Search Publications
Flare-accelerated Electrons in the Kappa Distribution from X-Ray Spectra with the Warm-target Model
Kontar, Eduard P.; Luo, Yingjie; Bhattacharjee, Debesh
X-ray observations provide important and valuable insights into the acceleration and propagation of nonthermal electrons during solar flares. Improved X-ray spectral analysis requires a deeper understanding of the dynamics of energetic electrons. Previous studies have demonstrated that the dynamics of accelerated electrons with a few thermal speed…
Magnetic Fields in a Sample of Planet-hosting M Dwarf Stars from Kepler, K2, and TESS Observed by APOGEE
Wanderley, Fábio; Cunha, Katia; Smith, Verne V. +8 more
Stellar magnetic fields have a major impact on space weather around exoplanets orbiting low-mass stars. From an analysis of Zeeman-broadened Fe I lines measured in near-infrared SDSS/APOGEE spectra, mean magnetic fields are determined for a sample of 29 M dwarf stars that host closely orbiting small exoplanets. The calculations employed the radiat…
Molecular Hydrogen Line Identifications in Solar Flares Observed by IRIS: Lower Atmospheric Structure from Radiometric Analysis
Jaeggli, Sarah A.; Daw, Adrian N.
A rich spectrum of molecular hydrogen (H2) emission lines is seen in sensitive observations from the far-ultraviolet (FUV) channels of the Interface Region Imaging Spectrograph (IRIS) during flare activity in solar active region NOAA Active Region 11861. Based on this observation, we have determined 37 new line identifications by compar…
Rotational Velocities and Radii Estimates of Low-mass Pre-main-sequence Stars in NGC 2264
Rhode, Katherine L.; Rebull, Luisa M.; Gray, Laurin M. +2 more
Investigating the angular momentum evolution of pre-main-sequence (PMS) stars provides important insight into the interactions between Sun-like stars and their protoplanetary disks, and the timescales that govern disk dissipation and planet formation. We present projected rotational velocities (v sin i values) of 254 T Tauri stars (TTSs) in the ∼3…
Long-term Evolution in Ionization of Ejecta Illuminated by Eta Carinae
Corcoran, Michael F.; Moffat, Anthony F. J.; Damineli, Augusto +6 more
Changes in the flux and spectrum of Eta Carinae (η Car) since 1900 have been attributed to the evolution of the central binary by some. Others suggest evolution in the occulting ejecta. The brightness jump in the 1940s, which coincided with the appearance of narrow forbidden emission lines, may have been caused by the clearing and ionization of in…
On the Influence of the Solar Wind on the Propagation of Earth-impacting Coronal Mass Ejections
Gopalswamy, Nat; Srivastava, Nandita; Kumar, Sandeep +1 more
Coronal mass ejections (CMEs) are subject to changes in their direction of propagation, tilt, and other properties as they interact with the variable solar wind. We investigated the heliospheric propagation of 15 Earth-impacting CMEs observed during 2010 April to 2018 August in the field of view (FOV) of the Heliospheric Imager (HI) on board the S…
A Tale of Three Dwarfs: Cluster-based Star Formation Histories of Blue Compact Dwarf Galaxies
Calzetti, Daniela; Whitmore, Bradley C.; Chandar, Rupali +9 more
We present a new study of the cluster populations in the blue compact dwarf galaxies (BCD) ESO185-IG13, ESO338-IG04, and Haro11, based on new and archival high-resolution images taken by the Hubble Space Telescope, and the first to probe the populations older than ≈100 Myr. BCDs are believed to experience intense bursts of star formation (includin…
Temperature Intermittent Structures in the Fast Solar Wind
Wang, Xin; Wang, Yuxin; Song, Dongze +1 more
In the solar wind turbulence, proton temperature fluctuations are highly intermittent, especially at small scales in the inertial range. This phenomenon may contain information about solar wind intermittent heating. However, the physical nature of the temperature intermittency is not yet clear. Based on the measurements from Solar Orbiter between …
Electron Densities of Transition Region Loops Derived from IRIS O IV Spectral Data
Fu, Hui; Xia, Lidong; Huang, Zhenghua +4 more
Loops are fundamental structures in the magnetized atmosphere of the Sun. Their physical properties are crucial for understanding the nature of the solar atmosphere. Transition region loops are relatively dynamic and their physical properties have not yet been fully understood. With spectral data of the line pair of O IV 1399.8 Å and 1401.2 Å (
Aperture and Resolution Effects on Ultraviolet Star-forming Properties: Insights from Local Galaxies and Implications for High-redshift Observations
Leitherer, Claus; Berg, Danielle A.; Arellano-Córdova, Karla Z. +2 more
We present an analysis of the effects of spectral resolution and aperture scale on derived galaxy properties using far-ultraviolet (FUV) spectra of local star-forming galaxies from the International Ultraviolet Explorer (R ∼ 250, field of view (FOV) ∼ 10″ × 20″) and Cosmic Origins Spectrograph on the Hubble Space Telescope (R ∼ 15,000, FOV ∼ 2.″5)…