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Ultraviolet Insights into Red Dwarf Flares

I seem to be reminded every day of how many discoveries are lurking in our archives. On the question of red dwarf stars and the flare activity that could compromise the habitability of planets around them, the ten year dataset from GALEX is proving invaluable. The Galaxy Explorer Evolution spacecraft was launched in 2003 and operated until 2012. Bear in mind that it was designed to study the evolution of galaxies at ultraviolet wavelengths. But now this valuable mission’s archives are helping us track the study of nearby habitable planets.

Led by first author Chase Million (Million Concepts, State College PA), a project dubbed gPhoton has set about reprocessing more than 100 terabytes of GALEX data now at the Mikulski Archive for Space Telescopes (MAST), which is maintained at the Space Telescope Science Institute in Baltimore. Million worked with STScI’s Clara Brasseur to develop custom software that could tease out the signature of flares for several hundred red dwarf stars. Dozens have been detected so far, with the prospect of far more in the GALEX archive.

STScI-H-p1723a-1100x850

Image: Artist’s illustration of a red dwarf star orbited by a hypothetical exoplanet. Red dwarfs tend to be magnetically active, displaying gigantic arcing prominences and a wealth of dark sunspots. Red dwarfs also erupt with intense flares that could strip a nearby planet’s atmosphere over time, or make the surface inhospitable to life as we know it. Credit: NASA, ESA, and G. Bacon (STScI).

The software behind this project is significant because it can measure flare events that are much less energetic than previously detected from red dwarfs, reminding us that while major flares get our attention, persistent lower-strength flare activity could have the more dangerous cumulative effect on a closely orbiting planet. A significant amount of a flare’s total energy is released in the ultraviolet wavelengths GALEX observed, while the stars themselves are relatively dim at these wavelengths, offering contrast that made these results possible. The team was able to trace stellar variations lasting as little as a few seconds in the data.

“We have found dwarf star flares in the whole range that we expected GALEX to be sensitive to, from itty bitty baby flares that last a few seconds, to monster flares that make a star hundreds of times brighter for a few minutes,” said Million.

Many of the flares detected in the GALEX observations are similar to those that occur on our own Sun. But bear in mind that any planet in the habitable zone of a cool, dim red dwarf is going to be much closer to its host, making it subject to more of the flare’s energy than the Earth. Flares of large enough energy could play a role in stripping a planet of its atmosphere, while strong ultraviolet light from persistent flaring could damage living organisms.

The work was presented at the 230th meeting of the American Astronomical Society in Austin in early June. But the study is far from over. Clara Brasseur and team member Rachel Osten are now looking at stars that were observed both by GALEX and the Kepler mission, trying to track down similar flare activity. Hundreds of thousands of flares may be hidden in the data.

“These results show the value of a survey mission like GALEX, which was instigated to study the evolution of galaxies across cosmic time and is now having an impact on the study of nearby habitable planets,” said Don Neill, research scientist at Caltech in Pasadena, who was part of the GALEX collaboration. “We did not anticipate that GALEX would be used for exoplanets when the mission was designed.”

So we keep factors like these in mind as we assess the possible habitability of planets around stars like Proxima Centauri, LHS 1140 and TRAPPIST-1. While we’re learning that Earth-sized planets may be plentiful around red dwarfs, and that many may occur in the zone where liquid water could occur on the surface, the question of habitability is far from resolved.

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{ 27 comments… add one }
  • Rob Flores June 8, 2017, 14:42

    It increasingly looks like the Earth is in a charmed situation. A situation
    that few M-dwarfs will host.

    It’s telling that for 2 billion years after the great ice age fell aside, the crust and oceans were stable, the sun was relatively well behaved. There appear to no repeated cycles of energetic solar radiation disrupting the biosphere since that time. The main reason is probably that Once single celled life aerobic took root, an extra factor of stability ensued. Without the rise of blue green algae, none of this happens. Life gets stuck in a reductive energy cycle which places limits on metabolism and extent of life forms.

    So yes, Finding the frequency of 0xygated atmosphere is going to be a telling
    clue as to the frequency of animal life forms. The universe maybe full of
    anaerobic rock eaters, but unless they can orchestrate powerful
    energy extraction paths, they are not leaving those rocks.

    • ljk June 9, 2017, 8:36

      Much too early to tell if Earth is in a charmed spot in the galaxy. I mean, we are, obviously, but charmed should not also be taken for among the few or unique.

      We have barely scratch the surface of who or what is out there, despite how it may seem at present. I think many have mistaken the fact that we are aware and look at all for being an answer, when the truth is we just barely became aware of our cosmic surroundings and have only recently begun anything resembling serious searches.

      All we can maybe say for certain is that we are not being bombarded and/or visited by ETI, and even then we could probably be in the middle of some kind of highway or construction zone and still not have a clue due to how new we are at this.

      As for the red dwarfs, no, they are not looking terribly friendly at least to the evolution of any native species around them, but those flares and other factors may not be an issue for an advanced species utilizing them for their own purposes. Again, we are so young and new at this we barely know what the real story is, don’t let yourselves be fooled.

    • Ronald June 9, 2017, 8:41

      Rob, I agree, and I am increasingly confirmed in my solar chauvinism, i.e. that it is no coincidence that we orbit a G type star. Possibly, probably not even an optimal one, but a solar type star all the same. I dare to bet that there also a Goldilocks ‘zone’ for habitable stars, e.g. a spectral range of stars that are long-term suitable for habitable terrestrial planets with higher life. And that range probably corresponds with solar type stars, roughly from latest F, through G, to early K. Before that, a star is too short-lived for (higher) life to develop. After that, a planet has to be too close for comfort (in particular tidal locking and flaring).

  • Ivan Vuletich June 8, 2017, 21:57

    I wonder if this could make those super Earth’s with thick hellish atmospheres into something more habitable by eroding a significant proportion of their atmospheres.

  • Michael C. Fidler June 8, 2017, 22:31

    It is interesting that we have such speculation as to life developing around these planets orbiting M-dwarfs when we have no examples in our solar system. Every day new theories are being developed as to the conditions these planets would be under. I really think the astronomy community needs to be more open minded and tolerant of these poor little dwarfs for there are 23 M-dwarfs to every G-dwarf! http://www.atlasoftheuniverse.com/startype.html

    • Michael C. Fidler June 8, 2017, 22:47

      Some new updates:

      Dynamics and Collisional Evolution of Closely Packed Planetary Systems.
      “High-multiplicity Kepler systems (referred to as Kepler multis) are often tightly packed and may be on the verge of instability. Many systems of this type could have experienced past instabilities, where the compact orbits and often low densities make physical collisions likely outcomes. We use numerical simulations to study the dynamical instabilities and planet-planet interactions in a synthetically generated sample of closely-packed, high-multiplicity systems. We focus specifically on systems resembling Kepler-11, a Kepler multi with six planets, and run a suite of dynamical integrations, sampling the initial orbital parameters around the nominal values reported in Lissauer et al. (2011a), finding that most of the realizations are unstable, resulting in orbit crossings and, eventually, collisions and mergers. We study in detail the dependence of stability on the orbital parameters of the planets and planet-pair characteristics to identify possible precursors to instability, compare the systems that emerge from dynamical instabilities to the observed Kepler sample (after applying observational corrections), and propose possible observable signatures of these instabilities. We examine the characteristics of each planet-planet collision, categorizing collisions by the degree of contact and collision energy, and find that grazing collisions are more common than direct impacts. Since the structure of many planets found in Kepler multis is such that the mass is dominated by a rocky core, but the volume is dominated by a low-density gaseous envelope, the sticky-sphere approximation may not be valid, and we present hydrodynamic calculations of planet-planet collisions clearly deviating from this approximation. Finally, we rerun a subset of our dynamical calculations using instead a modified prescription to handle collisions, finding, in general, higher multiplicity remnant systems.”
      https://arxiv.org/abs/1706.01975

      On the Age of the TRAPPIST-1 System.
      “The nearby (d = 12 pc) M8 dwarf star TRAPPIST-1 (2MASS J23062928-0502285) hosts a compact system of at least seven exoplanets with sizes similar to Earth. Given its importance for testing planet formation and evolution theories, and for assessing the prospects for habitability among Earth-size exoplanets orbiting the most common type of star in the Galaxy, we present a comprehensive assessment of the age of this system. We collate empirical age constraints based on the color-absolute magnitude diagram, average density, lithium absorption, surface gravity features, metallicity, kinematics, rotation, and magnetic activity; and conclude that TRAPPIST-1 is a transitional thin/thick disk star with an age of 7.6±2.2 Gyr. The star’s color-magnitude position is consistent with it being slightly metal-rich ([Fe/H] ≃ +0.06), in line with its previously reported near-infrared spectroscopic metallicity; and it has a radius (R = 0.121±0.003 R⊙) that is larger by 8-14% compared to solar-metallicity evolutionary models. We discuss some implications of the old age of this system with regard to the stability and habitability of its planets.”
      https://arxiv.org/abs/1706.02018

      Constraining the Compositions of the TRAPPIST-1 Planets to Trace Snow Lines and Migration in M Dwarf Disks.
      “The TRAPPIST-1 system, containing 7 transiting planets with constrained masses and radii, offers a singular opportunity to understand planet formation in another system. Not only can individual planets’ bulk compositions be inferred, variations in composition (with respect to distance from the star) probe the composition of the TRAPPIST-1 disk and test models of planet formation. Other studies have shown that many of the TRAPPIST-1 planets are lower in density than rock and must either possess thick atmospheres or substantial liquid water/ice. The small masses of the planets argue against atmospheres. We use our ExoPlex mass-radius software package to constrain the fraction of each planet mass that is water. While we concur that planets f and g contain substantial (>50wt%) water/ice, we find b must be ≥6−8wt% water, but c must be ≤6−8wt% water. Since volatile fraction should increase with distance, the simplest interpretation is that both b and c each contain ≈7wt% water. Planets formed outside the snow line of TRAPPIST-1’s disk are expected to contain ∼50wt% water ice like f and g, but the much lower ice abundances of b and c imply they formed inside the snow line. The TRAPPIST-1 system is marked by multiple mean motion resonances; for this and other reasons, substantial inward migration of the planets to their present orbits is inferred. We calculate the location of the snow line in the TRAPPIST-1 disk as a function of time. Depending on how rapidly the planets formed, the TRAPPIST-1 planets are at 1/2 to 1/8 of their starting distances from the star. While we infer that b and c formed inside the snow line, they contain much more water than planets formed inside the snow line in the Solar System (Earth is <0.1wt% water), implying that the volatile gradient in TRAPPIST-1 was more gradual than in the Solar System."
      https://arxiv.org/abs/1706.02689

      Habitable Moist Atmospheres On Terrestrial Planets Near the Inner Edge Of the Habitable Zone Around M-dwarfs.
      "Terrestrial planets in the habitable zones (HZs) of low-mass stars and cool dwarfs have received significant scrutiny recently because their shorter orbital periods increase their chances of detection and characterization compared to planets around G-dwarfs. As these planets are likely tidal-locked, improved 3D numerical simulations of such planetary atmospheres are needed to guide target selection. Here we use a 3-D climate system model, updated with new water-vapor absorption coefficients derived from the HITRAN 2012 database, to study ocean covered planets at the inner edge of the HZ around late-M to mid-K stars (2600 K <= Teff 3000K undergo the classical “moist-greenhouse” (H2O mixing ratio > 10-3 in the stratosphere) at significantly lower surface temperature (~ 280K) in our 3-D model compared with 1-D climate models (~ 340K). This implies that some planets around low mass stars can simultaneously undergo water-loss and remain habitable. However, for star with Teff <= 3000K, planets at the inner HZ may directly transition to a runaway state, while bypassing the moist greenhouse water-loss entirely. We analyze transmission spectra of planets in a moist green- house regime, and find that there are several prominent H2O features, including a broad feature between 5-8 microns, within JWST MIRI instrument range. Thus, relying only upon standard Earth-analog spectra with 24-hour rotation period around M-dwarfs for habitability studies will miss the strong H2O features that one would expect to see on synchronously rotating planets around M-dwarf stars, with JWST."
      https://arxiv.org/abs/1705.10362

      On the Spin States of Habitable Zone Exoplanets Around M Dwarfs: The Effect of a Near-Resonant Companion.
      "One longstanding problem for the potential habitability of planets within M dwarf systems is their likelihood to be tidally locked in a synchronously rotating spin state. This problem thus far has largely been addressed only by considering two objects: the star and the planet itself. However, many systems have been found to harbor multiple planets, with some in or very near to mean-motion resonances. The presence of a planetary companion near a mean-motion resonance can induce oscillatory variations in the mean-motion of the planet, which we demonstrate can have significant effects on the spin-state of an otherwise synchronously rotating planet. In particular, we find that a planetary companion near a mean-motion resonance can excite the spin states of planets in the habitable zone of small, cool stars, pushing otherwise synchronously rotating planets into higher amplitude librations of the spin state, or even complete circulation resulting in effective stellar days with full surface coverage on the order of years or decades. This increase in illuminated area can have potentially dramatic influences on climate, and thus on habitability. We also find that the resultant spin state can be very sensitive to initial conditions due to the chaotic nature of the spin state at early times within certain regimes. We apply our model to two hypothetical planetary systems inspired by the K00255 and TRAPPIST-1 systems, which both have Earth-sized planets in mean-motion resonances orbiting cool stars."
      https://arxiv.org/abs/1705.09685

      No snowball on habitable tidally locked planets.
      "The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All orbit nearby M-stars and are likely tidally locked in 1:1 spin-orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet."
      https://arxiv.org/abs/1705.08904

      A seven-planet resonant chain in TRAPPIST-1.
      "he TRAPPIST-1 system is the first transiting planet system found orbiting an ultra-cool dwarf star. At least seven planets similar to Earth in radius and in mass were previously found to transit this host star. Subsequently, TRAPPIST-1 was observed as part of the K2 mission and, with these new data, we report the measurement of an 18.77 d orbital period for the outermost planet, TRAPPIST-1h, which was unconstrained until now. This value matches our theoretical expectations based on Laplace relations and places TRAPPIST-1h as the seventh member of a complex chain, with three-body resonances linking every member. We find that TRAPPIST-1h has a radius of 0.727 Earth radii and an equilibrium temperature of 173 K. We have also measured the rotational period of the star at 3.3 d and detected a number of flares consistent with a low-activity, middle-aged, late M dwarf."
      https://arxiv.org/abs/1703.04166

    • Rob Flores June 9, 2017, 11:15

      Well as a base starting point Of Solar System chauvinism

      1) Terrestrial from RE .8 to 1.2 planets in the H. Zone of a G class star are not going to be tide locked, at least for the vast majority of the primary’s time as main sequence star

      2) Will not have it’s atmosphere stripped away for billions of years.
      Liquid Core size and magnetic field being half of the protection besides distance from primary.

      3) Allows for the capture or accretion of large moon. I don’t think this
      is very likely in small red dwarf, in the HZ. The gravity well of the primary will interfere (my claim, not sure if scientifically proven)

      • Michael C. Fidler June 9, 2017, 19:23

        Ok, good point but how about Red Dwarf chauvinism:
        Using Trappist 1 as an example from an Alien viewpoint!

        1. Four large planets in habitable zone with large oceans covering half the planets on there antisolar side and land on the other half with a 1/3 of it in planets twilight habitable zone.

        2. and 3. Relatively large librations and tides caused by passage of nearby inner and outer planets. Atmosphere sustained by volcanic and oceanic out-gassing with large oxygen levels by splitting of water vapor into H and O near subsolar point. Large magnetic fields due to core and mantle tidal interaction with passing nearby planets.

        So it is all a matter of a perspective and it looks pretty rosy for life around all those rosy red dwarfs!!!

        • Michael C. Fidler June 11, 2017, 9:24

          THE SURFACE UV ENVIRONMENT ON PLANETS ORBITING M-DWARFS: IMPLICATIONS FOR PREBIOTIC CHEMISTRY & NEED FOR EXPERIMENTAL FOLLOW-UP.
          May 9, 2017
          “Interestingly, in this case planets orbiting active M-dwarfs may be more compelling candidates for abiogenesis scenarios, due to both the higher quiescent emission of such stars and the frequent flares from such stars, which will periodically illuminate the planet with elevated levels of UV that may power prebiotic photochemistry.”

          https://arxiv.org/pdf/1705.02350.pdf

          The Radiation Environment of Exoplanet Atmospheres.
          Oct. 29, 2014
          ” Exoplanets are born and evolve in the radiation and particle environment created by their host star. The host star’s optical and infrared radiation heats the exoplanet’s lower atmosphere and surface, while the ultraviolet, extreme ultraviolet and X-radiation control the photochemistry and mass loss from the exoplanet’s upper atmosphere. Stellar radiation, especially at the shorter wavelengths, changes dramatically as a host star evolves leading to changes in the planet’s atmosphere and habitability. This paper reviews the present state of our knowledge concerning the time-dependent radiation emitted by stars with convective zones, that is stars with spectral types F, G, K, and M, which comprise nearly all of the host stars of detected exoplanets.”

          http://www.mdpi.com/2078-1547/5/2/351

  • Michael June 9, 2017, 7:35

    If you are in the UK there will be a talk on early GAIA results at the

    Institute of Physics Lecture Series
    at the
    University of Hertfordshire

    Wednesday 28 June 2017 at 7.00pm

    It will be interesting if GAIA has some handle on the proportion of Red Dwarfs in our galaxy although they may be too dim to show up to any great degree.

    http://www.skiesunlimited.co.uk/HAG/9%20poster%20Richard%20Smart.pdf

  • Michael C. Fidler June 11, 2017, 10:00

    Could animal life evolve on exoplanets without plant life creating the oxygen?

    Very well done infographic on this subject:
    Extrasolar Biosignatures: Developing a Comprehensive Framework for Biosignature Recognition.

    http://sites.nationalacademies.org/cs/groups/ssbsite/documents/webpage/ssb_176461.pdf

    Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment.

    Abstract: Here we review how environmental context can be used to interpret whether O2 is a biosignature in extrasolar planetary observations. This paper builds on the overview of current biosignature research discussed in Schwieterman et al. (2017), and provides an in-depth, interdisciplinary example of biosignature identification and observation that serves as a basis for the development of the general framework for biosignature assessment described in Catling et al., (2017). O2 is a potentially strong biosignature that was originally thought to be an unambiguous indicator for life at high-abundance. In exploring O2 as a biosignature, we describe the coevolution of life with the early Earth’s environment, and how the interplay of sources and
    sinks in the planetary environment may have resulted in suppression of O2 release into the atmosphere for several billion years, a false negative for biologically generated O2. False positives may also be possible, with recent research showing potential mechanisms in exoplanet environments that may generate relatively high abundances of atmospheric O2 without a biosphere being present. These studies suggest that planetary characteristics that may enhance false negatives should be considered when selecting targets for biosignature searches. Similarly our ability to interpret O2 observed in an exoplanetary atmosphere is also crucially dependent on environmental context to rule out false positive mechanisms. We describe future hotometric,
    spectroscopic and time-dependent observations of O2 and the planetary environment that could increase our confidence that any observed O2 is a biosignature, and help discriminate it from potential false positives. The rich, interdisciplinary study of O2 illustrates how a synthesis of our understanding of life’s evolution and the early Earth, scientific computer modeling of star-
    planet interactions and predictive observations can enhance our understanding of biosignatures and guide and inform the development of next-generation planet detection and characterization missions. By observing and understanding O2 in its planetary context we can increase our confidence in the remote detection of life, and provide a model for biosignature development for other proposed biosignatures.

    https://arxiv.org/ftp/arxiv/papers/1705/1705.07560.pdf

  • Michael C. Fidler June 11, 2017, 10:05

    If the last link does not work, try this one:
    https://arxiv.org/abs/1705.07560

  • Michael C. Fidler June 11, 2017, 20:36

    Fungi are fairly resistant to exposure to doses of ionizing radiation!

    Planetary Landscapes shared Bosh’s video.

    “Mushrooms really are fascinating — Did you know that their DNA is closer to humans than plants?”
    https://www.facebook.com/bosh.tv/videos/1142981905780308/

    Astromycology: The “Fungal” Frontier.

    “Hollywood movies and horror novels have painted extraterrestrial life as green monsters, scouring the barren grounds of Mars and shooting any intruder with photon lasers. These disturbing imaginations, while far-fetched, do hold some truth about frightening outer space life forms, but not in the ways we imagine. During its orbit as the first modular space station, the satellite Mir experienced attacks from the least suspect extraterrestrial life form: mold. Splotches of fungal hyphae covered windows and control panels and gradually ate away at the hull’s interior during the latter part of the satellite’s life, and with it, any notion of a “sterile spaceship”.

    The discipline of astrobiology attempts to answer the larger mysteries about life: its origin, necessities for survival, and presence in other worlds. But astrobiology also has practical applications in considering how biological organisms may travel through space. In particular, human space travel would greatly benefit from studying a branch of fungal biology known as astromycology: the study of earth-derived fungi in space. Fungi offer both an opportunity and threat to human space travel. Problems arising from fungal intruders are both wide and relevant, ranging from providing food and decomposing biological material to breaking down spacecrafts. Interactions of intense radiation and lack of gravity with fungal growth underlie the opportunities and threats that fungi pose to human space travel.”

    https://harvardsciencereview.com/2015/06/02/astromycology-the-fungal-frontier/

    • Michael C. Fidler June 12, 2017, 23:14

      Space ethics to test directed panspermia.

      The hypothesis that Earth was intentionally seeded with life by a preceding extraterrestrial civilization is believed to be currently untestable. However, analysis of the situation where humans themselves embark on seeding other planetary systems motivated by survival and propagation of life reveals at least two ethical issues calling for specific solutions. Assuming that generally intelligence evolves ethically
      as it evolves technologically, the same considerations might be applied to test the hypothesis of directed panspermia: if life on Earth was seeded intentionally, the two ethical requirements are expected to be
      satisfied, what appears to be the case.

      https://arxiv.org/ftp/arxiv/papers/1407/1407.5618.pdf

  • ljk June 12, 2017, 12:07

    Not too long ago, most scientists scoffed at the idea of whole continents moving around the planet and life existing at the bottom of the oceans with miles of water pressure above and upon them. Or life existing in acidic and boiling hot springs. Or remote moons in our Sol system that seemed awfully darn cold.

    Does any of this prove that life could handle massive flares from red dwarf suns? No, but it should caution us to be entirely certain on the matter. We have been proven wrong so many times before. But that’s what discovery and science are all about.

  • Rob Flores June 12, 2017, 12:54

    Yes, It probably is possible for animal life to arise w/o O2 producing photosynthesis microbes. But not I think by producing their own O2.
    More likely microbes could find novel enzymes to extract more energy out of a reductive reaction. If there was enough energy, there would be the possibility of evolving small multi-celled animals. But because of the lower energy in the crustal “biosphere” compared to Oxydation, it would be Very SLOW…. to evolve. And more probably have a very sluggish metabolic level, (fairly inactive until it needs to feed or reproduce). Think thimble sized reptiles with 1/4 or less of their metabolic rate.
    In general I do not object to a non-oxygen biology, developing animal life.
    I just question their speed of evolution. This Is the one type of animal life that might arise in Red Dwarfs a couple meters From the surface. And Red dwarves have existed long enough to Maybe evolve something interesting in their crusts, but not Advanced life. I do not favor an Ocean evolution due to radiation bombardment (not only might it strip away H2 envelopes, It might keep Oceans from forming or delete their existence after a few billion years )

    • Michael C. Fidler June 12, 2017, 19:14

      I disagree, because we see the TRAPPIST 1 system with densities indicating large amounts of water still exist on them. This means oxygen2 is still being generated on them by the XUV flux photolytically even after the M Dwarfs are 7.6 billion years old!!!

      So instead of bio system generating the oxygen the photodissociation, photolysis, or photodecomposition of H2O from XUV rays from the M Dwarfs will generate large amounts of O2. These planets around the M and K Dwarfs will have animal life develop on them long before the G and F Dwarfs!
      Maybe some tasty huge mushrooms too!

      • Alex Tolley June 12, 2017, 22:04

        An oxidating atmosphere might
        prevent life from evolving as it may
        keep any carbon molecules in an oxidized
        state.

        • Michael C. Fidler June 14, 2017, 10:27

          Well looking at the “Astronomical Detection of Biosignatures From Extrasolar Planets” page 20, the images seems to indicate that a reflectivity cutoff at 1.8um or below would be a good indicator of high oxygen levels.
          http://sites.nationalacademies.org/cs/groups/ssbsite/documents/webpage/ssb_176461.pdf

          But what interest me the most is the concept of an ecosystem that would not need photosynthesis, something more like the food chain in deep oceans, but on land. Maybe having fungus feeders at the bottom going on up to the large predators. An interesting area of research would be to see just what types of organisms could develop in these different environments from examples we have here on earth. Could the animals have sprung full-blown at a very early stage in certain exoplanet systems and what of the oxygenate oceans that may be on these planets ?

          • Alex Tolley June 14, 2017, 14:11

            Without carbon (or other energy storing molecules) fixation, such a biosphere would rely on such compounds being brought to the surface from the planet’s interior. This is rather like Tom Gold’s “deeo hot bisophere” hypothesis, except that the methane and other carbon compunds would reach the surface before being metabolized. It is conceivable, I suppose, that energy could be trapped and stored by other means to prevent a fixed carbon biosphere from succumbing to entropy.

            • Michael C. Fidler June 14, 2017, 21:43

              What will happen to the carbon sinks in a oceanic world? Since the Trappist 1 water worlds would most probably have been covered with a deep layer of water when first born could strong XUV in the early life of the red dwarf possibly bringing the levels down to where land masses or tidal distribution of the planets oceans would leave them exposed? If life first began in the oceans on these planets , as may of happened on earth, would the carbon be available for evolving animal life forms? The oceans would most likely of been fully oxygenated and smokers or undersea volcanic activity should make the necessary chemical compounds and energy available for life.

  • Alexander Tolley June 15, 2017, 12:25

    The pronlem of an oxidizing world is that life may not get started. If you changed the Miller-Urey experiment (and other versions) from reducing to oxidizing by adding free O2, the result would be CO2, NOx and H2O, not amino acids. Similarly, peptides will not form as the amino acids will oxidize instead. So such a world would need anoxic deep ocean conditions if life was to emerge in a hot smoker environment, assuming that is a viable mechanism. How that could work I don’t know, as it requires an O2 sink at depths with no mixing. Perhaps stagnant oceans?

    • Michael C. Fidler June 16, 2017, 7:59

      Interesting table (10.3) from “Atmospheric Evolution on Inhabited and Lifeless Worlds” via Google books page 264.
      The O2 sinks seem to be strongest with active worlds like the earth with something like plate tectonics, since tidal heating may be active on many of these worlds. Both O2 and Carbon can be locked up in these systems as we have just seen in the latest end of the world press: “Terrifying Sea of Molten Carbon Hiding Under Western U.S.” http://mysteriousuniverse.org/2017/02/terrifying-sea-of-molten-carbon-hiding-under-western-u-s/.

      This brings us back to Tom Gold’s “deep hot bisophere” hypothesis (He is one of my favorite dissident scientist!) and this article brings up an important relation with: “Plimer has said that volcanic eruptions release more carbon dioxide (CO2) than human activity; in particular that submarine volcanoes emit large amounts of CO2 and that the influence of the gases from these volcanoes on the Earth’s climate is under-represented in climate models.” and “A 2015 study from The Earth Institute at Columbia University published in Geophysical Research Letters says activity from undersea volcanoes varies with tide, with greater activity at neap tide, and with more activity in ice ages with their lower sea levels. Dr. Maya Tolstoy, who conducted the study, says this might explain abrupt ends to ice ages.”
      https://wattsupwiththat.com/2017/02/16/vast-lake-of-molten-carbonate-discovered-under-the-continental-usa/
      I would think the more active the planet the more likely a balance system will take over as in chaos theory. The big question is what the interior of these planets are made up of and after 7.6 billion years how they would evolve? That is a long time for tidal, atmosphere, glacial, oceans and the interiors of these planets to reprocess itself. The Gaia hypothesis may have many more forms then we can imagine on all these varied stars systems and planets.
      https://en.wikipedia.org/wiki/Gaia_hypothesis

  • Geoffrey Hillend June 24, 2017, 16:30

    I still am biased against life evolving on a Earth sides planet around a red dwarf. Of course I could be wrong, but I have to see some actual biosignatures from spectroscopy which we don’t have yet. The reasons have already be given by astrophysicists like too much of ultra violet radiation, no magnetic field from a planet without a Moon. Life has to evolve first before it can adapt and with a lot of ultra violet radiation otherwise, it might never get started. The density is simply the mass divided by volume which does not guarantee a planet has water but it increases the changes.

    The problem is that O2 generated by the splitting of water molecules will not give you animal life unless they evolved from single celled organisms so you can have a sterile environment with water, and O2 in the spectroscopic signature. Waste products like Methane and ozone need to be found for a biosignature.

    The idea that underwater volcanoes is responsible for man made climate change is just another unscientific rumor. The man made Co2 production by mostly by coal power plants greatly exceeds all volcanic activity including underwater volcanoes. Man made Co2 has a different chemical composition than natural, volcanic out gassed Co2. Man made Co2 is higher in the C12 carbon isotope than C13. Since 1850 the C12 ratio has been increasing so that now there is more C12 than C13 over the past 150 years. Geochemists discovered this in tree rings since plants like the C12 isotope better. It’s also in the carbonate shells of sponges and corals. http://www.realclimate.org/index.php/archives/2004/12/how-do-we-know-that-recent-cosub2sub-increases-are-due-to-human-activities-updated/

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