Search Publications
Source of the Observed Enhancements in Thermospheric ΣO/N2 During Two Solar Eclipses in 2023
Zhang, Y.; Cantrall, C. E.; Mrak, S. +4 more
Two solar eclipse events in 2023 appeared to produce considerable enhancements in the thermospheric column density ratio of monatomic oxygen to molecular nitrogen (ΣO/N2) as measured by TIMED GUVI. We quantify potential sources for eclipse-induced ΣO/N2 changes and find that the observed enhancements arise from the ionospheri…
The X-Ray Emission Reveals the Coronal Activities of Semi-detached Binaries
Liu, Junhui; Wu, Jianfeng
X-ray emission is an important tracer of stellar magnetic activity. We carried out a systematic correlation analysis for the X-ray luminosity
The MODEST catalog of depth-dependent spatially coupled inversions of sunspots observed by Hinode/SOT-SP
Solanki, S. K.; Korpi-Lagg, A.; Castellanos Durán, J. S. +3 more
We present a catalog that contains depth-dependent information about the atmospheric conditions inside sunspot groups of all types. The catalog, which we named MODEST, is currently composed of 944 observations of 117 individual active regions with sunspots and covers all types of features observed in the solar photosphere. We used the SPINOR-2D co…
Spectra and Anisotropy of Solar Energetic Protons During GLE #65 on 28 October, 2003 and GLE #66 on 29 October, 2003
Mishev, Alexander L.; Koldobskiy, Sergey A.; Larsen, Nicholas +1 more
Solar Cycle 23 was the most active in ground-level enhancements (GLEs) with 16 events registered by the global neutron monitor network. In this paper, we study a very active period in October–November, 2003, which revealed an intense solar activity burst that led to several eruptive processes and produced a sequence of three GLEs. By applying stat…
Energy estimation of small-scale jets from the quiet-Sun region
Li, Dong; Ning, Zongjun; Shi, Fanpeng +3 more
Context. Solar jets play a role in coronal heating and the supply of solar wind.
Aims: In this study, we calculate the energies of 23 small-scale jets emerging from a quiet-Sun region in order to investigate their contributions to coronal heating.
Methods: We used data from the High-Resolution Imager (HRI) of the Extreme Ultraviolet Imag…
Mildly explosive eruptions at Martian low-shield volcanoes
Pieterek, Bartosz; Jones, Thomas J.
Ongoing acquisition of Martian surface imagery constantly provides new opportunities to reveal previously undiscovered small-scale volcanic landforms, yielding critical insights into volcanic processes, and challenging existing inferences. Here, using the most recent, high-resolution topographical data, we mapped the accumulation of pyroclastic de…
Fine structure of the age-chromospheric activity relation in solar-type stars: II. Hα line
Ribas, I.; Porto de Mello, G. F.; Almeida-Fernandes, F. +4 more
Excess chromospheric emissions within deep photospheric lines are effective proxies of stellar magnetism for FGK stars. This emission decays with stellar age and is a potential determinant of this important stellar quantity. We report absolutely calibrated H $\alpha$ chromospheric fluxes for 511 solar-type stars in a wide interval of precisely det…
The Evolution of Stellar X-Ray Activity and Angular Momentum as Seen by eROSITA, TESS, and Gaia
Stassun, Keivan G.; Kounkel, Marina
We have assembled a sample of ∼8200 stars with spectral types F5V–M5V, all having directly measured X-ray luminosities from eROSITA and rotation periods from TESS and having empirically estimated ages via their membership in stellar clusters and groups identified in Gaia astrometry (ages 3–500 Myr). This is the largest such study sample yet assemb…
Thermal Evolution of an Active Region Through Quiet and Flaring Phases as Observed by NuSTAR, XRT, and AIA
Reeves, Katharine K.; Grefenstette, Brian W.; Shih, Albert Y. +6 more
Solar active regions (ARs) contain a broad range of temperatures, with the thermal plasma distribution often observed to peak in the few millions of kelvin. Differential emission measure (DEM) analysis can allow instruments with diverse temperature responses to be used in concert to estimate this distribution. Nuclear Spectroscopic Telescope ARray…
Constraining the Progenitor of the Nearby Type II-P SN 2024ggi with Environmental Analysis
Niu, Zexi; Sun, Ning-Chen; Liu, Jifeng +3 more
The progenitors of Type II-P supernovae (SN) have been confirmed to be red supergiants. However, the upper mass limit of the directly probed progenitors is much lower than that predicted by current theories, and the accurate determination of the progenitor masses is key to understand the final fate of massive stars. Located at a distance of only 6…