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Buzz About Gliese 581g: Doubts of Its Existence; Aliens Signals Detected

Artists impression of Gliese 581g. Credit: Lynette Cook/NSF

Ever since the announcement of the discovery of exoplanet Gliese 581g, there has been a buzz in the news, on websites, Twitter – pretty much everywhere, about the first potentially habitable extrasolar planet. But the past couple of days there has been a different sort of buzz about this distant world. Two stories have surfaced and they both can’t be true. The first one is fairly off the deep end: an astrophysicist from Australia claims that while doing a SETI search two years ago, he picked up a “suspicious signal” from the vicinity of the Gliese 581 system, and a couple of websites have connected some dots between that signal and a potentially habitable Gliese 581g.

The second one is more sobering. At an International Astronomical Union meeting this week, other astronomers have raised doubts whether Gliese 581g actually exists.

Unless you’ve been under a rock the past two weeks, you likely know that this newest and most promising of potential habitable extra solar planets was described by the scientists who discovered it as a rocky world about 3 times the mass of Earth, and it orbits within the red dwarf star’s habitable zone, the place that is just right for water to remain as a liquid on a planetary surface. And it is fairly close to us, too, at about 20 light years away, located in the constellation Libra.

Also announced was the discovery of planet ‘f’, a 7-Earth mass planet with a 433-day orbit around Gliese 581.

Astronomer Steven Vogt announced the discoveries by his team, which used the HIRES instrument on the Keck I telescope in Hawaii. They also used 119 measurements from the HARPS instrument on the La Silla telescope at the European Southern Observatory in Chile.

On Monday, Steinn Siggurdson broke the news on his Dynamics of Cats blog that an astronomer who works on HARPS data at the Geneva Observatory, said at the IAU meeting this week that his team could not confirm the existence of Gliese 581 g.

In an article on the Astrobiology Magazine website today (Tuesday) the astronomer, Francesco Pepe, said that not only can they not confirm the existence of planet ‘g’, but also the ‘f’ planet.

In 2009, the Geneva team announced the discovery of planet ‘e’ in the Gliese 581 solar system. At approximately 1.9 Earth masses, this ‘e’ planet is the lowest mass extrasolar planet found at that time, and has a 3.15-day orbital period around the star.

Pepe said they have studied this planet-rich system frequently, gathering a total of 180 data points in 6.5 years (with about 60 of those data points since 2009) and they can only see evidence of the 4 previously announced planets b, c, d, and e.

There is a signal which could possibly be f, but the signal amplitude of this potential fifth planet is very low and basically at the level of the measurement noise, said Pepe.

The planets in the Gliese 581 system were discovered using spectroscopic radial velocity measurements. Planets ‘tug’ on the star they orbit, causing it to shift in position (stars and planets actually orbit a common center of mass). By measuring the star’s movement in the sky, astronomers can figure out what sort of planets are orbiting it. Multi-planet systems create a complicated signal, and astronomers must tease out the spectral lines to figure out what represents a planet, and what is just “noise” – shifts in the star light not caused by an orbiting planet. Astronomers have developed various ways to reduce such noise in their telescopic observations, but it still creates a level of uncertainty in detecting extrasolar planets.

The Geneva team plugged the HARPS data on Gliese 581 into computer models, and the models show “the probability that such a signal is just produced ‘by chance’ out of the noise is not negligible, of the order of several percents,” Pepe said. “Under these conditions we cannot confirm the presence of the announced planet Gliese 581 g.”

While this doesn’t definitively mean Gliese 581g doesn’t exist, it certainly casts doubt on it. More teams will be looking at the Gliese 581 star to try and determine what is really out there. This story is not over yet.

As for the alien signal, this news has met some pretty harsh criticism — even from Dr. Frank Drake, a leader in SETI community. Astronomer Ragbir Bhathal, a scientist at the University of Western Sydney, said he detected an unusual pulse of light nearly two years ago from the same region at Gliese 581, and with the news of the potential habitable world there, his claims came up again. In an article in Space.com Drake said is suspicious because Bhathal would not share his data with anyone.

You can read an article published in 2009 in the Australian about Bhathal’s claimed discovery.

About 

Nancy Atkinson is Universe Today's Senior Editor. She also works with Astronomy Cast, and is a NASA/JPL Solar System Ambassador.

Comments on this entry are closed.

  • gopher65 October 12, 2010, 3:27 PM

    Keep in mind that they’re not saying that one or both of these planets doesn’t exist, just that the probably that at least one of them does exist is only ~95%, based on current data.

    The original paper that detailed the possible existence of these two planets was actually fairly cautious, due to the poor quality of the data. (As opposed to the press release and that STUPID press conference where one of the idiot scientists actually said “There is a 100% chance of life on this planet”. Moron.)

  • Lawrence B. Crowell October 12, 2010, 6:15 PM

    This is a bit disappointing. Curiously I wrote a computer program to model this little solar system with the ephemeris data. I got it running last night. However, it can be applied to any solar system. I thought it would be interesting to determine if the planets in such a close space would have orbits that drifted over time due to mutual gravitation.

    The guy who made the 100% remark actually said something to the effect there was a 100% certainty for there to be a chance for life. A bit like saying “definately maybe.”

    LC

  • Paul October 13, 2010, 2:38 AM

    I’m disappointed at the reference to “loonies” and “far off the deep end”. Read up on what Bathal actually said: On one occasion only, he detected something that looked like a laser in the general vicinity of Gliese581. He had the data reviewed to show that there was some sort of signal among the noise. He has been trying to repeat the observation ever since without success. It seems to me he’s been following proper scientific protocols and is making no claims other than a one-off observation of an unconfirmed signal which has not been repeated. Doesn’t sound too “loonie” to me.

  • CrazyEddieBlogger October 12, 2010, 9:50 PM

    I think what he said was that there was “100% certainty for a chance of life”, which I took to mean that he thinks the planet is 100% habitable. not inhabited.

    In the greater context, he was talking about water being abundant everywhere we look, so he was in fact discounting the possibility that the planet is rocky, in the habitable zone, but does not have water – which I think is a fair statement.

    Of course things got spun out of control, but but that’s the messengers’ fault. He didn’t sign up to be a spokesman, but a scientist.

  • Paul Eaton-Jones October 12, 2010, 11:43 PM

    Ho ho ho. Once again scientists are left with egg on their faces by making extravagant claims on little on no evidence. By making such premature announcements they leave themselves and the wider scientific community open to ridicule, derision and less likely to be believed in future when THEY do have something sensational to tell. You only have to do a cursory trawl of the net to find how easily people turn away from ‘proper’ science and vilify rational thought and mainstream science. Even within the wider public scientists are viewed at best with suspiscion and at worse as liars this story will on;y confirm their fears.

  • Uncle Fred October 12, 2010, 11:46 PM

    I think this is pretty understandable. It did take 11 years of studied the data to discern this planet. There may be very few teams with access to the technology and time needed to confirm the existence of Gliese 581G. Truly cutting edge stuff here.

    As for the other stuff… there will always be loonies. Next thing you know Astrologers will claim that Glieses causes bad diarrhea.

  • idlelimey October 13, 2010, 12:20 AM

    Gliese 581G. Red Sun. Therefore it should be called Krypton and we should expect a Superman to come from it when it blows up in 1938. Since it’s about May 1990 over there I’d say he’s running late.

  • DjGrizzlyPaws October 13, 2010, 12:49 AM

    “the probability that such a signal is just produced ‘by chance’ out of the noise is not negligible, of the order of several percents,”……surely this isn’t such bad news? If the possibility of it being noise statistically is only a few percent we’re looking at a 20-1 or less chance there isn’t a planet there.

    I’ll settle for that till we get more data.

    Presuming it is confirmed soon, what is the next step for further analysis?

  • Niolator October 13, 2010, 3:36 AM

    Nonsense, it is of course agents from Gliese 581 trying to cover up their existence. ;-)

  • Salacious October 13, 2010, 5:41 AM

    Wow. Another trumped-up convoluted story taken from a modesty set of observations to be grossly embellished as scientific knowledge when all it is hyped up and obscene popularism. We saw the same claim with the most massive star ever found a few months ago, only to find not only was it known prior to it, but the authors lead the misleading statements not based the deduced facts.
    As for Bathal, he has been openly caught with his pants down before, questioning his real legitimacy in the science.
    The fault could also be placed with the reporters of the story and the ESO organisation – the same as Prof. Crowther story on the most massive star. Such unwarranted embellishment only bring disrepute to them and makes quality science to be equally be thrown out with the swill and the bathwater.

    Please. If you must make claim it is always best to err on the side of caution, stating things with qualifiers such as ‘probably’, ‘likely’ or ‘unlikely.’ Also, as Paul quite rightly says — “confirmation in the future with new observation will reveal if we have found a more earth-like planet as Gliese 581 seems to suggest.

    In the end, perhaps the adopted rules of scientific discovery should apply to the media commentators who start this media circus nonsense . I.e. On strike of incompetency is the end of ones carrier forever.

    Maybe then the media will err on the edges of caution and logic — instead of making themselves looking so flipping ignorant, inept and totally incompetent.

    So Nancy, again, thanks for exposing these fraudulent nitwits. (Pity all those ‘Little Johnnies’ have been suckered into believing this story is true.)

  • Roen October 13, 2010, 7:04 AM

    Such stories are often much deeper than we think we realize. Anyone who is afraid of a little ridiculing of science needs to remember how often retractions are normally made that we never hear about, regarding announcements that we never hear about. It’s all part of the corrective nature of science. Mistakes are to be revered as icons of its success, not ridiculed. We are proud of science not just because of its successes, but also because of the failures. In the end, the record stands for itself.

  • Spoodle58 October 13, 2010, 7:55 AM

    I agree that this is bad science, we just see more of it these days due to instant media access and I suppose we are only human after all and we do get excited.

    Its a also a great way to prepare. :)

  • HeadAroundU October 13, 2010, 9:00 AM

    So, what’s the point the article? Why not ignore it. Why waste a time?

  • Chalons October 13, 2010, 12:27 PM

    My professor is a co-author of the original paper about Gliese581 — Manfred Cuntz real cool guy. Anyways, I’m writing a paper about pseudoscience and i’m trying to explain “evidence as being falsifiable” and would really really really love it if the source from the article depicting doubt was actually linked! am i not seeing it?

  • Torbjorn Larsson OM October 13, 2010, 1:32 PM

    Once again scientists are left with egg on their faces by making extravagant claims on little on no evidence.

    Except that they didn’t, they made a 3 sigma test on their data. It is the current claims of “little or no evidence” or hyperbole of “obscene popularism” that are extravagant.

    Sorry to disappoint you, but confirmation by others is part of solid science, which both of these investigations seems to be part of.

    As opposed to the press release and that STUPID press conference where one of the idiot scientists actually said “There is a 100% chance of life on this planet”.

    What was reported: “Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent,” Vogt said to reporters.

    As commented on above, it wasn’t “chance of life” (inhabited) but “given the ubiquity and propensity of life to flourish wherever it can … the chances of life” (habitability) that was claimed to be 100 %, as the purported planet is within the liquid water zone.

  • Torbjorn Larsson OM October 13, 2010, 1:34 PM

    D’oh! Link and quote fail:

    What was reported: “”Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent,” Vogt said to reporters.”

  • gopher65 October 13, 2010, 3:25 PM

    I had indeed read that original statement (not just the breathless hyped-up reporting of what he said), and that isn’t how I read it. That still isn’t how I read it. I read it like this (his statement rephrased in plain speech): “Life is sticky stuff that starts and then doesn’t go away, so I think that this planet has at least microscopic life, without any doubt.”

    Regardless, even if he did mean his statement the way you interpret it (habitability, rather than inhabited), any scientist who utters the line “the chances of life on this planet are 100 percent” and then expects reporters to report that cautiously — well, he shouldn’t be allowed to give press conferences. The fact that he uttered that line to a room full of half-baked reporters shows an incredible lack of situational awareness that no media-interacting person should have.

  • Olaf October 13, 2010, 4:03 PM

    @gopher65
    I doubt that scientists get media training.

  • Salacious October 14, 2010, 7:07 AM

    I have read these replies and I feel that I have to comment. The published paper itself isn’t the problem here, and is far from being a waste of time.

    The entire issue here is that the paper is backed by private and government institutions who have a vested interest in seeing that their scientists are delivering. In this way it is more like an “performance evaluation” rather than seeking pure scientific research.

    Of course, if one can make one paper stand above others, and also make a name for the institution or scientists in your sphere of influence, naturally funding for even further research can be obtained. Here the temptation is to “make a splash” in the media — saying anything and everything that will satisfy the headlines (assuming they will know no better) and raise the profile of your work. Such attempts mean wantonly sacrificing the careful scientific tenants made in the published paper, then so be it. This becomes the often general explanation for the stretching of truth, only because of the presumed ‘difficulty’ of reducing ones findings down to twitter-ese soundbite-like morsels of alleged new facts.

    “Roen” (and others here) do miss the point somewhat. This story is never about retractions or mistakes in the published papers (that have anyway already been independently assessed for their scientific accuracy and methodology). The ridicule must be placed in the press release, and those that reported it. I.e. ESO. As I said before, it is also the insistences by the institutes and government agencies requiring ‘performance’ and ‘sufficient publicity’ to openly justify any future funding and support of projects that are essentially pure research.

    Note: If one feels duped by these announcement, don’t just only go for the astronomers in question, but also go for the media department and its manager of the institution. If still not satisfied, go to the boards of the universities and the institutions who fund them and point out the alleged apparent distortions made by these individuals; asking for an open and fully explanation. (You might quickly find such individuals might have their once unlimited tenures shortened or expunged. In this view, at least it might improve deceptions in the future via media press releases.)

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