a lack of high-cadence and high-spatial-resolution observati…
First Observational Evidence for an Interconnected Evolution between Time Lag and QPO Frequency among AGNs
Liu, Hao; Xue, Yongquan; Xia, Ruisong
Quasiperiodic oscillations (QPOs) have been widely observed in black hole X-ray binaries (BHBs), which often exhibit significant X-ray variations. Extensive research has explored the long-term evolution of the properties of QPOs in BHBs. In contrast, such evolution in active galactic nuclei (AGNs) has remained largely unexplored due to limited obs…
SMA Detection of an Extreme Millimeter Flare from the Young Class III Star HD 283572
Wilner, David J.; Rao, Ramprasad; Andrews, Sean M. +5 more
We present evidence of variable 1.3 mm emission from the 1 to 3 Myr, spectral-type G2–G5 class III young stellar object (YSO), HD 283572. HD 283572 was observed on eight dates with the Submillimeter Array between 2021 December and 2023 May, with a total on-source time of 10.2 hr, probing a range of timescales down to 5.2 s. Averaging all data obta…
The Fate of the Interstellar Medium in Early-type Galaxies. III. The Mechanism of Interstellar Medium Removal and the Quenching of Star Formation
Frayer, D. T.; Hughes, D. H.; Zavala, J. +15 more
Understanding how galaxies quench their star formation is crucial for studies of galaxy evolution. Quenching is related to a decrease of cold gas. In the first paper we showed that the dust removal timescale in early-type galaxies (ETGs) is about 2.5 Gyr. Here we present carbon monoxide and 21 cm hydrogen line observations of these galaxies and me…
On Its Way to the Neutron Star–White Dwarf Binary Graveyard, IGR J16194‑2810, A First Ascent M Giant X-Ray Binary
Fekel, Francis C.; Hinkle, Kenneth H.; Straniero, Oscar +5 more
A single-lined spectroscopic orbit for the M giant in the X-ray binary IGR J16194‑2810 is determined from a time series of optical spectra. The spectroscopic orbital period of 192.5 days is twice that of the photometric period, confirming that the M giant in the system is an ellipsoidal variable. The giant is identified as a first ascent giant app…
JWST Reveals CO Ice, Concentrated CO2 Deposits, and Evidence for Carbonates Potentially Sourced from Ariel's Interior
Hedman, Matthew M.; Grundy, William M.; Villanueva, Geronimo L. +21 more
The Uranian moon Ariel exhibits a diversity of geologically young landforms, with a surface composition rich in CO2 ice. The origin of CO2 and other species, however, remains uncertain. We report observations of Ariel's leading and trailing hemispheres, collected with NIRSpec (2.87–5.10 µm) on the James Webb Space Teles…
Toward a Self-consistent Evaluation of Gas Dwarf Scenarios for Temperate Sub-Neptunes
Madhusudhan, Nikku; Constantinou, Savvas; Moses, Julianne I. +6 more
The recent JWST detections of carbon-bearing molecules in a habitable-zone sub-Neptune have opened a new era in the study of low-mass exoplanets. The sub-Neptune regime spans a wide diversity of planetary interiors and atmospheres not witnessed in the solar system, including mini-Neptunes, super-Earths, and water worlds. Recent works have investig…