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Monster Hypergiant Star Discovered

Posted by Soulskill on from the go-big-or-go-home dept.

astroengine writes "A gargantuan star, measuring 1,300 times the size of our sun, has been uncovered 12,000 light-years from Earth — it is one of the ten biggest stars known to exist in our galaxy. The yellow hypergiant even dwarfs the famous stellar heavyweight Betelgeuse by 50 percent. While its hulking mass may be impressive, astronomers have also realized that HR 5171 is a double star with a smaller stellar sibling physically touching the surface of the larger star as they orbit one another. 'The new observations also showed that this star has a very close binary partner, which was a real surprise,' said Olivier Chesneau, of the Observatoire de la Côte d'Azur in Nice, France. 'The two stars are so close that they touch and the whole system resembles a gigantic peanut.'"

24 of 94 comments (clear)

  1. Can't wait until the merge by jfdavis668 · · Score: 2

    and explode.

    1. Re:Can't wait until the merge by davester666 · · Score: 3, Funny

      and then the hot star on star action will be over in a bright flash.

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  2. size? by BradMajors · · Score: 4, Insightful

    Is it 1,300 times as massive, has 1,300 times the volume, or what?

    1. Re:size? by JoeMerchant · · Score: 2

      Size: implies volume.

      However, the article's author throws around massive and mass as if they are also measuring the mass of the star "50% more massive than heavyweight Betelgeuse" - I don't think the actual astronomers are talking about mass...

    2. Re:size? by luna69 · · Score: 4, Informative

      > 1300 times as massive.

      No. Original paper says ~39 Msun. Radius is ~1300. A star massing 1300 Msun couldn't hold itself together, both in terms of gravitational and outward radiation pressure.
      Source: http://arxiv.org/pdf/1401.2628...

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    3. Re:size? by Jeremy+Erwin · · Score: 2

      That's for the system.

      Could an astronomer explain the \( 39_{--22}^{+40} \) notation? Seems a pretty big error margin, but I can't tell if it means "between 17 and 79 solar masses" or "between 22 and 40 solar masses"?

    4. Re:size? by reverseengineer · · Score: 4, Informative

      The 22 and 40 look like lower and upper bounds. In section 6.1 of the paper, it says, "we infer the lowest current mass of the system to be 22±5 [solar masses]" . They mention this value comes from a calculation based on Kepler's 3rd law. So it looks like the lower bound comes from orbital mechanics based on the orbit of the companion star and the upper bound of 40 comes from their interferometry observations and modeling of that data, but they consider it more likely that the true value is closer to the higher value.

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    5. Re:size? by Frobnicator · · Score: 2

      Correct, with decades of measurements it was estimated to be about 40 solar masses, but now that is being revised thanks to the smaller star.

      It is shedding lots of mass and is not very compact, and appears to be fluctuating internally and exploding externally. It is likely near the end of its life. So the outer shell appears to be 1315 times the diameter of Sol, but coming in at 40 Msun most of that is probably fairly sparse.

      Note that "end of its life" for a star is a really long time. At that size their life is relatively short for a star, about 5 million years, so it could possibly have a half million years left. Generations from now we could have interstellar ships visiting the star for additional research. I mean, even if it takes a thousand years for us to get the technology for fast interstellar travel plus the 12,000 light years of distance, the star will likely still be in its final stages. As for what will happen, nobody knows. It might collapse as a supernova, but astronomers can only speculate at the conditions that cause supernova; there have been no observed supernova in our galaxy since 1604, and the telescope data from that time doesn't exactly tell us details about the size and type of star involved. We can make educated guesses based on supernovae in distant galaxies, but those also are rather sparse on pre-collapse details.

      Supernova is only one possible outcome. It might eventually become a blue supergiant. It might eventually become a blue variable. If it eventually collapses the mass is near enough the 40 Msun boundary that both neutron stars and black holes are possible options. If it eventually collapses to a black hole quickly it could skip the dramatic show, it would just visibly vanish. If it eventually collapses slowly a supernova is possible, as are less energetic options. There is even the option of a double collapse, first to neutron star then to black hole, which possibly could result in a hypernova. It is also possible that a series of partial collapses could cause pieces to explode and break up rather than collapse, making a fun fireworks show lasting for ages. But really there is insufficient data; there are not enough data points to know what is going to happen. It might be fun to speculate, but like most stars we probably won't see anything interesting happen in our lifetimes. With our measly 100 year lives we can only record the tiniest window of the lifetime of stars.

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  3. It's mere gas by KiloByte · · Score: 2

    Saying that these stars touch each other is like saying Jupiter's diameter is comes at some random point within its atmosphere. Both include a large amount of very sparse gas, with boundaries being fuzzy.

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    1. Re:It's mere gas by JoeMerchant · · Score: 4, Informative

      The photosphere is a pretty clearly defined boundary.

      If you want to go all "stellar windy" on the sun, it extends out beyond Pluto.

    2. Re:It's mere gas by KiloByte · · Score: 3, Informative

      Like all proper planets (ie, Pluto and the ilk excluded), Jupiter consists of a ball of rock and some atmosphere. It just happens that Jupiter's atmosphere is extreme, consisting of 86-96% of the planet's mass. Yet, being gas, you can't tell where it starts and ends.

      --
      The creatures outside looked from Alt-Right to Antifa; but already it was impossible to say which was which.
    3. Re:It's mere gas by Wraithlyn · · Score: 2

      Jupiter is not thought to be composed of any significant amount of rock. Last I heard it doesn't even have a solid surface.

      Thought by whom? Heard from where? An Anonymous Coward on a random discussion board?

      "The core is often described as rocky, but its detailed composition is unknown, as are the properties of materials at the temperatures and pressures of those depths (see below). In 1997, the existence of the core was suggested by gravitational measurements,[31] indicating a mass of from 12 to 45 times the Earth's mass or roughly 4%–14% of the total mass of Jupiter.[30][33] The presence of a core during at least part of Jupiter's history is suggested by models of planetary formation involving initial formation of a rocky or icy core that is massive enough to collect its bulk of hydrogen and helium from the protosolar nebula."

      http://en.wikipedia.org/wiki/J...

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  4. Awesome!! by beheaderaswp · · Score: 2

    That binary system is going to make one heck of a supernova at some point in the distant future.

    Hopefully someone in cosmology will figure out what the energy release would be.

    Very very cool!

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    1. Re:Awesome!! by Frobnicator · · Score: 5, Informative

      That binary system is going to make one heck of a supernova at some point in the distant future.

      Maybe, probably not, but there is not enough data to know. It's been over four hundred years since the last recorded supernova in the Milky Way, and telescopes weren't that great in 1604. (Also the standard note about time and distance in astronomy, the star's light we see today is from about 12,000 years in our past. We cannot see today, we see the past.)

      There is not enough data to say what will happen, and there are only a few major options for a star that size: partial collapse, full collapse, or ablation.

      It might go through a series of partial collapses, with many small contractions end up ejecting huge chunks of the star, then re-expanding, and themselves re-exploding on their way out. This seems to be a fairly normal end-of-life pattern. Basically the core works like a fireworks launch platform as we see in summertime displays. Eventually the remaining core might be collapsed or not, but the show will be enjoyable. The result is a small nebula.

      It might collapse into a neutron star. It might even collapse to a black hole. Either of these collapses MIGHT lead to a supernova, or maybe even a hypernova, or have a bunch of gamma bursts, or, most boring, nothing much at all; it just collapses with a (relatively mild compared to supernova) explosion and the outer layers blow away. Modern astronomers never seen it happen up close, so everything is a guess. Now that the partner is known people might be able to make a better guess, but it is still a guess. Depending on when it explodes, if ever, it will likely form a big nebula.

      The actual article says the larger star is rapidly shedding mass. If it is throwing enough mass out fast enough (which will be affected by its binary partner) it will shrink enough to avoid a core collapse. In that case it will throw out a bunch of mass and in a few centuries appear as a small nebula.

      But again we don't know what will happen because there are no similar data points. If you are looking for nearby stars to go supernova, there is a short list of known supernova candidates that we can watch. Otherwise the supernova we see are from distant galaxies where we can only speculate about.

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    2. Re:Awesome!! by sinequonon · · Score: 2

      Another interesting question is whether the companion will survive the explosion, be ejected from the system, and have stripped off enough mass to go supernova itself some day. Potentially a high velocity supernova!

      --
      -Bob-
  5. Better info at ESO by Bl4d3 · · Score: 3, Informative

    1,300 times the diameter apparently -> http://www.eso.org/public/news...

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  6. HTF does that work? by Anonymous Coward · · Score: 2, Interesting

    The smaller part isn't "in orbit" in the traditional sense otherwise drag would pull it in. It's more like an asteroid that's too small for gravity to collapse it into a sphere, yet this thing is *just the opposite* in terms of size. The only thing I can think of is that the system must have absolutely stupendous spin and angular momentum. Either that, or there's a careful balance between the force pulling it in, and the heat pushing it away. That's more amazing to me than the size. How long can a system like that last in this form? Plainly it's stable enough for humans to emerge and observe it; but what do our models say about how such a beast forms and maintains itself?

  7. Monster Hypergiant Ribbon Found at Top of Website by Blaskowicz · · Score: 4, Funny

    A giant ribbon was found in our neighborhood, only one link away, said researchers. It is one of the ten tallest ribbons or panels found on the web, being nearly 100 pixels tall. The ribbon's purpose seems to provide useful links and social "features", but we couldn't investigate much of this. The ribbon is unmovable even when you scroll the webpage, and its considerable height causes a gravitational lensing effect called "reading through a mail slot". Amazingly, a smaller rectangle was spotted nearby, it reads "feedback". It actually touches with your scrollbar! The whole result looks "modern" and slightly big, but scientists are puzzled that it feels so readable and non-annoying. Apparently, many other websites including previous submissions to slashdot were much worse.

  8. DUDE! by DarthVain · · Score: 4, Funny

    Everything is connected man, everything!

    *cough*

    1. Re:DUDE! by angel'o'sphere · · Score: 2

      In fact it is. By gravity.
      And to a lower extend by electric and magnetic forces as well.

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    2. Re:DUDE! by Rufty · · Score: 3, Funny

      In fact it is. By gravity.

      That sucks.

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  9. Does this crack the top-10? by mythosaz · · Score: 2

    http://en.wikipedia.org/wiki/L...

    Seems to crack, maybe, the top-20.

    Some fascinating objects on that list...

  10. Re:When I hear about an object like this by atomicdragon · · Score: 3, Informative

    At a distance of 1 light year, it would be about 40 arcseconds across, so about the size of Jupiter as seen from Earth.

  11. Kinda dissapointed: by kfsone · · Score: 2

    Followed the link, "click[ed] to enlarge" and it's just a bright dot :(

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