Search Publications
High-resolution Observations of the Low Atmospheric Response to Small Coronal Heating Events in an Active Region Core
Testa, Paola; De Pontieu, Bart; Rouppe van der Voort, Luc +1 more
High-resolution spectral observations of the lower solar atmosphere (chromosphere and transition region) during coronal heating events, in combination with predictions from models of impulsively heated loops, provide powerful diagnostics of the properties of the heating in active region cores. Here, we analyze the first coordinated observations of…
Asteroseismic Study of KUV03442+0719 with Parallax Constraints
Bischoff-Kim, Agnes
Hydrogen atmosphere white dwarf KUV03442+0719 was first reported as a pulsator by Gianninas et al. in 2006. Follow-up campaigns by Su et al. revealed more periods. Some spectroscopic results suggest that KUV03442+0719 has a slightly below-average mass and an effective temperature of 11,000 K. However, Gaia data (parallax and magnitude) suggest tha…
Discovery of a New Molecular Bubble-Outflow Structure in the Taurus B18 Cloud
Ching, Tao-Chung; Duan, Yan; Li, Di +5 more
Star formation can produce bubbles and outflows, as a result of stellar feedback. Outflows and bubbles inject momentum and energy into the surrounding interstellar medium, and so are related to the overall energy balance of the molecular cloud. Molecular bubbles can be resolved by higher-resolution radio telescopes to quantify the effect of star f…
The "Canonical" White Dwarf Cooling Sequence of M5
Cadelano, Mario; Pallanca, Cristina; Salaris, Maurizio +5 more
Recently, slowly cooling white dwarfs (WDs) are a new class of WD that have been identified in two globular clusters (namely M13 and NGC 6752), showing a horizontal branch (HB) morphology with an extended blue tail. The cooling rate of these WDs is reduced by stable thermonuclear hydrogen burning in their residual envelope, and they are thought to…
Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial Action
Bird, Sarah A.; Xu, Y.; Liu, C. +5 more
We use the conjugate angle of radial action (θ R ), the best representation of the orbital phase, to explore the "midplane," "north branch," "south branch," and "Monoceros area" disk structures that were previously revealed in the LAMOST K giants. The former three substructures, identified by their 3D kinematical distributions, have be…
Decomposing the Spectrum of Ultraluminous X-Ray Pulsar NGC 300 ULX-1
Enoto, Teruaki; Noda, Hirofumi; Kobayashi, Shogo B. +3 more
A phase-resolved analysis on the X-ray spectrum of ultraluminous X-ray pulsar (ULXP) NGC 300 ULX-1 is performed with data taken with XMM-Newton and NuSTAR on 2016 December 16. In addition to the classical phase-restricting analysis, a method developed in active galactic nuclei studies is newly employed for ULXP. It has revealed that the pulsation …
Constraint on the Accretion of NGC 6946 X-1 Using Broadband X-Ray Data
Rana, Vikram; Ghosh, Tanuman
We analyze broadband X-ray data of NGC 6946 X-1 and probe plausible accretion scenarios in this ULX. NGC 6946 X-1 is a persistent soft source with broadband continuum spectra described by two thermal disk components. The cool accretion disk temperature T cool ~ 0.2 keV and the presence of a ~0.9 keV emission/absorption broad feature sug…
Not So Fast, Not So Furious: Just Magnetic
Villaver, Eva; Landstreet, John D.; Bagnulo, Stefano
WD 0810-353 is a white dwarf within the 20 pc volume around the Sun. Using Gaia astrometric distance and proper motions, and a radial velocity derived from Gaia spectroscopy, it has been predicted that this star will pass within 1 pc of the solar system in about 30 kyr. However, WD 0810-353 has been also shown to host a magnetic field with a stren…
Rapidly Evolving Transients in Archival ZTF Public Alerts
Filippenko, Alexei V.; Yang, Yi; Li, Wenxiong +8 more
We search the archival Zwicky Transient Facility public survey for rapidly evolving transient (RET) candidates based on well-defined criteria between 2018 May and 2021 December. The search yielded 19 bona fide RET candidates, corresponding to a discovery rate of ~5.2 events per year. Even with a Galactic latitude cut of 20°, eight of the 19 events…
Confinedness of an X3.1-class Solar Flare Occurred in NOAA 12192: Analysis from Multi-instrument Observations
Guglielmino, S. L.; Zuccarello, F.; Ferrente, F. +1 more
The nonassociation of coronal mass ejections with high energetic flares is sparse. For this reason, the magnetic conditions required for the confinedness of major flares is a topic of active research. Using multi-instrument observations, we investigated the evolution and effects of confinedness in an X3.1 flare, which occurred in active region (AR…