Letters

Neuhäuser, Dagmar L.; Neuhäuser, R.

doi:10.1002/wea.3172

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…5d for average cometary and solar activity, but the Sun was more active than on average in around A.D. 770. 84 Furthermore, for some 30 additional comets reported in historical documents from A.D. 750 and 886, it is specified in which constellation(s) they were seen 85 , so that we could compare all those reports with the positions of the planets at those dates to find possible close conjunctions. We then found three more possible cases: (i) Chinese observations report a comet in Orion for A.D. 852 Mar and Apr in the western evening sky with a long tail of 50 degrees 86 , which should be pointing away from the Sun, i.e.…”

Section: Abū Mamentioning

confidence: 99%

Tycho Brahe, Abū Ma^cshar, and the comet beyond Venus (ninth century A.D.)

Neuhäuser¹,

Kunitzsch

Mugrauer³

et al. 2016

Journal for the History of Astronomy

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From his observations of the a.d. 1572 supernova and the a.d. 1577 comet, Tycho Brahe concluded that such transient celestial objects are outside the Earth’s atmosphere, and he quoted the ninth century a.d. Persian astrologer and astronomer Abū Macshar: Dixit Albumasar, Cometa supra Venerem visus fuit; i.e., the latter had reported much earlier that comets were seen beyond Venus. However, even from a more detailed Latin translation, the observations and logic behind Abū Macshar’s conclusion were not understandable. We present here the original Arabic text (manuscript Ankara, Saib 199) together with our translation and interpretation: Abū Macshar reported that he had observed Venus in (or projected onto) the tail of a comet and concluded that the comet was behind Venus because he had observed the extinction of Venus due to the cometary tail to be negligible (light of Venus was unimpaired). He then concluded that the comet would be located behind Venus. He also mentioned that others had observed Jupiter and Saturn in cometary tails, so that those comets would even be located beyond those two outer planets – in the sphere of the stars. The dates of the observed close conjunctions were not mentioned; using known orbital elements for a few comets, we found a few close conjunctions between comets and planets from a.d. 770 to 868, but we cannot be sure regarding which conjunctions were reported. While the argument of Abū Macshar is not correct (as cometary tails are optically thin), the conclusion – namely that comets are outside the Earth’s atmosphere and beyond the moon – is correct. This may have helped Tycho Brahe to come to his revolutionary conclusion.

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Section: Abū Mamentioning

confidence: 99%

Tycho Brahe, Abū Ma^cshar, and the comet beyond Venus (ninth century A.D.)

Neuhäuser¹,

Kunitzsch

Mugrauer³

et al. 2016

Journal for the History of Astronomy

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“…The first spectacular example is observation of quantum jumps, i.e. dark periods in the fluorescence spectrum of an optically driven trapped ion [25][26][27][28]. The experiments fueled the interest in the theory of repeated quantum measurements.…”

Section: Introductionmentioning

confidence: 99%

On Repeated Measurements of a Quantum Particle in a Harmonic Potential

Gampel

Gajda

2023

Acta Phys. Pol. A

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We study evolution of a quantum particle in a harmonic potential whose position and momentum are repeatedly monitored. A back-action of measuring devices is accounted for. Our model utilizes a generalized measurement corresponding to the Positive Operator-Valued Measure. We assume that upon measurement the particle's wavefunction is projected onto one of possible detector states depending on the observed result. We chose these post-measurement states to be moving Gaussian wavepackets. The Wave Function Quantum Monte-Carlo formalism is used to simulate single quantum trajectories of the particle. We show how classical trajectories emerge in course of observation and study in detail dispersion of position and momentum of the particle.

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“…It is often difficult to confirm whether an aurora-like description in a historical document actually refers to an aurora display or a different phenomenon such as atmospheric optics (e.g., Usoskin et al 2017;Neuhäuser & Neuhäuser 2018). Supplementary information, such as time, directions, and the moon phase, is useful in examining the probability that a description is actually a record of an aurora display.…”

Section: Introductionmentioning

confidence: 99%

“…There are also Chinese, Korean, and Japanese records that can be regarded as candidates for auroral displays in these regions (Yau, Stephenson & Willis 1995;Xu, Pankenier & Jiang 2000;Lee et al 2004;Kawamura et al 2016), where the geographic latitude (30 ∼ 40 degree) is lower than that of central Europe and the magnetic latitude is even lower (20 ∼ 30 degree). However, it is uncertain how much of them are the record of true aurora (Usoskin et al 2017;Neuhäuser & Neuhäuser 2018).…”

Section: Introductionmentioning

confidence: 99%

Intense Geomagnetic Storm during Maunder Minimum Possibly by a Quiescent Filament Eruption

Isobe

Ebihara

Kawamura

et al. 2019

ApJ

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The sun occasionally undergoes the so-called grand minima, in which its magnetic activity, measured by the number of sunspots, is suppressed for decades. The most prominent grand minima, since the beginning of telescopic observations of sunspots, is the Maunder minimum (1645-1715), when the sunspots became rather scarce. The mechanism underlying the grand minima remains poorly understood as there is little observational information of the solar magnetic field at that time. In this study, we examine the records of one candidate aurora display in China and Japan during the Maunder minimum. The presence of auroras in such mid magnetic latitudes indicates the occurrence of great geomagnetic storms that are usually produced by strong solar flares. However, the records of contemporary sunspot observations from Europe suggest that, at least for the likely aurora event, there was no large sunspot that could produce a strong flare. Through simple theoretical arguments, we show that this geomagnetic storm could have been generated by an eruption giant quiescent filament, or a series of such events.

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Letters

Cited by 6 publications

References 2 publications

Tycho Brahe, Abū Ma^cshar, and the comet beyond Venus (ninth century A.D.)

Tycho Brahe, Abū Ma^cshar, and the comet beyond Venus (ninth century A.D.)

On Repeated Measurements of a Quantum Particle in a Harmonic Potential

Intense Geomagnetic Storm during Maunder Minimum Possibly by a Quiescent Filament Eruption

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Letters

Cited by 6 publications

References 2 publications

Tycho Brahe, Abū Macshar, and the comet beyond Venus (ninth century A.D.)

Tycho Brahe, Abū Macshar, and the comet beyond Venus (ninth century A.D.)

On Repeated Measurements of a Quantum Particle in a Harmonic Potential

Intense Geomagnetic Storm during Maunder Minimum Possibly by a Quiescent Filament Eruption

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Resources

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Tycho Brahe, Abū Ma^cshar, and the comet beyond Venus (ninth century A.D.)

Tycho Brahe, Abū Ma^cshar, and the comet beyond Venus (ninth century A.D.)