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The chromospheric Lyman-alpha line of neutral hydrogen (Ly$\alpha$; 1216 \r{A}) is the most intense emission line in the solar spectrum, yet until recently observations of flare-related Ly$\alpha$ emission have been scarce. Here, we examine…

Solar and Stellar Astrophysics · Physics 2023-07-25 Harry J. Greatorex , Ryan O. Milligan , Phillip C. Chamberlin

The Lyman-alpha (Ly{\alpha};1216 {\AA}) line is the brightest emission line in the quiescent solar spectrum and radiates a significant fraction of the available nonthermal energy during flares. Despite its importance, there is a lack of…

Solar and Stellar Astrophysics · Physics 2025-04-25 Luke Majury , Ryan Milligan , Elizabeth Butler , Harry Greatorex , Maria Kazachenko

The Lyman-alpha Solar Telescope (LST) on board the Advanced Space-based Solar Observatory (ASO-S) is the first payload to image the full solar disk and the solar corona in both white-light (WL) and ultraviolet (UV) H I Lya, extending up to…

Lyman-$\alpha$ (Ly$\alpha$) is the strongest emission line in the accretion-generated UV spectra from T-Tauri stars and, as such, plays a critical role in regulating chemistry within the surrounding protoplanetary disks. Due to its resonant…

Solar and Stellar Astrophysics · Physics 2024-02-20 Seok-Jun Chang , Nicole Arulanantham , Max Gronke , Gregory J. Herczeg , Edwin A. Bergin

The hydrogen Lyman-$\alpha$ (H {\sc i} Ly$\alpha$) emission during solar flares has rarely been studied in spatially resolved images and its physical origin has not been fully understood. In this paper, we present novel Ly$\alpha$ images…

Solar and Stellar Astrophysics · Physics 2022-09-21 Ying Li , Qiao Li , De-Chao Song , Andrea Francesco Battaglia , Hualin Xiao , Säm Krucker , Udo Schühle , Hui Li , Weiqun Gan , M. D. Ding

As the Lyman-alpha (Lya) line of neutral hydrogen is the brightest emission line in the solar spectrum, detecting increases in irradiance due to solar flares at this wavelength can be challenging due to the very high background. Previous…

Solar and Stellar Astrophysics · Physics 2021-03-31 Ryan O. Milligan

We describe the initial results of a deep long-slit emission line search for redshifted (2.7<z<4.1) Lyman-alpha. These observations are used to constrain the fluorescent Ly-alpha emission from the population of clouds whose absorption…

Astrophysics · Physics 2015-06-24 Andrew J. Bunker , Francine R. Marleau , James R. Graham

The chromospheric Lyman-alpha line of neutral hydrogen (\lya; 1216\AA) is the strongest emission line in the solar spectrum. Fluctuations in \lya\ are known to drive changes in planetary atmospheres, although few instruments have had the…

Solar and Stellar Astrophysics · Physics 2020-08-26 Ryan O. Milligan , Hugh S. Hudson , Phillip C. Chamberlin , Iain G. Hannah , Laura A. Hayes

The Ly$\alpha$ emission line is one of the main observables of galaxies at high redshift, but its output depends strongly on the neutral gas distribution and kinematics around the star-forming regions where UV photons are produced. We…

Lyman-alpha (Lya) is intrinsically the brightest line emitted from active galaxies. While it originates from many physical processes, for star-forming galaxies the intrinsic Lya luminosity is a direct tracer of the Lyman-continuum (LyC)…

Astrophysics of Galaxies · Physics 2019-03-27 David Sobral , Jorryt Matthee

[Abridged] We investigate the physical properties of a Lyman continuum emitter candidate at $z=3.212$ with photometric coverage from $U$ to MIPS 24$\mu$m band and VIMOS/VLT and MOSFIRE/Keck spectroscopy. Investigation of the UV spectrum…

We provide a comprehensive analysis of Ion3, the most distant LyC leaker at $z=3.999$, using multi-band HST photometry and X-Shooter spectroscopy. Deep HST F390W imaging probe uncontaminated LyC flux blueward $\sim$880{\AA}, while the…

Despite being the most prominent emission line in the solar spectrum, there has been a notable lack of studies devoted to variations in Ly$\alpha$ emission during solar flares in recent years. However, the few examples that do exist have…

Solar and Stellar Astrophysics · Physics 2016-03-02 Ryan O. Milligan , Phillip C. Chamberlin

We report the archival discovery of Lyman-$\alpha$ emission from the bright ultraviolet galaxy Y002 at $z=7.677$, spectroscopically confirmed by its ionized carbon [CII] 158$\mu$m emission line. The Ly$\alpha$ line is spatially associated…

Empirical relations between major UV and extreme UV spectral lines are one of the inputs for models of chromospheric and coronal spectral radiances and irradiances. They are also needed for the interpretation of some of the observations of…

Low mass, low metallicity galaxies at low to moderate ($z\lesssim3$) redshifts offer the best opportunity for detailed examination of the interplay between massive stars, ionizing radiation and gas in sources similar to those that likely…

Astrophysics of Galaxies · Physics 2019-10-16 Dawn K. Erb , Danielle A. Berg , Matthew W. Auger , David L. Kaplan , Gabriel Brammer , Max Pettini

There are very few reports of flare signatures in the solar irradiance at H i Lyman {\alpha} at 121.5 nm, i.e. the strongest line of the solar spectrum. The LYRA radiometer onboard PROBA2 has observed several flares for which unambiguous…

Solar and Stellar Astrophysics · Physics 2015-06-11 M. Kretzschmar , M. Dominique , I. E. Dammasch

Aims: Out of a novel observing technique, we publish for the first time, SoHO-SUMER observations of the true spectral line profile of hydrogen Lyman-alpha in quiescent prominences. With SoHO not being in Earth orbit, our high-quality data…

Solar and Stellar Astrophysics · Physics 2015-05-18 W. Curdt , H. Tian , L. Teriaca , U. Schühle

Based on the Sloan Digital Sky Survey Data Release 16, we have detected the large-scale structure of Ly$\alpha$ emission in the Universe at redshifts $z = 2$--3.5 by cross-correlating quasar positions and Ly$\alpha$ emission imprinted in…

Astrophysics of Galaxies · Physics 2022-09-28 Xiaojing Lin , Zheng Zheng , Zheng Cai

We study the average Ly$\alpha$ emission associated with high-$z$ strong (log $N$(H I) $\ge$ 21) damped Ly$\alpha$ systems (DLAs). We report Ly$\alpha$ luminosities ($L_{\rm Ly\alpha}$) for the full as well as various sub-samples based on…

Astrophysics of Galaxies · Physics 2016-12-14 Ravi Joshi , Raghunathan Srianand , Pasquier Noterdaeme , Patrick Petitjean
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