URochester: Gigantic Ring System Around J1407b

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Gigantic ring system around J1407b much larger, heavier than Saturn’s
University of Rochester | Leiden Observatory | 2015 Jan 26

Artist’s conception of the extrasolar ring system circling the young giant planet or brown dwarf J1407b. The rings are shown eclipsing the young sun-like star J1407, as they would have appeared in early 2007. (Credit: Ron Miller)

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Astronomers at the Leiden Observatory, The Netherlands, and the University of Rochester, USA, have discovered that the ring system that they see eclipse the very young Sun-like star J1407 is of enormous proportions, much larger and heavier than the ring system of Saturn. The ring system – the first of its kind to be found outside our solar system – was discovered in 2012 by a team led by Rochester’s Eric Mamajek.

A new analysis of the data, led by Leiden’s Matthew Kenworthy, shows that the ring system consists of over 30 rings, each of them tens of millions of kilometers in diameter. Furthermore, they found gaps in the rings, which indicate that satellites (“exomoons”) may have formed. The result has been accepted for publication in the Astrophysical Journal.

“The details that we see in the light curve are incredible. The eclipse lasted for several weeks, but you see rapid changes on time scales of tens of minutes as a result of fine structures in the rings,” says Kenworthy. “The star is much too far away to observe the rings directly, but we could make a detailed model based on the rapid brightness variations in the star light passing through the ring system. If we could replace Saturn’s rings with the rings around J1407b, they would be easily visible at night and be many times larger than the full moon.”

“This planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn’s rings are today,” said co-author Mamajek, professor of physics and astronomy at the University of Rochester. “You could think of it as kind of a super Saturn.” ...

Modeling Giant Extrasolar Ring Systems in Eclipse and the Case of J1407b:
Sculpting by Exomoons? - Matthew A. Kenworthy, Eric E. Mamajek

• Astrophysical Journal 800(2):126 (2015 Feb 20) DOI: 10.1088/0004-637X/800/2/126
  arXiv.org > astro-ph > arXiv:1501.05652 > 22 Jan 2015

[BMAONE23]

If Saturn's rings were the same size as those around J1407b, they would be easily visible from Earth at night and would be many times larger than a full Moon.

Original story from the BBC

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Exorings on the Horizon
University of Antioquia | 2015 Mar 04

Schematic representation of the transit of a ringed planet in front of its star. When compared with the light curve of an non-ringed analogue (dashed line) the transit of a ringed planet is deeper (the relative flux diminish by a larger fraction) and longer. (Zuluaga et al 2015)

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Astronomers from the Harvard-Smithsonian Center for Astrophysics and the University of Antioquia (Medellin-Colombia) have devised a novel method for identifying rings around extrasolar planets (exorings). The method is relatively simple and can be used to rapidly analyze large photometric database and to find a list of exoring candidates deserving further analysis.

Exoplanetary science is one of the most prolific sources of astronomical discoveries since the invention of telescopes. Once you get used to a suprising finding, such as the discovery of an Earth-twin, another exciting discovery beckons, capturing the imagination of scientists and non-scientists. Although we cannot predict the next exoplanetary discovery, several breakthroughs, such as the discovery of the first exomoon or the direct image of an Earth-like planet, have been in the line for years. Exorings are also one of these long-awaited discoveries.

Recently, a group of astronomers lead by Erik Mamajek of the Rochester University, announced the discovery of a huge disk orbiting the "Super-Jupiter" J1407b. Beside the initial excitement, the actual nature of the object and its "rings" is still debated. The planet could actually be a brown-dwarf and the rings a version in miniature of a protoplanetary disk.

Rings are common in the Solar System. Jupiter, Saturn, Uranus and Neptune have rings of different sizes. Even smaller objects, such as asteroids and cometary nuclei, could have their own rings. Searching for ringed planets beyond the Solar System is as natural as searching for moons and magnetic fields, two other common phenomena associated with planets. ...

A novel method for identifying exoplanetary rings - Jorge I. Zuluaga et al

• Astrophysical Journal Letters 803(1):L14 (2015 Apr 10) DOI: 10.1088/2041-8205/803/1/L14
  arXiv.org > astro-ph > arXiv:1502.07818 > 27 Feb 2015, 15 Apr 2015 (v2)
  Exorings computer code

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Giant Rings around Exoplanet Turn in the Wrong Direction
Netherlands Research School for Astronomy | 2016 Oct 11

(c) Ron Miller

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Researchers from Japan and the Netherlands who were previously involved in the discovery of an exoplanet with huge rings have now calculated that the giant rings may persist more than 100,000 years, as long as the rings orbit in the opposite direction compared to that of the planet around the star. Their findings are accepted for publication in the journal Astronomy & Astrophysics.

The researchers Steven Rieder (RIKEN, Japan) and Matthew Kenworthy (Leiden University, the Netherlands) studied the star J1407. This young sun-like star showed a strange series of eclipses in 2007. The researchers proposed an explanation in 2015: there should be a planet with a gigantic ring system that is orbiting the star. The rings should be over a hundred times larger than the rings of Saturn.

In 2016, the researchers carried out simulations to see whether such a massive ring system can be stable for a long time. Before the simulations there were doubts about this hypothesis since the exoplanet orbits in a very eccentric orbit - sometimes the planet gets close to the star, and the gravitational effect of the star could disrupt the rings.

Now the simulations show that the system is stable and can persist for more than 10,000 orbits of 11 years. According to lead author Steven Rieder there is one premise, though: "The system is only stable when the rings rotate opposite to how the planet orbits the star." ...

Constraints on the size and dynamics of the J1407b ring system - Steven Rieder, Matthew A. Kenworthy

• Astronomy & Astrophysics 596:A9 (Dec 2016) DOI: 10.1051/0004-6361/201629567
  arXiv.org > astro-ph > arXiv:1609.08485 > 27 Sep 2016 (v1), 21 Nov 2016 (v3)

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Net Closes Around Planet with Giant Rings Thanks to Photos from 1890
Netherlands research School for Astronomy (NOVA) | 2018 Oct 15

Meticulous analysis of hundreds of photographic plates from the star J1407 between 1890 and 2007 show no stellar eclipses. Robin Mentel, a master student at Leiden University, could not detect eclipses of the star J1407 by a planet hypothesized to have giant rings, called J1407b. However, an eclipse may have been missed since the measurement series contains gaps. ...

Robin Mentel studied J1407, a sun-like star, 16 million years young at about 460 light-years from Earth in the constellation Centaurus. In 2007, the star showed a strange series of star eclipses. In 2015, a team of researchers, including Mentel’s supervisor Matthew Kenworthy, came out with an explanation for those eclipses. A planet, J1407b, with a huge ring system that was more than a hundred times larger than Saturn's ring system, would orbit the star. In 2016, Kenworthy and colleagues showed that the ring system can only really hold on if the rings move against the orbit direction of the planet around the star. And now, in 2018, the Leiden team has shown that in large periods between 1890 and 2007 no star eclipses have taken place.

Two years ago, Mentel, who was still a bachelor's student visiting Leiden from Germany, studied 490 photographic plates with J1407 on it. The oldest records are from the Harvard DASCH survey and date from 1890. There are also records from collections from Bamberg and Sonneberg observatories. Mentel compared the brightness of the star J1407 with two equally bright stars close by on the sky. If the star J1407 was obscured at some point, it would appear to be fainter on the photo than the two nearby stars. Mentel could not detect any eclipses. As an extra check, Mentel compared J1407 with a third star that was just as weak as an eclipsing J1407.

Thanks to these results, the researchers could then calculate how long the period between two eclipses might be. Mentel and his colleagues think that in 2021 or 2024 there may be another star eclipse and so they will have to wait until another eclipse event confirms it. ...

Constraining the Period of the Ringed Secondary Companion to
the Young Star J1407 with Photographic Plates ~ R.T. Mentel et al

• Astronomy & Astrophysics (accepted 04 Sep 2018) DOI: 10.1051/0004-6361/201834004
  arXiv.org > astro-ph > arXiv:1810.05171 > 11 Oct 2018