back to article Supermassive black hole turns unlucky star into spaghetti

Astronomers have watched a star be destroyed by the process of spaghettification, a rare event triggered when a sun strays too close to a black hole. AT2019qiz was ripped apart by a supermassive black hole in the constellation of Eridanus. Though it is 215 million light years from Earth, it is the closest star we've seen …

  1. Neil Barnes Silver badge
    Boffin

    spaghettification

    Possibly the best word ever to have come from the study of black holes.

    1. ThatOne Silver badge
      Coat

      Re: spaghettification

      I've always wondered how spaghetti were made. Now I know.

      1. aj69

        Re: spaghettification

        There must be a weight loss opportunity here.

        1. Arthur the cat Silver badge

          Re: spaghettification

          There must be a weight loss opportunity here.

          Unfortunately it comes with a life loss downside.

      2. Trigonoceps occipitalis

        Re: spaghettification

        It grows on trees in Italy.

        1. KarMann Silver badge
          Headmaster

          Re: spaghettification

          Actually, in Ticino, Switzerland, although it is the very southernmost bit of Switzerland, bordering on Italy, and Italian-speaking.

  2. EBG

    yes or no ?

    This article says that the supermassive black hole spaghettified an infalling star. The sidebar linked article " what would happen if Earth fell in" says that only normal black holes spaghettify and that with a supermassive BH, you fall inside the event horizon before the field gradient gets big enough.

    1. Paul Kinsler Silver badge

      Re: yes or no ?

      There are all kinds of hidden and non-hidden assumptions here, but perhaps the most obvious difference is that stars are just big balls of gas; but the earth is rocky, and so has more intrinsic structural integrity.

      1. Wellyboot Silver badge

        Re: yes or no ?

        Getting my head around the (truly mind boggling) forces involved here required some serious reading. Gravity can literally pull any object apart because it's operating at the sub-atomic level and everything has a structural limit while gravity just keeps on increasing as you add mass.

        From the perspective of the singularity in a supermassive, the difference in structural integrity between a gas cloud and a neutron star is insignificant, both will arrive as a particle stream, the only difference is how far away it happens.

        1. This post has been deleted by its author

        2. Claptrap314 Silver badge

          Re: yes or no ?

          The question is whether the object spaghettifies before or after it crosses the event horizon. Smaller, denser, objects spaghettiffy later than larger, less dense ones. For a large enough black hole, planets will cross the event horizon intact.

    2. Wellyboot Silver badge

      Re: yes or no ?

      In a supermassive the spaghettification happens after passing the event horizon, it's just that there's no way to view the process from outside. Theres quite a distance (many AU) between event horizon and the actual singularity itself.

      Anything with less mass than a star wouldn't have the inbuilt gravity to hold itself together long enough to reach the event horizon.

      1. 2+2=5 Silver badge

        Re: yes or no ?

        > In a supermassive the spaghettification happens after passing the event horizon

        Does it though? Crossing the event horizon means there's no way back. The gravitational field is more than strong enough prior to that to pull the star apart.

        1. Wellyboot Silver badge

          Re: yes or no ?

          No way back, but there's still an ever increasing gravity pull that will eventually rip anything apart down to the sub atomic level.

          The more massive an object is, the nearer it will be able to approach a singularity before it's own gravity is swamped.

          1. 2+2=5 Silver badge

            Re: yes or no ?

            Your original point was "In a supermassive the spaghettification happens after passing the event horizon, it's just that there's no way to view the process from outside."

            I'm just pointing out that spaghettification starts before the event horizon, therefore it has a chance of being seen by astronomers. I assumed that is what is being seen in this case.

            1. Anonymous Coward
              Boffin

              Re: yes or no ?

              For large enough BHs, objects falling in won't be disrupted before they pass the event horizon. For a star the mass and size of our Sun not to be spaghettified until after it had passed the event horizon the mass would be about 114 million solar masses.

    3. Anonymous Coward
      Boffin

      Re: yes or no ?

      The answer to this is that what disrupts objects falling into a BH is not the strength of the gravitational field, it's the variation of that strength over the extent of the object falling in. This is normally called a 'tidal' effect because it's the same effect that causes the Moon to raise tides on the Earth.

      As an object falls towards a BH, the difference between the field it feels on the side away from the BH and that it feels on the side closest to it increases, and it increases without bound (it becomes as large as you like) as you approach the singularity. At some point this difference in field overcomes whatever is holding the object together and it falls apart, becoming spaghettified.

      Any large object like a planet or a star is held together entirely by gravity – in particular planets don't have significantly more 'structural integrity' than stars. So it is not that planets are somehow stronger than stars that means that planets will get spaghettified later.

      Rather it is that stars are much larger than planets, so they experience hugely larger tidal forces as they approach the BH, and thus get disrupted much sooner.

      A nice way of thinking about it is to realise that what matters, really, is how large the infalling object is compared to the radius of the BH's event horizon. The larger it is, the larger the tidal forces across it and the sooner it will get disrupted. If it is very dense, like a neutron star or something, it will tend to hold together for longer (neutron stars are also rather small, of course).

      If the object is small enough compared to the radius of the BH's event horizon, it won't get disrupted until after it has passed the horizon (at least not classically). If it's much larger, it will.

      In this case you can see that the star being disrupted is indeed pretty large compared to the BH: from the paper referenced in the article the BH has a mass of about a million solar masses while the star has a mass of about 1. This means that the radius of the BH's event horizon is only about 4 times the radius of the Sun. If we assume the star had a radius about the same as the Sun you can see it's really fairly large compared to the BH, which is why it will get disrupted.

      For the technically-minded there is a rather easy expression for the distance at which an object will be disrupted: R_t = R_* (M_h / M_*)^(1/3) (approximately). Here R_t is the radius at which a star will be disrupted, the 'tidal radius', R_* is the radius of the star, M_h is the mass of the black hole and M_* is the mass of the star.

      For a million-solar-mass BH, this means that the Sun would be disrupted about at about 23 times the radius of the event horizon, while Earth would be disrupted only about 14 times the radius. For a hundred-million solar-mass BH the Earth would only be disrupted inside the event horizon.

      Note that there are other nasties that happen as you approach a BH even if you dont get disrupted. You probably don't want to be too close to an active accretion disk, for instance.

  3. Dr Scrum Master

    FSM?

    Truly 'tis a glimpse of his noodly appendage!

    1. Sgt_Oddball Silver badge
      Paris Hilton

      Re: FSM?

      That's one noodle of his I'd rather not be touched by though...

      Though it does raise the question... Are his meatballs made of black holes... Or are black holes made of his meatballs?

      1. steelpillow Silver badge

        Re: FSM?

        Dam! was just about to make the same observation.

        Clearly the star is being offered as a living sacrifice to the FSM in some unimaginable Cosmic Alien ritual. May I suggest that we terminate all efforts to contact alien civilizations, with immediate effect?

      2. Peter Prof Fox

        Confusion

        You're getting confused with meatyorites.

    2. This post has been deleted by its author

    3. Chris G Silver badge

      Re: FSM?

      Forsooth, 'tis a testament to the all encompassing power of his Noodly Holiness!

      All bow to the Great Cosmic Pasta!

  4. Anonymous Coward
    Anonymous Coward

    suggested name for the black hole

    Little Richard

  5. Spherical Cow
    Joke

    Please Sir, I want some more

    "They were able to study the relationship between the radiation emitted during the black hole’s feast, and the material erupting from the star as it was eaten for the first time."

    How many times do they expect it to be eaten?

  6. Inventor of the Marmite Laser Silver badge

    This IS El Reg, after all. Shouldn't it be called Linguinification?

  7. drankinatty

    Without the dust, can we better infer the imprint of information on the event-horizon?

    Information loss is quite the quandary in black-hole physics. If the amount of information in the universe is constant, then what becomes of it once it reaches the event-horizon? Will a clear unshrouded event like this one help answer that question? And what form the storage may take? (or at least the information related to 1/2 the matter not ejected)?

    1. Anonymous Coward
      Boffin

      Re: Without the dust, can we better infer the imprint of information on the event-horizon?

      Unfortunately it doesn't help. Due to the unbounded redshift as things approach the horizon we never really get any information from it, other than on absurdly long timescales.

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