New data about two distant asteroids give a clue to the possible ‘Planet Nine’

Posted: February 22, 2017 by oldbrew in Astronomy, research, solar system dynamics

Proposed path of Planet 9 around the sun with Neptune and several notable TNOs for reference [credit: Wikipedia]

Proposed path of Planet 9 around the sun with Neptune and several notable TNOs for reference [credit: Wikipedia]

Researchers suggest the pair may have got too close to the hypothetical Planet Nine, resulting in their current orbits.

The dynamical properties of these asteroids, observed spectroscopically for the first time using the Gran Telescopio CANARIAS, suggest a possible common origin and give a clue to the existence of a planet beyond Pluto, the so-called ‘Planet Nine’, reports

In the year 2000 the first of a new class of distant solar system objects was discovered, orbiting the Sun at a distance greater than that of Neptune: the “extreme trans Neptunian objects” (ETNOs). Their orbits are very far from the Sun compared with that of the Earth.

We orbit the Sun at a mean distance of one astronomical unit (1 AU which is 150 million kilometres) but the ETNOs orbit at more than 150 AU. To give an idea of how far away they are, Pluto’s orbit is at around 40 AU and its closest approach to the Sun (perihelion) is at 30 AU. This discovery marked a turning point in Solar System studies, and up to now, a total of 21 ETNOs have been identified.

Recently, a number of studies have suggested that the dynamical parameters of the ETNOs could be better explained if there were one or more planets with masses several times that of the Earth orbiting the Sun at distances of hundreds of AU.

In particular, in 2016 the researchers Brown and Batygin used the orbits of seven ETNOs to predict the existence of a “superearth” orbiting the sun at some 700 AU. This range of masses is termed sub Neptunian. This idea is referred to as the Planet Nine Hypothesis and is one of the current subjects of interest in planetary science.

However, because the objects are so far away the light we receive from them is very weak and until now the only one of the 21 trans Neptunian objects observed spectroscopically was Sedna.

Now, a team of researchers led by the Instituto de Astrofísica de Canarias (IAC) in collaboration with the Complutense University of Madrid has taken a step towards the physical characterization of these bodies, and to confirm or refute the hypothesis of Planet Nine by studying them.

The scientists have made the first spectroscopic observations of 2004 VN112 and 2013 RF98, both of them particularly interesting dynamically because their orbits are almost identical and the poles of the orbits are separated by a very small angle. This suggests a common origin, and their present-day orbits could be the result of a past interaction with the hypothetical Planet Nine.

This study, recently published in Monthly Notices of the Royal Astronomical Society, suggests that this pair of ETNOs was a binary asteroid which separated after an encounter with a planet beyond the orbit of Pluto.

The report continues here.

  1. oldbrew says:

    Asteroid 2007_TG422 (shown on the same side of the diagram as the two asteroids in the report) has a very similar orbit period to dwarf planet Sedna (lower left in the diagram).

    Using JPL Horizons with an observed orbital arc of 5 years, the barycentric orbital elements for epoch 2008-May-14 generate a semi-major axis of 503 AU and a period of 11,300 years. For comparison, probable dwarf planet Sedna has a barycentric semi-major axis of 506 AU and a period of 11,400 years.

    Update: note also they’ve drawn Planet Nine with a semi-major axis about the same size as these two (i.e. Sedna and TG422), but on the opposite side of the diagram.

    But that doesn’t match the diagram below, where Planet Nine’s SMA looks more like that of uo3_L91 (again, opposite side).

  2. hunter says:

    We are in a golden age of Astronomy. This is amazing and reminds one of the proverb about the universe being stranger than we can imagine.

  3. oldbrew says:

    NASA is holding a news conference [today] to discuss “new findings on planets that orbit stars other than our sun, known as exoplanets,” according to a statement from the agency.

    The news conference begins at 1 p.m. EST (1800 GMT). No other specifics about the “new findings” have been made public, but “details … are embargoed by the journal Nature” until 1 p.m. EST, according to the statement.

    The news conference will feature five speakers

  4. c777 says:

    Interesting one here, Earth sized Planets with water?, in a relatively close stars Goldilocks zone.?

    [reply] thanks – we’ve just posted this:

  5. Bloke down the pub says:

    Nasa reports that the planets are in the Goldilocks zone because although they are much closer to their star than the Earth is to the Sun, Trapiste 1 is a cool red dwarf which emits less energy. However, the energy that reaches the planets is at the IR end of the spectrum compared to the energy that reaches the Earth. If, as Nasa claims, the planets have water at the surface, won’t a higher proportion of the energy reaching the upper atmosphere be intercepted and re-emitted as long wave? This would presumably mean that the planet surface would be much colder than would be the case if they received an equivalent amount of energy at shorter wave lengths?

  6. oldbrew says:

    They are talking it up, but that’s their line of work and the public is paying for it so it’s expected.