back to article Einstein Probe finds two stars that have spent 40 million years taking turns eating each other

The Einstein Probe space telescope has spotted evidence of one star consuming matter from another. The first clue that led to this discovery was an X-ray flash emanating from the Small Magellanic Cloud, around 200,000 light years from Earth. The flash was unexpected so scientists were keen to learn more. The flash was spotted …

  1. Flocke Kroes Silver badge

    Unfamiliar unit

    The square degree is not a unit I see very often. Switching to SI: 1.1sr didn't help. 8.7% of a sphere is more helpful to me. Before anyone asks: about 2100 times the solid angle of Wales.

    1. Anonymous Coward
      Anonymous Coward

      Re: Unfamiliar unit

      It kind of makes sense though. I just saw it, thought that's 60 squared (I don't usually do square roots in my head, but it's the number of seconds in an hour so jumped out at me) and assumed it meant 60 degrees vertical by 60 degrees horizontal.

    2. Bill Gray Silver badge

      Re: Unfamiliar unit

      The full sky is about 40000 square degrees, or deg² (and, of course, 4π sr). Square degrees, square arcseconds and, more rarely, square arcminutes get frequent use in astronomy.

      The solid angle of Wales is dependent on one's location, of course. But if you were at the center of a hollow earth, looking up at Wales from the underside, it would cover about 1.66 square degrees.

  2. STOP_FORTH Silver badge
    Mushroom

    Disappointment

    There is a growing list of things that are going to collapse or go supernova. It's like waiting for a damp firework to go off.

    I realise that I am not the main character in the entire Universe but please, could something blow up, flare up, collapse or go kablooie?

    1. UCAP Silver badge

      Re: Disappointment

      "Where's the kaboom? There was supposed to be an Earth-shattering kaboom!"

    2. Luiz Abdala Silver badge
      Mushroom

      Re: Disappointment

      Let's just say we need to be at the exact distance where we can see things going klabooie and not be taken out by them.

      I heard about some stars that emit a lethal jet of radiation through their poles when they go boom, and these were calculated to be lethal for over 1 million LY in the direction they happen to aim.

      Like being in the city of Halifax when a ship carrying 7000 tons of explosives caught fire resulting from a collision and blew up. The city became a center for eye injuries, given the amount of people looking at the ship's immolation behind glass windows when it detonated, and where within range.

      https://en.wikipedia.org/wiki/Halifax_Explosion

      So yeah, it is a bit comforting not being inside the blast radius of the space wedgie* of the week.

      *Star Trek reference.

      1. UCAP Silver badge
        Mushroom

        Re: Disappointment

        I heard about some stars that emit a lethal jet of radiation through their poles when they go boom, and these were calculated to be lethal for over 1 million LY in the direction they happen to aim.

        That only occurs when a giant star goes supernova via a core implosion, where the core then collapses right the way down to a black hole. You tend to get high-energy particles emitted in a pair of very narrow polar jets. These are suspected to be the source of the long-duration gamma ray bursts that hit earth.

      2. eldakka

        Re: Disappointment

        > I heard about some stars that emit a lethal jet of radiation through their poles when they go boom, and these were calculated to be lethal for over 1 million LY in the direction they happen to aim.

        You are most likley referring to Gamma-Ray bursts (GRBs), but you are off by a couple orders of magnitude. A GRB would most likely have to be within 10,000 LY to be dangerous to the Earth, which basically limits it to having to be within our own galaxy. But since the the events casing GRBs are quite rare (estimated at between 1 in every 10k years and 1 in every 1million years in a galaxy our size) and the jets are tightly focused, you'd be pretty unlucky for a star within 10k LY to be pointing directly at our Solar system when it does go supernova.Which isn't to say it can't or won't, but it is extremely rare and is believed to have happened at least once in our past (4-5 billion years is a long time, long enough for incredibly rare events to have happened a time or 2 or three).

    3. HorseflySteve

      Re: Disappointment

      Keep watching Corona Borealis. Tau is expected to go nova anytime now; not a total kablooie but shedding some outer material.

      Corona Borealis should be visible in early mornings before dawn, if I've got me celestial mapping correct.

      1. STOP_FORTH Silver badge

        Re: Disappointment

        Good example. I've been watching that damp squib since last year. It's not even going to be that spectacular.

    4. Anonymous Coward
      Anonymous Coward

      Re: could something blow up, flare up, collapse or go kablooie?

      SN 1987A

      You are south of the equator right? You could have seen it if you were alive and grown up enough in 1987.

      1. STOP_FORTH Silver badge

        Re: could something blow up, flare up, collapse or go kablooie?

        I have been South of the Equator four times. First time was in 1996, so I missed that one. Didn't even notice the neutrinos.

        1. M.V. Lipvig Silver badge

          Re: could something blow up, flare up, collapse or go kablooie?

          I did - they itch.

          1. STOP_FORTH Silver badge

            Re: could something blow up, flare up, collapse or go kablooie?

            Disc world doesn't have an Equator! Or does it?

            1. UCAP Silver badge

              Re: could something blow up, flare up, collapse or go kablooie?

              It has The Edge - a bit like an equator but rather more abrupt when you go over it.

  3. HorseflySteve

    "The larger of the two stars started to expand, as stars do late in life"

    It's not just stars that happens to (looks sadly at the dial on the bathroom scales)

    One more piece of evidence that we are stardust and, while not golden, apparently increasing in density with age....

  4. I don't know, stop asking me.

    > the white dwarf is around 120 percent the mass of our Sun and approaching the Chandrasekhar limit at which it will implode into an even denser neutron star or go full supernova.

    Wait, doesn't a star need approx. 8M before it can go supernova?

    1. HorseflySteve

      Not all types, it seems. I think the suggestion is that it will be a class 1a supernova as described here: https://www.astronomy.com/science/the-different-types-of-supernovae-explained/

      1. I don't know, stop asking me.

        Thanks for the link.

        It's so hard to keep up as a non-astronomer. ;-)

    2. UCAP Silver badge

      You are correct for a Type 1b, Type 1c or Type 2 supernova - they are all caused by stellar core implosion and the star needs to be at least 8 solar masses to trigger it. However a Type 1a supernova is caused by the deflagration of a white dwarf; it only needs to be somewhere around the Chandrasekhar limit.

  5. Dinanziame Silver badge
    Pint

    Title sounds like a NSFW celebrity leak

    Well done

    1. cray74

      Re: Title sounds like a NSFW celebrity leak

      Upon reading the title, my thought was, "Well, as one does in a good long-term partnership."

      1. frankvw Bronze badge

        Two stars taking turns eacing each other

        That is some hot star-on-star action!

  6. John_Dorie

    (*Adopts best Kenneth Williams voice) Ohh matron, take them away!

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