Search Publications
Chromospheric Heating from Local Magnetic Growth and Ambipolar Diffusion under Nonequilibrium Conditions
Martínez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo H. +3 more
The heating of the chromosphere in internetwork regions remains one of the foremost open questions in solar physics. In the present study, we tackle this old problem by using a very-high-spatial-resolution simulation of quiet-Sun conditions performed with radiative MHD numerical models and interface region imaging spectrograph (IRIS) observations.…
Interpreting the Si II and C II Line Spectra from the COS Legacy Archive Spectroscopic SurveY Using a Virtual Galaxy from a High-resolution Radiation-hydrodynamic Simulation
Wilkins, Stephen M.; Martin, Crystal L.; Garel, Thibault +19 more
Observations of low-ionization state metal lines provide crucial insights into the interstellar medium (ISM) of galaxies, yet, disentangling the physical processes responsible for the emerging line profiles is difficult. This work investigates how mock spectra generated using a single galaxy in a radiation-hydrodynamical simulation can help us int…
Internal Kinematics and Structure of the Bulge Globular Cluster NGC 6569
Vesperini, Enrico; Cadelano, Mario; Pallanca, Cristina +8 more
In the context of a project aimed at characterizing the properties of star clusters in the Galactic bulge, here we present the determination of the internal kinematics and structure of the massive globular cluster NGC 6569. The kinematics has been studied by means of an unprecedented spectroscopic data set acquired in the context of the ESO-VLT Mu…
Extinction of Taurus, Orion, Perseus, and California Molecular Clouds Based on the LAMOST, 2MASS, and Gaia Surveys. I. 3D Extinction and Structure
Jiang, Biwei; Zhao, He; Sun, Mingxu +1 more
The 3D extinction and structure are studied for the Taurus, Orion, Perseus, and California molecular clouds based on the LAMOST spectroscopy. Stellar color excess is calculated with the intrinsic color index derived from the atmospheric parameters in the LAMOST DR8 catalog and the observed color index in the Gaia EDR3 and the 2MASS PSC. In combina…
Observational Signatures of Electron-driven Chromospheric Evaporation in a White-light Flare
Warmuth, Alexander; Li, Dong; Ning, Zongjun +7 more
We investigate observational signatures of explosive chromospheric evaporation during a white-light flare (WLF) that occurred on 2022 August 27. Using the moment analysis, bisector techniques, and the Gaussian fitting method, redshifted velocities of less than 20 km s‑1 are detected in low-temperature spectral lines of Hα, C I, and Si I…
Dust-buried Compact Sources in the Dwarf Galaxy NGC 4449
Ji, Zhiyuan; Smith, Linda J.; Calzetti, Daniela +10 more
Multiwavelength images from the Hubble Space Telescope covering the wavelength range 0.27-1.6 µm show that the central area of the nearby dwarf galaxy NGC 4449 contains several tens of compact sources that are emitting in the hydrogen recombination line Paβ (1.2818 µm) but are only marginally detected in Hα (0.6563 µm) and undete…
Serendipitous Nebular-phase JWST Imaging of SN Ia SN 2021aefx: Testing the Confinement of 56Co Decay Energy
Galbany, L.; Morrell, Nidia; Leroy, Adam K. +29 more
We present new 0.3-21 µm photometry of SN 2021aefx in the spiral galaxy NGC 1566 at +357 days after B-band maximum, including the first detection of any Type Ia supernova (SN Ia) at >15 µm. These observations follow earlier JWST observations of SN 2021aefx at +255 days after the time of maximum brightness, allowing us to probe the t…
Stellar Characterization and Radius Inflation of Hyades M-dwarf Stars from the APOGEE Survey
Pascucci, Ilaria; Bizyaev, Dmitry; Pan, Kaike +23 more
We present a spectroscopic analysis of a sample of 48 M-dwarf stars (0.2 M ⊙ < M < 0.6 M ⊙) from the Hyades open cluster using high-resolution H-band spectra from the Sloan Digital Sky Survey/Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. Our methodology adopts spectrum synthesis with LTE MARCS …
Irregular Proton Injection to High Energies at Interplanetary Shocks
Wimmer-Schweingruber, Robert F.; Dresing, Nina; Vainio, Rami +8 more
How thermal particles are accelerated to suprathermal energies is an unsolved issue, crucial for many astrophysical systems. We report novel observations of irregular, dispersive enhancements of the suprathermal particle population upstream of a high-Mach-number interplanetary shock. We interpret the observed behavior as irregular "injections" of …
The Early Light Curve of the Type Ia Supernova 2021hpr in NGC 3147: Progenitor Constraints with the Companion Interaction Model
Wheeler, J. Craig; Im, Myungshin; Kim, Dohyeong +19 more
The progenitor system of Type Ia supernovae (SNe Ia) is expected to be a close binary system consisting of a carbon/oxygen white dwarf (WD) and a nondegenerate star or another WD. Here, we present results from high-cadence monitoring observations of SN 2021hpr in a spiral galaxy, NGC 3147, and constraints on the progenitor system based on its earl…