Search Publications
Recoiling Supermassive Black Hole in Changing-look AGN Mrk 1018
Kim, D. -C.; Evans, A. S.; Yoon, Ilsang
The spectral type of Mrk 1018 changed from Type 1.9 to 1 and returned back to 1.9 over a period of 40 years. We have investigated physical mechanisms responsible for the spectral change in Mrk 1018 by analyzing archival spectral and imaging data. Two kinematically distinct broad-line components, blueshifted and redshifted components, are found fro…
Parameterizations of Chromospheric Condensations in dG and dMe Model Flare Atmospheres
Kowalski, Adam F.; Allred, Joel C.
The origin of the near-ultraviolet and optical continuum radiation in flares is critical for understanding particle acceleration and impulsive heating in stellar atmospheres. Radiative-hydrodynamic (RHD) simulations in 1D have shown that high energy deposition rates from electron beams produce two flaring layers at T ∼ 104 K that develo…
IRIS Observations of Magnetic Interactions in the Solar Atmosphere between Preexisting and Emerging Magnetic Fields. I. Overall Evolution
Young, Peter R.; Murabito, Mariarita; Guglielmino, Salvo L. +2 more
We report multiwavelength ultraviolet observations taken with the IRIS satellite, concerning the emergence phase in the upper chromosphere and transition region of an emerging flux region (EFR) embedded in the preexisting field of active region NOAA 12529 in the Sun. IRIS data are complemented by full-disk observations of the Solar Dynamics Observ…
Statistical Study of Magnetic Nonpotential Measures in Confined and Eruptive Flares
Ravindra, B.; Doddamani, V. H.; Vemareddy, P. +1 more
Using Solar Dynamics Observatory/Helioseismic and Magnetic Imager vector magnetic field observations, we studied the relation between the degree of magnetic non-potentiality with the observed flare/coronal mass ejection (CME) in active regions (ARs). From a sample of 77 flare/CME cases, we found in general that the degree of non-potentiality is po…
HST Grism Observations of a Gravitationally Lensed Redshift 9.5 Galaxy
Hoag, A.; Bradač, M.; Brammer, G. +11 more
We present deep spectroscopic observations of a Lyman break galaxy (LBG) candidate (hereafter MACS1149-JD) at z ∼ 9.5 with the Hubble Space Telescope (HST) WFC3/IR grisms. The grism observations were taken at four distinct position angles, totaling 34 orbits with the G141 grism, although only 19 of the orbits are relatively uncontaminated along th…
The Recent Growth History of the Fornax Cluster Derived from Simultaneous Sloshing and Gas Stripping: Simulating the Infall of NGC 1404
Churazov, Eugene; Jones, Christine; Nulsen, Paul E. J. +7 more
We derive the recent growth history of the Fornax Cluster, in particular the recent infall of the giant elliptical galaxy NGC 1404. We show, using a simple cluster minor merger simulation tailored to Fornax and NGC 1404, that a second or more likely third encounter between the two reproduces all the main merger features observed in both objects; w…
Optical-Mid-infrared Period-Luminosity Relations for W UMa-type Contact Binaries Based on Gaia DR 1: 8% Distance Accuracy
Wang, Shu; Deng, Licai; de Grijs, Richard +2 more
W Ursa Majoris (W UMa)-type contact binary systems (CBs) are useful statistical distance indicators because of their large numbers. Here, we establish (orbital) period-luminosity relations (PLRs) in 12 optical to mid-infrared bands (GBVRIJHK s W1W2W3W4) based on 183 nearby W UMa-type CBs with accurate Tycho-Gaia parallaxes. The 1σ dispe…
Interplanetary Type II Radio Bursts from Wind/WAVES and Sustained Gamma-Ray Emission from Fermi/LAT: Evidence for Shock Source
Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji +4 more
We present quantitative evidence that interplanetary type II radio bursts and sustained gamma-ray emission (SGRE) events from the Sun are closely related. Out of about 30 SGRE events reported in Share et al. we consider 13 events that had a duration exceeding ∼5 hr to exclude any flare-impulsive phase gamma-rays. The SGRE duration also has a linea…
Volans-Carina: A New 90 Myr Old Stellar Association at 85 pc
Faherty, Jacqueline K.; Gagné, Jonathan; Mamajek, Eric E.
We present a characterization of the new Volans-Carina Association (VCA) of stars near the Galactic plane (b ≃ -10°) at a distance of ≃75-100 pc, previously identified as group 30 by Oh et al. We compile a list of 19 likely members from Gaia DR2 with spectral types B8-M2, and 46 additional candidate members from Gaia DR2, 2MASS, and AllWISE with s…
Resolving the Powerful Radio-loud Quasar at z ∼ 6
Walter, Fabian; Bañados, Eduardo; Momjian, Emmanuel +2 more
We present high angular resolution imaging (23.9 × 11.3 mas, 138.6 × 65.5 pc) of the radio-loud quasar PSO J352.4034-15.3373 at z = 5.84 with the Very Long Baseline Array (VLBA) at 1.54 GHz. This quasar has the highest radio-to-optical flux density ratio at such a redshift, making it the radio-loudest source known to date at z ∼ 6. The VLBA observ…