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Correlating Intrinsic Stellar Parameters with Mg II Self-Reversal Depths
Anna Taylor, Audrey Dunn, Sarah Peacock +2
The Mg II h&k emission lines (2803, 2796 A) are a useful tool for understanding stellar chromospheres and transition regions due to their intrinsic brightness, relatively low inter…
The MUSCLES Extension for Atmospheric and Transmission Spectroscopy: UV and X-ray Host-star Observations for JWST ERS & GTO Targets
Patrick R. Behr, Kevin France, Alexander Brown +8
X-ray through infrared spectral energy distributions (SEDs) are essential for understanding a star's effect on exoplanet atmospheric composition and evolution. We present a catalog…
Coronal Heating as Determined by the Solar Flare Frequency Distribution Obtained by Aggregating Case Studies
James Paul Mason, Alexandra Werth, Colin G. West +999
Flare frequency distributions represent a key approach to addressing one of the largest problems in solar and stellar physics: determining the mechanism that counter-intuitively he…
Coronal X-Ray Emission from Nearby, Low-Mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects
Alexander Brown, P. Christian Schneider, Kevin France +8
The high energy X-ray and ultraviolet (UV) radiation fields of exoplanet host stars play a crucial role in controlling the atmospheric conditions and the potential habitability of…
Disentangling Stellar and Airglow Emission Lines from HST-COS Spectra
Fernando Cruz Aguirre, Allison Youngblood, Kevin France +1
H I Ly (1215.67 Å) and the O I triplet (1302.17, 1304.86, and 1306.03 Å) are bright far-ultraviolet (FUV) emission lines that trace the stellar chromosphere. Observations of ste…
FUMES III: Ultraviolet and Optical Variability of M Dwarf Chromospheres
Girish M. Duvvuri, J. Sebastian Pineda, Zachory K. Berta-Thompson +2
We obtained ultraviolet and optical spectra for 9 M~dwarfs across a range of rotation periods to determine whether they showed stochastic intrinsic variability distinguishable from…
A Pilot Survey of an M Dwarf Flare Star with Swift's UV Grism
Shashank Chavali, Allison Youngblood, Rishi R. Paudel +5
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 prebi…
X-ray Emission from the Exoplanet Hosting LTT 1445 Triple Star System
Alexander Brown, Cynthia S. Froning, Allison Youngblood +5
JWST will be able to observe the atmospheres of rocky planets transiting nearby M dwarfs. The M dwarf triple star system LTT 1445, at a distance of 6.86 pc, hosts some of the neare…
The Mouse that Squeaked: A small flare from Proxima Cen observed in the millimeter, optical, and soft X-ray with Chandra and ALMA
Ward S. Howard, Meredith A. MacGregor, Rachel Osten +10
We present millimeter, optical, and soft X-ray observations of a stellar flare with an energy squarely in the regime of typical X1 solar flares. The flare was observed from Proxima…
Testing Lyman alpha emission line reconstruction routines at multiple velocities in one system
David J. Wilson, Allison Youngblood, Odette Toloza +6
The 1215.67A HI Lyman alpha emission line dominates the ultraviolet flux of low mass stars, including the majority of known exoplanet hosts. Unfortunately, strong attenuation by th…
Constraining the Physical Properties of Stellar Coronal Mass Ejections with Coronal Dimming: Application to Far Ultraviolet Data of Eridani
R. O. Parke Loyd, James Mason, Meng Jin +9
Coronal mass ejections (CMEs) are a prominent contributor to solar system space weather and might have impacted the Sun's early angular momentum evolution. A signal diagnostic of C…
The Mysterious Affair of the H in AU Mic
Laura Flagg, Christopher Johns-Krull, Kevin France +8
Molecular hydrogen is the most abundant molecule in the Galaxy and plays important roles for planets, their circumstellar environments, and many of their host stars. We have confir…
AU Microscopii in the FUV: Observations in Quiescence, During Flares, and Implications for AU Mic b and c
Adina D. Feinstein, Kevin France, Allison Youngblood +13
High energy X-ray and ultraviolet (UV) radiation from young stars impacts planetary atmospheric chemistry and mass loss. The active Myr M dwarf AU Mic hosts two exoplanet…
Intrinsic Lyman alpha Profiles of High-Velocity G, K, and M Dwarfs
Allison Youngblood, J. Sebastian Pineda, Thomas Ayres +5
Observations of H I Lyman alpha, the brightest UV emission line of late-type stars, are critical for understanding stellar chromospheres and transition regions, modeling photochemi…
Brown dwarfs as ideal candidates for detecting UV aurora outside the Solar System: Hubble Space Telescope observations of 2MASS J1237+6526
Joachim Saur, Clarissa Willmes, Christian Fischer +5
Context: Observations of auroral emissions are powerful means to remotely sense the space plasma environment around planetary bodies and ultracool dwarfs. Therefore successful sear…
Simultaneous Multiwavelength Flare Observations of EV Lacertae
Rishi R. Paudel, Thomas Barclay, Joshua E. Schlieder +17
We present the first results of our ongoing project conducting simultaneous multiwavelength observations of flares on nearby active M dwarfs. We acquired data of the nearby dM3.5e…
The M-dwarf Ultraviolet Spectroscopic Sample I. Determining Stellar Parameters for Field Stars
J. Sebastian Pineda, Allison Youngblood, Kevin France
Accurate stellar properties are essential for precise stellar astrophysics and exoplanetary science. In the M-dwarf regime, much effort has gone into defining empirical relations t…
Discovery of an Extremely Short Duration Flare from Proxima Centauri Using Millimeter through FUV Observations
Meredith A. MacGregor, Alycia J. Weinberger, R. O. Parke Loyd +17
We present the discovery of an extreme flaring event from Proxima Cen by ASKAP, ALMA, HST, TESS, and the du Pont Telescope that occurred on 2019 May 1. In the millimeter and FUV, t…
The high-energy spectrum of the nearby planet-hosting inactive mid-M dwarf LHS 3844
Hannah Diamond-Lowe, Allison Youngblood, David Charbonneau +5
To fully characterize the atmospheres, or lack thereof, of terrestrial exoplanets we must include the high-energy environments provided by their host stars. The nearby mid-M dwarf…
FUMES. II. Ly Reconstructions of Young, Active M Dwarfs
Allison Youngblood, J. Sebastian Pineda, Kevin France
The HI Ly (1215.67 $\unicode{xC5}$) emission line dominates the far-UV spectra of M dwarf stars, but strong absorption from neutral hydrogen in the interstellar medium makes obs…
The Far Ultraviolet M-dwarf Evolution Survey. I. The Rotational Evolution of High-Energy Emissions
J. Sebastian Pineda, Allison Youngblood, Kevin France
M-dwarf stars are prime targets for exoplanet searches because of their close proximity and favorable properties for both planet detection and characterization. However, the potent…
The Mega-MUSCLES Spectral Energy Distribution Of TRAPPIST-1
David J. Wilson, Cynthia S. Froning, Girish M. Duvvuri +19
We present a 5A-100um Spectral Energy Distribution (SED) of the ultracool dwarf star TRAPPIST-1, obtained as part of the Mega-MUSCLES Treasury Survey. The SED combines ultraviolet…
Reconstructing the Extreme Ultraviolet Emission of Cool Dwarfs Using Differential Emission Measure Polynomials
Girish M. Duvvuri, J. Sebastian Pineda, Zachory K. Berta-Thompson +16
Characterizing the atmospheres of planets orbiting M dwarfs requires understanding the spectral energy distributions of M dwarfs over planetary lifetimes. Surveys like MUSCLES, HAZ…
Ca II H&K stellar activity parameter: a proxy for stellar Extreme Ultraviolet Fluxes
A. G. Sreejith, L. Fossati, A. Youngblood +2
Atmospheric escape is an important factor shaping the exoplanet population and hence drives our understanding of planet formation. Atmospheric escape from giant planets is driven p…