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Among the identified solar inertial modes, the high-latitude mode with azimuthal order $m=1$ (HL1) has the largest amplitude and plays a role in shaping the Sun's differential rotation profile. We aim to study the evolution of the HL1 mode parameters, utilizing Dopplergrams from the Mount Wilson Observatory (MWO), GONG, and HMI, covering together five solar cycles since 1967. We calculated the averages of line-of-sight Doppler signals over longitude, weighted by the sine of longitude with respect to the central meridian, as a proxy for zonal velocity at the surface. We measured the mode's power and frequency from these zonal velocities at high latitudes in sliding time windows of three years. We find that the amplitude of the HL1 mode undergoes very large variations, taking maximum values at the start of solar cycles 21, 22 and 25, and during the rising phases of cycles 23 and 24. The mode amplitude is anticorrelated with the sunspot number (corr=$-0.50$) but not correlated with the polar field strength. Over the period 1983-2022 the mode amplitude is strongly anticorrelated with the rotation rate at latitude $60^\circ$ (corr=$-0.82$), i.e., with the rotation rate near the mode's critical latitude. The mode frequency variations are small and display no clear solar cycle periodicity above the noise level ($\sim \pm 3$~nHz). Since about 1990, the mode frequency follows an overall decrease of $\sim 0.25$ nHz/year, consistent with the long-term decrease of the angular velocity at $60^\circ$ latitude. We expect that these very long time series of the mode properties will be key to constrain models and reveal the dynamical interactions between the high-latitude modes, rotation, and the magnetic field., Comment: submitted to A&A on 05.09.2024

The Sun's global inertial modes are very sensitive to the solar differential rotation and to properties of the deep solar convection zone which are currently poorly constrained. These properties include the superadiabatic temperature gradient, the latitudinal entropy gradient, and the turbulent viscosity. The inertial modes also play a key role in controlling the Sun's large-scale structure and dynamics, in particular the solar differential rotation. This paper summarizes recent observations and advances in the (linear and nonlinear) modeling of the solar inertial modes., Comment: Submitted on 05-Mar-2024 for publication in procs. IAU Symp 365, Eds. A. Getling and L. Kitchatinov

In a nonrelativistic potential quark model framework, we carry out a serious calculation of the all-heavy pentaquarks by adopting the explicitly correlated Gaussian method.A complete mass spectrum for the $1S$ states is obtained. For the $cccc\bar{c}$, $cccc\bar{b}$, $bbbb\bar{c}$, $bbbb\bar{b}$, $ccbb\bar{c}$, and $bbcc\bar{b}$ systems, the obtained states are compact and lie far above the lowest dissociation baryon-meson threshold. While, in the $cccb\bar{c}$, $cccb\bar{b}$, $bbbc\bar{c}$, and $bbbc\bar{b}$ systems with $\{123\}4\bar{5}$ symmetry, the two low-lying configurations with $J^P=5/2^-$ and $3/2^-$ have a typical molecular structure due to the special role of the color-Coulomb interactions, they may be good candidates of stable states below the dissociation baryon-meson thresholds., Comment: 12 pages, 3 figures

We use nearly two decades of helioseismic data obtained from the GONG (2002-2020) and HMI (2010-2020) ring-diagram pipelines to examine the temporal variations of the properties of individual equatorial Rossby modes with azimuthal orders in the range $6 \le m \le 10$. We find that the mode parameters obtained from GONG and HMI are consistent during the data overlapping period of 2010-2020. The power and the frequency of each mode exhibit significant temporal variations over the full observing period. Using the GONG data during solar cycles 23 and 24, we find that the mode power averaged over $6 \le m \le 10$ shows a positive correlation with the sunspot number ($0.42$), while the averaged frequency shift is anti-correlated ($-0.91$). The anti-correlation between the average mode power and frequency shift is $-0.44$.

Context. In local helioseismology, the travel times of acoustic waves propagating in opposite directions along the same meridian inform us about horizontal flows in the north-south direction. The longitudinal averages of the north-south helioseismic travel-time shifts vary with the sunspot cycle. Aims. We aim to study the contribution of inflows into solar active regions to this solar-cycle variation. Methods. To do so, we identify the local flows around active regions in the horizontal flow maps obtained from correlation tracking of granulation in SDO/HMI continuum images. We compute the forward-modeled travel-time perturbations caused by these inflows using 3D sensitivity kernels. In order to compare with the observations, we average these forward-modeled travel-time perturbations over longitude and time in the same way as the measured travel times. Results. The forward-modeling approach shows that the inflows associated with active regions may account for only a fraction of the solar-cycle variations in the north-south travel-time measurements. Conclusions. The travel-time perturbations caused by the large-scale inflows surrounding the active regions do not explain in full the solar-cycle variations seen in the helioseismic measurements of the meridional circulation. Keywords: Sun: activity -- Sun: helioseismology, Comment: 12 pages, 12 figures

The oscillations of a slowly rotating star have long been classified into spheroidal and toroidal modes. The spheroidal modes include the well-known 5-min acoustic modes used in helioseismology. Here we report observations of the Sun's toroidal modes, for which the restoring force is the Coriolis force and whose periods are on the order of the solar rotation period. By comparing the observations with the normal modes of a differentially rotating spherical shell, we are able to identify many of the observed modes. These are the high-latitude inertial modes, the critical-latitude inertial modes, and the equatorial Rossby modes. In the model, the high-latitude and critical-latitude modes have maximum kinetic energy density at the base of the convection zone, and the high-latitude modes are baroclinically unstable due to the latitudinal entropy gradient. As a first application of inertial-mode helioseismology, we constrain the superadiabaticity and the turbulent viscosity in the deep convection zone., Comment: Forthcoming article, Astronomy and Astrophysics