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Space

Star System With Right-Angled Planets Surprises Astronomers (nytimes.com) 39

Posted by EditorDavid from the perpendicular-planets dept.
Long-time Slashdot reader fahrbot-bot shared this report from the New York Times about a "particularly unusual" star about 150 light-years away that's orbited by three planets: What's unusual is the inclinations of the outer two planets, HD 3167 c and d. Whereas in our solar system all the planets orbit in the same flat plane around the sun, these two are in polar orbits. That is, they go above and below their star's poles, rather than around the equator as Earth and the other planets in our system do.

Now scientists have discovered the system is even weirder than they thought. Researchers measured the orbit of the innermost planet, HD 3167 b, for the first time — and it doesn't match the other two. It instead orbits in the star's flat plane, like planets in our solar system, and perpendicular to HD 3167 c and d. This star system is the first one known to act like this...

The unusual configuration of HD 3167 highlights just how weird and wonderful other stars and their planets can be. "It puts in perspective again what we think we know about the formation of planetary systems," said Vincent Bourrier from the University of Geneva in Switzerland, who led the discovery published last month in the journal Astronomy & Astrophysics.

"Planets can evolve in really, really different ways."
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Star System With Right-Angled Planets Surprises Astronomers More

Star System With Right-Angled Planets Surprises Astronomers

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  • Awww shit. (Score:3, Insightful)

    by thegarbz ( 1787294 ) on Sunday November 07, 2021 @10:38AM (#61965703)

    HD 3167 b is about to get its arse demoted to a Pluto reject.

  • would've been one of those cases too. First the discovery of everything floating and orbiting and the natural spinning on their respective axes ... but hey the moon doesn't do that ...

  • Clearly a megastructure of the Tyson sphere type . (Score:5, Informative)

    by tekram ( 8023518 ) on Sunday November 07, 2021 @10:50AM (#61965731)
    under construction in polar orbits. As originally envisioned in fictional accounts, the Dyson-sphere concept is often interpreted as an artificial, hollow sphere of matter around a star. This perception is based on a literal interpretation of Dyson's original short paper introducing the concept. In response to letters prompted by some papers, Dyson replied, "A solid shell or ring surrounding a star is mechanically impossible. The form of 'biosphere' which I envisaged consists of a loose collection or swarm of objects traveling on independent orbits around the star"

    • Or, it's just a rouge planet that was captured in the stars' gravity. So no Dyson-sphere or reformulation of how solar systems develop necessary.

  • The unusual configuration of HD 3167 highlights just how weird and wonderful other stars and their planets can be. "It puts in perspective again what we think we know about the formation of planetary systems," said Vincent Bourrier from the University of Geneva in Switzerland, who led the discovery published last month in the journal Astronomy & Astrophysics.

    Also affects the possibility of what is a habitable planet and what isn't.

  • Well hard to develop spaceflight for the natives (Score:4, Interesting)

    by Crashmarik ( 635988 ) on Sunday November 07, 2021 @11:10AM (#61965767)

    The Delta V between the inner and outer planets will be enormous. Have to kill the existing angular momentum and match the target, instead of just adjusting the existing momentum.

    • I'm not a rocket scientist but I think the timing of departure would just be so that when you reach your destination it is on the same plane as your departure planet?

      • Re:Well hard to develop spaceflight for the native (Score:4, Informative)

        by Anonymous Coward on Sunday November 07, 2021 @12:37PM (#61965963)

        You could end up at the same point as the planet, but you would be traveling at vastly different velocities

        For example, Earth travels at about 30 km/s, and Mars travels at about 24 km/s, both in similar planes and in the same direction. That means you have to change velocity by about 6 km/s to move from one to the other.

        If Earth and Mars were at right angles in their orbits, you would effectively have kill your motion in your plane and then accelerate in the other. So, your change in velocity would be something like 54 km/s.

        (Overly simplistic, but hopefully it gets the point across.)

        • If you hit it perfectly, after your deceleration could you simply enter the planets orbit? Your orbit would be on the same plane, at that point it's just the planet moving, your velocity/direction did not change by anything you did.

          Would the planets gravity sort of drag you along as it moved, that is how orbits work right?

          • Let's quantify that: the speed of your spacecraft is 0, and the planet's speed is about 30 km/s. The planet attracts the spacecraft at 1 G, or 10 m/s^2. So you need 3000 seconds of being in the planet's vicinity to match speed. But the planet is moving away from you rapidly: after 60 seconds, it's ~2000 km away and gravity has dropped to 5 m/s^2.

            So you're chasing the planet, but at a lower speed than the planet. This means it's inevitable your orbit starts to change, and you'll enter an elliptical orbit aro

        • I make the delta-vee closer to 38km/s than 54 km/s, but your point stands.
  • Just again proves the basic principle of probability theory; given enough trials any possible outcome must occur.

  • What a stupid description.

  • I think it's entirely possible this isn't as rare as believed but rather the assumption that it didn't happen caused scientists to overlook previous instances of abhorrent data as being sensor glitches or something else that is inline with the prior theory. It's always fun when they discover a new phenomena because then old data gets revisted with new eyes.

  • Holy shit Batman, let's get the Bat Probe up to Uranus and check it out!
  • From what we know about our solar system, the planetary orbits are not as expected, as there were many collisions since formation. Isn't the most likely reason a similar event?
    • I'm not a Physicist, but I would wonder if the system could have been normal, but at some point a massive object, like a brown dwarf or something could have passed through the system and bent the orbit of the 2 outer planets and possibly kick other planets out of the system all together.
      • Something violent has probably happened, likely the ejection of one body (by close approaches with two others, including the primary). But also possibly an "interloper" body from "far away" coming in and stirring things about before being ejected again.
  • Our solar system is just one among an uncountable number of solar/ planetary systems. There will always be variations, and just because the planets in our solar system all orbit in the same plane, it doesn't mean that every other solar system will be the same. Soon they might find a system in which the sun orbits a giant central planet (ridiculous, I know) or maybe with irregular hulahoop like or spiraling orbits.(if they exist, please write about them)
  • if they use Daylight Savings Time?
    • If they have an obliquity greater than about 15 degrees, yes.

      Most of the bleating I hear about DST comes from people living at low latitudes. Up here (57 deg from the equator), it makes a big difference.

      • I would think at 57 degrees an hour would make even less difference. I'm above 49N, and with our change last weekend it now gets light an hour earlier in the morning, and darker an hour earlier at night. Makes exactly no difference to my life, and the people who care seem to be evenly split between people who want more light in the morning and people who want more in the evening. Still going to be mostly dark in the coming months so at least I can laugh at them all.
        • Aye, well. I live at 57degN ; I've worked, for months at a time, as far as nearly 63degN (a bit less than 100km S of the Arctic Circle). Evan at 57 N, if you're working on night shift, you can not see sunlight for several months at a time. I do sometimes consider getting vitamin D supplements, but rotating day- and night- shift on a reasonable schedule (2-3 weeks, varies between people) is probably a better solution. But sometimes you don't get a choice.

  • I assume the reason that "normal" solar systems have planets lying in a plain is that the angular momentum of the dust cloud from which they formed spins it into a flat sheet, So orbits at 90 degrees are decidedly odd. Perhaps "little green men" moved them there as a sign.

    Got to be worth a punt.

    (Note: best use that term now, before it gets ruled "sizeist", "colourist "and "sexst".)

    • Worth a punt ... but we have similar examples within the satellite systems in the Solar system. Several of the minor satellites of Saturn and Jupiter are at high inclinations to the plane of their primary's main satellite systems, while Neptune's system includes the retrograde and highly eccentric (e~=0.7) Nereid. The orbital mechanics people have no problems generating these systems by small bodies coming in from "afar" (in the Jovian and Saturnian cases) and the capture of Triton by Neptune from the Kuipe
    • The first diagram on this page [harvard.edu] (it's a PostScript file - you'll need Ghostscript, or something similar to render it) shows the relative orientation of a lot of satellites of outer solar system planets. There's an obvious tendency towards orbiting close to the primary's equatorial plane, but a number at high inclinations, as described for this system.
  • I have been wondering how to move Venus out to an L4* orbit from Earth in order to cool it and make it habitable but the problem has always been that it passes to close to Earth on the way and will set up a resonance. Perhaps the local intelligences have the same problem and decided to tilt the orbit first in order to reduce the interaction.

    *L4 ... other Lagrange points are still available and, yes, I realise that Venus is too massive for the L4 orbit to be stable.

  • Uh, define polar orbit. How do they know what the spin axis of the star is?

    • You look at line-splitting or line-broadening in your spectroscope. The approaching limb has a blue shift ; the receding limb has a red shift. From that you can derive a surface rotation speed in km/s.

      Temperature, range and luminosity gives you the radius (well, surface area - proportional to the radius).

      Unless you see literal clouds of material being spun off the equator into the neighbourhood, you've got some limits on the surface speed (and "centripetal" force) at the equator, and that constrains your

  • Nothing wrong with that, but I thought it sounded a bit familiar. Mostly I was wondering how I'd missed that story in my daily trawl of new stuff on Arxiv. The "1706" part of the URL answered that : 2017, month 06.

    Interesting system. People have been realising while the observational astronomers have uncovered these weird and wonderful systems, just how bad we have been at extrapolating from our nice little Keplerian fishpond to how the Real World (TM) really plays.

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