Search Publications
Characteristics of Nanoflare Heating in a Coronal Bright Point
Hahn, Michael; Savin, Daniel Wolf; Ho, Brandon
We have obtained constraints on the nanoflare energy distribution and timing for the heating of a coronal bright point. Observations of the bright point were made using the Extreme Ultraviolet Imaging Spectrometer on Hinode in slot mode, which collects a time series of monochromatic images of the region leading to unambiguous temperature diagnosti…
A Low-speed Intruder Star in Hyades: A Temporary Residence
Hu, Qingshun; Zhang, Yu; Esamdin, Ali +4 more
We hereby report a low-speed (about 21 km s-1 with respect to the Sun) intruder member in the Hyades cluster based on the data in the literature. The results show that the star is a nonnative member star for Hyades, with its radial velocity being smaller than the radial velocity of the Hyades cluster, even exceeding the standard deviati…
Deriving Thermonuclear Supernova Properties from Gamma-Ray Line Measurements
Leising, M. D.
We illustrate methods for deriving properties of thermonuclear, or Type Ia, supernovae, including synthesized 56Ni mass, total ejecta mass, ejecta kinetic energy, and 56Ni distribution in velocity, from gamma-ray line observations. We simulate data from a small number of published SNe Ia models for a simple gamma-ray instrume…
Potential Habitability as a Stellar Property: Effects of Model Uncertainties and Measurement Precision
Tuchow, Noah W.; Wright, Jason T.
Knowledge of a star's evolutionary history combined with estimates of planet occurrence rates allows one to infer whether a star would be a good target in a search for biosignatures, and to quantify this intuition using long-term habitability metrics. In this study, we analyze the sensitivity of the biosignature yield metrics formulated by Tuchow …
The Variability Behavior of NGC 925 ULX-3
Middleton, Matthew J.; Roberts, Timothy P.; Walton, Dominic J. +5 more
We report the results of a 2019-2021 monitoring campaign with Swift and associated target-of-opportunity observations with XMM-Newton and NuSTAR, examining the spectral and timing behavior of the highly variable ultraluminous X-ray source (ULX) NGC 925 ULX-3. We find that the source exhibits a 127-128-day periodicity, with fluxes typically ranging…
Compact and Variable Radio Emission from an Active Galaxy with Supersoft X-Ray Emission
Li, Di; Liu, Daizhong; Yang, Lei +15 more
RX J1301.9+2747 is a unique active galaxy with a supersoft X-ray spectrum that lacks significant emission at energies above 2 keV. In addition, it is one of few galaxies displaying quasiperiodic X-ray eruptions that recur on a timescale of 13-20 ks. We present multiepoch radio observations of RX J1301.9+2747 using GMRT, Very Large Array (VLA), and…
Multiwavelength Observations of MWC 297: Constraints on Disk Inclination and Mass Outflow
Vacca, William D.; Sandell, Göran
MWC 297 is a young, early-type star driving an ionized outflow and surrounded by warm, entrained dust. Previous analyses of near- and mid-IR interferometric images suggest that the emission at these wavelengths arises from a compact accretion disk with a moderate (i < 40°) inclination. We have obtained 5-40 µm images of MWC 297 with FORCA…
Quantifying Chemical and Kinematical Properties of Galactic Disks
Hu, Guozhen; Shao, Zhengyi
We aim to quantify the chemical and kinematical properties of Galactic disks with a sample of 119,558 giant stars having abundances and 3D velocities taken or derived from the APOGEE DR17 and Gaia EDR3 catalogs. A Gaussian mixture model is employed to distinguish the high-α and low-α sequences along the metallicity by simultaneously using chemical…
Measuring the Nonaxially Symmetric Surface Temperature Distribution of the Central Compact Object in Puppis A
Gotthelf, E. V.; Halpern, J. P.; Perna, R. +1 more
The surface temperature distributions of central compact objects (CCOs) are powerful probes of their crustal magnetic field strengths and geometries. Here we model the surface temperature distribution of RX J0822-4300, the CCO in the Puppis A supernova remnant, using 471 ks of XMM-Newton data. We compute the energy-dependent pulse profiles in 16 e…
Detection of a Superluminous Spiral Galaxy in the Heart of a Massive Galaxy Cluster
Lovisari, Lorenzo; Ogle, Patrick; Jones, Christine +5 more
It is well established that brightest cluster galaxies (BCGs), residing in the centers of galaxy clusters, are typically massive and quenched galaxies with cD or elliptical morphology. An optical survey suggested that an exotic galaxy population, superluminous spiral and lenticular galaxies, could be the BCGs of some galaxy clusters. Because the c…