Search Publications
Hubble Space Telescope Images of SN 1987A: Evolution of the Ejecta and the Equatorial Ring from 2009 to 2022
Matsuura, Mikako; Fransson, Claes; Kirshner, Robert P. +9 more
Supernova (SN) 1987A offers a unique opportunity to study how a spatially resolved SN evolves into a young SN remnant. We present and analyze Hubble Space Telescope (HST) imaging observations of SN 1987A obtained in 2022 and compare them with HST observations from 2009 to 2021. These observations allow us to follow the evolution of the equatorial …
Constraining Wind-driven Accretion onto Gaia BH3 with Chandra
Cappelluti, Nico; Hasinger, Günther; Pacucci, Fabio
Gaia BH3 is the most massive known stellar-origin black hole in the Milky Way, with a mass M • ≈ 33 M ⊙. Detected from Gaia's astrometry, this black hole is in the mass range of those observed via gravitational waves, whose nature is still highly debated. Hosted in a binary system with a companion giant star that is too far a…
Young Stellar Objects in NGC 346: A JWST NIRCam/MIRI Imaging Survey
Hirschauer, Alec S.; Fahrion, Katja; Lenkić, Laura +17 more
We present a JWST imaging survey with NIRCam and MIRI of NGC 346, the brightest star-forming region in the Small Magellanic Cloud. By combining aperture and point-spread function photometry of 11 wavelength bands across these two instruments, we have detected more than 200,000 unique sources. Using a near-infrared color analysis, we observe variou…
A Two-zone Accretion Disk in the Changing-look Active Galactic Nucleus 1ES 1927+654: Physical Implications for Tidal Disruption Events and Super-Eddington Accretion
Ho, Luis C.; Ricci, Claudio; Trakhtenbrot, Benny +1 more
The properties of slim accretion disks, while crucial for our understanding of black hole growth, have yet to be studied extensively observationally. We analyze the multiepoch broadband spectral energy distribution of the changing-look active galactic nucleus 1ES 1927+654 to derive the properties of its complex, time-dependent accretion flow. The …
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…