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Red Dwarf Planets: Too Dry for Life?

Sometimes I imagine an ancient place where a dim sun hangs unmoving at zenith, and a race of philosophers and poets works out life’s verities under an unchanging sky. Could a place like this, on a terrestrial world orbiting an M-class red dwarf, really exist? A new paper by Jack Lissauer (NASA Ames) casts doubt on the idea. Lissauer argues that planets inside an M dwarf’s habitable zone are probably lacking in water and other volatiles, and are thus unable to produce life as we know it.

The question is important because M dwarfs make up as much as 75 percent of the stars in our part of the galaxy. If we include them as candidates for life, we add a hundred billion or more potential habitats in the Milky Way alone. We’ve known for some time that although the proximity of such a terrestrial M dwarf planet to its star would cause it to be tidally locked — one side in constant light, the other in darkness — habitable regions might still occur on the dayside given a dense enough atmosphere to transport heat globally.

But ponder the water question. Remarkably, the Earth itself is volatile-poor, with oceans and other reservoirs of near-surface water accounting for less than 0.03 percent of our planet’s mass. Lissauer believes that most of Earth’s water probably came from planetesimals that originally condensed beyond 2.5 AU. Our planet needed, in other words, help from farther out in the Solar System, and it can be shown that primitive meteorites from the outer regions of the asteroid belt have over 100 times as much water as those closer in.

But if our terrestrial world relied on such sources, could an M dwarf planet have done the same? Lissauer sees problems with the scenario. Stars are more luminous when they’re forming than when they reach the main sequence. In the case of M dwarfs, the difference in luminosity is significant. The zones that could become habitable around these stars are hotter during the planet formation period than similar zones around Sun-like stars. The so-called ‘snow line,’ which separates regions where rocky planets form from regions of icy planet formation, is proportionately more distant from an M dwarf’s habitable zone than it would be around a star like the Sun.

Another problem: planets take less time to form in the habitable zone of an M dwarf than they would around more massive stars because orbital periods are shorter and planetesimals bang into each other more frequently and with higher impact speeds. If anything, these frequent impacts may cause the young planet to lose gases and water rather than gaining them.

In short, our would-be terrestrial world forms in a volatile-poor environment and seems unable to retain what water it does accumulate. Lissauer’s conclusion is clear, and it makes grim reading for my imaginary M dwarf civilization:

In sum, under nominal circumstances, planets in main sequence habitable zones around M stars are likely to be fully formed and in their final orbits by the time the gaseous circumstellar disk has dissipated or several million years after planetesimal formation, whichever is later. If growth is in situ, dynamical and thermal factors imply that the planets are unlikely to have large volatile inventories, and planetary masses are likely to be small. The large collision speeds of impacting comets, as well as the high activity and luminosities of young M stars, may lead to substantial mass loss from planetary atmospheres, depleting any reservoirs of volatiles that planets within the HZs are able to accrete.

A bleak picture for living worlds indeed. Are there any mitigating factors? Perhaps. A water-rich world could conceivably migrate inwards to the habitable zone of an M dwarf while the gaseous protoplanetary disk was still present, retaining some water even during the star’s active youth. Eccentric orbits can also be found that could allow water worlds to attain stability within the habitable zone.

But on balance, these exceptions look to be few. Writes Lissauer, “…the number of such planets is probably small, and Sun-like stars, despite being considerably less numerous, may well be the hosts of far more habitable planets.”

The paper is Lissauer, “Planets Formed in Habitable Zones of M Dwarf Stars Probably are Deficient in Volatiles,” in press at Astrophysical Journal Letters. Abstract available.

Comments on this entry are closed.

  • Ronald March 29, 2007, 9:41

    Inward migration and particularly eccentric orbits will not do much good either, I am afraid, because of the very narrow HZ around red dwarfs. Apart from the already mentioned tidal locking, flare bursts, …
    So much for red dwafs, back to sunlike stars.

  • Stephen March 29, 2007, 12:15

    1 Cor 13:12 Now we see a blurred image in a [telescope] mirror. Then we will see very clearly.

  • Gregory Benford March 29, 2007, 12:41

    But your comment:
    Are there any mitigating factors? Perhaps. A water-rich world could conceivably migrate inwards to the habitable zone of an M dwarf while the gaseous protoplanetary disk was still present, retaining some water even during the star’s active youth. Eccentric orbits can also be found that could allow water worlds to attain stability within the habitable zone.

    –leaves the opening for moons of gas giants, that may have migrated inward. Moons may regain some lost volatiles, deep in the potential well of the giant. Plus they are somewhat screened from the primary by the giant. Still, this is a sobering result. I still think a detailed study of planets around nearby Ms is a good idea.

  • Administrator March 29, 2007, 13:47

    The other problem re M dwarfs is that gas giants themselves may be rare around them, although the tiny sample we’ve got for study leaves that question open. Much more work needed, a thought that Paul Shankland and the GEMSS team (http://gemss.wordpress.com/) will surely support!

  • andy March 29, 2007, 15:09

    Problem with migration is that if present systems are any indication, it tends to dump planets well inside the habitable zones, especially if the properties of currently-known M-dwarf planets are anything to go by. Worlds like Gliese 876 d may have substantial volatile content, but any water ocean would be a supercritical fluid, which has very different solubility properties to the liquid form. Could life evolve in a supercritical ocean? Perhaps. See [url=http://www.iop.org/EJ/abstract/0953-8984/15/24/101/]Is high-pressure water the cradle of life?[/url]

  • andy March 29, 2007, 15:10

    Ah blast, too much PHPBB. Here’s the link again. Is high-pressure water the cradle of life?

  • Administrator March 29, 2007, 15:15

    Andy, that’s quite an interesting paper. Let me quote the abstract for those who haven’t followed the link:

    “Several theories have been proposed for the synthesis of prebiotic molecules. This letter shows that the structure of supercritical water, or high-pressure water, could trigger prebiotic synthesis and the origin of life deep in the oceans, in hydrothermal vent systems. Dimer geometries of high-pressure water may have a point of symmetry and a zero dipole moment. Consequently, simple apolar molecules found in submarine hydrothermal vent systems will dissolve in the apolar environment provided by the apolar form of the water dimer. Apolar water could be the medium which helps precursor molecules to concentrate and react more efficiently. The formation of prebiotic molecules could thus be linked to the structure of the water inside chimney nanochannels and cavities where hydrothermal piezochemistry and shock wave chemistry could occur.”

    The citation is Marie-Paule Bassez J. Phys.: Condens. Matter 15 (2003), L353-L361

  • andy March 30, 2007, 5:09

    BTW clarification: by “inside the habitable zone” I meant “interior to” as opposed to “located within”.

  • philw March 30, 2007, 9:57

    At the other end of the spectrum (pun intended) bright, perky F stars should have wide habitable zones capable of hosting 2-4 rocky worlds with water oceans. Problem being that F stars are less common than G and worse yet, they leave the main sequence after just a couple thousand million years, before multicellular life forms had a chance to evolve here if we’re typical. Great places to ‘terraform’ by seeding with oxygen producing bacteria and multicellular life once that pesky stardrive problem gets fixed. The resultant biosphere could have a couple hundred million year spree before a solution to the Giant problem would be needed.

  • Christopher L. Bennett March 30, 2007, 12:01

    I remember an earlier post on Centauri Dreams calling attention to a suggestion from the Systemic blog, a hypothesis that Alpha Centauri’s planets, after being dried out by the heat from the twin suns, may have been replenished by Proxima Centauri orbiting through the system’s Oort Cloud and perturbing cometary bodies inward. Might not the same mechanism apply here? Perhaps solitary M dwarfs may have dry planets, but binary/multiple M stars might be a different matter.

    The problem there, though, is that if I recall correctly, the percentage of M dwarfs that have companions is lower than the percentage of larger stars that have companions. Still, quite a few of them would. And even if the probability of habitable planets is low, the sheer number of M dwarfs is so high that there’d probably still be a sizeable number of habitable M-dwarf planets.

  • Administrator March 30, 2007, 12:21

    Christopher, it’s an interesting hypothesis about comet perturbations, but Lissauer seems to suggest that such impacts might not be as effective in the M dwarf scenario. Here’s something on that from the paper. Lissauer is talking about the differences in planetary accretion around an M dwarf vs. other types of star: “…Moreover, orbital velocities are faster, implying higher impact speeds, so late accretion of volatile-rich bodies that condensed farther from the star may well remove more atmospheric gasses and water than they provide. Thus, while lower mass pre-main sequence stars remain more luminous than their main sequence luminosities for a longer time, Earth-mass planets forming in HZs around these stars accrete more rapidly, of material that is likely less water-rich, and within a dynamical environment in which they are more likely to lose atmospheric volatiles via impact erosion.”

    So the mechanism doesn’t seem to work for M dwarfs, in Lissauer’s view. But that tantalizing business about Alpha Centauri still holds, and I think Laughlin and company are right about it: We’re going to find water worlds around Centauri B and perhaps A. Unless, of course, David Trilling is right about binary separations (in the post we look at today).

  • Paul Shankland April 1, 2007, 9:50

    I am glad the thread is evolving a bit away from the dramatic conclusion that M-dwarfs are no longer a good place to search based on one pre-print that points out a partial picture. I think looking at sun-like stars is important, but hte thing is, expect some time to get the answer about terrestrials – they are less populous, more distant, harder to detect sub-Jovians etc etc… We need to look at both in any event. But Red Dwarfs are within reach and statistically potentially far more significant.

    Seems like in fact red dwarf campaigns are taking root in alot of studies, and for good reason. Even in small numbers among themselves, iron worlds about them may still be statistically significant. Think about it like the Drake Equation extrapolated to terrestrial densities and censuses… Besides, this speculation is based on a limited understanding of planetary formation (the war of the core accretionists vs. the gravitational instabilitists is stil raging based more on theory than pan-scale data), has still to have a clear solution, as the facts are not all in, not even close. Really what the _census_ needs is broad observations followed by broad modelling and statistics, and then physics. … IMO.

    After all we have seen that tidally locked planets can have HZs, there is mixing in all manner of systems, sufficiently capable civilizations could influence dry terrestrials in m systems, there exist resourses in dry iron planets that should interest civilations, m system kuiper belts have yet to be fully understood and still could inject volatiles (if you note mercury missing volatiles, you might also note Venus… you should also note our Jovian and how its moons (like Euroopa) behave; and there are just a scad of [did I mention close-by] m stars out there to make even .01% a decent number….

    I doubt Jack intended to infer slowing up on looking at red dwarfs… After all the science of characterization based on empirical observation would not let educated guessing stop seeking of facts on a large scale. I also am not sure that the notion of low-volatility is completely vetted – I am unconvinced by his paper that a sense of convection does not exist… I will think on that one… Sure m stars have ‘challenges’ – but I think a more likely place to get sooner terrestrial detections, than (our limit of detecting) jovians about sunlike stars… It’s about stats right now, just like the Fe/H argument…. Take a look at the NASA budget anyway – note SIM Planetquest, TPF C & I… Note Kepler’s abilities, and Gaia… I think looking at Red Dwarf’s more than ever, is important, and most ‘do-able’…

    Let me ponder more on the paucity of volatiles…. and get back…
    Best to all,

  • Eric James April 1, 2007, 12:07

    Here’s a question:

    If life evolved on earth once, how come it hasn’t done so again and again?

  • Edg Duveyoung April 1, 2007, 12:43

    Pretty simple answer: the life what’s here done ate anything new trying to “get into the life business.”

    Once life arrived here, it changed the so-called “primordial soup’s” mix of chemicals. Whatever was in the soup that prompted life to emerge probably got changed so much that life could not emerge again from the “nutritionally depleted soup.”

    Since all life is left handed, I’m betting that the life we find at the bottom of the ocean was life that drifted into that environment and made a home — not that it evolved there from scratch. If life is created from scratch anywhere on Earth, probably it has evolved in some very special place like these undersea vents.

    http://nai.arc.nasa.gov/news_stories/news_detail.cfm?ID=75 concerns this parity issue.


  • Administrator April 1, 2007, 13:00

    Paul, thanks so much for these comments on Jack Lissauer’s M dwarf work, which provide so much helpful context. And let me remind anyone following the M dwarf story — which gets more interesting every week, in my view — that the Global Exoplanet M Dwarf Search Survey that Paul is so active in can be found here:


    Remember, it wasn’t long ago that nobody thought M dwarfs could be considered candidates for terrestrial planets. We have a long way to go — Paul mentions our questions regarding such key issues as M dwarf Kuiper belts, etc. — and the parameters of the M dwarf planet search are very much in play.

  • Paul Shankland April 1, 2007, 14:28

    My pleasure – :-) And like I said somewhere else, both the XO-1 U Fla guys and Dave Charbonneau at Harvard seem to like the GEMSS-like idea of distributed red dwarf searches. Both have reps for good, solid, empirical bases for there work (as I would hope to aspire to as well).

    I do find it ironic that, Lissauer is a believer in Jupiter as protector of the inner Solar terrestrials from bombardment, and in _that_ case, since an M System is less likely to have such big-brother protection, Kuiper ices indeed could wander in more ‘convectively’ and easily… and populate the inner (HZ area) with volatiles in the ‘melt belt’…. right where it’s needed. The theory is interesting, and educated theories are food for thought, but I still feel statistically and empirically comfortable with red dwarfs as the best current case for terrestrials, perhaps in melt-belt HZs….


  • Christopher L. Bennett April 1, 2007, 15:10

    As I understand it, one of the paper’s arguments is that the smaller orbits around M dwarfs suggest higher orbital speeds (though I’m not sure of that, since doesn’t the smaller mass of the star have the opposite effect on orbital speed?), so that collisions would be harder/faster and would splash more stuff out into space than they left behind. Are you saying that this “convective” wandering of icy bodies would be less violent and leave more volatiles behind?

    Come to think of it, what happens to that stuff that splashes out into space upon impact? It doesn’t just disappear, right? Presumably it would still be around in the planet’s orbital vicinity. Well, the solar wind and light pressure would tend to push it out, but a dimmer star would have a weaker effect, I’d think. So a fair amount of the stuff that “splashed” might still fall back to the planet in a later orbit. Or maybe not — I’m just guessing.

  • Administrator April 1, 2007, 16:54

    It’s a good question, Christopher. My own guess is that under Lissauer’s scenario, an incoming comet that slammed into a forming planet would leave its volatiles scattered all over the place, and in the warmth of the M dwarf’s habitable zone, they would soon dissipate. Remember, these materials would have crossed the ‘snow line’ from the outer system and moved into the inner system at some point — they’re now warm and, like comets we observe as they approach the Sun, shedding material. Whether or not this scenario is correct is something we don’t know yet, and it’s clear from Paul’s comments that there is no consensus on this.

  • Eric James April 1, 2007, 22:33

    Edg Duveyoung Says:
    April 1st, 2007 at 12:43

    Pretty simple answer: the life what’s here done ate anything new trying to “get into the life business.”

    I don’t buy that. Carnivorous life couldn’t have developed until cell mobility developed. Besides, what’s to prevent the new life from taking a form that isn’t digestible by more modern species? What’s to prevent it from occurring in isolation somewhere? Why haven’t we duplicated it in an isolated lab experiment?

  • Eric James April 1, 2007, 22:37

    Can water molecules easily dissipate into space? Aren’t they too heavy? I think even Mars’ water is generally conserved in the polar caps (even though the atmosphere has been depeleted by the solar wind).

  • Adam April 2, 2007, 1:07

    Hi Eric

    Carnivory is an animal invention, but single-celled life is quite adept at chemically and physically attacking other microbes. Bacteria cause a lot of their disease side-effects by the chemicals they release to “digest” bigger cells. And don’t forget the quite spectacular eruptions that viruses cause – hence why the kind that infest bacteria are called “bacteriophages” by effectively consuming the cells they attack.

    As for lab duplication, perhaps we haven’t hit upon the right mix yet, nor left enough chemicals simmering for long enough for self-replicating clusters to develop? No one currently can say.

  • Adam April 2, 2007, 3:46

    Hi Eric

    You’re quite right about water, but it’s dissociated very efficiently by UV light in Mars’s upper atmosphere and the hydrogen can then escape – in theory. Recent measurements indicate a much lower than expected water loss rate, so something is causing it to stay low in the atmosphere – on Earth the water freezes out before it hits the stratosphere, but Venus wasn’t so lucky and (probably) lost most of its hydrogen to space.

    Nitrogen molecules are even heavier, but interactions with solar wind ions cause the molecules to “explode” and the atoms then have enough energy to escape a planet as small as Mars. If we could (meta-)stabilise atomic nitrogen it would make a fantastic rocket fuel – utterly non-polluting and an exhaust velocity of about ~ 8 km/s.

  • Eric James April 2, 2007, 21:51


    What I’m driving at is it seems apparent that life isn’t very likely to spontaneously erupt any old place. Here we are on a nice, temperate, life encrusted planet and yet it seems to have only happened once.

    I suppose it’s possible that many microbes might be the result of parallel evolution. But supposing life starts around deep ocean thermal vents, why isn’t it still happening? Aren’t they essentially the same as they’ve always been?

  • Adam April 3, 2007, 0:33

    Hi Eric

    How do you know it’s not still happening?

    But more importantly just what are you driving at? Panspermia? Creationism? Something else? Get to the point.

  • Eric James April 4, 2007, 1:40

    What I’m driving at is the origin of life really bugs me. Scientists have been researching it quite thoroughly and haven’t been able to replicate an origination, nor have they found evidence of newly forming life-like compounds in nature that are clearly progressing toward origination. Particularly, they haven’t verified evidence of precursors around the deep sea smokers it’s so often speculated that life originated around in the primal past to begin with (even though these deep sea smokers remain relatively unchanged from those of the primal past).

    Therefore, it seems highly unlikely that life will exist elsewhere, especially where conditions are even slightly more difficult than on earth. If life was a natural consequence, commonly found in hospitable extraterrestrial environments, then here… where the conditions are ideal… we should expect the primal soup around deep sea smokers to produce new strains of primitive life on a regular basis. In other words, the earth should regularly be infested with new strains. Or at the least, precursors should abound.

    If these new strains come into existence and can’t reproduce efficiently or compete, they’ll naturally die off. However, the process should be apparent in samples taken from deep sea smokers. I can’t find any references to this being the case.

    Also, what’s to prevent hardier species from regularly appearing? Why has the earth only supported life as we know it? Why aren’t new types of life evolving with wholly different characteristics than the simple primitive algae (commonly suggested as the first viable species) that have been with us for about 4 billion years?

    Also, if as Edg suggested, hardier species naturally wipe out the more primitive new forms, why do we still have so much primitive algae around that is apparently unchanged from the oldest examples of fossilized algae? Obviously, primitive forms can be quite hardy from the start. I would also note that algae generally doesn’t eat or compete with other life forms. It generally (and quite passively) gets its nutrients and energy from the environment.

    Can it be successfully argued that the first species in any origination must be primitive algae? Is no other outcome possible?

  • andy April 4, 2007, 11:30

    Except there isn’t a “primaeval soup” around black smokers. Early Earth was far richer in organics (rather like Titan warmed up) than the present day environment: we don’t have organic particles raining out of the sky.

    Also, while primitive lifeforms may LOOK essentially unchanged, you can bet there have been a whole host of changes since the origin of life. Not all evolutionary changes involve gross morphological differences.

    Also, algae DOES compete with other organisms – many species produce toxins, and also output waste products into their environment. This is why algal blooms are such a problem. Algae has to compete with other lifeforms: there are always viruses, “predation” by other organisms, other organisms that would use the same resources. Just because an organism is an autotroph does not mean it is not competing! In fact today’s algae/cyanobacteria are almost certainly far more advanced than the first organisms.

    Remember that the black smoker niche is occupied TODAY by organisms which have evolved for that environment for billions of years and developed whole suites of novel chemical tricks to exist in that environment. Any new lifeform generated in such an environment would presumably have to arise from some fairly basic self-replicating system that exists in the vent, thus wouldn’t have the same resources to draw on.

    And since plausible self-replicating systems which could lead to a second abiogenesis are themselves composed of basic organic molecules, this means they are likely to end up as food for the established organisms, which would put an end to their development into something more advanced. Plus, these days we have molecular oxygen around, which is pretty reactive and tends to destroy organic molecules. Remember the environment of the Earth’s surface has been altered by the presence of the existing biosphere.

  • Edg Duveyoung April 4, 2007, 13:27

    Yeah, what Andy said — and then some.

    Asimov defined life as “a local decrease of entropy by enzymatic processes” — something like that. And I was very satisfied with that at the time, but nowadays, it’s not too hard to imagine all sorts of other “livingness.”

    Newton believed that beings lived on/in the Sun. And, well, er, why not!

    Low temp chemistries that have enough dynamism to support life’s “need for speed” are hard to imagine — even if we allow for the exotics like silicon based life forms in the “still pretty cold” 900+ degree scenarios. That carbon ring sure beats most contenders for flexibility on today’s close-to-frozen Earth.

    But when I try to imagine what would it would “take” for life to exist on/in the Sun, well, hey, not so hard as I thought! Why not posit magnetic beings whose blood streams are hot plasma flowing along powerful 4000 gauss “arteries?”

    Well, it’s been written about by the best — Olaf had the stars being conscious beings, so this is not a new concept.

    How much we cling to our local time’s knowledge set, sigh.

    A 100 years from now, every book on the planet will be, at the least, “writ funny like,” and the tide of paradigms we love today may have ebbed completely. Our favorite definitions slip Khunishly from our grasps.

    Maybe we’ll find a Rosetta stone for dolphins, and wouldn’t that start a flurry of talking-to-the-animals, hee hee! I really like how the penguins, at the end of the film, Happy Feet, “discover aliens” — humanity — and try to communicate with them. Just so may we find ourselves with alien transmitters already attached to our backs if we but look a bit squinty eyed at ourselves. What? What? You don’t think it’s possible for alien nanobots from space to be living quite comfortably in our blood streams?

    And what after that?

    Oh, there’s clues abounding, but who has the eyes to see?

    Luke 19

    39 And some of the Pharisees from among the multitude said unto him, Master, rebuke thy disciples.

    40 And he {Jesus} answered and said unto them, “I tell you that, if these should hold their peace, the stones would immediately cry out.”

    Maybe every grain of sand has a “consciousness” we know not of — yet. Maybe we don’t have to spelunk Mars to find some crawly thingy, and instead we just need to “get stoned” and listen to the “sound of material structure” something like what they say about birds who are said to hear the sound of atmosphere’s flow over the mountain ranges as very low notes always being sung. Maybe everything sings if we listen a bit closer. Once there were the “music of the spheres,” so perhaps we’ll hear Earth herself speak up one day.

    Maybe the sound of one hand clapping is something conceptually heard — the sound understood to be inherent in the hand’s structure — if only it had a partner to bang against. What partner do we need to imagine in order to hear one rock clapping?

    Oh, I know this is pushing a lot of buttons out there in readersville — stones speaking, Jesus quotes, living stars — in a nice, respectful, pure science blog, OUTRAGEOUS, but hey, take your mind out for a stroll — let your imagination off that ego’s leash, and have a whack at it.

    Horton heard a who after all, right?



  • ljk April 4, 2007, 16:29

    Title: The HARPS search for southern extra-solar planets. X. A m sin i = 11 Mearth planet around the nearby spotted M dwarf GJ 674

    Authors: X. Bonfils, M. Mayor, X. Delfosse, T. Forveille, M. Gillon, C. Perrier, S. Udry, F. Bouchy, C. Lovis, F. Pepe, D. Queloz, N. C. Santos, J.-L. Bertaux

    (Submitted on 2 Apr 2007)


    Context: How planet properties depend on stellar mass is a key diagnostic of planetary formation mechanisms.

    Aims: This motivates planet searches around stars which are significantly more massive or less massive than the Sun, and in particular our radial velocity search for planets around very-low mass stars.

    Methods: As part of that program, we obtained measurements of GJ 674, an M2.5 dwarf at d=4.5 pc, which have a dispersion much in excess of their internal errors. An intensive observing campaign demonstrates that the excess dispersion is due to two superimposed coherent signals, with periods of 4.69 and 35 days.

    Results: These data are well described by a 2-planet Keplerian model where each planet has a ~11 Mearth minimum mass. A careful analysis of the (low level) magnetic activity of GJ 674 however demonstrates that the 35-day period coincides with the stellar rotation period. This signal therefore originates in a spot inhomogeneity modulated by stellar rotation. The 4.69-day signal on the other hand is caused by a bona-fide planet, GJ 674b.

    Conclusion: Its detection adds to the growing number of Neptune-mass planets around M-dwarfs, and reinforces the emerging conclusion that this mass domain is much more populated than the jovian mass range. We discuss the metallicity distributions of M dwarf with and without planets and find a low 11% probability that they are drawn from the same parent distribution. Moreover, we find tentative evidence that the host star metallicity correlates with the total mass of their planetary system.


    submitted to A&A (January 09, 2007)


    astro-ph (Astrophysics)

    Cite as:

    arXiv:0704.0270v1 [astro-ph]

    Submission history

    From: Xavier Bonfils [view email]

    [v1] Mon, 2 Apr 2007 21:25:56 GMT (849kb,D)


  • Eric James April 5, 2007, 2:02

    Ah baloney!

    The ocean floor is awash in organic materials raining down from above. Not only is this material organic, it’s made of the very same proteins, RNA, DNA and what have you that life requires. A veritable readymix for creating life. Why are there no obvious precursors (at the least)?

    Also, there are lots of places where oxygen is in short supply but organics and energy abound.

    Excuses for why life might not arise daily shouldn’t be sought. Instead, places where life should arise need to be carefully studied. We need to understand why it isn’t happening.

  • andy April 5, 2007, 6:20

    Ah, so you shift the goalposts.

  • ljk April 5, 2007, 9:14

    Perhaps because 4 billion years ago it was easier for new
    life to get a start on Earth where there was very little
    competition from other organisms.

    How long would a newly developing life form last on
    Earth with the gazillions of species crawling all over it
    these days, all of them looking for a meal.

  • Eric James April 6, 2007, 23:22

    That too is baloney. There is so much wasted (un-eaten) biomass on earth that it’s commonplace. Biomass even abounds in low or no oxygen content systems. For instance: Complete bodies, over a thousand years dead, are pulled from peat bogs.

    Therefore, to assume that any precursor or emerging species is going to automatically be eaten is unrealistic.

    We often state that water is necessary for life (as we know it) to begin on extraterrestrial worlds. Here we have water in unbelievable abundance, and yet we cannot find a single instance of an obvious precursor to life emerging from the magnificent ooze of our abundant organic materials.

  • ljk April 16, 2007, 16:28

    Title: The multiplicity of planet host stars – New low-mass companions to planet host stars

    Authors: M. Mugrauer, A. Seifahrt, R. Neuhaeuser

    (Submitted on 13 Apr 2007)

    Abstract: We present new results from our ongoing multiplicity study of exoplanet host stars, carried out with the infrared camera SofI at ESO-NTT. We have identified new low mass companions to the planet host stars HD101930 and HD65216. HD101930AB is a wide binary systems composed of the planet host star HD101930A and its companion HD101930B which is a M0 to M1 dwarf with a mass of about 0.7Msun separated from the primary by ~73arcsec (2200AU projected separation). HD65216 forms a hierarchical triple system, with a projected separation of 253AU (angular separation of about 7arcsec) between the planet host star HD65216A and its close binary companion HD65216BC, whose two components are separated by only ~0.17arcsec (6AU of projected separation). Two VLT-NACO images separated by 3 years confirm that this system is co-moving to the planet host star. The infrared photometry of HD65216B and C is consistent with a M7 to M8 (0.089Msun), and a L2 to L3 dwarf (0.078Msun), respectively, both close to the sub-stellar limit. An infrared spectrum with VLT-ISAAC of the pair HD65216BC, even though not resolved spatially, confirms this late spectral type. Furthermore, we present H- and K-band ISAAC infrared spectra of HD16141B, the recently detected co-moving companion of the planet host star HD16141A. The infrared spectroscopy as well as the apparent infrared photometry of HD16141B are both fully consistent with a M2 to M3 dwarf located at the distance of the planet host star.


    MNRAS accepted, 8 pages, 6 figures, and 1 table


    Astrophysics (astro-ph)

    Cite as:

    arXiv:0704.1767v1 [astro-ph]

    Submission history

    From: Markus Mugrauer [view email]

    [v1] Fri, 13 Apr 2007 15:19:57 GMT (244kb)