Search Publications
Investigations of Flaring Plasma Parameters during an M-class Flare Using the Differential Evolution Method and XSM/Chandrayaan-2 Observations
Awasthi, Arun Kumar; Sylwester, Barbara; Sylwester, Janusz +2 more
We employ the differential evolution (DE) method to analyze observations from the Solar X-Ray Monitor on board the Chandrayaan-2 spacecraft. DE belongs to the family of evolutionary algorithms that find solutions using mechanisms inspired by biological processes. This approach enables us to simultaneously calculate the distribution of the differen…
Detecting and Characterizing Young Quasars. III. The Impact of Gravitational Lensing Magnification
Hennawi, Joseph F.; Belli, Sirio; Tacchella, Sandro +8 more
We test the impact of gravitational lensing on the lifetime estimates of seven high-redshift quasars at redshift z ≳ 6. The targeted quasars are identified by their small observed proximity zone sizes, which indicate extremely short quasar lifetimes (t Q ≲ 105yr). However, these estimates of quasar lifetimes rely on the ass…
Magellanic System Stars Identified in SMACS J0723.3-7327 James Webb Space Telescope Early Release Observations Images
Holwerda, Benne W.; Koekemoer, Anton M.; Pirzkal, Nor +23 more
We identify 71 distant stars in James Webb Space Telescope/NIRCam early release observations (ERO) images of the field of galaxy cluster SMACS J0723.3-7327 (SMACS 0723). Given the relatively small (~10°) angular separation between SMACS 0723 and the Large Magellanic Cloud (LMC), it is likely that these stars are associated with the LMC outskirts o…
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…