back to article Blast from the past: Boffins find the fastest exploding non-supernova star

Eta Carinae is one the strangest star systems in space. When it exploded in the 19th century, it became the second brightest star in the sky. Now, scientists studying "light echoes" have found that it was also the fastest non-fatal outburst of any star system. The blast spewed clouds of material at 10,000 to 20,000 kilometers …

  1. Chris Miller

    Given Eta Carinae is 'only' 7,500 light years away, a supernova would be quite spectacular (perhaps as bright as the full moon). Particularly if it produced a gamma ray burst and if this was angled towards earth (which could be much brighter than the sun, for a few seconds). But astronomers consider either event to be improbable (though not impossible).

    1. Wellyboot Silver badge

      >>'Only' 7,500 light years away<< You're not wrong!

      While 7,500 is on the cosmological doorstep the amount of sky the earth occupies at that distance (and the chance of a gamma burst hitting us) is vanishingly small.

      It would be quite the spectator event, (but obviously not visible from UK due to cloud)

      1. Tom Paine Silver badge

        Are the gamma rays in a GRB directional, then? I always pictured it as radiating in all directions. Something new every day, eh.

    2. cray74

      Particularly if it produced a gamma ray burst and if this was angled towards earth

      Which wouldn't be a problem for Earth. GRBs are only threatening if they fire within a few parsecs of Earth, at which distance they could cause serious ozone degradation, a bit of a 'GRB winter' and some acid rain.

      1. Chris Miller

        GRBs are only threatening if they fire within a few parsecs of Earth

        Not according to these guys.

        Judging by the pictures of the 'dumbbell', it looks like the axis of Eta Carinae is about 40° off a direct line to us, and it's thought that GRBs spread over no more than 10°, so we're safe, as long as the axis hasn't shifted since the event that created these clouds (which is conceivable because this is a multiple system).

  2. Zimmer
    Joke

    Astronomical Events in UK

    When it does explode I forecast cloudy skies for the UK for the duration of the supernova...

    (as per all Astronomical events here, we rarely get to see them first hand).

    1. Anonymous Coward
      Anonymous Coward

      Re: Astronomical Events in UK

      " When it does explode I forecast cloudy skies for the UK for the duration of the supernova... "

      I now think it is "British Astronomer Luck". I always thought it was just the climate in the UK, but this year, while on holiday in an area of Southern France known for having the most periods of clear skies a year in Europe, there was the eclipse of the moon. "blood moon eclipse", "Longest eclipse of the century", "micro-moon", "mars nearby", etc...

      So I excitedly went up the nearest hill to finally observe an astronomical event with my own two eyes, only to find a very UK-esqe scene. Nothing by a sea of overcast clouds, in late July of all times!

      It was completely overcast from start to finish. Thankfully it cleared up shortly after the eclipse was done, so no risk of me seeing any astronomical events as per usual. So, at some point I think the universe conspires to hide its majesty from me regardless of where I am.

      Saying that though, the days before and after that one have had nothing but clear skies day and night, and out here the French actually turn off the streetlights after 1am, so you get some amazing dark sky views. So I still get some better views than I have ever managed in the UK. Next time I will bring my gear and try to take some photos.

      1. Tom 7 Silver badge

        Re: Astronomical Events in UK

        I've often wondered if I should get some form of above cloud transport for events like this. Then I remembered noctilucent clouds.

        And as for Eta Carinae being above the clouds would probably mean the GRB would render you blind anyway, either permanently or with a shit load of Cherenkov.

        1. Chris G Silver badge

          Re: Astronomical Events in UK

          During the recent lunar eclipse the sky here in Valencia was perfectly clear, my wife called me from Ibiza to go and look at it.

          The whole thing took place in clear skies like the celestial clockwork it is, right behind the mountains to the East of me.

        2. Anonymous Coward
          Anonymous Coward

          Re: Astronomical Events in UK

          That's when we get the rise of the triffids/rats/robots etc.

      2. Ogi
        Pint

        Re: Astronomical Events in UK

        Saying that though, the days before and after that one have had nothing but clear skies day and night, and out here the French actually turn off the streetlights after 1am, so you get some amazing dark sky views. So I still get some better views than I have ever managed in the UK. Next time I will bring my gear and try to take some photos.

        That is something at least. Round my part of the UK they replaced the sodium streetlights with those god-awful glaring white LED ones, which never turn off at night. It is so bad you can't even see a single star anymore, but at least you can make out the moon (if it isn't cloudy)

        To make it worse, the white streetlight now enters my bedroom so brightly it affects my sleep, so now looking to get blackout blinds just to not have light pollution in the house.

        Alas my gear has spent the last few years gathering dust, and the way things are going, opportunities to make use of it are getting rarer and rarer.

        I am beginning to think being an amateur astronomer is a bit masochistic in this day and age. You spend a lot of effort and money on kit, you end up staying up till odd hours at night and/or freezing your bollocks off outside waiting for the event, you constantly come against bad weather and the rest of humanity (that seems to love to light up the night as bright as the day), and the only place left you can really live to enjoy your hobby is so far out the sticks you would have to adopt a hermit lifestyle in a log cabin in the middle of nowhere.

        ... I still enjoy it though, in those rare moments when the universe aligns with my goals.

        Pint because I could really do with one right now, its Friday!

        1. Anonymous Coward
          Anonymous Coward

          Re: Astronomical Events in UK

          > the only place left you can really live to enjoy your hobby is so far out the sticks you would have to adopt a hermit lifestyle in a log cabin

          Well, turn this around and make an advantage out of it: Find a couple other amateur astronomers, buy together a log cabin in the sticks and go there from time to time to make some observations - along with some quality time sipping a drink in front of the fireplace while conversing with like-minded people...

          1. LDS Silver badge

            Re: Astronomical Events in UK

            Use a remote controlled telescope. Just your log cabin needs to be safe enough for the equipment there....

    2. LDS Silver badge
      Happy

      Re: Astronomical Events in UK

      I think cloud doesn't matter, the Carina constellation is not visible from Northern Europe.

      The fact it was observed using "Gemini South telescope, the Blanco telescope, and the Magellan Telescope" was a clue...

  3. Keith Oborn

    "bounced off of"?

    Please desist

  4. This post has been deleted by its author

    1. molletts

      Re: Holy cow that's an awesome photo!

      That's the real thing.

      I remember the first time I saw a picture of Eta Carinae (or, rather, the Homunculus Nebula around it). I was about 8 or 9 and the picture was in a book I'd been given for Christmas (I think it was probably "The Natural History of the Universe" but I don't have it to hand right now to check). It completely blew my mind, being used to seeing colourful but otherwise rather flat-looking clouds of ionised gas.

      I still think "holy cow" every time I see it.

      1. AgentMyth

        Re: Holy cow that's an awesome photo!

        I felt the same way about a picture of the Carina Nebula (tenuous link to Eta Carinae) that NASA produced from Hubble.

        Some times it's hard to find the full picture, but here is is for reference:

        https://www.nasa.gov/multimedia/imagegallery/image_feature_1146.html

  5. Paul Herber

    pedantry ...

    "When it exploded in the 19th century".

    ITYM

    "When the light reached astronomers eyes on Earth in the 19th Century"

  6. Paul Herber
    Facepalm

    pedantry ...

    "When it exploded in the 19th century".

    ITYM

    "When the light reached astronomers' eyes on Earth in the 19th Century"

    I had to edit this post, my initial posting missed out the apostrophe. Give a pedant a good kicking ...

    1. codger

      "When it exploded in the 19th century" was: pedantry ...

      With all respect, "When it exploded in the 19th century" is correct.

      If you wanted to reformulate all such statements with a distance correction, you would need to know the exact distance to every object

      I'm OK with "The light from the explosion left Eta Carinae 7,500 years ago when humans only had black and white television" in popular articles but as far as scientists are concerned, time of events witnessed on our earth is only to be measured with clocks and calendars here on earth.

      Have a great day (as measured by an earthly clock, of course)

  7. nanchatte

    I just have to say this from time to time... Bloody hell there are some smart people out there who think up these sorts of tests and investigations!

  8. Maelstorm Bronze badge
    Boffin

    The story of Eta Carinae

    Eta Carinae has an estimated mass between 90-120 M☉. Unlike our sun which will for a white dwarf and a planetary nebula, Eta Carinae will go out with a bang: A Type II Supernova. This type of supernova is a core collapse supernova. What happens is that the star rapidly burns through it's fuel to offset gravity, forming heavier and heavier elements until it starts making iron. During the nucleosynthisis process, the elements form shells around the core, similar to a Russian nesting doll. This is due to the fact that the specific gravity of the elements in question have a certain density. Since Iron is the heaviest, it sinks all the way to the center of the core.

    Iron will fuse, but it will not produce energy when it does, so the star is robbed of the energy it needs to support itself against gravity. Then the core collapses. If the core mass is > 1.4 M☉ (the Chandrasekhar Limit), it will form a black hole. The star is then eaten from the inside out, and the black hole will spin up rapidly, throwing matter out through the poles at very high temperatures and energies (aka the gamma ray burst). To produce gamma rays, the matter must be heated up to billions of Kelvin.

    This is a very simplified version of what happens. In case you are wondering, Astronomy is an interest of mine and I have taken a number of courses on it. In fact, Type II Supernovas was the subject of my thesis paper in my writing intensive class which was Astronomy. So, when it comes to Astronomy, you probably could group me in with the boffins.

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