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Space Science

A Close Encounter Of The Stellar Kind 19

Beowulf_Boy writes "Acording to the APOD on July 7th, The star in this image known as Gliese (Gl) 710 (currently 63 lightyears away), will be only 1 Lightyear from Sol in 1.5 million years. Currently, it is much to faint to be seen by the naked eye, but, in 1,502,000 A.D. it will be at .6 magnitude, rivaling the current bright star of Antares. Although Gliese 710 will not apparently present any major dangers, it could possibly scatter debris out of the Oort cloud, cause many more comets and meteors than usual. This future stellar encounter was discovered by researchers Joan Garcia-Sanchez and Robert Preston (JPL), and collaborators while studying stars in the solar neighborhood using data from the Hipparcos Astrometry Satellite."
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A Close Encounter Of The Stellar Kind

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  • We consider the possible influence of a star light years away more than a million years from now, but fail to track most of the near-earth objects, which would pose a much more immediate threat to life on Earth than any star! Do they just pick a large object at random and say, 'Okay, how could this affect Earth?' or what?

    The purpose of this research was almost certainly not to find threats to Earth - it was to get a better map of dim stars in our area, which lets us check some of our models of star formation and celestial dynamics in our area of the galaxy.

    It also provides another data point for planetary system models (by giving us a better idea of how frequent close stellar encounters are, which certainly affect sytem formation), and (if they're finding stars in addition to just measuring their courses) a better estimate for the amount of normal matter in the universe (there has been debate over how much of it is bound up in dim stars and sub-stellar objects like brown dwarfs).

    What most likely happened here is someone noticed that this star in their survey would come close to earth, and said "hey, neat, free publicity for our project".

    Most astronomy is pure research - there won't *be* an application for most of it.
  • There is nothing in the linked abstract [harvard.edu] (AJ subscribers can see the full story [uchicago.edu]) to suggest that this star is in any kind of Sol-related orbit.

    What is "shockingly similar" between a hypothesized orbiting star and one which happens to pass nearby?

  • On the other hand, it's much easier to track a steller object, which is basically unaffected by anything smaller than other stars, than an asteroid which is affected by everything else in the solar system.
  • We can see our clock ticking. Divine retribution seems to be a million years away.

    Behold the start of a glorious day:
    Divine Retribution is on its long way.
    Through the deep void it never does stray:
    Divine Retribution is on its long way.

    It does not stray, but it tarries a bit --
    Divine Retribution is a long way away --
    And our Lord God shall throw a great fit
    On Divine Retribution's late Day.

    It takes its time, there is no big rush,
    On this Divine Retribution's late way.
    Penitents desperate, through the church doors do push,
    In hopes Retribution to sway.

    Yet in some dark, foul smelling quarter,
    The Fiend of Heaven doth say,
    "What is the fuss? What is the matter?
    Divine Retribution's a million years away!

    "And if this dread threat truly doth come,
    As Divine Retribution well may,
    Profit! Loss! Check ye the sum!
    And Divine Retribution thus weigh!

    "The punishment fits, and would deter --
    Let Divine Retribution have its say --
    And were I immortal, true, I would prefer
    To avoid Retribution's dread way.

    "But a million years is a long time ahead,
    And I too have something to say:
    Most, in a hundred year's time, will already be dead
    And for Divine Retribution can't stay.

    "And fear not some Divine resurrection:
    Such is not Divine Retribution's Good way,
    But sleep safe in sweet Death's good protection,
    And let Divine Retribution have its day.

    "For what sort of Divine Unknowable
    Would make this Divine Retribution's way
    Such to steal from the earth, as if with a shovel,
    Just to punish on Divine Retribution's dark day?

    "T'would needs be a Divine most Retributive
    To send such Retribution this way,
    And to such blasphemy is Nature prohibitive
    And would make Divine Retribution thus stray."

  • The coincidence is quite remarkable, but the numbers don't seem right for this to be Nemesis. (It may have Nemesis-like effects when it gets here, but still.)

    This thing is 65 light-years away. Now, I haven't run the numbers through Kepler's Third Law, but my intuition is that anything that far out, and in an actual orbit, would have an orbital period in the billions of years-plus area. Not a mere 30 million years or so.

    The space.com page you linked to contains this diagram [space.com] which shows the predicted orbital range for Nemesis to be in the 1- to 3-lightyear separation range. This seems plausible, and I'll bet the astronomers who came up with it have run the numbers through the Third Law and liked what they saw.

    Even with a highly eliptical orbit, it doesn't gel that the star would be 65 light-years away and due to arrive in a mere 1.5 million years (out of a 30 year cycle.) That would mean that it's been swinging around for a long while and is "almost here." How far away would it have to swing, 700 light-years? With that sort of range, we'd never have a regular period for it of 30 million years. Other stars would capture it, or otherwise screw up its orbit, as it swung by.

    So, intruiging, but I believe, wrong.

    --

  • 1.5 Million years is a wink of an eye in relation to the age of the earth. So how often does stuff like this happen? With our galaxy colliding into the Andromeda galaxy, I wonder if there will be even closer calls eventually.
  • personally, I think I'm gonna set up my lawn chair and cooler out back right now, don't wanna miss this! Oort cloud and everything, this should be quite a show...

    So what time does it start?
  • Your third reference, unfortunately, is either dreadfully misinformed or an outright nutcase (and I suspect the latter, after following a couple of his further links). I wouldn't quote his information as supportive of the Nemesis theory at all -- he doesn't even realize that Earth's rotation axis is dramatically inclined relative to the Sun's, nor that Polaris is over a thousand lightyears away and not associated with the Solar System at all.

    And those are just a couple of the most glaring errors -- his short page is littered with them. There ain't no physics there.

    ---

  • Does Bruce Willis get to go up and nuke the star?
    --------------

    "Passion Rules Reason." Blood of the Fold

  • The article said the *bright* star Antares, not the *brightest* star Antares.
  • It's not hard to predict the future positions of nearby stars, thanks to the Hipparcos satellite, which obtained proper motions (motion across the sky) of hundreds of nearby stars. Combine the proper motion with a radial velocity from spectroscopy, and you have the star's current 3D space velocity wrt the Sun.

    Stars in the solar neighborhood are gravitationally isolated, because of the great distances between them (even one light year is a *huge* distance, from a gravitational point of view). So, a star's path is far less complicated than, say, an asteroid's orbit in the solar system.

    In any case, the astronomers undoubtedly estimated their uncertainty in the measurement, but as is often the case, the error bars don't make it in the press release.

  • Currently, it is much to faint to be seen by the naked eye, but, in 1,502,000 A.D. it will be at .6 magnitude, rivaling the current bright star of Antares.

    Sirius is the brightest star with an apparent magnitude of -1.46. Antares is about the 15th brightest star with an apparent magnitude of 0.96.

  • The last detailed description of the "probable" orbit of Nemesis was something that might best be described as an attempt to draw a rose without lifting pen from paper. The real beauty of this proposed orbit for Nemesis was more its ability closely fit the very odd pattern that impacts seem to have. They seem to be getting spaced farther and farther apart, and not quite in tune with anything. But there is a real period there; or at least something that looks suspiciously like one. When one sees the impact data, it certainly doesn't look random. Sure, its not quite evenly spaced, but it certainly seems to have a pattern. To some extent, I would think rounding to the nearest million would probably be fine due to the scale of distances the objects travel, and the fair number of variables involved would introduce a fair amount of noise. On the surface it would certainly seem straigh forward enough. Create an fairly simple model of nemesis disturbing the oort cloud and throwing a bunch of rocks towards the sun, and inevitably earth, and compare it to a truly random set, or better yet run each 100 times, and see which looks more like the observed. (This idea is so terribly obvious, I'd be amazed if it hasn't been done.) This is where the elegance of Nemesis comes into it own. Those who would like to blame the oscillations of our solar system through the galactic plane have a fair amount of hand waving attached to their argument. Nemesis, other than the idea the sun might have an unknown companion star, doesn't really. In fact, some current ideas of star formation predict campanion stars to be quite common (hence the earlier link). The fact is since our sun is so unremarkable in an abundance of respects why should it be more remarkable in this? It certainly is an idea worth considering (not that you have denied this, but there are those who do), and it's elegance has quite an appeal. Then on top of it someone just happens to find a star that seems to have all the right properties and is arriving on time? It seems to me, that this might be one of those moments of serendipity.

    With reguard to the paper you linked to. First off, it was a letter to the editor, which while not quite the same thing as a letter to the editor of say Discover, is a little bit differnet than a typical paper (In my experience). They typically reperesent an opposing or unrepresented view point. That said, the writer certainly has an interesting and legitimate point of veiw (ie the subjective choice of the researchers concerned with proving their points might create a pattern more agreeable with their arguments). I would argue that their conclusion, the period for mass extinctions is every 2.8 million years as opposed to ~28 million, is likewise flawed. They don't do a lot of justification for what they consider the threshold where a die off become a mass extinction. But the various researchers involved aren't looking for just any mass extinction, they're looking for a specific kind. One that kills nearly everything, everywhere caused by an extraterrestrial object. So while the periodic extinctions they find, may well have a greater significance, or stand out more than those chosen by proponants of the "galactic carousel" or Nemesis, but they really don't address the point of those proponants. Essentially they say, this period for our much larger set of mass extinctions is more statistically convincing, than this subset, which may not have a causal relation. When they do look at the impact crater data, they find that those who came before Muller, Alvarezet al introduced, unwittingly, a significant bias into the data. The writer interestingly implies in their conclusion that this introduction of human bias into the data has totally corrupted it and made it of nominal value. And like all letters to the editor, it's really just an excuse to bust out the asbestos skivvies and shout, "Flame On!"

    The arduous task for future geological research is to determine more accurate (preferably non-integer) revised ages for impact craters to eliminate the "haman-signal", which may lead may then lead to a detection of real periodicity.

    -- from the conclusion of The "human" statistics of terrestrial impact cratering rate in PDF [lanl.gov]

    The individual who wrote the paper doesn't acctually test any of the models. He just tests the data, determines that it has been tainted to some degree, accidently, then takes his ball and goes home. Ok. But in the end that says very little about the merits of Nemesis, or one of its competitors "the galactic carousel" (our solar system moving in basically a sinusoidal manner through the galactic plane). Again, that's probably why its in the letters section. It's an interesting addition, but really says very little about these models, and more than anything admonishes people to remember where the data they're relying on came from. As long as I'm wandering, I'd just like to say, science journal flames are the best. It also goes to show that what journals print is at least in part determined by who the paper is sent to and if they agree with you. Fermi's paper to Nature on the nature of neutrino's gets regected because everyone knows neutrinos aren't real, they're a bookkeeping method. And I'm pretty sure Ponds and Fleishman(sp?) fired off at least one paper on cold fusion which got accepted. How you get a PhD in Chemistry without knowing about convection will forever escape me. Science journals are like every other human endevour, prone to human error. So while a paper submitted to a peer reviewed journal might garner more of my respect than say a newspaper article, on its face it garners no more than another paper. After all, have not both been peer reviewed? A short anecdote about data. One lab I did way back, hit exactly the predicted value, but the catch was it was +/- 50% of that value. Oops. I took the point of view that we coincidently hit the "book" value, but would could say little if anything due to the unreliability of the data. Turns out the TA's disagreed, while you might not want to build a bridge relying on such data, you can speak about probable trends. Its just one of those things that sticks with you.

    As far as divine retribution goes, that was my lame play off Nemesis the Greek Goddess of just retribution. I'm not going to comment on the state of the art in 1 million AD, and I probably couldn't accurately predict 10 years ahead. But that said, it's not going to be one comet from the Oort cloud on an earth crossing trajectory. It will be many many heading towards the sun. Who knows, maybe thousands. This would certainly complicate matters a little. But still, I get your point :).

    But if Nemesis does exist, I'll certainly offer it a toast, after all without it, we'd still be rodents foraging for seeds in the brush. Then there is the whole thing about being able to appreciate the vulnerability of yourself, your tribe, whatever with respect to the void, forces of chaos etc, predict the probable form of armeggedon, and quite another to be able to circle Judgement day on your calander.

  • Nemesis: The Death Star

    I certainly considering odd that a faint star should happen to be about a light year from our sun at the same time a hypothesized faint star is expected to be about a light year from our sun. But that's me. I can see how these nearly identical predictions could seem unrelated to some people. Just an observation now. But I didn't suggest that the people who found it thought that it might be, or even considered it could be Nemesis. In fact, considering that's not what it's named, I'm willing to bet they didn't. I did however highlight the similarity of this star to the aforementioned Nemesis, and provide what I thought were some interesting links about that star.

    The obvious question is, given some true statements about a star, why would it be unreasonable to assume that there are true statements about that same star which are not initially given and cannot be derived?

  • by Kibo ( 256105 ) <naw#gmail.com> on Sunday July 08, 2001 @02:25PM (#99123) Homepage
    This seems shockingly similar to the prediction of Dr. Richard Muller of a companion star to our own sun. He theorized that this star would fly by every 30 million years or so, disturb the Oort cloud, and send a great many missles towards the inner solar system. He predicted the fairly complicated orbit of this star, too complicated for me to describe here, in his book Nemesis: The Death Star. A fitting name considering how many species this companion star has wiped out.

    What NASA says about Nemesis. [nasa.gov]

    An excellent overview from IndiaWorld. [indiaworld.co.in]

    Why Nemesis isn't a wacked out theory, and might even be expected. [aplg.com]

    A fairly detailed account at space.com [space.com]

    We can see our clock ticking. Divine retribution seems to be a million years away But the animal smaller than dogs can take solace, as IIRC this might be Nemesis' last fly by, so they will inherit the earth for an indeterminate period of time.

  • ...the fairly complicated orbit of this star, too complicated for me to describe here...

    According to the links, the star is in an highly excentric elliptical orbit. A pretty good image can also be seen on the space.com link you give. This means, the orbit should be similar to long-period comets. Some graphs showing the orbit of the Hale-Bopp comet can be seen here [nasa.gov].

    There are also some scientist who think the claimed 30 million year periodicity is not real, but a result of impact crater data rounded to nearest round millions of years. You can get the artcile by entering the number 9701104 in the field here [lanl.gov]. The paper has been published in an international refereed astronomical journal, Astronomy and Astrophysics [springer.de]

    My personal opinion is that Nemesis is propably not lurking out there, but I think it would be worthwhile to check it.

    Divine retribution seems to be a million years away

    I think that in one million year, out tech can stop the comets that this star might drop from the Oort cloud. Even with present tech, we get a good early warning. A 'killer comet' would probably be detected at least half a year before the possible impact. I'd be much more worried about the Near-Earth Asteroids - they may remain undetected until a few weeks before D-day.

  • Might as well down your beers now. According to the article on IndiaWorld [indiaworld.co.in]:
    For a common man there is no need to worry. The next shower of comets is millions of years away. Before they cause mass extinction, mankind will destroy itself by pollution, rising sea levels, wars and possibly nuclear weapons.
    Besides, as Homer said: [snpp.com]
    It'll burn up in our atmosphere and what's ever left will be no bigger than a chihuahua's head.
  • by NaturePhotog ( 317732 ) on Sunday July 08, 2001 @04:56PM (#99126) Homepage
    Given the tales of near collision [cnn.com] with an asteroid back in 1998, followed up a day later with a retraction [cnn.com], I wonder about the ability to accurately calculate something this far out in the future and that far away to start. The asteroid was only 30 years in the future, and they were off by quite a bit (30,000 miles then 600,000, a factor of 20). Not to be a doubting Thomas, but how can they predict intra-galactic positions over 1.5 million years in the future with any kind of accuracy? Maybe I should have kept auditing that astrophysics course in the summer of '83...
  • Scientists' prediction capabilities seem to be applied very erratically. We consider the possible influence of a star light years away more than a million years from now, but fail to track most of the near-earth objects, which would pose a much more immediate threat to life on Earth than any star! Do they just pick a large object at random and say, 'Okay, how could this affect Earth?' or what? It just seems like it would make more sense to organize our tracking, and study bigger threats first.

C makes it easy for you to shoot yourself in the foot. C++ makes that harder, but when you do, it blows away your whole leg. -- Bjarne Stroustrup

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