Search Publications
Asteroseismic modelling of the chemically peculiar B-type pulsator with an asymptotic period spacing - a Cen
Walczak, Przemysław; Kopacz, Agnieszka
A Cen is recognized as a magnetic variable star with peculiar helium abundance. The presence of large surface spots induces flux modulation, allowing for the derivation of the surface rotational period (~8.8 d). TESS photometry has unveiled additional signals that we interpreted as SPB-type pulsation. Furthermore, we managed to find a regular peri…
Refinement of Global Coronal and Interplanetary Magnetic Field Extrapolations Constrained by Remote-sensing and In Situ Observations at the Solar Minimum
Feng, Li; Gan, Weiqun; Shi, Guanglu +2 more
Solar magnetic fields are closely related to various physical phenomena on the Sun, which can be extrapolated with different models from photospheric magnetograms. However, the open flux problem (OFP), the underestimation of the magnetic field derived from the extrapolated model, is still unsolved. To minimize the impact of the OFP, we propose thr…
Overview of a large observing campaign of Jupiter's aurora with the Hubble Space Telescope combined with Juno-UVS data
Bonfond, B.; Nichols, J. D.; Gérard, J. -C. +8 more
Between February and September 2019, Jupiter's ultraviolet aurorae were frequently observed during a large campaign of the Hubble Space Telescope (HST GO-15638). The campaign included approximately 10 visits around each of the perijoves of the Juno spacecraft orbits 18 to 22 around Jupiter. During this time, the solar activity was minimal, giving …
Nature of the Distant Component in the Triple System DV Cam
Zejda, M.; Bakış, V.
DV Cam (HD 34233) is a relatively bright spectroscopic binary system exhibiting complex variability. This study presents an extensive analysis of its orbital dynamics and pulsational behavior using multi-source photometric data, including the Hipparcos, ground-based, and TESS satellite observations. The O–C residuals analysis reveals a sinusoidal …
Solar Chromospheric Heating by Magnetohydrodynamic Waves: Dependence on the Inclination of the Magnetic Field
Shimizu, Toshifumi; Koyama, Mayu
A proposed mechanism for solar chromospheric heating is magnetohydrodynamic waves propagating upward along magnetic field lines and dissipating their energy in the chromosphere. In particular, compressible magnetoacoustic waves may contribute to the heating. Theoretically, the components below the cutoff frequency cannot propagate into the chromos…
Long-Term Trends in Subsurface Flows of Solar Cycle 23 to 25
Komm, Rudolf
We study the long-term variation of the zonal and meridional flows from Solar Cycle 23 to 25 derived with ring-diagram analysis applied to Global Oscillation Network Group (GONG) and Helioseismic and Magnetic Imager (HMI) Dopplergrams. We focus mainly on the subsurface flows averaged over depths from 2.0 Mm to 11.6 Mm since their long-term variati…
The global mapping of electron precipitation and ionospheric conductance from whistler-mode chorus waves
Gillespie, Dillon; Connor, Hyunju Kim; Ma, Qianli +4 more
Auroral precipitation is the second major energy source after solar irradiation that ionizes the Earth's upper atmosphere. Diffuse electron aurora caused by wave-particle interaction in the inner magnetosphere (L < 8) takes over 60% of total auroral energy flux, strongly contributing to the ionospheric conductance and thus to the ionosphere-the…
Synoptic maps from two viewpoints. Preparing for maps from SDO/HMI and SO/PHI data
Solanki, S. K.; Schou, J.; Valori, G. +2 more
Context. Over recent decades, various kinds of magnetic synoptic chart products have seen major improvements in observation cadence, resolution, and processing, but their creation is still limited by the 27.27 day rotation rate of the solar surface.
Aims: Co-observation from a second vantage point away from the Earth-Sun line with SO/PHI enab…
On the nature of the eccentric eclipsing binary star SY Phe with a pulsating γ Dor component
Erdem, Ahmet; Sürgit, Derya; Engelbrecht, Chris A. +3 more
Spectroscopic observations of the eccentric binary system SY Phe were made at the South African Astronomical Observatory in 2019, 2020, and 2021, and its mid-resolution spectra were obtained. The radial velocities of the component stars were measured using the cross-correlation method and Fourier disentangling of the spectra. The spectral type (he…
A machine learning approach to estimate mid-infrared fluxes from WISE data
Fonseca-Bonilla, Nuria; Cerdán, Luis; Noriega-Crespo, Alberto +1 more
Context. While the Wide-field Infrared Survey Explorer (WISE) is the largest, best quality infrared all-sky survey to date, a smaller coverage mission, Spitzer, was designed to have better sensitivity and spatial resolution at similar wavelengths. Confusion and contamination in WISE data result in discrepancies between them. Aims. We aim to presen…