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Interstellar extinction in ultraviolet is the most severe in comparison with optical and infrared wavebands and a precise determination plays an important role in correctly recovering the ultraviolet brightness and colors of objects. By…

Solar and Stellar Astrophysics · Physics 2018-08-01 Mingxu Sun , B. W. Jiang , He Zhao , Jian Gao , Shuang Gao , Mingjie Jian , Haibo Yuan

Stellar flares are a frequent occurrence on young low-mass stars around which many detected exoplanets orbit. Flares are energetic, impulsive events, and their impact on exoplanetary atmospheres needs to be taken into account when…

Earth and Planetary Astrophysics · Physics 2017-12-13 J. M. Chadney , T. T. Koskinen , M. Galand , Y. C. Unruh , J. Sanz-Forcada

We study the origin of the UV-excess in star clusters by performing N-body simulations of six clusters with N=10k and N=100k (single stars & binary systems) and metallicities of Z=0.01, 0.001, and 0.0001, using PETAR. All models initially…

Astrophysics of Galaxies · Physics 2022-09-14 Xiaoying Pang , Qi Shu , Long Wang , M. B. N. Kouwenhoven

Using a recent census of flare stars from the Kepler survey, we have explored how flare activity evolves across stellar main sequence lifetimes. We utilize a sample of 347 stars with robust flare activity detections, and which have rotation…

Solar and Stellar Astrophysics · Physics 2019-02-13 James R. A. Davenport , Kevin R. Covey , Riley W. Clarke , Austin C. Boeck , Jonathan Cornet , Suzanne L. Hawley

Magnetic storms on stars manifest as remarkable, randomly occurring changes of the luminosity over durations that are tiny in comparison to the normal evolution of stars. These stellar flares are bursts of electromagnetic radiation from…

Solar and Stellar Astrophysics · Physics 2024-02-13 Adam F. Kowalski

Stellar flares present challenges to the potential habitability of terrestrial planets orbiting M dwarf stars through inducing changes in the atmospheric composition and irradiating the planet's surface in large amounts of ultraviolet…

Globular clusters are gravitationally bound stellar systems containing on the order of 100,000 stars. Due to the high stellar densities in the cores of these clusters, close encounters and even physical collisions between stars are…

Astrophysics · Physics 2007-05-23 Christian Knigge

We present a survey of far-ultraviolet (FUV; 1150 - 1450 Ang) emission line spectra from 71 planet-hosting and 33 non-planet-hosting F, G, K, and M dwarfs with the goals of characterizing their range of FUV activity levels, calibrating the…

The Galaxy Evolution Explorer (GALEX) satellite has obtained high time resolution ultraviolet photometry during a large flare on the M4 dwarf star GJ 3685A. Simultaneous NUV (1750 - 2800A) and FUV (1350 - 1750A) time-tagged photometry with…

We report multi-wavelength observations of four solar flares on 2014 July 07. We firstly select these flares according to the soft X-ray (SXR) and extreme ultraviolet (EUV) emissions recorded by the Extreme Ultraviolet Variability…

Solar and Stellar Astrophysics · Physics 2021-05-05 Dong Li , Alexander Warmuth , Lei Lu , Zongjun Ning

When stars form in small groups (N = 100 - 500 members), their circumstellar disks are exposed to little EUV radiation but a great deal of FUV radiation from massive stars in the group. This paper calculates mass loss rates for…

Astrophysics · Physics 2009-11-10 Fred C. Adams , David Hollenbach , Gregory Laughlin , Uma Gorti

Superflares on solar-type stars has been a rapidly developing field ever since the launch of $\it Kepler$. Over the years, there have been several studies investigating the statistics of these explosive events. In this study, we present a…

Solar and Stellar Astrophysics · Physics 2020-04-22 Lauren Doyle , Gavin Ramsay , J. Gerard Doyle

The habitability of planets around M dwarfs ($\lesssim 0.5 M_\odot$) can be affected by the XUV (X rays + extreme UV) emission of these stars, with flares occasionally increasing the XUV flux by more than 2 orders of magnitude above…

Earth and Planetary Astrophysics · Physics 2022-03-22 Laura Neves Ribeiro do Amaral , Rory Barnes , Antígona Segura , Rodrigo Luger

We use a new interdisciplinary approach to study the UV surface habitability of Proxima $b$ under quiescent and flaring stellar conditions. We assumed planetary atmospheric compositions based on CO$_2$ and N$_2$ and surface pressures from…

We have discovered ultraviolet halos extending as far as 5{\deg} around four (of six) bright UV stars using data from the GALEX satellite. These halos are due to the scattering of the starlight from nearby thin, foreground dust clouds. We…

Astrophysics of Galaxies · Physics 2011-09-13 Jayant Murthy , Richard Conn Henry

The radius and surface composition of an exploding massive star,as well as the explosion energy per unit mass, can be measured using early UV observations of core collapse supernovae (SNe). We present the first results from a simultaneous…

Stellar flares are short-duration ($<$ hours) bursts of radiation associated with surface magnetic reconnection events. Stellar magnetic activity generally decreases as a function of both age and Rossby number, $R_0$, a measure of the…

Solar and Stellar Astrophysics · Physics 2024-05-03 Adina D. Feinstein , Darryl Z. Seligman , Kevin France , Jonathan Gagné , Adam Kowalski

The near-ultraviolet (NUV) spectral region is a useful diagnostic for stellar flare physics and assessing the energy environment of young exoplanets, especially as relates to prebiotic chemistry. We conducted a pilot NUV spectroscopic flare…

Ultraviolet radiation is a double-edged sword to life. If it is too strong, the terrestrial biological systems will be damaged. And if it is too weak, the synthesis of many biochemical compounds can not go along. We try to obtain the…

Solar and Stellar Astrophysics · Physics 2010-03-08 Jianpo Guo , Fenghui Zhang , Xianfei Zhang , Zhanwen Han

All-sky photometric time-series missions have allowed for the monitoring of thousands of young ($t_{\rm age} < 800$Myr) to understand the evolution of stellar activity. Here we developed a convolutional neural network (CNN),…