Feb 222017

OK, now this *is* interesting…

Wonderful Potentially Habitable Worlds Around TRAPPIST-1

Seems a full *seven* roughly Earth-mass/size planets have been detected around the terribly small, dim, cool star TRAPPIST-1 (so named because of the TRAPPIST telescope in Chile). And three or four of them are  in roughly the “Goldilocks zone” where liquid water can exist.

TRAPPIST-1 is 12.1 parsecs away. Which means two things:

1) Go ahead and get those Kessel Run jokes out of your system

2) We won’t be sending crews there anytime soon.

At just 8% the mass of Sol, TRAPPIST-1 is a tiny little thing. The planets are tucked in *close…* closest is at 0.01 AU, the furthest at 0.06 AU. This will probably have two effects:

1) Tidal locking. Chances are good the planets will always keep on face to the star. Through the plaents are close enough to each other that some sort of resonance might be at play.

2) Depending on how well behaved TRAPPIST-1 is, the Goldilocks Zone might still be a nightmare region of solar flares and X-Ray bursts, as was recently shown with Proxima b. TRAPPIST-1 *seems* relatively well behaved, but the star itself was only recently discovered so there isn’t that much data on it long-term.


Planetary data from Wiki:

The TRAPPIST-1 planetary system[4][19]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b 0.85±0.72 M 0.01111 1.51087081 ± 0.00000060 < 0.081 89.65 ± 0.25° 1.086 ± 0.035 R
c 1.38±0.61 M 0.01522 2.4218233 ± 0.0000017 < 0.083 89.67 ± 0.17° 1.056 ± 0.035 R
d 0.41±0.27 M 0.021 ± 0.06 4.049610 ± 0.000063 < 0.070 89.75 ± 0.16° 0.772 ± 0.030 R
e 0.62±0.58 M 0.028 6.099615 ± 0.000011 < 0.085 89.86 ± 0.11° 0.918 ± 0.039 R
f 0.68±0.18 M 0.037 9.206690 ± 0.000015 < 0.063 89.680 ± 0.034° 1.045 ± 0.038 R
g 1.34±0.88 M 0.045 12.35294 ± 0.00012 < 0.061 89.710 ± 0.025° 1.127 ± 0.041 R
h unknown M 0.063+0.027
unknown 89.80 ± 0.07° 0.755 ± 0.034 R


TRAPPIST-1 is about half a billion years old, which means that if life has arisen on one or more of its planets it *probably* hasn’t had time to evolve great complexity yet. But on the other hand, the star is so cool and slow burning that its lifespan is expected to be on the order of a *trillion* years. Long before this star reaches adolescence, the rest of the universe will have grown into a pretty dark, uninteresting place. Unless a Giant Green Space Hand swats it, TRAPPIST-1 will be one of the last stars burning in the universe.

 Posted by at 4:02 pm
  • Michel Van

    The Planetary system was discover by Belgian Michaël Gillon
    Who re-baptized “2MASS J23062928-0502285” into TRAPPIST-1 (a Belgium beer )

    Michaël Gillon will start Planetssystem survey
    of all nearby M class stars around us.
    that Program he labels as “SPECULOOS” (a Popular Belgium spiced shortcrust biscuit)

    That Man has a Belgium sense of Humor…

    • publiusr

      I was thinking Trappist monks…

      • Paul451

        The monks brew the beer.

  • se jones

    This graphic really ties the room together.
    TRAPPIST-1 system will make an excellent local for interstellar space movie action.
    Oh I know, TRAPPIST-1C as the planet where the Na’vi of Pandora are re-located, after the Marines go back ‘n kick their skinny blue asses. Sounds like the youngish TRAPPIST-1 system would make a good fixer-upper for the reservation.

    How many stars have their own website on day one? http://www.trappist.one/#

    (*totally* unrelated: the NOVA episode tonight on “Why Trains Crash” is really really good, lots ‘o mayhem and sploding fireballs. Geezuz, that Lac-Mégantic rail disaster in Canada…unbelievable)


    • Scottlowther

      Are the distances and *sizes* to scale there? Can’t be. No way that would be stable.

      Re: Nova… haven’t watched too much of that lately, but I caught the “Super battery” episode and was massively disappointed with the hyperactive idiot doing the show. But I’ve got the DVR set up to record the next showing of the train crash episode.

      • The Sol System certainly isn’t to scale, but Jovian one might be.

        The distance between the orbits of some of these planets is as little as 1.5 times the distance from the Earth to The Moon. They are all closer to their primary than Mercury is to Sol. That’s why I was wondering about if tidal factors amongst some of them might mitigate tidal lock.

        • se jones

          >very skewed scale. That’s a logarithmic scale.

          The primary takeaway is that the TRAPPIST-1 system is very close to our Jovian system in scale. If you replace Jupiter with an M class dwarf star, then replace the Jovian moons with Earth sized rocky planets – you’re there.

          In a similar manner, if you substitute Alpha Centauri A for the sun, Alpha Centauri B (red dwarf) would be a bigger, brighter Neptune. So, if you were on an “earth II” planet orbiting Alpha Centauri A at 1 au, Alpha Centauri B would appear as just a bright red “star” in the night sky.

          • publiusr

            Just in.

            A possible exo-moon the size of Neptune.


            I’ve always had an interest in this system..

            The star is brighter than our sun–and its big gas giant is about where our asteroid belt would be in terms of distance. But with the star being brighter, any Europa type water filled moon would have an effective insolation distance of Mars–especially with a gas giant serving as a reflector.

            But I was a bit pessimistic as to how big a Jovian type moon can be.

            No more…

          • se jones

            Tis interesting.
            A big impediment to the evolution of higher organisms on moons, is they are almost always tidally locked to their primary, and thus they have slow rotation and no intrinsic magnetic field. No magnetic field means no ozone layer, maybe even no atmosphere and lots of nasty radiation.

            But…the latest results from Cassini show Saturn’s field is 100% lined up with Saturn’s axis of rotation, which upsets all current theory on how planetary dynamos are supposed to work. So ya never know.

      • publiusr

        Cutting the battery up with shears…should have had Randi or someone along with him on that one…

  • Bruce

    And when you think about those Earthlike planets that had life and breathable air like you said
    from Star Wars,Star Trek and Lost in Space.

  • Se Jones is right. These planets are so close together you don’t need FTL or anything past what we have now to make a space opera viable.

    They are remarkably similar in size with much less variation than our solar system’s rocky planets, ranging from a bit larger than Mars to a tad bigger than Earth. Given the proximity of the planets to one another (as little as 1.5 times the distance to the moon) and super short orbital periods (years on these worlds range from 1.5 to 20 DAYS) they would periodically subject their neighbors to tidal forces, that would provide tides in optimistically supposed seas and perhaps facilitate magnetic fields on the smaller planets in much the same way that Ganymede has one. This would greatly increase the possibility of life. Finally, since I’m engaging in highly optimistic ponderings, such tidal forces might interfere with and prevent the assumed tidal locking in a few cases.

    I wonder what water and plants would look like under that light. Scott pointed out in another post that the light from even a red star would look to us like normal light, but red spectral stars lack blue light so a nitrogen atmosphere like ours wouldn’t be blue, rather it would be clear, possibly enough to have a night sky at noon on a dry day looking away from the sun. I suppose the same would hold true for water. It wouldn’t appear blue. However this star is so cool its probably missing most greens too. Plants, oceans and rainbows would look….different.

    • Scottlowther

      > the light from even a red star would look to us like normal light,

      The star in this case has a surface temperature of 2550 kelvin. Incandescent light bulbs generally heat their tungsten filaments to 2,000 to 3,000 K, so the light from this star would probably look like normal pre-LED room lighting.

      From the Wiki “color temperature” page:


      1700 K
      Match flame, low pressure sodium lamps (LPS/SOX)

      1850 K
      Candle flame, sunset/sunrise

      2400 K
      Standard incandescent lamps

      2550 K
      Soft white incandescent lamps

      2700 K
      “Soft white” compact fluorescent and LED lamps

      3000 K
      Warm white compact fluorescent and LED lamps

      3200 K
      Studio lamps, photofloods, etc.

      3350 K
      Studio “CP” light

      4100 – 4150 K
      Moonlight [2]

      5000 K
      Horizon daylight

      5000 K
      Tubular fluorescent lamps or cool white / daylight

      compact fluorescent lamps (CFL)

      5500 – 6000 K
      Vertical daylight, electronic flash

      6200 K
      Xenon short-arc lamp [3]

      6500 K
      Daylight, overcast

      6500 – 9500 K
      LCD or CRT screen

      15,000 – 27,000 K
      Clear blue poleward sky

    • se jones

      >subject their neighbors to tidal forces
      b & c should be extremely volcanically active from tidal heating, d e & f less so, but tidal volcanism may still be significant. These worlds are large enough that they should still retain a lot of heat from the earlier epoch when they were migrating to their present stable, resonate periods.

      With sidereal periods on the order of an Earthy week, d e & f would probably have intrinsic fields somewhere between Ganymede’s (very weak) field and the serious intrinsic fields we have in the rapidly spinning Earth and the gas/ice giants. Of course, the TRAPPIST system is quite young, so these large rocky worlds could still retain some field strength from their formation epoch as well.

      Once the Square Kilometre Array is up and running, we might be able to “listen” to the noise from the induced fields of b thru f. These magnetospheres *may* be modulated by volcanic activity pumping gases into these planets atmospheres (total SWAG), thus giving us another remote sensing tool.

      I don’t think magnetic fields would make much difference to life on d e or f, these rocky planets would retain a significant atmosphere which would protect their surface from TRAPPIST 1’s energetic plasma. In fact, if any of these worlds have lots of atmospheric methane, and they a weak intrinsic field, the plasma wind from TRAPPIST 1 could make life *more* likely as complex hydrocarbons are formed and they rain down on the surface like manna from heaven.

      Can’t decide if this the most exciting time to be alive as we make all these discoveries, or if it’s the most frustrating time to be alive as our primitive technology makes these worlds *so* damn far away, and we blow most of our money on F-35s and Littoral Combat Ships.

  • Bob

    My bags are packed. When does the ship leave?