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The Fe I 6173 {\AA} line is widely used in the measurements of vector magnetic fields by instruments including the Helioseismic and Magnetic Imager (HMI). We perform non-local thermodynamic equilibrium calculations of this line based on…

Solar and Stellar Astrophysics · Physics 2018-04-10 Jie Hong , M. D. Ding , Ying Li , Mats Carlsson

Identifying infall motions is crucial for our understanding of accretion processes in regions of star formation. The NH3 (1,1) hyperfine intensity anomaly (HIA) has been proposed to be a readily usable tracer for such infall motions in…

Astrophysics of Galaxies · Physics 2024-11-06 Gang Wu , Christian Henkel , Dongdong Zhou , Friedrich Wyrowski , Karl M. Menten , Jarken Esimbek

Coronal loops form the basic building blocks of the magnetically closed solar corona yet much is still to be determined concerning their possible fine-scale structuring and the rate of heat deposition within them. Using an improved…

Solar and Stellar Astrophysics · Physics 2021-07-07 Thomas Williams , Robert W. Walsh , Stephane Regnier , Craig D. Johnston

Transition-edge sensors (TESs) are used as very sensitive thermometers in microcalorimeters aimed at detection of different wavelengths. In particular, for soft X-ray astrophysics, science goals require very high resolution…

Instrumentation and Detectors · Physics 2021-02-19 E. Taralli , C. Pobes , P. Khosropanah , L. Fabrega , A. Camon , L. Gottardi , K. Nagayoshi , M. Ridder , M. Bruijn , J. R. Gao

We present observations of the first two supernovae discovered with the recently installed Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The supernovae were found in Wide Field Camera images of the Hubble Deep Field North…

It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona low-FIP elements, such as Fe, Si,…

Solar and Stellar Astrophysics · Physics 2016-06-22 Harry P. Warren , David H. Brooks , George A. Doschek , Uri Feldman

Atomic ionised regions with strong continuum emission are often associated with regions of high-mass star formation and low-frequency (<2GHz) observations of these regions are needed to help build star formation models. The region toward…

Astrophysics of Galaxies · Physics 2021-12-08 Chenoa D. Tremblay , Tyler L. Bourke , James A. Green , John M. Dickey , O. Ivy Wong , Tim J. Galvin

Gaia is the cornerstone mission of the European Space Agency. From late 2013 it will start collecting superb astrometric, photometric and spectroscopic data for around a billion of stars of our Galaxy. While surveying the whole sky down to…

Instrumentation and Methods for Astrophysics · Physics 2012-10-23 Lukasz Wyrzykowski , Simon Hodgkin , Nadejda Blogorodnova , Sergey Koposov , Ross Burgon

We perform the first measurement of the thermal and ionization state of the intergalactic medium (IGM) across 0.9 < z < 1.5 using 301 \lya absorption lines fitted from 12 HST STIS quasar spectra, with a total pathlength of \Delta z=2.1. We…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-06 Teng Hu , Vikram Khaire , Joseph F. Hennawi , Todd M. Tripp , Jose Oñorbe , Michael Walther , Zarija Lukic

One of the major differences between various explosion scenarios of Type Ia supernovae (SNe Ia) is the remaining amount of unburned (C+O) material and its velocity distribution within the expanding ejecta. While oxygen absorption features…

Cassiopeia A (Cas A) as the nearby young remnant of a core-collapse supernova is the best candidate for astrophysical studies in supernova explosion and its environment. We studied hard X-ray emissions from Cas A using the ten-year data of…

High Energy Astrophysical Phenomena · Physics 2016-07-13 Wei Wang , Zhuo Li

Aims: This paper aims to demonstrate the importance of short-exposure extreme ultraviolet (EUV) observations of solar flares in the study of particle acceleration, heating and energy partition in flares. This work highlights the…

Present-day semi-empirical models of solar irradiance (SI) variations employ spectra computed on one-dimensional atmosphere models (1D models) representative of various solar surface features to reconstruct SI changes measured on timescales…

Solar and Stellar Astrophysics · Physics 2017-06-14 A. Cristaldi , I. Ermolli

The sensitivity of stellar spectra to alpha/Fe abundance changes is investigated with the aim to be detected photometricly and employed for scientific goals of the GAIA mission. A grid of plane parallel, line blanketed, flux constant, LTE…

Astrophysics · Physics 2009-11-07 Grazina Tautvaisiene , Bengt Edvardsson

In this paper we advance the simple analytic photometric redshift estimator for Type Ia supernovae (SNe Ia) proposed by Wang (2007), and use it to study simulated SN Ia data. We find that better than 0.5% accuracy in z_phot (with…

Astrophysics · Physics 2009-11-13 Yun Wang , Gautham Narayan , Michael Wood-Vasey

Following our previous study of Artificial Intelligence Assisted Inversion (AIAI) of supernova analyses (Chen et al. 2020), we train a set of deep neural networks based on the one-dimensional radiative transfer code TARDIS (Kerzendorf & Sim…

High Energy Astrophysical Phenomena · Physics 2022-11-15 Xingzhuo Chen , Lifan Wang , Lei Hu , Peter J. Brown

Nanoflares in quiet-Sun regions during solar cycle 24 are studied with the best available plasma diagnostics to derive their energy distribution and contribution to coronal heating during different levels of solar activity. Extreme…

Solar and Stellar Astrophysics · Physics 2022-05-25 Stefan Purkhart , Astrid M. Veronig

We have expanded upon earlier work that investigates the relative importance of coronal loops with isothermal $versus$ multithermal cross-field temperature distributions. These results are important for determining if loops have…

Solar and Stellar Astrophysics · Physics 2017-05-29 J. T. Schmelz , G. M. Christian , R. A. Chastain

The Pierre Auger Observatory is planned to be upgraded so that the energy spectrum of cosmic rays can be studied down to 0.1 EeV and the muon component of showers can be determined. The former will lead to a spectrum measured by one…

Astrophysics · Physics 2007-10-10 Pierre Auger Collaboration , A. Etchegoyen

Context. The contribution of quiet-Sun regions to the solar irradiance variability is currently unclear. Some solar-cycle variations of the quiet-Sun physical structure, such as the temperature gradient, might affect the irradiance. The…

Solar and Stellar Astrophysics · Physics 2018-09-05 M. Faurobert , M. Carbillet , L. Marquis , A. Chiavassa , G. Ricort