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On the Ratios of Si IV Lines (λ1394/λ1403) in an Emerging Flux Region
Isobe, Hiroaki; Tripathi, Durgesh; Nived, V. N. +1 more
The resonance lines of Si IV formed at λ1394 and 1403 Å are the most critical for the diagnostics of the solar transition region in the observations of the Interface Region Imaging Spectrograph (IRIS). Studying the intensity ratios of these lines (1394 Å/1403 Å), which under optically thin conditions is predicted to be two, helps us to diagnose th…
The Extreme CNO-enhanced Composition of the Primitive Iron-poor Dwarf Star J0815+4729
Burgasser, Adam J.; Aguado, David S.; Allende Prieto, Carlos +2 more
We present an analysis of high-resolution Keck/HIRES spectroscopic observations of J0815+4729, an extremely carbon-enhanced, iron-poor dwarf star. These high-quality data allow us to derive a metallicity of [Fe/H] = -5.49 ± 0.14 from the three strongest Fe I lines and to measure a high [Ca/Fe] = 0.75 ± 0.14. The large carbon abundance of A(C) = 7.…
A Habitable-zone Earth-sized Planet Rescued from False Positive Status
Vanderburg, Andrew; Bryson, Steve; Latham, David W. +9 more
We report the discovery of an Earth-sized planet in the habitable zone of a low-mass star called Kepler-1649. The planet, Kepler-1649 c, is 1.06 ${}_{-0.10}^{+0.15}$ times the size of Earth and transits its 0.1977 ± 0.0051 ${M}_{\odot }$ "mid" M-dwarf host star every 19.5 days. It receives 74% ± 3% the incident flux of Earth, giving it an equilibr…
Estimating the Temperature and Density of a Spicule from 100 GHz Data Obtained with ALMA
Shibata, Kazunari; Shimojo, Masumi; Narukage, Noriyuki +6 more
We succeeded in observing two large spicules simultaneously with the Atacama Large Millimeter/submillimeter Array (ALMA), the Interface Region Imaging Spectrograph (IRIS), and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. One is a spicule seen in the IRIS Mg II slit-jaw images and AIA 304 Å images (Mg II/304 Å spi…
Plasma Diagnostics from Active Region and Quiet-Sun Spectra Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian Distribution
Dudík, Jaroslav; Dzifčáková, Elena; Mason, Helen E. +2 more
We perform plasma diagnostics, including that of the non-Maxwellian κ-distributions, in several structures observed in the solar corona by the Extreme-Ultraviolet Imaging Spectrometer (EIS) on board the Hinode spacecraft. To prevent uncertainties due to the in-flight calibration of EIS, we selected spectral atlases observed shortly after the launc…
A White-light Flare Powered by Magnetic Reconnection in the Lower Solar Atmosphere
Chen, Yajie; Song, Yongliang; Tian, Hui +3 more
White-light flares (WLFs), first observed in 1859, refer to a type of solar flare showing an obvious enhancement of the visible continuum emission. This type of enhancement often occurs in most energetic flares, and is usually interpreted as a consequence of efficient heating in the lower solar atmosphere through nonthermal electrons propagating d…
The Relationship between Chirality, Sense of Rotation, and Hemispheric Preference of Solar Eruptive Filaments
Wang, Yuming; Liu, Rui; Jiang, Chaowei +4 more
The orientation, chirality, and dynamics of solar eruptive filaments are key to our understanding of the magnetic field of coronal mass ejections (CMEs), and therefore to predicting the geoeffectiveness of CMEs arriving at Earth. However, confusion and contention remain over the relationship between the filament chirality, magnetic helicity, and t…
ALMA Observations of Giant Molecular Clouds in M33. II. Triggered High-mass Star Formation by Multiple Gas Colliding Events at the NGC 604 Complex
Kuno, Nario; Tokuda, Kazuki; Tachihara, Kengo +13 more
We present the results of ALMA observations in 12CO(J = 2 - 1), 13CO(J = 2 - 1), and C18O(J = 2 - 1) lines and 1.3 mm continuum emission toward a massive (∼106 M⊙) giant molecular cloud associated with the giant H II region NGC 604 in one of the nearest spiral galaxies, M33, at an angular reso…
Two Episodes of a Filament Eruption from a Fan-spine Magnetic Configuration
Yang, Jiayan; Hong, Junchao; Li, Haidong +1 more
In this paper, we present detailed observations of a filament eruption associated with a B6.0 flare, a jet-like coronal mass ejection (CME), and a type-III radio burst on 2013 March 2. The filament, which is located at the northwest edge of active region (AR) 11183, experienced a partial and then a full eruption. Each episode of the filament erupt…
The (Re)appearance of NGC 925 ULX-3, a New Transient ULX
Fürst, Felix; Middleton, Matthew J.; Roberts, Timothy P. +8 more
We report the discovery of a third ULX in NGC 925 (ULX-3), detected in 2017 November by Chandra at a luminosity of LX = (7.8 ± 0.8) × 1039 erg s-1. Examination of archival data for NGC 925 reveals that ULX-3 was detected by Swift at a similarly high luminosity in 2011, as well as by XMM-Newton in 2017 January at a …