{"id":3359,"date":"2015-03-17T06:26:02","date_gmt":"2015-03-17T06:26:02","guid":{"rendered":"http:\/\/revoscience.com\/en\/?p=3359"},"modified":"2015-03-17T06:26:02","modified_gmt":"2015-03-17T06:26:02","slug":"a-second-minor-planet-may-possess-saturn-like-rings","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/a-second-minor-planet-may-possess-saturn-like-rings\/","title":{"rendered":"A second minor planet may possess Saturn-like rings"},"content":{"rendered":"

Researchers detect features around Chiron that may signal rings, jets, or a shell of dust.<\/strong><\/em><\/span><\/p>\n

\"download<\/a>CAMBRIDGE, Mass. —\u00a0There are only five bodies in our solar system that are known to bear rings. The most obvious is the planet Saturn; to a lesser extent, rings of gas and dust also encircle Jupiter, Uranus, and Neptune. The fifth member of this haloed group is Chariklo, one of a class of minor planets called centaurs: small, rocky bodies that possess qualities of both asteroids and comets.<\/span><\/p>\n

Scientists only recently detected Chariklo\u2019s ring system \u2014 a surprising finding, as it had been thought that centaurs are relatively dormant. Now scientists at MIT and elsewhere have detected a possible ring system around a second centaur, Chiron.<\/span><\/p>\n

In November 2011, the group observed a stellar occultation in which Chiron passed in front of a bright star, briefly blocking its light. The researchers analyzed the star\u2019s light emissions, and the momentary shadow created by Chiron, and identified optical features that suggest the centaur may possess a circulating disk of debris. The team believes the features may signify a ring system, a circular shell of gas and dust, or symmetric jets of material shooting out from the centaur\u2019s surface.<\/span><\/p>\n

\u201cIt\u2019s interesting, because Chiron is a centaur \u2014 part of that middle section of the solar system, between Jupiter and Pluto, where we originally weren\u2019t thinking things would be active, but it\u2019s turning out things are quite active,\u201d says Amanda Bosh, a lecturer in MIT\u2019s Department of Earth, Atmospheric and Planetary Sciences.<\/span><\/p>\n

Bosh and her colleagues at MIT \u2014 Jessica Ruprecht, Michael Person, and Amanda Gulbis \u2014 have published their results in the journal\u00a0Icarus.<\/em><\/span><\/p>\n

Catching a shadow<\/strong><\/span><\/p>\n

Chiron, discovered in 1977, was the first planetary body categorized as a centaur, after the mythological Greek creature \u2014 a hybrid of man and beast. Like their mythological counterparts, centaurs are hybrids, embodying traits of both asteroids and comets. Today, scientists estimate there are more than 44,000 centaurs in the solar system, concentrated mainly in a band between the orbits of Jupiter and Pluto.<\/span><\/p>\n

While most centaurs are thought to be dormant, scientists have seen glimmers of activity from Chiron. Starting in the late 1980s, astronomers observed patterns of brightening from the centaur, as well as activity similar to that of a streaking comet.<\/span><\/p>\n

In 1993 and 1994, James Elliot, then a professor of planetary astronomy and physics at MIT, observed a stellar occultation of Chiron and made the first estimates of its size. Elliot also observed features in the optical data that looked like jets of water and dust spewing from the centaur\u2019s surface.<\/span><\/p>\n

Now MIT researchers \u2014 some of them former members of Elliot\u2019s group \u2014 have obtained more precise observations of Chiron, using two large telescopes in Hawaii: NASA\u2019s Infrared Telescope Facility, on Mauna Kea, and the Las Cumbres Observatory Global Telescope Network, at Haleakala.<\/span><\/p>\n

In 2010, the team started to chart the orbits of Chiron and nearby stars in order to pinpoint exactly when the centaur might pass across a star bright enough to detect. The researchers determined that such a stellar occultation would occur on Nov. 29, 2011, and reserved time on the two large telescopes in hopes of catching Chiron\u2019s shadow.<\/span><\/p>\n

\u201cThere’s an aspect of serendipity to these observations,\u201d Bosh says. \u201cWe need a certain amount of luck, waiting for Chiron to pass in front of a star that is bright enough. Chiron itself is small enough that the event is very short; if you blink, you might miss it.\u201d<\/span><\/p>\n

The team observed the stellar occultation remotely, from MIT\u2019s Building 54. The entire event lasted just a few minutes, and the telescopes recorded the fading light as Chiron cast its shadow over the telescopes.<\/span><\/p>\n

Rings around a theory<\/strong><\/span><\/p>\n

The group analyzed the resulting light, and detected something unexpected. A simple body, with no surrounding material, would create a straightforward pattern, blocking the star\u2019s light entirely. But the researchers observed symmetrical, sharp features near the start and end of the stellar occultation \u2014 a sign that material such as dust might be blocking a fraction of the starlight.<\/span><\/p>\n

The researchers observed two such features, each about 300 kilometers from the center of the centaur. Judging from the optical data, the features are 3 and 7 kilometers wide, respectively. \u00a0The features are similar to what Elliot observed in the 1990s.<\/span><\/p>\n

In light of these new observations, the researchers say that Chiron may still possess symmetrical jets of gas and dust, as Elliot first proposed. However, other interpretations may be equally valid, including the \u201cintriguing possibility,\u201d Bosh says, of a shell or ring of gas and dust.<\/span><\/p>\n

Ruprecht, who is a researcher at MIT\u2019s Lincoln Laboratory, says it is possible to imagine a scenario in which centaurs may form rings: For example, when a body breaks up, the resulting debris can be captured gravitationally around another body, such as Chiron. Rings can also be leftover material from the formation of Chiron itself.<\/span><\/p>\n

\u201cAnother possibility involves the history of Chiron\u2019s distance from the sun,\u201d Ruprecht says. \u201cCentaurs may have started further out in the solar system and, through gravitational interactions with giant planets, have had their orbits perturbed closer in to the sun. The frozen material that would have been stable out past Pluto is becoming less stable closer in, and can turn into gases that spray dust and material off the surface of a body. \u201d\u00a0\u00a0<\/span><\/p>\n

An independent group has since\u00a0combined<\/span><\/a>\u00a0the MIT group\u2019s occultation data with other light data, and has concluded that the features around Chiron most likely represent a ring system. However, Ruprecht says that researchers will have to observe more stellar occultations of Chiron to truly determine which interpretation \u2014 rings, shell, or jets \u2014 is the correct one.<\/span><\/p>\n

\u201cIf we want to make a strong case for rings around Chiron, we\u2019ll need observations by multiple observers, distributed over a few hundred kilometers, so that we can map the ring geometry,\u201d Ruprecht says. \u201cBut that alone doesn\u2019t tell us if the rings are a temporary feature of Chiron, or a more permanent one. There\u2019s a lot of work that needs to be done.\u201d<\/span><\/p>\n

Nevertheless, Bosh says the possibility of a second ringed centaur in the solar system is an enticing one.<\/span><\/p>\n

\u201cUntil Chariklo\u2019s rings were found, it was commonly believed that these smaller bodies don\u2019t have ring systems,\u201d Bosh says. \u201cIf Chiron has a ring system, it will show it\u2019s more common than previously thought.\u201d<\/span><\/p>\n

This research was funded in part by NASA and the National Research Foundation of South Africa.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Researchers detect features around Chiron that may signal rings, jets, or a shell of dust. CAMBRIDGE, Mass. —\u00a0There are only five bodies in our solar system that are known to bear rings. The most obvious is the planet Saturn; to a lesser extent, rings of gas and dust also encircle Jupiter, Uranus, and Neptune. The […]<\/p>\n","protected":false},"author":6,"featured_media":3360,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-3359","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52-300x159.jpg",300,159,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",95,51,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",308,164,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",96,51,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/03\/download-52.jpg",150,80,false]},"author_info":{"info":["Amrita Tuladhar"]},"category_info":"News<\/a>","tag_info":"News","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/3359","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=3359"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/3359\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/3360"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=3359"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=3359"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=3359"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}