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Space

Planet That Shouldn't Exist Found (arstechnica.com) 49

Posted by msmash from the how-about-that dept.
The exoplanet 8 Ursae Minoris b should not exist. It orbits its host star at just half the Earth-Sun distance, and by all indications, the star should have gone through a phase in which it bloated up enough to engulf that entire orbit and then some. Yet 8 Ursae Minoris b definitely appears to exist. From a report: There is a handful of potential explanations, none of them especially likely. The people who discovered the planet are suggesting that it survived because its host star got distracted by swallowing a white dwarf instead. 8 Ursae Minoris b was discovered using the radial velocity method, which watches for changes in a star's light that occur as planets tug the star back and forth as they orbit. This tugging creates a blue shift in the light when the planet is pulling the star in the direction of Earth and a red shift when the star is pulled away from Earth.

But the planet is unlikely to be tugging the star directly toward Earth, so we tend to only measure the component of the star's motion that's in our direction. We'd see the same apparent motion of the star if a light planet's orbit was oriented directly toward Earth or a very heavy planet that has a relatively skewed orbit. At best, radial velocity measurements give us an estimate of the minimum mass of the planet; it could potentially be larger. So we know that, at minimum, 8 Ursae Minoris b is a big planet, at over 1.6 times the mass of Jupiter. It also resides close to its host star, completing a full orbit in just 93 days. That places it at half an Astronomical Unit (AU, the typical distance between Earth and the Sun) from its star.

Observations also hint at a second body orbiting the star at least five AU. The evidence for that is weak given the current data, but it may have a significant role in shaping the system. On its own, there's nothing especially unusual about the 8 Ursae Minoris exosolar system. Where things get weird is when you consider the star at the center of the system.
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Planet That Shouldn't Exist Found More

Planet That Shouldn't Exist Found

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  • Exceptions are awesome (Score:3)

    by Baron_Yam ( 643147 ) on Wednesday June 28, 2023 @01:43PM (#63640722)

    If you don't know what a car is, and only ever see cars driving down a highway, you might rightly decide "cars are things that move along highways".

    You see one car crash in a ditch, you suddenly have a chance to learn a lot about where your model was lacking.

    • Re:Exceptions are awesome (Score:5, Informative)

      by greytree ( 7124971 ) on Wednesday June 28, 2023 @01:50PM (#63640744)
      Indeed.
      The expression "The exception proves the rule" comes from Cicero: "exceptio probat regulam in casibus non exceptis", which means "the exception confirms the rule in cases not excepted".
      • Iâ(TM)ve always wondered. When the sun expands. Assume it engulfs earth. Earth is a big solid mass that is VERY dense. The Sun is a plasma, maybe even just somewhat of a solid core, but mostly a gas. If you look at the supergiant stars, they are relatively low density, and their bodies are lower density than our atmosphere. What happens when the star eventually retracts? The earth may be obfuscated by the sun at some point, but maybe it maintains its integrity and comes out like a car passing through a

        • Re: (Score:2)

          by tragedy ( 27079 )

          Depends on how long it stays in there, I would think. The Earth may be a big mass, but it's tiny compared to the Sun. Ignoring the photosphere, the temperature of the surface of the sun is higher than the boiling point of tungsten. That might change in a red giant expansion scenario, but you're still talking about furnace that should be hot enough to boil pretty much any substance on Earth. I'm not sure how fast Earth's outer layers will boil away, but I'm going to guess pretty fast. Not to mention the eros

          • Re: (Score:2)

            by Calydor ( 739835 )

            I'm actually curious whether the planet would melt, be ripped apart, or harden to essentially a ceramic ball.

            I mean, in all three scenarios life is OVER on this planet, but what exactly is the planet's fate at the end?

            • My comment speculated that a red giant at its extreme has an average density several orders of magnitude lower than the earths average density. Will the oceans boil off? Yeah probably. The atmosphere would surely be gone completely, if not barely there. The land mass? Probably cooked. But, would the orbital dynamics of the planet cease completely? I dont know. I would think maybe not. The surface would not be moving at earth-like speeds, but it's probably so thin that it wont really matter. Right now, we ar

              • Re: (Score:2)

                by tragedy ( 27079 )

                The average density of the sun is higher than water, but lower than rock. Of course it is less dense at the surface and gets steadily denser on the way down. I'm not sure what the mass distribution would be like as a red giant. Obviously lower average density, and presumably low density at the surface and increasing to the core, but I'm wondering if the same forces that drive the expansion might affect that. Even if not, even a very thin atmosphere (which will still be orders of magnitude denser than the so

                • I just looked it up and read out of curiosity. If the Sun becomes a Red Supergiant, its density when burning helium would be about 0.1kg/m3 on average, we should consider that the earth is far from the core if it were in such a large star. For comparison, the earth is 5520kg/m3. That gives the earth an edge of 55200x the average density of a red supergiant. If we assume it's twice on the inside, and half on the outside, that would be 100,000x. Like I said, a car driving through fog. Would it slow down? Prob

                  • Re: (Score:2)

                    by tragedy ( 27079 )

                    I just looked it up and read out of curiosity. If the Sun becomes a Red Supergiant, its density when burning helium would be about 0.1kg/m3 on average, we should consider that the earth is far from the core if it were in such a large star. For comparison, the earth is 5520kg/m3. That gives the earth an edge of 55200x the average density of a red supergiant. If we assume it's twice on the inside, and half on the outside, that would be 100,000x. Like I said, a car driving through fog. Would it slow down?

                    That, even at the outside, is far, far denser than the solar wind. The Earth's atmosphere gets that dense somewhere below 18 km. A re-entering space capsule is well done with the burning plasma ninmbus around it by that point. That's a good thing because, if it hasn't bled off that velocity by the time it reaches that depth in the atmosphere, it doesn't stand a chance. And, once again, a re-entering capsule has many, many times less kinetic energy wrapped up in the difference between the relative velocity o

        • Earth is a big solid mass that is VERY dense

          No not really. Its mostly molten with a very thin skin of solid non molten rock and water around. Now most of that "molten" isn't molten in the same way free flowing lava is, its more super heated soft but dense rock, but its soft enough that the sun could pull that sucker apart without batting an eyelid.

    • Re: (Score:2)

      by lsllll ( 830002 )
      This. In my opinion scientists have an extremely narrow mind when it comes to how things "should be". They often gauge only based on their knowledge. For instance, the prerequisite of all life being carbon based (which is not necessarily so [wikipedia.org]), or that planets having to be in a Goldilocks zone to be able to sustain life are just two where if you consider that the Universe is infinite, then all things become possible.

      • There has been volumes and volumes of discussion by scientists about life that isn't carbon based, and likewise of life outside the "goldilocks" (liquid water) zone.

        The problem is, in the absence of any examples, it ends up being simply speculation. Scientists talk about it all they like, but so far the only examples of life are the ones we see: based on carbon compounds, and existing with liquid water solvent.

        As a quick plug, check out the just-issued anthology "Life Beyond Us", from the European Astrobiol

        • Life needs an energy gradient and a way to store information. To store information you need stable molecules that can move around and arrange themselves in multiple ways and then stay put relative to other molecules. Moving around pretty much means soluble in a liquid and having multiple ways and staying put pretty much means carbon. You can't base your chemistry on boron or nitrogen because you really don't get multiple ways and staying put. You can't use silicon because the energy gradients are either

          • It's a perfectly plausible argument, but unfortunately "a plausible argument" is not quite the same as a known fact. Without confirmation by looking at life that stems from a different origin, it's also speculation.

            Quite simply, being surrounded by carbon-based life, your opinion is biased by what you see.

            • You want people to prove a negative, which isn't going to happen.

              We have observations and reasoning, and the subject has been covered in detail exhaustively by people far better educated in the relevant disciplines than you are.

              It's INFORMED speculation, and entirely reasonable. We can also exclude life that's based on refracted wavelengths of the colour blue.

              • You want people to prove a negative, which isn't going to happen.

                Incorrect. I want people to say "We don't know" when the situation is that we don't know.

                ...It's INFORMED speculation, and entirely reasonable.

                As long as you understand that informed speculation is still speculation, I'm all aboard.

      • 1) Ask a biochemist why carbon is the most likely basis for life. Then ask an astronomer. It's not because they're 'narrow minded' and only looking at Earth because that's all we know. There are reasons - nothing else is as chemically suitable for complexity, nothing even nearly as useful is as ubiquitous.

        2) In an infinite universe, all possible things will exist but that is not the same thing as all things being possible. There is, in fact, an infinitely vast gap between the two statements

      • The idea of non carbon life non-artificial life isn't particularly plausible, but not necessarily impossible. Carbon has a lot of properties that work in its favor, notably its somewhat unique ability to form exceedingly complicated molecules and its abundance in space (Its rudimentary for stars to create it. Hydrogen fuses to Helium, Helium fuses to carbon via the triple alpha process, and viola you have carbon). There really isn't any other candidates chemically.

        Silicon *maybe*, but Silicon is significant

    • Re: (Score:2)

      by Tablizer ( 95088 )

      Cars are things that are intended to move along highways & roads. However, defining something based on intention can be sticky. But without it, a sliding block of ice counts.

  • Before it was really big... (Score:1)

    by Anonymous Coward

    now, it is merely big.

    Why couldn't it have started out at the very edge of where the star expanded to. Where atmospheric drag would be minimal but non-zero. Also, the planet was primarily made up of a large nickel-iron core with a thick layer of carbon materials. The carbon acts as a carbon-carbon ablative heat shield (see Parker solar probe), and the nickel-iron core provides the mass to keep it together and keep in orbit during during the star's nova cycle. Think bowling ball through the air versus pi

    • There was once a genre of science fiction about the Sun unexpectedly going nova or of alien civilizations facing extinction when their star goes nova.

      Current astrophysical insight into this is that a nova is specific to a star in its final stage of life as a white dwarf, also requiring this star to be closely orbiting another star from which it is pulling mass from. When enough mass accumulates on the high-gravity surface of the ultra-dense white dwarf, it can go "boom" in a moderate thermonuclear explo

  • H2G2 (Score:5, Funny)

    by chill ( 34294 ) on Wednesday June 28, 2023 @02:08PM (#63640818) Journal

    Ursa Minor Beta is a rich and sunny planet and one of the most popular holiday destinations in the Universe. It is always Saturday afternoon on this planet, just before the beach bars close - except for the few places where it is eternally Saturday evening. This is why the locals always invite visitors to "Have a nice diurnal anomaly!"

    "When you are tired of Ursa Minor Beta you are tired of life."
      -- Quote from Playbeing magazine, as a result of which the planet's suicide rate quadrupled overnight.

    • Re:H2G2 (Score:4, Funny)

      by tragedy ( 27079 ) on Wednesday June 28, 2023 @04:27PM (#63641230)

      Go stick your head in a pig!

      • Re: (Score:2)

        by tragedy ( 27079 )

        Replying to myself. I think I misremembered the Sirius Cybernetics Corporation Complaints dept. as being on Ursa Minor Beta. Now I'm thinking the books don't name the planet.

        • Re: (Score:3)

          by chill ( 34294 )

          Close.

          The only profitable division of the company is its Complaints division, which takes up all of the major landmasses on the first three planets in the Sirius Tau system. The theme song for the Complaints division is Share and Enjoy, and has since become the theme apparent for the company as a whole. The main office building and headquarters for the company was originally built to represent this motto, but due to bad architecture it sank halfway into the ground, killing many talented young complaints exe

          • Re: (Score:2)

            by tragedy ( 27079 )

            Right, it was the Guide headquarters that was on Ursa Minor Beta (temporarily, at least, while they sucked the planet dry).

    • Ursa Minor Beta is a rich and sunny planet and one of the most popular holiday destinations in the Universe. It is always Saturday afternoon on this planet, just before the beach bars close - except for the few places where it is eternally Saturday evening. This is why the locals always invite visitors to "Have a nice diurnal anomaly!"

      "When you are tired of Ursa Minor Beta you are tired of life." -- Quote from Playbeing magazine, as a result of which the planet's suicide rate quadrupled overnight.

      But how do you know that a thought has filled your mind and how do you make it leave?

  • When you're talking billions of stars each with a few planets on average, you're bound to get some extremely unlikely outliers. The lottery is easy to win when you buy billions of tickets.

  • Those aliens must be insane (Score:3)

    by Whateverthisis ( 7004192 ) on Wednesday June 28, 2023 @03:43PM (#63641088)
    I just finished the first Three Body Problem book. Thinking of a planet who's population exists simply because it's sun got distracted swallowing another star would create a society I don't think I want to meet.

    yes, I know it's a gas giant/super Jupiter, blah blah. It's just interesting to think about all the crazy variations of star systems people are finding now and how cosmic-horror level horrific they must be.

    • There was a weird obsession within the Three Body Problem series with planets being destroyed by their stars. Trisolaris being an inciting incident made sense, but also the chain reactions of planets falling into stars was brought by some other random star system and in the Wallfacer's Mercury project. The vast majority of exoplanets known at the time that the books were written where extremely close to their stars as it predated the Kepler Mission so it seems like that had a huge influence on the plots.

      • The whole book was a weird obsession of nonsense. The three body problem, means that such a system is chaotic, and will inevitably end in one of the objects being swalliod by one of the other, or much much more likely: Being yeeted out of the system.

  • It's the Impossible Planet!

  • If it exists, it is clearly not impossible. What is lacking is our knowledge of how stars and planetary systems evolve. Perhaps the star did not behave as we expect or perhaps the planet was not in that orbit at the time. We will never know. We can only revise our models to conform to reality; reality has no requirement to conform to our models.

  • Literally.

    "by all indications, the star should have gone through a phase in which it bloated up enough to engulf that entire orbit and then some"

    All this proves is that some baseline assumptions by astronomers and astrophysicists are wrong; this should be abundantly obvious as the vastness of the universe and the teeny sipping-straw of incoming information sort of implies that we're making VERY broad assumptions based on VERY incomplete data. Much of what we assume to be true will absolutely be wrong.

    In th

    • I think it's often a casualty of the socio-political-religious culture wars.

      Millions of professional scientists and nerds with a deep math/science education got tired of every statement of uncertainty or controversy or alternative-theory becoming a place for Bible-literalists to place their wedge and then bang away with the hammer of "Ah HAH! Gotcha! You admit the science is unsettled therefore you can't say the God of King James doesn't exist therefore the God of King James does exist. Evolution is just a

  • So we have the possibility of a potential existence.

    But that's certain.

  • Has anyone considered the possibility that the plant was captured or changed orbits AFTER it's sun's expand-and-contract phase? I think the biggest shortcoming among astrophysicists is their assumption that every phenomena remains fixed throughout all space and time, which even dark matter can be handwaved away by assuming the constants don't remain constant.

  • The universe is under no obligation to make sense to you.

  • So by this logic, shouldn't exist either...

    • So by this logic, shouldn't exist either...

      Did you miss this bit?

      the star should have gone through a phase in which it bloated up enough to engulf that entire orbit and then some.

      It was the second sentence...
      Or sun hasn't gone through this phase yet. So Mercury can exist until then.

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