Jan 09 2018

Tabby’s Star Mystery Partly Solved

Published by under Astronomy
Comments: 9

It’s not aliens.

So far, no astronomical mystery has turned out to be aliens, although this hypothesis seems to come up every time. The first detections of signals from pulsars were named LGMs for “little green men.”

I’m not really criticizing this – part of me wishes the mystery will turn out to be evidence of an alien technological civilization. I always think of how plausible that is for an explanation. But still it should be last on the list. Chances are overwhelming that we are just seeing some new or unusual natural phenomenon. It’s a big complex universe out there.

In this case astronomers found a genuine mystery – a star that dimmed and brightened over time to a degree never seen before. The star has the designation KIC 8462852, and has been nicknamed “Tabby’s Star” after the astronomer who first described it, Tabetha Boyajian (she actually led a team of 200 astronomers involved in the work).

The intensity of the light coming from the star, which is a little bigger and 4.7 times brighter than our sun and is about 1300 light years away, dims at irregular intervals by as much as 22%. This could not be caused by a planet passing in between us – even a Jupiter-sized planet would only block about 1% of the light from the star. And what’s with the irregular period? Dimming from an object in orbit should be very regular.

The best hypothesis was that a swarm or cloud of something was blocking the light. It would have to be a big and dense cloud, however. This hypothesis had problems also, however, because such a cloud should be heated up and glowing in the infrared, but we don’t see it.

The “swarm” idea sparked the notion of a Dyson swarm, which is a hypothesized high-tech structure surrounding a star used to capture the light for energy. An advanced civilization, for example, could power themselves with either a large single structure of solar cells, or a swarm of smaller ones.

No scientists really took the alien megastructure hypothesis seriously, even though it could not be entirely ruled out. It was just way too early to get excited, and it was overwhelmingly likely that a natural explanation was to be found. But scientists love a mystery in any case, and whatever was going on around Tabby’s star was likely to be new and interesting.

What astronomers needed was a lot more data. So Boyajian and others started a kickstarter campaign to fund the telescope time they would need to gather that data. The campaign was successful, exceeding their needed $100,000. Last week they published the result of their analysis and…no aliens.

What they did was look at the different wavelengths of light to see how they were dimmed. If the swarm that is causing the dimming is comprised of solid objects, whether rocks, planetary debris, comets, or solar panels, then all wavelengths should be dimmed equally. That’s not what they found. They found that different wavelengths were dimmed to different degrees at different times.

That is what you would expect to find if the cloud (circumstellar material) blocking the light were comprised of very tiny particles (smaller than a micron), like dust. So that is what they concluded – there is a dense dust cloud around Tabby’s star blocking the light from our perspective. This also makes sense in terms of the variable periods, because different densities in the cloud could cause random fluctuations in the amount of light blocked.

But of course now astronomers just have a new mystery – what caused this massive fine dust cloud around Tabby’s star? Comets are very dusty, and a dust cloud like this could result from a comet – but it’s a lot of dust. It’s also probably close to the star, which means it is also probably a recent phenomenon as a dust cloud would likely not survive long that close to a star that bright. This also still doesn’t explain the lack of an infrared glow from the cloud.

The results also don’t rule out that the star is dimming and brightening on its own, and not just being blocked from view. And of course, some hopefuls have pointed out that it could be a swarm of alien nanobots or similar microscopic technology. Sure.

There is still more science to be done here, but this latest result does add a significant piece to the puzzle. It’s also cool that the research was crowd-funded. That’s a great way to get private citizens involved in science, and to fund more science. That may, in fact, be the bigger story here. Yeah for crowdfunding cool science.

9 responses so far

9 thoughts on “Tabby’s Star Mystery Partly Solved”

  1. Damlowet says:

    If I have read the release properly, apparently other stars with even greater ‘dimming’ have been uncovered after the discovery of Tabby’s star, which makes this more commonplace.

    Damien

  2. curt says:

    Look who’s jumping to conclusions.

    This is clearly a case of an advanced, aging civilization seeding their solar system with nano-dust in order to combat self-induced planetary warming. The variation in the dimming is evidence this civilization has engineered custom seasons to provide optimal crop and vacation conditions.

  3. tb29607 says:

    I think I saw an article by Dr. Egnor about this a while back. He was using the fact that scientists were considering a designed structure as an explanation as confirmation that intelligent design is a valid theory.
    Not sure how you make the leap from aliens building a mechanical structure in accordance with known science, to magically altering DNA in some undescribed way, but I doubt I need to point that out to anyone here.

  4. Willy says:

    tb29607: Thanks for bringing that up. It is remarkable that humans can often see only what they want to see. We all must be on guard about that same “sin”.

  5. ilchymis says:

    It is neat to see crowdsourced research. But I wonder whether funding science through Kickstarter will even further incentive researchers to push the most sensational possible interpretations of their work.

    Would this have been as well funded by the general public if it we weren’t talking about aliens?

  6. bend says:

    “It’s also cool that the research was crowd-funded. That’s a great way to get private citizens involved in science, and to fund more science.”
    Ooooh. I’m not so bullish on crowd-funding science as you are, Steve. I think it may lead to a preference for flashy and superficially exciting projects and neglect the more fundamental and boring projects that may ultimately have a bigger return on investment. And to the extent that science is perceived as already funded, we may run the risk of legislators, who control the purse strings, cutting public support to mitigate what is seen as redundancy.

  7. Willy says:

    bend is, I think, spot on in his comments about possible downsides to crowd funding. Thirty or so years ago, my state voted to have a lottery. I was a supporter (even though I don’t play lotteries) because I figured the funding would help many important programs and maybe even reduce taxes. My father–a very good and wise man–explained to me that there would be no tax reductions and that, further, to whatever extent “good” programs received funding from the lottery, the result would be that their state tax funding would be reduced and the moneys would go elsewhere but would NOT result in tax reductions.

    He was correct. It was a good lesson for me.

    A further thought–imagine crowd sourced funding for creation research. I think crowd sourced science has as much downside as social media, maybe more.

  8. Charity are kind of “crowd funding” (sometimes, othertimes it is a “crowd” of one rich person),
    so can give us an idea where crowd-funding may lead science.

  9. bend says:

    Yehouda, that’s a good point. And it’s not infrequent that I hear from some political pontification, “we don’t need to spend so much money on welfare, because we have churches and private charities that will take care of the poor, and they’d do a much better job if we had lower taxes so people could donate more.” I don’t know to what extent the perception of the effectiveness of private charities affects public spending to address the same problems. But I think that there’s real potential for a much bigger effect from crowd-sourced science.
    It’s easy to recognize homelessness, malnutrition, abandoned pets, etc. And so when charities or the government fail to meet these needs, it’s apparent. In this way public and private funding may reach some kind of equilibrium where the outcome is at least minimally socially acceptable. The needs of science are less apparent to the public. Most people may not understand why we need to do basic research as the costs are high and the payoffs, though substantial, are possibly decades and decades away from any kind of realization.
    Willy’s lottery analogy is, I think, apt. New revenue streams don’t act in a vacuum. Creating one incentive for one group of people affects the incentives for others.

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