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Space Science

A Black Hole Threw a Star Out of the Milky Way Galaxy (nytimes.com) 116

Posted by msmash from the closer-look dept.
There are fastballs, and then there are cosmic fastballs. Now it seems that the strongest arm in our galaxy might belong to a supermassive black hole that lives smack in the middle of the Milky Way. From a report: Astronomers recently discovered a star whizzing out of the center of our galaxy at the seriously blinding speed of four million miles an hour. The star, which goes by the typically inscrutable name S5-HVS1, is currently about 29,000 light-years from Earth, streaking through the Grus, or Crane, constellation in the southern sky. It is headed for the darkest, loneliest depths of intergalactic space. The runaway star was spotted by an international team of astronomers led by Ting Li of the Carnegie Observatories. They were using a telescope in Australia for a study known as the Southern Stellar Stream Spectroscopic Survey -- the S5. The star is about twice as massive as our own sun and ten times more luminous, according to Dr. Li. Drawing on data from the European Space Agency's Gaia spacecraft, which has charted the positions and motions of some 1.3 billion stars in the Milky Way, the astronomers traced the streaking star back to the galactic center. That is the home of a black hole known as Sagittarius A*, a gravitational monster with the mass of four million suns.
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A Black Hole Threw a Star Out of the Milky Way Galaxy More

A Black Hole Threw a Star Out of the Milky Way Galaxy

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  • I like that they related the size of the star to that of our own sun. The gravity needed to launch such a mass is astounding to contemplate!

  • Lawyer up (Score:4, Funny)

    by 110010001000 ( 697113 ) on Monday November 18, 2019 @10:51AM (#59426110) Homepage Journal

    Sounds like the star needs to hire a lawyer. No matter what you think about stars, their rights need to be respected equally.

  • Won't you come and wash away the rain...

  • At that speed, it would take Voyager 1 only a little over 143 days to get from Earth to its current location - as opposed to the 42 years it's actually taken.

    • If my math is right it is about 0.5% c?

  • We didn't ask to be in the milky way (Score:1)

    by Anonymous Coward
    We didn't ask to be in the milky way. We demand to be thrown out too. I've had enough of this undemocratic shit. The people have spoken

    • Re: (Score:1)

      by Anonymous Coward

      You are free to leave at your leisure. Please leave keys and forwarding address on the way out. Note that less than 60M years notice will forfeit your deposit.

    • We're not gonna stop the world just so you can get off!

  • We received a signal (Score:3)

    by jfdavis668 ( 1414919 ) on Monday November 18, 2019 @10:59AM (#59426154)
    from a newly discovered planet orbiting this star. It translated as "HHHHEEEEEELLLLLLLLPPPPPPP!"

  • Seems amazing it would survive the acceleration (Score:4, Interesting)

    by SuperKendall ( 25149 ) on Monday November 18, 2019 @11:00AM (#59426158)

    Maybe it's just because it is so massive, but I would have thought pretty much anything would have broken up being accelerated to that degree over what must have been a very short duration. I would love to understand how that is possible.

    • Depends mostly on how quickly it was accelerated.

    • Re:Seems amazing it would survive the acceleration (Score:5, Informative)

      by r2kordmaa ( 1163933 ) on Monday November 18, 2019 @01:57PM (#59426994)
      Freefall does not feel as if you are being accelerated, even though you very much are. Only tidal forces rip things to pieces near massive objects, that star clearly did not get close enough.

    • Maybe it's just because it is so massive, but I would have thought pretty much anything would have broken up being accelerated to that degree over what must have been a very short duration. I would love to understand how that is possible.

      "Very short" in stellar terms is still years on Earth. S14, the fastest star orbiting the black hole, at 3.83% c, still takes 55 years to complete its orbit. Slower stars that are still very near in stellar terms take thousands of years to complete their orbits. S5-HVS1 took years to approach, pass, and retreat from Sgr A*.

  • Let's say the black hole was facing a different way, inward facing. And tossed that star our way instead of out of the ball park?

    I guess there would be other problems though already. Stars being sucked into the black hole, instead of being tossed out.

    • Re: (Score:2)

      by spun ( 1352 )

      Black holes don't face any particular way. Stars ARE being sucked into the black hole at the center of our galaxy. Gravity always points towards the center of mass.

      Think of it like this: some asteroids hit the earth (similar to stars being sucked into a black hole) but some asteroids whiz by the earth, having their trajectories altered by earth's gravity.

      Operating by itself, even the most massive black hole can't alter the speed at which things fly away from it. Things that fall into its gravity well would

      • Thank you for the information.

      • Re: (Score:2)

        by gtall ( 79522 )

        That, and it would be one massively lucky shot for the black hole to hit our solar system with a star shot out.

  • 4,000,000 * 1,609
    is 6,437,376 km by hour
    So 6,437,376 km by hour * 60 minutes * 60 seconds is
    23,174,553,600 km by seconds is
    23,174,553,600, 000 m /s is faster then the speed of light at
                            299 792 458 m / s

    Or something wrong somewhere ?

    • 6,437,376 km per hour. So you DIVIDE by (60*60) to get km/s.

    • Ok it's monday morning, I mess up
      6,437,376 / (60 *60) = 1788.16 km/s or 178,816,000 m/s
      178,816,000 m/s
      299 792 458 m / s

      • Your math is still slightly off:

        6,437,376 km/hour * 1,000 = 6,437,376,000 m/hour

        6,437,376,000 m/hour / (60[mins] * 60[secs]) = 1,788,160 m/second

        The speed of light is 299,792,458 m/second.

        The star is traveling at 0.596% the speed of light.

      • Ok it's monday morning, I mess up 6,437,376 / (60 *60) = 1788.16 km/s or 178,816,000 m/s 178,816,000 m/s 299 792 458 m / s

        And then don't add the extra zeroes. 1788.16 km/s = 1,788,160 m/s. :)

    • Maybe you should divide by 60 minutes and seconds.

    • Manual unit conversions in 21st century are for chumps. Let me just make your life a whole lot easier going forward https://www.wolframalpha.com/i... [wolframalpha.com]
  • Very impressive sounding speed, until you consider that it's still only a little over one half of one percent the speed of light.
  • Normally such velocities would be expressed in kilometers per second or to make it more impressive sounding in percentages of c, but certainly not in miles per hour.
  • Milky Way and Andromeda galaxies are bound to collide (in about 4 billion years). No, this doesn't mean planet-to-planet collisions. But yes, there is a chance this will knock our Solar System out... lost in space... aaaugh. --Not that it matters, there will be no life on Earth then anyway -- a goal that might also be achieved much sooner, by other means. Anyway, don't carry black holes around with you, people, the damn critters are dangerous. https://en.wikipedia.org/wiki/... [wikipedia.org]

  • About 0.0059C (Score:3)

    by Rick Schumann ( 4662797 ) on Monday November 18, 2019 @02:09PM (#59427046) Journal
    ..for those of you too lazy to do the math. ;-)
    Put in those terms it doesn't seem that fast, but something that massive going that fast? Fast, as in yipe! ;-)
  • They heard about humans and decided to move to a better galaxy.

  • We already knew (Score:4, Funny)

    by nospam007 ( 722110 ) * on Monday November 18, 2019 @02:32PM (#59427194)

    "might belong to a supermassive black hole that lives smack in the middle of the Milky Way. "

    It already exploded, the Pierson Puppeteers are already fleeing.

    • Except the Puppeteers didn't need, or especially desire, a star. Plus, they were heading for the Andromeda galaxy, not the middle of nowhere.

      All the same, maybe this is the explanation for the Fermi Paradox.

      Maybe all sufficiently advanced civilizations inevitably come to the conclusion they need to move their star system out away from our galaxy, indeed, from all galaxies.

      If true, that might be considered a bit disturbing.

      • "Maybe all sufficiently advanced civilizations inevitably come to the conclusion they need to move their star system out away from our galaxy, indeed, from all galaxies."

        I see a traffic congestion problem far, far in the future in a galaxy far, far away.

  • In galactic terms, S5-HVS1 is the equivalent of a 5-digit UID here on Slashdot.

    Stars in Milky Way / human population = 35:1

    That's roughly 1.5 decimal digits.

    Plus we're filtering less aggressively on the star population than the human population, with the vast majority of Slashdot's historical userbase selected from human category YWM: melatonin-deprived hairy nutsacks that aren't yet grey (though we're beginning to yield our former youthful ground on that last one). The necessity of letters+digits over digi

    • Re: (Score:2)

      by epine ( 68316 )

      Appears I Googled a dated statistic, and the 250 billion estimate is now well into the low trillions.

      Drawing on data from the European Space Agency's Gaia spacecraft, which has charted the positions and motions of some 1.3 billion stars in the Milky Way, the astronomers traced the streaking star back to the galactic center.

      Wikipedia resolutely presents the established number as 100–400 billion.

      Gaia Maps 1.7 Billion Stars, Widens Cosmic Census [skyandtelescope.com] — 25 April 2018

      Containing data from 22 months of obse

  • 4 million miles an hour a tottaly utterly useless to measure the speed. I am betting the published article mention either km per second (about 1800 km.s-1), and/or % of light speed (0.6%) or any similar measure but nowhere near million of miles an hour. I abandoned all hopes that slashdot editor would come to the 21th century and mention scientific unit in a scientific context rather than crappy used-by-nearly-nobody 19th century units. But "by hour" ? Somebody copied the lay person article without even bot
  • That's one way of looking at it... OR.... The Galaxy is FLYING way from the star which is stationary.

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