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posted by martyb on Monday August 14 2017, @06:42AM   Printer-friendly
from the my-friends-just-call-me-"2MASS-J23062928-0502285" dept.

TRAPPIST-1 was known to be at least 500 million years old. Now astronomers estimate it to be between 5.4 and 9.8 billion years old:

Scientists now have a good estimate for the age of one of the most intriguing planetary systems discovered to date– TRAPPIST-1, a system of seven Earth-size worlds orbiting an ultra-cool dwarf star about 40 light-years away. Researchers say in a new study that the TRAPPIST-1 star is quite old: between 5.4 and 9.8 billion years. This is up to twice as old as our own solar system, which formed some 4.5 billion years ago.

[...] At the time of its discovery, scientists believed the TRAPPIST-1 system had to be at least 500 million years old, since it takes stars of TRAPPIST-1's low mass (roughly 8 percent that of the Sun) roughly that long to contract to its minimum size, just a bit larger than the planet Jupiter. However, even this lower age limit was uncertain; in theory, the star could be almost as old as the universe itself. Are the orbits of this compact system of planets stable? Might life have enough time to evolve on any of these worlds?

Previously:
Seven Earth-Sized Exoplanets, Including Three Potentially Habitable, Identified Around TRAPPIST-1
TRAPPIST-1h Orbital Details Confirmed


Original Submission

Related Stories

Seven Earth-Sized Exoplanets, Including Three Potentially Habitable, Identified Around TRAPPIST-1 41 comments

Astronomers have observed enough planetary transits to confirm the existence of seven "Earth-sized" exoplanets orbiting TRAPPIST-1, an ultra-cool (~2550 K) red dwarf star about 39.5 light years away. Three of the exoplanets are located inside the "habitable zone" of their parent star. These three orbit from 0.028 to 0.045 AU away from the star:

Astronomers using the TRAPPIST–South telescope at ESO's La Silla Observatory, the Very Large Telescope (VLT) at Paranal and the NASA Spitzer Space Telescope, as well as other telescopes around the world, have now confirmed the existence of at least seven small planets orbiting the cool red dwarf star TRAPPIST-1. All the planets, labelled TRAPPIST-1b, c, d, e, f, g and h in order of increasing distance from their parent star, have sizes similar to Earth.

The exoplanets are presumed to be tidally locked. The six closest to TRAPPIST-1 have been determined to be rocky, while the seventh, TRAPPIST-1h, requires additional observations to determine its characteristics due to its longer orbital period.

Mass estimates for the planets range from 0.41 Earth masses (M) to 1.38 M. Radii range from 0.76 Earth radii (R) to 1.13 R.

Spitzer, Hubble, and other telescopes will continue to make observations of the TRAPPIST-1 planetary system, but the best data will likely come from the James Webb Space Telescope (JWST), which is scheduled to launch in late 2018. JWST will allow the atmospheres and temperatures of many exoplanets to be characterized, which will help to settle whether the "habitable zones" of red dwarf stars are actually hospitable.

Artist illustrations and data for the TRAPPIST-1 system compared to Mercury, Venus, Mars, and Earth.

Here's a website dedicated to the star.

Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1 (DOI: 10.1038/nature21360) (DX)


Original Submission

TRAPPIST-1h Orbital Details Confirmed 6 comments

Astronomers have confirmed the orbital period for the outermost known exoplanet orbiting TRAPPIST-1: TRAPPIST-1h:

Scientists using NASA's Kepler space telescope identified a regular pattern in the orbits of the planets in the TRAPPIST-1 system that confirmed suspected details about the orbit of its outermost and least understood planet, TRAPPIST-1h.

[...] Astronomers from the University of Washington have used data from the Kepler spacecraft to confirm that TRAPPIST-1h orbits its star every 19 days. At six million miles from its cool dwarf star, TRAPPIST-1h is located beyond the outer edge of the habitable zone, and is likely too cold for life as we know it. The amount of energy (per unit area) planet h receives from its star is comparable to what the dwarf planet Ceres, located in the asteroid belt between Mars and Jupiter, gets from our sun.

[...] The team calculated six possible resonant periods for planet h that would not disrupt the stability of the system, but only one was not ruled out by additional data. The other five possibilities could have been observed in the Spitzer and ground-based data collected by the TRAPPIST team.

[...] TRAPPIST-1's seven-planet chain of resonances established a record among known planetary systems, the previous holders being the systems Kepler-80 and Kepler-223, each with four resonant planets.

Previously: Three New Earth-Like Planets Discovered Around an Ultra Cool Red Dwarf
Seven Earth-Sized Exoplanets, Including Three Potentially Habitable, Identified Around TRAPPIST-1
Powerful Solar Flares Found at TRAPPIST-1 Could Dim Chances for Life


Original Submission

Induction Heating Could Cause TRAPPIST-1 Exoplanets to Melt 6 comments

Star's magnetic field could turn habitable-zone planets into magma soup

[A] team of European researchers has identified something else that could have an immense effect on habitability: the star's magnetic field. Under the right conditions, planets close to a star will experience a strong but variable magnetic field, which can cause induction heating. In the case of one system with several habitable zone planets, the induction heating could be strong enough to convert them into oceans of magma.

[...] The European team behind the new report focused on M dwarf stars. Because these are small, relatively cool objects, their habitable zones are close to the star and well within the region where the star's magnetic field is quite strong. They also have magnetic fields that are strong to begin with, sometimes in the area of thousands of Gauss. The magnetic field of our Sun is typically 10 to 1,000 times weaker.

Not all M dwarfs rotate quickly enough for this to matter. Proxima Centauri, which hosts the closest known exoplanet, takes more than 80 days to complete a rotation. But there is a nearby M dwarf that completes a rotation in only three days: TRAPPIST-1, which hosts at least seven planets, three of them in the habitable zone. So, the team decided to model how much of an effect induction heating might have on these bodies.

[...] For TRAPPIST-1c, the third planet out from the star, induction heating reaches more than 60 percent of the heat released in the planet by radioactive decay. That's enough to melt the entire surface, turning it into a magma ocean in nearly all the different model conditions sampled. The same conditions are likely on TRAPPIST-1d, the one in the habitable zone, where induction heating can be above half the amount of heat released by radioactive decay.

Red dwarf exolife killer or a way to expand the habitable zone further out?

Magma oceans and enhanced volcanism on TRAPPIST-1 planets due to induction heating (DOI: 10.1038/s41550-017-0284-0) (DX)

Previously: Seven Earth-Sized Exoplanets, Including Three Potentially Habitable, Identified Around TRAPPIST-1
Powerful Solar Flares Found at TRAPPIST-1 Could Dim Chances for Life
TRAPPIST-1h Orbital Details Confirmed
TRAPPIST-1 Older than Our Solar System
Hubble Observations Suggest TRAPPIST-1 Exoplanets Could Have Water


Original Submission

TRAPPIST-1 Exoplanets May Have Too Much Water to Support Life 30 comments

TRAPPIST-1's exoplanets appear to have migrated closer to TRAPPIST-1 over time until they reached their current orbits. This migration appears to have allowed them to retain too much water to support life:

What [the ASU-Vanderbilt team] found through their analyses was that the relatively "dry" inner planets ("b" and "c") were consistent with having less than 15 percent water by mass (for comparison, Earth is 0.02 percent water by mass). The outer planets ("f" and "g") were consistent with having more than 50 percent water by mass. This equates to the water of hundreds of Earth-oceans. The masses of the TRAPPIST-1 planets continue to be refined, so these proportions must be considered estimates for now, but the general trends seem clear.

"What we are seeing for the first time are Earth-sized planets that have a lot of water or ice on them," said Steven Desch, ASU astrophysicist and contributing author.

But the researchers also found that the ice-rich TRAPPIST-1 planets are much closer to their host star than the ice line. The "ice line" in any solar system, including TRAPPIST-1's, is the distance from the star beyond which water exists as ice and can be accreted into a planet; inside the ice line water exists as vapor and will not be accreted. Through their analyses, the team determined that the TRAPPIST-1 planets must have formed much farther from their star, beyond the ice line, and migrated in to their current orbits close to the host star.

[...] "We typically think having liquid water on a planet as a way to start life, since life, as we know it on Earth, is composed mostly of water and requires it to live," Hinkel explained. "However, a planet that is a water world, or one that doesn't have any surface above the water, does not have the important geochemical or elemental cycles that are absolutely necessary for life."

Called it.

Also at Phys.org.

Inward migration of the TRAPPIST-1 planets as inferred from their water-rich compositions (DOI: 10.1038/s41550-018-0411-6) (DX) (arXiv)

Related: Powerful Solar Flares Found at TRAPPIST-1 Could Dim Chances for Life
TRAPPIST-1 Older than Our Solar System
Hubble Observations Suggest TRAPPIST-1 Exoplanets Could Have Water
Induction Heating Could Cause TRAPPIST-1 Exoplanets to Melt
Another TRAPPIST-1 Habitability Study


Original Submission

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  • (Score: 1) by EEMac on Monday August 14 2017, @12:09PM (1 child)

    by EEMac (6423) on Monday August 14 2017, @12:09PM (#553608)

    As a 110% introvert, I want to visit one of those planets on my next vacation.

    Cool, quiet, and no people for 39.5 light years? Sign me up!

    • (Score: 0) by Anonymous Coward on Monday August 14 2017, @03:51PM

      by Anonymous Coward on Monday August 14 2017, @03:51PM (#553724)

      But the Zorkians will be curious about your pink appendages and want to fiddle with each and every one.

  • (Score: 0) by Anonymous Coward on Monday August 14 2017, @02:00PM (3 children)

    by Anonymous Coward on Monday August 14 2017, @02:00PM (#553660)

    Our CMD analysis therefore reinforces a supersolar metallicity for TRAPPIST-1, but cannot constrain its age.

    [...]

    the current unavailability of appropriate evolutionary models encapsulating these effects again prevents us from extracting meaningful age constraints from this physical parameter.

    [...]

    These estimates provide a lower limit to TRAPPIST-1's age that is already incorporated into the age range proposed by Filippazzo et al. (2015).

    [...]

    Given the apparent interplay between surface gravity and metallicity effects in index-based gravity metrics for late M dwarfs, we discount the INT-G classification as evidence of youth for TRAPPIST-1.

    [...]

    As anticipated, the uncertainties are considerable and do little to reduce the overall uncertainty in the system's age.

    [...]
    Since neither the specific mechanism of spin-down nor the initial rotation rate are known for this source, at best we can conclude that TRAPPIST-1 is likely older than 300 Myr, the age at which the \fast" track periods exceed 3.3 days.

    [...]
    Given the lack of empirical calibrations for age/activity among the latest M dwarfs, we are unable to more specifcally quantify TRAPPIST-1's age from these measures.

    https://arxiv.org/pdf/1706.02018.pdf [arxiv.org]

    The entire thing is based on the velocity of the star relative to the galaxy:

    We drew 107 stars at each simulated time step, and computed the fraction of draws as a function of age whose UVW velocities were within 5� of those of TRAPPIST-1.

    How did they get the ages of these other stars to begin with, I have no idea.

    • (Score: 2) by GreatAuntAnesthesia on Monday August 14 2017, @02:06PM (1 child)

      by GreatAuntAnesthesia (3275) on Monday August 14 2017, @02:06PM (#553664) Journal

      How did they get the ages of these other stars to begin with, I have no idea.

      By using really powerful space-based telescopes and gravitational lensing, astronomers are able to zoom right in on the stars and read their birthday cards.

      • (Score: 0) by Anonymous Coward on Monday August 14 2017, @03:58PM

        by Anonymous Coward on Monday August 14 2017, @03:58PM (#553730)

        I believe the combination of elements changes over time. If you know what kind (size) of star it is, then you can check its element proportion signature using spectragraphs against models which are calibrated using other methods, such as star clusters born at the same time but with different kinds of stars. The metal content may also be a clue: older stars tend to have less metal because each cycle of "nova-ing" produces more metals (including carbon).

    • (Score: 0) by Anonymous Coward on Monday August 14 2017, @02:17PM

      by Anonymous Coward on Monday August 14 2017, @02:17PM (#553675)

      Also, why are people using fonts that have special characters for if, iff, etc? What possible advantage is there to this?

  • (Score: 2) by dry on Monday August 14 2017, @07:16PM

    by dry (223) on Monday August 14 2017, @07:16PM (#553807) Journal

    Another question is how long before the cores of these exo-planets cool down? Eventually, even the Earth's core will cool down, resulting in limited volcano-ism with no out gassing, so CO2 concentrations drop, less green house affect and less CO2 for any plants that may live there. And the magnetic field no longer protecting the atmospheres of these exo-planets, assuming the dwarf star has much star wind. Often these stars are flare stars which would have a stellar wind as well as much more radiation.

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