Search Publications
Where Is the Flux Going? The Long-term Photometric Variability of Boyajian’s Star
Kochanek, C. S.; van Saders, Jennifer; Shappee, Benjamin J. +5 more
We present ∼800 days of photometric monitoring of Boyajian’s Star (KIC 8462852) from the All-Sky Automated Survey for Supernovae (ASAS-SN) and ∼4000 days of monitoring from the All Sky Automated Survey (ASAS). We show that from 2015 to the present the brightness of Boyajian’s Star has steadily decreased at a rate of 6.3 ± 1.4 mmag yr-1,…
The High-velocity Stars in the Local Stellar Halo from Gaia and LAMOST
Du, Cuihua; Li, Hefan; Liu, Shuai +2 more
Based on the first Gaia data release and spectroscopy from the LAMOST Data Release 4, we study the kinematics and chemistry of the local halo stars. The halo stars are identified kinematically with a relative speed of at least 220 km s-1 with respect to the local standard of rest. In total, 436 halo stars are identified. From this halo …
A Long Hard-X-Ray Look at the Dual Active Galactic Nuclei of M51 with NuSTAR
Harrison, F. A.; Hornschemeier, A. E.; Ptak, A. +14 more
We present a broadband X-ray spectral analysis of the M51 system, including the dual active galactic nuclei (AGNs) and several off-nuclear point sources. Using a deep observation by NuSTAR, new high-resolution coverage of M51b by Chandra, and the latest X-ray torus models, we measure the intrinsic X-ray luminosities of the AGNs in these galaxies. …
Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars
Brandt, W. N.; Luo, B.; Fan, X. +8 more
We present XMM-Newton imaging spectroscopy of 10 weak emission-line quasars (WLQs) at 0.928≤slant z≤slant 3.767, six of which are radio-quiet, and four that are radio-intermediate. The new X-ray data enabled us to measure the power-law photon index, at rest-frame energies >2 keV, in each source with relatively high accuracy. These measurements …
Asymmetry in Solar Torsional Oscillation and the Sunspot Cycle
Antia, H. M.; Nandy, Dibyendu; Lekshmi, B.
Solar torsional oscillations are migrating bands of slower- and faster-than-average rotation, which are strongly related to the Sun’s magnetic cycle. We perform a long-term study (16 yr) of hemispherical asymmetry in solar torsional oscillation velocity using helioseismic data for the first time. We study the north-south asymmetry in the velocity …
Resolving Star Formation on Subkiloparsec Scales in the High-redshift Galaxy SDP.11 Using Gravitational Lensing
Verma, A.; Lamarche, C.; Stacey, G. J. +7 more
We investigate the properties of the interstellar medium, star formation, and the current-day stellar population in the strongly lensed star-forming galaxy H-ATLAS J091043.1-000321 (SDP.11), at z = 1.7830, using new Herschel and Atacama Large Millimeter/submillimeter Array (ALMA) observations of far-infrared fine-structure lines of carbon, oxygen,…
The Discovery of a New Massive Molecular Gas Component Associated with the Submillimeter Galaxy SMM J02399-0136
Ivison, R. J.; Smail, Ian; Frayer, David T. +3 more
We present CO(1-0), CO(3-2), and CO(7-6) observations using the Green Bank Telescope (GBT) and the Atacama Large Millimeter Array (ALMA) of the z = 2.8 submillimeter galaxy SMM J02399-0136. This was the first submillimeter-selected galaxy discovered and remains an archetype of the class, comprising a merger of several massive and active components…
The Acceleration Process of a Solar Quiescent Filament in the Inner Corona
Chen, Y.; Song, H. Q.; Cheng, X. +5 more
Coronal mass ejections (CMEs) are frequently associated with filament eruptions. Theoretical studies propose that both magnetic reconnection and ideal magnetohydrodynamic instability of magnetic flux ropes can convert coronal magnetic energy into the filament/CME kinetic energy. Numerical simulations and analytical considerations demonstrate that …
Mapping Excitation in the Inner Regions of the Planetary Nebula NGC 5189 Using HST WFC3 Imaging
Karovska, Margarita; Montez, Rodolfo, Jr.; Maksym, W. Peter +1 more
The planetary nebula (PN) NGC 5189 around a Wolf-Rayet [WO] central star demonstrates one of the most remarkable complex morphologies among PNe with many multiscale structures, showing evidence of multiple outbursts from an asymptotic giant branch (AGB) progenitor. In this study, we use multiwavelength Hubble Space Telescope Wide Field Camera 3 ob…
Thirty-fold: Extreme Gravitational Lensing of a Quiescent Galaxy at z = 1.6
Brammer, G.; Toft, S.; Richard, J. +4 more
We report the discovery of eMACSJ1341-QG-1, a quiescent galaxy at z = 1.594 located behind the massive galaxy cluster eMACSJ1341.9-2442 (z = 0.835). The system was identified as a gravitationally lensed triple image in Hubble Space Telescope images obtained as part of a snapshot survey of the most X-ray luminous galaxy clusters at z > 0.5 and s…