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posted by CoolHand on Wednesday August 31 2016, @08:52AM   Printer-friendly
from the number-9-number-9-number-9 dept.

The sample size of icy rocks that appear to have their orbits affected by a Neptune-like "Planet Nine" is growing larger:

For the past few years, [Scott] Sheppard of [the Carnegie Institution for Science], [Chadwick] Trujillo [of Northern Arizona University] and David Tholen of the University of Hawaii have been hunting for objects in the far outer solar system using several different instruments, including the Subaru Telescope in Hawaii and the Dark Energy Camera, which is installed on a 4-meter telescope at the Cerro Tololo Inter-American Observatory in Chile. [...] The astronomers discovered several dozen previously unknown bodies, including a roughly 155-mile-wide (250 km) object called [2014 FE72] that gets an incredible 4,000 AU from the sun at its most distant point. That puts it out in the outer Oort Cloud — the realm of comets.

[...] They also discovered two 125-mile-wide (200 km) objects, known as 2014 SR349 and 2013 FT28, that "cluster" in one of the key orbital parameters (known as argument of perihelion), furthering strengthening the case for Planet Nine's existence. (The objects' names reflect the years that they were first spotted in the survey; their discovery is being announced in the new study.) "We have 15 or so of these extreme objects now, and all of them cluster in this argument of perihelion angle," Sheppard said.

Furthermore, he added, the five most distant of these 15 extreme objects share similarities in another orbital characteristic as well, one called longitude of perihelion. Significantly, the far-flung five are too distant to be realistically affected by any gravitational tugs from Neptune (whose influence could be the reason the other 10 objects' longitudes of perihelion don't line up). It would take just two or three more such additional finds to put Planet Nine on solid ground, Sheppard said. "I think statistics-wise, in the next year to two years we'll probably find enough of these small, extreme objects to really say if Planet X exists or not," he said. [...] "We need like 10 or 20 of these smaller extreme objects, and we can probably nail down much better where Planet X would be out there," Sheppard said.

2014 SR349, 2013 FT28, and 2014 FE72.

Also at the Carnegie Institution for Science.


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  • (Score: 2) by butthurt on Wednesday August 31 2016, @10:45PM

    by butthurt (6141) on Wednesday August 31 2016, @10:45PM (#395905) Journal

    Unless, of course, Nemesis exists!

    The Nemesis theory was devised to account for this regularity in the timing of the mass extinctions reported by Raup and Sepkoski. According to this model, a companion star orbiting the Sun perturbs the Oort comet cloud every 26 Myr causing comet showers in the inner solar system. One or more of these comets strike the Earth causing a mass extinction.

    --http://muller.lbl.gov/pages/lbl-nem.htm [lbl.gov]

    THE THEORIZED COMPANION STAR, THROUGH ITS GRAVITATIONAL PULL, UNLEASHES A FURIOUS STORM OF COMETS IN THE INNER SOLAR SYSTEM LASTING FROM 100,000 TO TWO MILLION YEARS. SEVERAL OF THESE COMETS STRIKE THE EARTH.

    --http://www2.lbl.gov/Science-Articles/Archive/extinctions-nemesis.html [lbl.gov]

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  • (Score: 1, Interesting) by Anonymous Coward on Thursday September 01 2016, @12:08AM

    by Anonymous Coward on Thursday September 01 2016, @12:08AM (#395945)

    AC who referred to it as Nemesis here. That's what I was thinking of. Looking at that Wikipedia article, the orbital period of this Planet X would only be 15,000 years. Thanks for the links. I didn't know this (from muller.lbl.gov):

    The expected orbit lifetime when the solar system was formed was (presumably) about 5.5 billion years. When nearby stars pass the solar system, the orbit of Nemesis is given slight boosts in energy. The Nemesis orbit becomes larger and less stable. At present, the Nemesis orbit has a semi-major axis of about 1.5 light-years, and the orbit is expected to remain bound to the sun for only another billion years.

    Note that the Nemesis theory predicts that the periodicity should not be precise. Perturbations from passing stars are not sufficient to disrupt the orbit, but they are sufficient to cause a slight (a few Myr) jitter in the interval between extinctions.