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Shards, Axis Ratios and Interstellar Objects

It being the day after the Thanksgiving holiday here in the States, I hadn’t planned a post, but a few more things have cropped up about ‘Oumuamua that I can quickly tuck in here. Now that I’ve learned how to pronounce it (oh MOO-uh MOO-uh), it doesn’t seem nearly as intimidating — it’s the lineup of vowels that trips up the unwary. On the other hand, Jim Benford suggested on Wednesday that we avoid the vowels altogether and call this thing ‘the Shard.’

Here’s the photo Jim sent of the Shard, a 95-story London skyscraper sometimes called The Shard of Glass. It’s 309.7 metres high, the tallest building in the United Kingdom, featuring 11,000 panes of glass with a total surface area of 56,000 square metres. What draws Jim’s attention is the 6 to 1 aspect ratio, with ‘Oumuamua’s thought to be 10 to 1. Jim might also have referenced London’s BT Tower (8 to 1), but what the Guinness Book of World Records calls the “most slender tower” turns out to be the i360 observation tower in Brighton, at a whopping 41 to 1.

With ‘Oumuamua, though, we now have to ask whether the 10 to 1 ratio is actually correct, as Jason Wright noted in a recent post. The problem here is that, unlike the situation with Boyajian’s Star, we have a small dataset to work with, and according to Wright (Penn State), researchers are getting different aspect ratios, ranging all the way from the aforementioned 10 to 1 down to a relatively ordinary 3 to 1.

If the latter is the case, the interstellar object may look something more like Haumea than the Shard. “I’ll need to see a lot more data and hard, critical analysis of the anomalies in ‘Oumuamua before I get interested in the SETI angle at the level I am for Tabby’s Star,” adds Wright.

Greg Laughlin (UC-Santa Cruz) also weighed in on ‘Oumuamua with a new paper (citation below) and accompanying article in Scientific American. Laughlin dubs our visitor “exhilaratingly bizarre” and goes on to describe its unusual arrival, in which, despite accruing 20 kilowatts of energy per square meter at perihelion, it showed no evidence of cometary activity. It was fun to see that Greg also refers to ‘Oumuamua at one point as “a crazily elongated shard.”

But what drew my attention in Greg’s post was how difficult the ejection of debris from a newly forming planetary system seems to be. Getting such a shard free from the host star demands a gravitational assist from a massive planet located at a large distance from the star — terrestrial worlds in our Solar System would fall far short, though the gas giants could manage the feat.

If objects like ‘Oumuamua are common and if they are made predominantly of ice, as we would expect in an outer stellar system, then it implies, says Laughlin, that almost every star in the Milky Way hosts a Neptune-class planet at roughly the distance of our own Neptune from the Sun.

And if it really is rock or metal? Then we deal with another scenario entirely:

…in the highly unlikely event ‘Oumuamua is indeed a refractory slab of rock or metal, as suggested by its complete lack of coma, then its appearance is extremely hard to understand. Only a few percent of stars host planets that are capable of ejecting volatile-free debris from warm regions deep within a gravitational well. They flat-out can’t generate the vast overall swarm implied by ‘Oumuamua’s recent passage, suggesting that another visit by a similar object won’t happen for a very long time.

A long time indeed. According to Laughlin’s calculations of that scenario, ‘Oumuamua could travel for 10 quadrillion years before coming into similar proximity to another star.

At that far distant time, the galaxy will be a very different place, in which all the stars that now shine warmly down on planets will be expired white dwarfs, warmed a few degrees above absolute zero by the flicker of proton decay.

The paper is Laughlin, G. & Batygin, K. (2017) “On the Consequences of the Detection of an Interstellar Asteroid,” submitted to Research Notes of the AAS (abstract).


Comments on this entry are closed.

  • Henk November 24, 2017, 12:04

    Is it necessary for a planet to be the cause? Double, or triple star systems appear to be quite common. Could the second star in a (close) binary system be responsible for ejecting asteroids, and possibly be more effective at that than a planet which is less massive? Having a star as the cause may also be helpful in boiling of volatiles before it exits the home system.

    • J. Jason Wentworth December 14, 2017, 7:04

      Henk, yours is only the second such speculation about this that I’ve seen online (I’ve been wondering if a double-star or multiple-star system might have ejected Oumuamua with such a high velocity). Since something like half of all stars in the Milky Way belong to such systems (which are well-represented even among our Sun’s “nearby” neighbor stars), such ejected objects need not be at all rare. Also, many astronomers think that multiple-star systems may often be pretty “dry,” so Oumuamua’s apparent lack of volatiles may not be unusual, either.

  • HSchirmer November 24, 2017, 13:24

    Asteroid ejected from around a brown dwarf?

    If solar systems experience “grand tack” or nice model resonances,
    then the planets around brown dwarves, or the Jovian sized moons around steppenwolf planets probably experiance the same orbital shenanigans.

    “There are more things in heaven and earth, Horatio, than are dreamt of in your [sci-fi].” William Shakespear.
    …And, occasionally, they get flung our way…

  • W. B. November 24, 2017, 13:25

    What’s all the fuss about? It’s just another piece of Krypton flying by.

    • Ljk November 24, 2017, 14:30

      Hey at least it wasn’t another Dana joke.

      • Ljk November 24, 2017, 14:31


  • Alex Tolley November 24, 2017, 13:32

    If the object is refractory, then I suspect that it cannot be as unusual as the article suggests. I have similar thoughts on this as Henk above. If it is icy, then why no outgassing? To me, this implies it must be rocky. That it is covered in carbon compounds like tholins to give it its reddish color like outer system icy bodies may be quite expected given its history.

    The excitement over its shape may also be misplaced if it is indeed less elongated than some analyses suggest. While it is fun to speculate about an artificial object, perhaps as dead as our Pioneer and Voyager probes will be when they plunge into another star system, it may be quite an ordinary object. I hope it proves both refractory and common because that will suggest that we need to rethink our calculations about such objects in interstellar space and that such objects will be amenable to close examination in the future when we have the technology to launch probes at high velocity and rendezvous, with a very short response time.

    • Scott Heyer November 24, 2017, 21:14

      Not sure I understand ..in the highly unlikely event ‘Oumuamua is indeed a refractory slab of rock or metal, as suggested by its complete lack of coma, then its appearance is extremely hard to understand. Only a few percent of stars host planets that are capable of ejecting volatile-free debris from warm regions deep within a gravitational well. They flat-out can’t generate the vast overall swarm implied by ‘Oumuamua’s recent passage, suggesting that another visit by a similar object won’t happen for a very long time. Why would a rock or parts of a blasted planet (eon’s ago) not be able to be blown out into some other solar system’s or planets gravitational force…. and pick up a path based on this? Also the mention of warm regions deep within a gravitational well kinda Eludes me..so if it’s not a rock…

  • Spaceman November 24, 2017, 15:12

    Great post-Thanksgiving post, Paul! These are professional astronomers, Henk, do you really think they overlooked in their calculations the possibility that interaction between stars in a multiple system could have flung this object our way (instead of a planet)?

  • Rajsun November 24, 2017, 19:28

    Quote: ” …then its appearance is extremely hard to understand. Only a few percent of stars host planets that are capable of ejecting volatile-free debris from warm regions deep within a gravitational well. They flat-out can’t generate the vast overall swarm implied by ‘Oumuamua’s recent passage, suggesting that another visit by a similar object won’t happen for a very long time.”

    Pardon me if I come across as being crazy but the alien conjecture aside, could it not be possible that this shard may have been a piece torn off from an asteroid, planetoid or even a planet e.g. when the parent object got shredded by its system’s host star such as an asymptotic giant branch star, a white dwarf or a neutron star and then expelled and condemned to a life of unending wandering?

  • David Herne November 25, 2017, 1:15

    Thanks for posting today Paul. Oumuamua perhaps makes the case for a Breakthrough-Starshot-like capability that could target solar system objects and events at short notice.

  • ericSECT November 25, 2017, 8:23

    Seems a normal Jupiter that spirals in to become a hot Jupiter could do the trick of ejecting lotsa refractory asteroids out of the parent system.

    • HSchirmer November 25, 2017, 13:13

      The problem is, the dry objects close to the star are also deep in the star’s gravity well. Jupiter ejecting comets from 5 AU is like a baseball bat hitting baseballs out of a ballpark. Hot Jupiter ejecting asteroids from 1 AU is like a baseball bat hitting bowling balls out of the ballpark.

  • Michael November 25, 2017, 16:21

    I am just wondering if this is part of a kuiper belt object as they can have extreme tilts that was chipped off at a great distance. If we had a head on collision in which the object was slowed down in the collision it could have then fallen towards the sun at a much higher velocity.

    • HSchirmer November 26, 2017, 9:50

      Many Kuiper objects seem to be binary, which means complex orbital dynamics (3 or 4 body encounter) so you can get a hyperbolic orbit (falling towards the sun) without a head-on collission. The problem a Kuiper objects theory is that Kuiper objects generally have lots of ice, we didn’t detect ice coming off this object as it came around the sun.

      Getting back to binary objects, ‘Oumuamua came within about 50 solar radii of the sun; this raises an interesting possibility. If ‘Oumuamua arrived as a binary, (like asteroid 69230 Hermes), then it’s possible that one half is now captured into solar orbit.

  • David Ivory November 26, 2017, 8:48

    Don’t be afraid of diphthongs – vowels are your friends so “moua the meria”. You’ll find that Oumuamua has one at the beginning – Oh-OO-M00-uh-Moo-uh – otherwise if would be Omuamua.

  • stephen November 28, 2017, 0:27

    Maybe there’s no outgassing because, over millions of years, it already lost its volatiles, and all that’s left is rock.

    There are many estimates of its length-width ratio. Maybe over the course of years it has endured multiple impacts and has a very irregular shape, like a cow or an octopus. So in one direction it’s 1:3, in another direction it’s 1:10.

    Is that too unlikely?

    I sure hope they do send a probe to take a look.

  • ljk November 28, 2017, 10:53


    ‘Oumuamua: Interstellar Asteroid

    Illustration Credit: European Southern Observatory, M. Kornmesser

    Explanation: Nothing like it has ever been seen before. The unusual space rock ‘Oumuamua is so intriguing mainly because it is the first asteroid ever detected from outside our Solar System — although likely many more are to follow given modern computer-driven sky monitoring. Therefore humanity’s telescopes — of nearly every variety — have put ‘Oumuamua into their observing schedule to help better understand this unusual interstellar visitor. Pictured is an artist’s illustration of what ‘Oumuamua might look like up close.

    ‘Oumuamua is also intriguing, however, because it has unexpected parallels to Rama, a famous fictional interstellar spaceship created by the late science fiction writer Arthur C. Clarke. Like Rama, ‘Oumuamua is unusually elongated, should be made of strong material to avoid breaking apart, is only passing through our Solar System, and passed unusually close to the Sun for something gravitationally unbound.

    Unlike a visiting spaceship, though, ‘Oumuamua’s trajectory, speed, color, and even probability of detection are consistent with it forming naturally around a normal star many millions of years ago, being expelled after gravitationally encountering a normal planet, and subsequently orbiting in our Galaxy alone.

    Even given ‘Oumuamua’s likely conventional origin, perhaps humanity can hold hope that one day we will have the technology to engineer ‘Oumuamua — or another Solar System interloper — into an interstellar Rama of our own.

  • ljk November 29, 2017, 10:50

    NASA has provided an FAQ on ‘Oumuamua here:


    Discovering the First Interstellar Asteroid — Olivier Hainaut tells us about a visitor from outside our Solar System

    Interview with: Olivier Hainaut

    24 November 2017: Big news came out earlier this month — for the first time ever, astronomers discovered an asteroid from outside our Solar System. ESO’s Very Large Telescope played a key role …


  • ljk November 29, 2017, 11:52

    Could private industry (SpaceX) get a probe to ‘Oumuamua soonest?


  • Harry R Ray December 1, 2017, 10:35

    Apparently Oumuamua IS rotating along BOTH of its axes, but in a NON-UNIFORM WAY, like Hyperion. In other words, it is tumbling CHAOTICALLY! “Oumuamua is tumbling.” by Wesley C. Fraser, Petr Pravec, Alan Fitzsimmons, Pedro Lacerda, Michele T. Bannister, Colin Snodgrass, Igor Smoli’c.

    • Michael Fidler December 2, 2017, 6:26

      James Oberg gave a comment under the article “`Oumuamua: Listening To An Interstellar Interloper” and I relied about the paper “1I/’Oumuamua is tumbling”. I’m definitely think that something is going on with this object then just simple tumbling.

      James Oberg November 22, 2017, 23:41
      If it were an artificially fabricated object, there might be flat external surface areas creating random specular reflections during the rotation that could be so brief they wouldn’t be noticed, but just summed into an integrated ‘brightness’ over the instrument’s observation interval. Is ANYBODY dialing their gear to seek brief bright flashes? It’s a long shot, of course, but….

      Michael Fidler December 1, 2017, 10:42
      1I/’Oumuamua is tumbling.

      Take a look at the light curve at 1.05, it’s definitely doing something but the question is what? The curve is also changing as time progresses, I just hope someone is doing polarization studies of the light from 1I/’Oumuamua!

      “The discovery of 1I/2017 U1 (‘Oumuamua) has provided the first glimpse of a planetesimal born in another planetary system. This interloper exhibits a variable colour, within a range that is broadly consistent with local small bodies such as the P/D type asteroids, Jupiter Trojans, and dynamically excited Kuiper Belt Objects. 1I/’Oumuamua appears unusually elongated in shape, with an axial ratio exceeding 5:1. Rotation period estimates are inconsistent and varied, with reported values between 6.9 and 8.3 hours. Here we analyse all reliable optical photometry reported to date. No single rotation period can explain the exhibited brightness variations. Rather, 1I/’Oumuamua appears to be in an excited rotational state undergoing Non-Principal Axis (NPA) rotation, or tumbling. A satisfactory solution has apparent lightcurve frequencies of 0.135 and 0.126 hr-1 and implies a longest-to-shortest axis ratio of 5:1, though the available data are insufficient to uniquely constrain the true frequencies and shape. Assuming a body that responds to NPA rotation in a similar manner to Solar System asteroids and comets, the timescale to damp 1I/’Oumuamua’s tumbling is at least a billion years. 1I/’Oumuamua was likely set tumbling within its parent planetary system, and will remain tumbling well after it has left ours”.



      “We observed the newly discovered hyperbolic minor planet 1I/‘Oumuamua (2017 U1) on 2017 October 30 with Lowell Observatory’s 4.3-m Discovery Channel Telescope. From these observations, we derived a partial lightcurve with peak-to-trough amplitude of at least 1.2 mag. This lightcurve segment rules
      out rotation periods less than 3 hr and suggests that the period is at least 5 hr. On the assumption that the variability is due to a changing cross section, the axial ratio is at least 3:1. We saw no evidence for a coma or tail in either individual images or in a stacked image having an equivalent exposure time of 9000 s”.


    • Michael Fidler December 2, 2017, 7:31

      Lost in space – Aliens understanding of geomagnetic storms if living around planets of M dwarfs may have caused the development of advanced MHD drives by them. Imagine what a flare would cause on the surface of these planets such as the Trappist 1 system. We only began to understand the power involved in geomagnetic storms in 1859, imagine what that would be like happening on a daily or weekly occurrence.

      Could this unusual light curve be caused by an artificial magnetic field that would be required to protect any advanced lifeforms from the hard particles and radiations coming from solar and interstellar space. A MHD drive would have both an acceleration and breaking capacity plus when not in use a protective field for the passengers. This also could use a planetary laser array to accelerate it for a close pass to their star ionized corona to reach Relativistic speeds with the MHD drive.

      MHD propulsion by absorption of laser radiation.

      Surface Charged Smart Skin Technology for Heat Protection, Propulsion and Radiation Screening.

      From “`Oumuamua: Listening To An Interstellar Interloper”.

      Michael Fidler November 28, 2017, 2:43
      Magneto-hydrodynamic (MHD) – A craft flying past the Sun could use the Suns ionized corona to brake the spacecraft. The craft would have a very strong external MHD magnetic field when in operation. This should cause the splitting spectral lines due to the Zeeman effect and possibly the Stark effect. Of course now it would not be visible but if it is using a fluctuating field it may still show up as polarization of the light coming from the craft.

      This is very reminiscent of the huge cigar shaped mother-ships that were observed during the 1954 French wave.

  • Harry R Ray December 3, 2017, 14:49

    Or, The Klingons could just be using an otherwise very ordinary interstellar space rock for target practice.

    • Michael Fidler December 3, 2017, 22:04

      Could be!

      Tumbling motion of 1I/’Oumuamua reveals body’s violent past.

      “Models of the Solar System evolution show that almost all the primitive material leftover from the formation of the planets was ejected to the interstellar space as a result of dynamical instabilities. Accordingly, minor bodies should also be ejected from other planetary systems and should be abundant in the interstellar space. The number density of such objects, and prospects for their detection as they penetrate through the Solar System, were speculated about for decades, recently rising high hopes with the Pan-STARRS5,6 and LSST7
      surveys. These expectations materialized on 18 October 2017 with the Pan-STARRS’s discovery of 1I/’Oumuamua. Here we report homogeneous photometric observations of this body from Gemini North, which densely cover a total of 8 hr over two nights. A combined ultra-deep image of 1I/’Oumuamua shows no signs of cometary activity, confirming the results from earlier, less sensitive searches. Our data also show an enormous range of brightness variations > 2.5 mag , larger than ever observed in the population of Solar System objects, suggesting a very elongated shape of the body. But most significantly, the light curve does not repeat exactly from one rotation cycle to another and its double-peaked periodicity of 7.5483±0.0073 hr from our data is inconsistent with earlier determinations. These are clear signs of a tumbling motion, a remarkable characteristic of 1I/’Oumuamua’s rotation, consistent with a catastrophic collision in the distant past. This first example of an impacted minor body of exosolar origin indicates that collisional evolution of minor body populations in
      other planetary systems is not uncommon.


      • Michael Fidler December 4, 2017, 6:52

        Ok, lets take the spare New Horizons spacecraft and find enough plutonium-238 from Russia, China, France or whoever to power it and also an EmDrive or Mach Effect Drive, send it off on Musk’s Falcon Heavy rocket instead of a Tesla Roadster. The Falcon would give it the big push and the Em or Mach drive would get it to 1I/’Oumuamua in weeks or a month. After it arrives the drives could put it in orbit around 1I/’Oumuamua for a much more leisurely exploration of the object.
        Anybody have a better idea?

        NASA’s Peer-Reviewed Paper on the EmDrive Is Now Online.


        The actual paper: Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum

        Read More: https://arc.aiaa.org/doi/10.2514/1.B36120

  • Michael Fidler December 4, 2017, 7:27

    An a very interesting update from Barty on the EmDrive form about the Martin Tajmar Talk.




    Martin Tajmar Talk
    Nov 24th 2017
    Last week I were in the lucky situation to attend a public talk/presentation by Marin Tajmar about gravitation research and “exotic space propulsion systems”.

    Here I want to share my expressions:

    Tajmar is a very good speaker and a very congenial person.
    You can feel his enthusiasm and that this research is his life.

    He first gave a general introduction about gravity and masses, and that it is actually possible to get some type of mass (piezo crystalls) to “behave like negative mass” which resulted in a working lab prototype of the Mach effect thruster (guess you heard about it ).
    He said that a new paper about his Mach effect thruster prototype, which was already replicated by several labs all over the world, is currently in the process of peer review of a major science journal and should be released “within a year”.

    He also talked about the EM Drive and his findings which were published a while ago. He said that his theory about the EM Drive effect is, that it is also a Mach effect, but on the electromagnetic level (he compared electomagnetism vs. gravitoelectromagnetism).

    Here it became (obviously) interesting, because he said that he has “very promising” new findings and results, but he is yet not allowed talk about them because he’s currently working on a new peer reviewed paper covering this new data.
    He said it should be published within a year and we can expect that space exploration will totally change over the next 10 – 20 years.

    So nothing really new so far, except that he was visibly excited about his new EM Drive results.

    And, last but not least, he talked about a small fusion reactor on which he is currently working with good results.
    Summarized I would say we should keep an eye on this guy. Good things to come from him.

  • Harry R Ray December 4, 2017, 10:27

    The ULTIMATE PROOF of the EM drive concept could come if it were found that Oumuamua was actually USING one! WATCH THE SKIES!!!!!!

  • Harry R Ray December 4, 2017, 18:54

    Food for thought: One(ONLY, apparently)telescope(NOT)did a series of observations of Oumuamua which were not(no pun intended)consistant with ANY KIND OF TUMBLING, whereras EVERY OTHER TELESCOPE used to observe Oumuamua showed at least SOME KIND OF TUMBLING! To me, this means either one of two things: ONE; the NOT observations were COMPLETELY FLAWED due to some kind of technical error, OR: TWO: Oumuamua is DELIBERATELY CHANGING ITS AXIS OF ROTATION PERIODICALLY through some NON- EXTERNAL(i.e. NO heat) MECHANISM(EM drive?)! I hope that the Hubble and Spitzer observations of Thanksgiving week can give us a CLEARER answer on this VERY SOON!!!!

    • Harry R Ray December 4, 2017, 21:20

      “NOT” stands for: Nordic Optical Telescope. The observations they made came one day after Oumuamua was announced, back in mid-October.

    • Michael Fidler December 5, 2017, 5:58

      I’m wondering if this unusual light curve is caused by a binary system and that is why it is changing over time. Need to do some comparative analysis of the different telescopes at the same time period to see if there may be a parallax effect.

  • Tom Mazanec December 12, 2017, 12:15

    The report of Project Lyra https://arxiv.org/pdf/1711.03155.pdf

  • ljk December 14, 2017, 11:57

    Oddball Object Tumbling among the Stars Could Disrupt Planetary Science

    The solar system’s first-observed interstellar emissary hints at undiscovered populations of exoplanets and violent origins

    By Nola Taylor Redd on December 13, 2017


  • ljk December 18, 2017, 12:51

    The Mystery Of The ‘Oumuamua’ Asteroid with SETI Institute’s Seth Shostak

    December 16, 2017 at 7:48 AM ET

    Heard on Weekend Edition Saturday

    NPR’s Scott Simon asks the SETI Institute’s Seth Shostak about what scientists have learned so far about a recently detected interstellar object.


    I realize the reports and hosts on NPR are not unintelligent people, but it might be nice if at least a few of them actually tried to learn a bit from the other side of the Two Cultures once in a while. They would never dare try to appear so ignorant when presenting a news story on politics, by contrast. But science topics appear to give them carte blanche to look like they couldn’t even be bothered to skim through a Wikipedia entry for two minutes.

    If the supposedly intellectual and open-minded NPR cannot be bothered when it comes to science, no wonder most other news media are just as bad if not worse.

  • ljk December 19, 2017, 10:39

    “Oumuamua Update” –‘Our Alien Visitor Was Exposed to Cosmic Rays for Billions of Years Before Entering Our Star System’

    December 18, 2017


    To quote:

    “We have discovered that the surface of `Oumuamua is similar to small solar system bodies that are covered in carbon-rich ices, whose structure is modified by exposure to cosmic rays,” said Alan Fitzsimmons at Queen’s University, Belfast. “We also found that a half-meter thick coating of organic-rich material could have protected a water-ice-rich comet-like interior from vaporizing when the object was heated by the sun, even though it was heated to over 300 degrees centigrade.”

    Scientists at Queen’s University Belfast have led worldwide investigations into a mysterious object that passed close to Earth after arriving from deep interstellar space. Since the object was spotted in October, Fitzsimmons and Dr Michele Bannister from the School of Mathematics and Physics at Queen’s University led an international team of astronomers to piece together a profile of the strange visitor, which has been named `Oumuamua.

    “We’ve discovered that this is a planetesimal with a well-baked crust that looks a lot like the tiniest worlds in the outer regions of our solar system, has a greyish/red surface and is highly elongated,” said Bannister.

    “It’s fascinating that the first interstellar object discovered looks so much like a tiny world from our own home system. This suggests that the way our planets and asteroids formed has a lot of kinship to the systems around other stars.”

  • Harry R Ray December 20, 2017, 10:29

    Paul Gilster: Please check out this new paper up on the exoplanet.eu website(and PRESUMABLY up on ArXiv as well)”Interstellar communication. Searching X-ray spectra for narrowband communication.” by Michael Hippke, Duncan H. Forgan ASAP. Then, could you ask Dr Hippke three questions. ONE: Has anyone looked at Oumuamua with either Chandra or XMM-Newton? TWO: Has anyone DATA-MINED existing recent observations by Swift for possible X-ray emmissions from Oumuamua(narrowband or NOT)? THREE: Does he have any plans to observe Oumuamua for narrowband X-ray transmissions coming from Oumuamua? Non-natural narrowband X-ray transmissions from Oumuamua would be the holy grail, but ANY KIND of natural transmissions would tell us A LOT about this object that we MAY NOT ALREADY KNOW!

    • ljk December 20, 2017, 12:36

      Here is the paper online:


      Interstellar communication. VI. Searching X-ray spectra for narrowband communication

      Michael Hippke, Duncan H. Forgan

      (Submitted on 18 Dec 2017)

      We have previously argued that targeted interstellar communication has a physical optimum at narrowband X-ray wavelengths λ≈1 nm, limited by the surface roughness of focusing devices at the atomic level (arXiv:1711.05761). We search 24,247 archival X-ray spectra (of 6,454 unique objects) for such features and present 19 sources with monochromatic signals.

      Close examination reveals that these are most likely of natural origin. The ratio of artificial to natural sources must be <0.01%. This first limit can be improved in future X-ray surveys.

      Comments: 3 pages, 2 figures, 1 table

      Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)

      Cite as: arXiv:1712.06639 [astro-ph.IM]
      (or arXiv:1712.06639v1 [astro-ph.IM] for this version)

      Submission history

      From: Michael Hippke [view email]

      [v1] Mon, 18 Dec 2017 19:34:48 GMT (556kb,D)


  • ljk December 20, 2017, 12:26

    Poorly titled and written article aside, one might think 60 years after the launch of Sputnik 1 and currently five probes leaving our Sol system that we should have at least one or more vessels ready to go for such things as an interstellar interloper or some celestial event in our planetary backyard suddenly appearing.


  • ljk December 29, 2017, 13:27

    Oumuamua’s path in our solar system

    By Guy Ottewell in Space | December 27, 2017

    You’ve probably read about this unprecedented visitor from interstellar space. Astronomer Guy Ottewell thought you’d like to see its trajectory through our solar system.


  • ljk January 19, 2018, 16:07

    Update on an Interstellar Asteroid

    By Susanna Kohler on 19 January 2018


    What Does This Visitor Imply?

    Masses and semimajor axes of known exoplanets. Colors correspond to the ratio of escape velocity to circular velocity. The presence of ‘Oumuamua implies a vast and cool, as-yet undetected population of planets. [Laughlin & Batygin, 2017]
    Gregory Laughlin of Yale University and Konstantin Batygin of Caltech (and Planet Nine fame) explore some of the consequences of ‘Oumuamua’s parameters. They argue that its current passage, if it’s not a fluke, suggests the presence of an enormous number (1027) of such objects in our galaxy alone — enough to account for two Earth-masses of material for every star in the galaxy. Flinging asteroids like ‘Oumuamua out into interstellar space isn’t easy, though; the multi-body interaction that causes this requires the system to contain a giant and long-period planet like our Neptune or Jupiter. Taken together, this information suggests that every star in the galaxy may host a Neptune-like planet at a Neptune-like distance.

    More information on ‘Oumuamua is sure to come in the next few months as scientists continue to process their data from the asteroid’s swift passage. In the meantime, this interstellar visitor continues to challenge our understanding of our nearby surroundings and the broader context of the galaxy around us.