Journal of Geophysics

Jupiter's primordial beat of superoutbursting stars

2024-12-31T04:23:55+00:00

The decadal global magnetoactivity evolution profile that precedes short-burst pulses in magnetar 4U 0142+61 and superhumps (superoutbursts) in dwarf novae now also emerges from mean least-squares spectra of >12 billion mission-integrated Galileo–Cassini–Juno 1996–2020 annual samplings of Jupiter ⪅8nT global magnetic field. For the first time in any planetary magnetosphere, the profile has revealed a ubiquitous primordial physical property: the presence of a high-power, pulsar-like global dynamic from temporally mapping hyperlow-frequency (<1μHz) systematic dynamics of Jovian magnetospheric signature in the solar wind (Rieger-resonance band of 385.8–64.3 nHz or ~0.3·10⁹–3·10⁹ erg energetic perturbations). The signature served as a proxy of Jovian magnetoactivity expressed in mean least-squares-spectral magnitudes as a novel method for measuring relative field dynamics. The magnetoactivity impressed thus and entirely into the solar wind, and it encompassed the well-known, solar system-permeating ~154-day Rieger period and its first six harmonics. Statistical fidelity of the spectral peaks remained within a very high (Φ≫12) range of 10⁷–10⁵, reflecting the signature’s completeness and incessantness. The magnetoactivity upsurge from spectral means that maintained a stunning ~20% field variance (total annual energy budget) began reformatting the signature around 1999, gradually transforming it into the anomalous state by 2002, as supported by an increased anisotropic splitting of spectral peaks. By contrast, a comparison against 2005–2016 Cassini global samplings revealed a calm Saturnian magnetoactivity at a low ⪅1% field variance except for every ~7.1 yrs when it is ⪅5%, possibly due to orbital–tidal forcing. While this discovery of planetary pulsars as a new pulsar class calls for redefining pulsars to include failed stars, a global pulsation profile of the magnetar–novae type in a failed-star-turned-planet calls for beacon-orbiter missions to monitor Jupiter’s activity and its disruption capacity to solar system infrastructure. Shannon’s theory-based rigorous Gauss–Vaniček least-squares spectral analysis revolutionizes astrophysics by directly computing relative dynamics of global astrophysical fields and space physics by rigorously simulating completed orbits and fleet formations from a single spacecraft.

ARK: https://n2t.net/ark:/88439/x001607

Permalink: https://geophysicsjournal.com/article/347

Omerbashich (2024) Sun dims as failed star Jupiter tries to go full-on pulsar. J. Geophys. 66(1):15-24

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Sun dims as failed star Jupiter tries to go full-on pulsar

2024-12-31T04:24:58+00:00

A Sun–Jupiter decade-scale magnetic tangling appears from Wilcox Solar Observatory 1975–2021, N–S≲150 μT mean field data as a global response of solar magnetic fields to the recently discovered pulsar-like varying evolution of Jupiter global magnetoactivity in the 385.8–64.3 nHz (1–180-day) band of Rieger resonance of the solar wind since 2001. The Jovian sudden deviation has been so high at an extreme ≲20% field variance that it appears to have forced solar magnetoactivity devolution into an inverse-matching response at an effectively moderate ≲1.5% mean field variance. Thus, as Jupiter's decadal magnetoactivity evolved in a rare, increasingly sinusoidal fashion, seen in astronomy not only in magnetars but dwarf-novae as well, the Sun began reducing its magnetoactivity in a decreasingly sinusoidal fashion ~2002 (the epoch of Abbe number drop) to the solar cycle 24 extreme minimum. For a check, 2004–2021 WIND spacecraft data revealed a <0.5-var% (<5-dB) calm ≲50 nT interplanetary magnetic field at L1, slightly undulated by the Jupiter evolution. This revelation excluded the solar wind or the Sun as impulse sources, which agrees with the statistical fidelity waning down Jupiter–L1–Sun diffusion vector spaces, as 10⁷–10³–10². Magnetic tangling of stars with their hot (<0.1 AU) Jupiters was blamed in the past for observed star pulsation and superflaring 10²–10⁷ times more energetic than the strongest solar flare. Accordingly, the Sun's apparent ante-impulse locking creates a shock-absorbing mechanism—a routine Sun shutter response to Jupiter's remnant yet recurrent attempted phasing into the flare-brown-dwarf state—with which the Sun enters a grand minimum (sleep mode). I then propose that, since the mechanism must be primordial, Jupiter intermittently becomes an indirect driver of climate on Earth as the Sun prepares to discharge the mechanism-stored energy as a non-extinction ~10³²-erg superflare (currently overdue). At the same time, this shutting-venting magnetism buffer represents a universal stellar defense mechanism by which stars repel other (active and inactive) incoming stars. The discovery explains Milky Way observations of the ~1:3 relative scarcity of companion-stars systems and why binaries, and progressively multinaries, occur more often with the stellar mass increase, i.e., as this sifting mechanism—remarkably efficient in dwarfs as predominant yet less massive star type—naturally weakens, yielding to gravity. The mechanism could be vital to our understanding of the origin of Jupiter, star formation processes, and the nature of gravity.

ARK: https://n2t.net/ark:/88439/x010002

Permalink: https://geophysicsjournal.com/article/322

Omerbashich (2024) Jupiter's primordial beat of superoutbursting stars. J. Geophys. 66(1):1-14

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NRIAG North African Earthquake Catalog

2025-01-04T20:31:28+00:00

Northern Africa and the Eastern Mediterranean encountered multiple natural disasters in the last decade, including earthquakes. While it is a long-known fact that the primary active tectonic structure here is in Sub-Saharan Africa, there are recent assessments of North African earthquake seismicity characteristics. With those studies in mind, and since databases of historical and instrumented earthquakes commonly are treated as tools crucial in evaluating the risk of future earthquakes, we have compiled a comprehensive and consistent North African earthquake catalog spanning 112 BCE to March 2023 CE and using both database types. The compilation comprised instrumented seismicity records from local and international sources, covering the area between 20N˚ to 40N˚ and -20E˚ to 40E˚. The datasets contain all known earthquakes with a magnitude M≥3 (to emphasize that the catalog is incomplete for all earthquakes M>3), totaling 138886 of those events. After cross-examining it against presently available information, we removed all duplicate earthquakes from our compilation. In addition, we performed declustering with two algorithms to eliminate any dependent events. We subsequently tested the updated catalog for completeness. Finally, we employed an orthogonal regression method to derive empirical relationships and determine moment magnitudes, M_w. The study analyzes seismic source zones, determining a- and b-values and maximum estimated magnitudes for 54 seismogenic zones of nine regions according to two declustering approaches at estimated minimum magnitudes of M3.0 and M3.5. The highest b-value, 1.09, is in Shore Egypt/Red Sea, while the highest a-value, 4.27, is in the Atlantic offshore. In our study, we relied on previous works, and our results agree with the results of those.

ARK: https://n2t.net/ark:/88439/x030101

Permalink: https://geophysicsjournal.com/article/352

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Lg wave attenuation of Northeast India Archaean as a new standard for Earth's most seismic regions

2024-12-31T04:27:08+00:00

Physical modeling of Lg-wave attenuation is used in designing resilient and safer civil engineering structures and is thus vital for seismic hazard mitigation. I here report an attenuation model for one of the most active seismic sources of Himalayas-determined Northeastern region (NER) of India—the Eastern Shillong Plateau–Mikir Hills (ESPMH) tectonic domain—based on four well-constrained regional crustal earthquakes between 2007–2011. Frequency-dependent attenuation of Lg wave has crustal quality factor Q_Lg≈48.92±1.08 and its frequency dependency of η≈0.97±0.16. The model is strictly high-frequency dependent (η=0.97), indicating that Lg attenuates dominantly by the scattering mechanism. The attenuation becomes critically high around the frequency of 0.5 Hz, the same as in the most tectonically active regions of the world. The extra low value of Q_o=48.92 is the lowest reported from any continental part of our planet, which reveals a most attenuative Earth's crust posing a high seismic threat. As the results imply an extensive, seismically potentially destructive presence of melts/aqueous phases in Earth's crust, the probability of a damaging earthquake in and around ESPMH is non-negligible. Multiple additional factors contribute to the gross attenuation of Lg, as it is reasonable to account for the anomalously high attenuation in the NER Archaean as dominantly lithologically hardest and Earth-oldest terrane, making the new model pertinent to Earth's tectonically most active regions.

ARK: https://n2t.net/ark:/88439/x055006

Permalink: https://geophysicsjournal.com/article/357

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