back to article Forget superstars, this HYPERGIANT star is 1,300 times the size of OUR SUN

Sixty years of professional and amateur observations have turned up a new surprise in the constellation of Centaur: a huge, heavy and bright monster that's the largest yellow star ever seen. The hypergiant, HR 5171 A, has impressive vital statistics: the European Southern Observatory's Very Large Telescope Interferometer team …


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  1. Steven 1


    The Universe is full of such weird shit :)

  2. Stu 18


    That is truly awesomely wow! Sorry, just can't help but post my amazement.

    1. Destroy All Monsters Silver badge

      Re: WOW

      This must be the Doge Star.

  3. Anonymous Coward
    Anonymous Coward

    Black hole in the making?

    How far away?

    1. Voland's right hand Silver badge

      Re: Black hole in the making?

      First things first, someone needs to put things into perspective.

      No boom today, boom tomorrow. There will always be a boom tomorrow. Boom.

      6-7 magnitude fop a star that is not a white or blue giant means it somewhere fairly close. A quick google shows 12k light years. Difficult to judge really. If it goes supernova we may end up with way more tan than we would like. Not particularly bad though - the last close supernova (the crab nebula) was 6.5k away.

      1. Z-Eden
        Thumb Up

        Re: Black hole in the making?

        Thumbs up for the B5 reference!

    2. Rich 11

      Re: Black hole in the making?

      Yep. It's about twice as massive as necessary for it to end up as a black hole. And if it's been cooling noticeably over just 40 years, it may not be far off going supernova.

      1. Rich 11

        Re: Black hole in the making?

        I've just finished reading the paper. The authors suggest that contact between the two stars may only have happened 30 years ago (well, ~12,030 years ago, but you know what I mean) and that's what's responsible for the apparent cooling. The mass-transfer could last for tens of thousands of years and depending on how that changes the orbital distance between the two stars, their evolution is uncertain. Fascinating stuff.

    3. TeeCee Gold badge

      Re: Black hole in the making?

      Never mind the Black Hole, oodles of those around.

      1300 solar masses is getting into Hypernova territory and when it eventually collapses, we could see a decent sized Gamma Ray Burst from it.

      That could present something of a problem.

      1. Destroy All Monsters Silver badge
        Paris Hilton

        "Disaster Area, a plutonium rock band from the Gagrakacka Mind Zones"

        AFAIK that might depend on whether there is a lack of "metal" in the star. You also need to be in a cone centered on the axis of rotation to get, and whether you are within a cone centered on the axis of rotation to get a good atmosphere-reforming blast.

      2. cray74

        Re: Black hole in the making?

        Psst. The star is 39 solar masses. Its diameter is 1300x that of Sol, not the mass.

  4. Martin Budden

    It's visible to the naked eye yet we've only just worked out what it is! Still a bit of catching up to do in the southern hemisphere?

    1. Anonymous Coward
      Anonymous Coward

      Those downunder didn't know who oelilag was until they knew who we were talking about.

    2. Chris 239

      I'm also a bit surprised how the extremely unusual nature of a relatively close naked eye visible star has only just been discovered.

  5. Winkypop Silver badge
    Thumb Up

    It's full of stars!

    And bloody great big ones too.

  6. Horridbloke

    How big?

    Well I know what I'll be doing on Universe Sandbox later.

  7. Kaltern

    Looks like an intersteller Weeble.

  8. kmac499

    Thin Star Stuff

    Ok so the 'A' start is 1300 times the diameter and 39 times the mass of our sun.

    Which is about 2.2 billion times the volume (1300^3) for the 39 solar masses to slosh about in.

    Giving it an average density 0.000000018 of the Suns.

    Ok that doesn't affect the supernovae Physics, but it's more a howling ball of hot fog at the moment.

    1. Michael Hoffmann

      Re: Thin Star Stuff

      Which makes me wonder whether, once it starts shedding layers as they frequently do, enough mass will remain above the Chandrasekhar limit to go neutron star or black hole.

      It may end with a whimper, not a bang...

    2. Anonymous Coward
      Anonymous Coward

      Re: Thin Star Stuff

      "Giving it an average density 0.000000018 of the Suns"

      or about 40,000 times less than sea level air density on Earth!?

  9. Anonymous Coward
    Anonymous Coward

    Just imagine

    The size of plants you could grow!

  10. Colin Brett

    Life, Jim?

    "Let's get that diameter in perspective: drag-and-drop HR 5171 A in place of our sun, and it's good-bye to Mercury, Venus, Earth, Mars, the asteroid belt, Jupiter and Saturn."

    So would that place Uranus, Neptune and Pluto in the Goldilocks Zone? Or would they all be like Daddy Bear's porridge?

    Inquiring minds want to know.


    1. cray74

      Re: Life, Jim?

      Even if Neptune & Co were in the Goldilocks zone, it wouldn't be for long, and it'd be a Goldilocks zone inhabitated by bears.

      Stars like that are unstable on human time scales. Today they're a yellow star 1300 times Sol's diameter, tomorrow a core hiccup makes them an even-larger red giant, and the next day they cool and contract a bit. (Where "day" might mean "decade" or "century.")

      Further, low density stars like this are producing epic solar winds that carry away entire solar masses of their own fumes. A terrestrial planet in the Goldilocks zone will have its atmosphere sand-blasted away very quickly (where "quickly" means "decades" or "millennia," give or take a few orders of magnitude.)

  11. The last doughnut

    That is tremendous

    Should point out that it is only yellow on the surface. Inside all of that hot fog is an extremely hot core. No need to start worrying until it starts to collapse again.

    1. Destroy All Monsters Silver badge

      Re: That is tremendous

      Better than a star that is yellow inside.

  12. Charlie van Becelaere

    So how thick

    would my hat's aluminium foil lining have to be to prevent gamma radiation mucking with my brain?

  13. Euripides Pants

    Gotta give it a better name

    I vote for "Lumpy".

    1. Mpeler
      Paris Hilton

      Re: Gotta give it a better name

      Since it looks like a peanut, and it could be the beginning of a supernova, how about

      Carter Starter?

      (showing my age there....)

      Paris, because she's a hot blond (yellow) star....

  14. DaiKiwi

    Bright Light! Bright Light!

    By rough calcualtions, if it was at the same distance as Alpha Centauri or Sirius (4-8 ly) it would be brighter than the full moon. If it was 300 ly away it would be still be visible during the day.

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