The discovery of the second ring in ‘Kwaoa’ both outside the borders of Roche| Sorae Portal site to the universe

Some bodies in the solar system have rings, such as Saturn. In the beginning, the rings were formed by the four giant planets that areJupiter, Saturn, Uranus, NeptuneSince it was only known inHowever, in 2014 the asteroidCharikloStarting with the discovery of the ring inKyronAndHaumea,AndquaoarBut the rings were found (※ 1) 。

* 1 … However, the existence of the Chiron ring is controversial, and there is also a negative opinion that it does not exist. This makes Kwaor’s ring the seventh or eighth ring discovered in the Solar System.

The Kwaoar ring was just published in a research paper in February 2023, and revealed in an analysis of observational data obtained from 2018 to 2021.

Rings of small celestial bodies are very thin and dim, so they cannot be observed directly with a telescope.star eclipseIt must be observed. When an asteroid crosses in front of a star, the star appears to temporarily disappear from the Earth because it is hidden by the asteroid. This is a phenomenon called a stellar eclipse. When a celestial body without a ring crosses, the fixed star only disappears once, but in the case of a celestial body with a ring, The ring intersects before and after the intersection of the body, so the fixed star repeats the disappearance and reappearance several times.. By accurately measuring the timing and duration of the disappearance of a fixed star, we can obtain information such as the distance from the ring to the celestial body, the width of the ring, and the number of rings.

However, star eclipses are not a rare phenomenon. Since there is usually no way to know the existence of rings in advance, whether or not a ring is found on an object depends on chance.

An international research team, including the researchers who reported the first detection of a quawar ring, analyzed observational data from the eclipse that occurred on August 9, 2022. Since the existence of a ring had already been suggested, this observation was a rare opportunity to make a presupposition about the existence of the ring as well. to quaor itself.

During this eclipse, Kwaoar was expected to cross in front of the star cataloged as “Gaia DR3 4098214367441486592,” which is observable in Hawaii and North America. Resulting in,Measure the detailed shape of quarrels and discover new ringswas successful.

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【▲ Fig. 2: The shape of the main body of the quawar is estimated from the eclipse. It turns out that it is most likely not a simple sphere or rugby ball shape, but a more complex shape called the triaxial asymmetrical ellipsoid (Credit: CL Pereira, et.al.)]

First, the shape of the main body of the quarr is explained in detail. The radius at its longest point was estimated at about 579.5 km, but its shape is not a simple spheroid or that of a rugby ball (spheroid), but a more complex one called a “triaxial asymmetric ellipsoid”. It is inferred as an ellipse with different radii measured along the three axes, a kind of “hot water bottle” shape. This is quite a difference, considering that it was previously estimated as a rugby ball with an average radius of about 555.0 km.

【▲ Fig. 3: Gaia DR3 4098214367441486592 brightness change. The brightness changes as the Quaoar body and ring cross the front. A second loop (Q2R) is detected in this observation. In addition, since the change in brightness due to the first ring (Q1R) is asymmetric from left to right, it was inferred that the dark part is biased to one side (Credit: CL Pereira, et.al.)]

In addition, the ring (Q1R), whose discovery was announced in February 2023, has a fairly accurate size and detailed structure determined by this observation. The ring radius is 4057 ± 6 km, and the ring contains thin, dark parts, indicating that only part of the ring is shaded in an arc shape.

Moreover, this timeNewly discovered second ring (Q2R). The radius of the second ring is 2520 ± 20 km, and it was found to be more internal than the first ring and narrower than the first ring. In addition, this observation also revealed that, unlike the first episode, there is no clear structure like the arc.

Both flask ringsRoach limitOutside. This is a feature that distinguishes it from other celestial rings. The Roche limit is a value that determines the size of a satellite orbiting a celestial body. Objects orbiting a star receive tidal forces from the star. The strength of the tidal force increases with the diameter of the rotating celestial body as it approaches the main star. Therefore, a celestial body that is too close to the main star and has a certain size will be shattered by the tidal force and cannot exist. This specific distance is called the Roche limit. (※ 2) 。

* 2 … The giant planets have satellites orbiting within Roche’s borders. Whether or not a celestial body actually refractes at the Roche limit depends on the size and density of the celestial body, so it is believed that small low-density satellites can exist even within the Roche boundary.

All known rings other than Quoaar lie within or at the boundary of the Roche limit, so the rings were thought to be concentrations of matter that could not become satellites due to tidal forces. In other words, outside the Roche boundary, matter aggregates to form satellites, so there are no rings. However, the two rings found at Kwaoar lie outside Roche’s borders, contradicting this theory.

[الشكل 4: الحلقتان اللتان تم اكتشافهما هذه المرة خارج حدود Roche ، ويُعتقد أنهما في علاقة رنين مداري مع فترة دوران Quoaar أو الفترة المدارية لـ Waywot (Credit: CL Pereira، et.al. / الحروف اليابانية لديها تمت مراجعته من قبل المؤلف)]

According to traditional theory, it is estimated that the Kwaor Ring, which lies far beyond Roche’s borders, will become a single cluster, or satellite, in less than 100 years. For Quoaar’s rings to remain intact without forming satellites, there must be some physical phenomenon that prevents them from clumping together.

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The research team believes that the period of rotation of Quoaar itself and the presence of the Waywot satellite are the keys. The orbital period of Loop I is three times that of Quoaar and one-sixth that of Waywot. The orbital period of the second ring is 1.4 times the period of the ring’s rotation, which can be expressed as a scalar ratio of 5:7.

In this way, the relation in which the orbital period of a ring or celestial body is an integer ratio to the other orbital elements is calledtrack echoIt is called. The orbital period related to the orbital resonance is stable, but the other orbital periods are unstable, so there is a limitation on the orbital period.

In the case of a quark ring, the materials that make up the ring are thought to be perturbed by orbital resonance, preventing them from forming a single mass, and at the same time preventing them from dissipating and annihilating the ring. In addition, the arc-like structure seen in the first ring can also be explained by considering that the orbital resonance causes matter to be concentrated at a biased site.

In addition, the discovery of rings outside Roche’s bounds has forced a revision of the ring formation theory itself. The discovery of a second ring in Quawar indicates that rings outside Roche’s bounds may not be uncommon. Additional observations of quaoar ring properties may rewrite theories about ring properties and formation, and may also shed light on mysteries surrounding rings that have already been discovered.

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Text: Rare Aya