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Bright Network, UVA, and the Physical Modeling of Solar Spectral and Total Irradiance in Recent Solar Cycles
Fontenla, J. M.; Landi, E.
In this paper we study the total solar irradiance (TSI) and the spectral solar irradiance (SSI) by applying the solar disk image decomposition algorithm (SDIDA) and solar irradiance synthesis algorithm (SISA) methods. These methods were applied to space-based observations in previous works, but in this work, they are applied to ground-based observ…
Quantifying Turbulent Dynamics Found within the Plasma Sheets of Multiple Solar Flares
McKenzie, David E.; Freed, Michael S.
It is vital to our understanding of solar flares that we discern how turbulent motion can affect the magnetic reconnection process. The objective of this study is to quantify the velocity and vorticity structures inherent in the observed motions found in a plasma sheet above arcades during a solar flare. The most noticeable features in these plasm…
The Advanced Spectral Library (ASTRAL): Reference Spectra for Evolved M Stars
Ayres, Thomas R.; Carpenter, Kenneth G.; Nielsen, Krister E. +3 more
The HST Treasury Program Advanced Spectral Library Project: Cool Stars was designed to collect representative, high-quality UV spectra of eight evolved F-M type cool stars. The Space Telescope Imaging Spectrograph (STIS) echelle spectra of these objects enable investigations of a broad range of topics, including stellar and interstellar astrophysi…
The Long-term Secular Mass Accretion Rate of the Recurrent Nova T Pyxidis
Williams, Robert E.; Sion, Edward M.; Godon, Patrick +1 more
We present Hubble Space Telescope ultraviolet spectroscopy of the recurrent nova T Pyxidis obtained more than five years after its 2011 outburst, indicating that the system might not have yet reached its deep quiescent state. The ultraviolet data exhibit a 20% decline in the continuum flux from the pre-outburst deep quiescence state to the post-ou…
Possible Association of Two Stellar Bowshocks with Unidentified Fermi Sources
Luque-Escamilla, P. L.; Romero, G. E.; Martí, J. +2 more
The bowshocks of runaway stars had been theoretically proposed as gamma-ray sources. However, this hypothesis has not been confirmed by observations to date. In this paper, we present two runaway stars (λ Cep and LS 2355) whose bowshocks are coincident with the unidentified Fermi gamma-ray sources 3FLG J2210.1+5925 and 3FGL J1128.7-6232, respectiv…
Discovery of New Coronal Lines at 2.843 and 2.853 µm
DeLuca, Edward E.; Judge, Philip G.; Samra, Jenna E. +1 more
Two new emission features were observed during the 2017 August 21 total solar eclipse by a novel spectrometer, the Airborne Infrared Spectrometer (AIR-Spec), flown at 14.3 km altitude aboard the NCAR Gulfstream-V aircraft. We derive wavelengths in air of 2.8427 ± 0.00009 µm and 2.8529 ± 0.00008 µm. One of these lines belongs to the 3{{…
z ∼ 2.5-3 Ionizers in the GOODS-N Field
Barger, A. J.; Cowie, L. L.; Oesch, P. +4 more
We use deep F275W imaging from the Hubble Deep UV Legacy Survey (HDUV) and G280 grism spectroscopy from the Hubble Space Telescope/WFC3, along with new and archival optical spectra from Keck/DEIMOS, to search for candidate ionizing sources in the GOODS-N field at z ∼ 2.5-3. Spectroscopic identification of our UV-selected sources are 99% complete t…
Gradual Streamer Expansions and the Relationship between Blobs and Inflows
Hess, P.; Wang, Y. -M.
Coronal helmet streamers show a continual tendency to expand outward and pinch off, giving rise to flux ropes that are observed in white light as “blobs” propagating outward along the heliospheric current/plasma sheet. The blobs form within the r ∼ 2-6 R ⊙ heliocentric range of the Large Angle and Spectrometric Coronagraph (LASCO) C2 in…
Space-based Coronagraphic Imaging Polarimetry of the TW Hydrae Disk: Shedding New Light on Self-shadowing Effects
Debes, John H.; Schneider, Glenn; Chen, Christine H. +6 more
We present Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer coronagraphic imaging polarimetry of the TW Hydrae protoplanetary disk. These observations simultaneously measure the total and polarized intensity, allowing direct measurement of the polarization fraction across the disk. In accord with the self-shadowing hypothe…
Size Distributions of Solar Proton Events and Their Associated Soft X-Ray Flares: Application of the Maximum Likelihood Estimator
D'Huys, Elke; Cliver, Edward W.
We use the maximum likelihood estimator to determine the slope (α) of the power-law size distribution of the peak proton fluxes of a subsampled set of 106 ∼ 25 MeV solar energetic proton (SEP) events from 1997 to 2016 associated with western hemisphere soft X-ray (SXR) flares: α = 1.28 ± 0.03. For the peak SXR fluxes of a subsample of 110 SEP-asso…