“The fault, dear Brutus, is not in our stars,
But in ourselves, that we are underlings.”
Thus Cassius speaking to Brutus in Shakespeare’s Julius Caesar, trying to convince him that what happens to us comes not from some malign fate but from our own actions. I’m sure he’s right, too, but I admit there are days when I wonder. For the stars seem aligned in such a way that whenever there is a significant news conference about exoplanets, I have a schedule conflict. This is true yet again today, so that I’m writing before the NASA-hosted news briefing and will have to set this up to post automatically after the embargo expires.
Here, though, are the main points. We have found Kepler 62f, an interesting world about 1.4 times the size of Earth and most likely rocky. When you add up the other known facts about the planet, the attention builds. Discovered through Kepler data in the constellation Lyra, this world receives about half the heat and radiation that the Earth does, while orbiting its star every 267.3 days. The University of Washington’s Eric Agol lays out the case for this intriguing planet:
“The planets this small that we have found until now have been very close to their stars and much too hot to be possibly habitable. This is the first one Kepler has found in the habitable zone that satisfies this small size. Kepler 62f is the smallest size and the most promising distance from its star, which by these measures makes it the most similar exoplanet to Earth that has been found by Kepler.”
The best guess — and remember that we lack knowledge of Kepler 62f’s mass and density — is that we’re looking at a rocky world with an atmosphere, but Agol doubts it’s a thick gaseous envelope like Neptune’s. We seem to be looking at a planet a bit larger and somewhat cooler than the Earth, and it’s not alone in this system, where four other planets are known to exist. One of these, Kepler 62e, is a fellow traveler in the star’s habitable zone. It’s about 1.61 times the size of Earth and orbits every 122.4 days, giving it 20 percent more stellar flux than the Earth.
Image: The newly discovered planets named Kepler 62e and f are super-Earths in the habitable zone of a distant sun-like star. The largest planet in the image, Kepler 62f, is farthest from its star and covered by ice. Kepler 62e, in the foreground, is nearer to its star and covered by dense clouds. Closer in orbits a Neptune-size ice giant with another small planet transiting its star. Both habitable-zone planets may be capable of supporting life. Credit: David A. Aguilar (CfA)
Two small super-Earths in the habitable zone make for understandable excitement. Modeling at the Harvard-Smithsonian Center for Astrophysics (CfA) suggests that both these planets are water worlds, completely covered with a global ocean. Might they have life? Lisa Kaltenegger (Max Planck Institute for Astronomy/CfA) speculates:
“These planets are unlike anything in our solar system. They have endless oceans. There may be life there, but could it be technology-based like ours? Life on these worlds would be under water with no easy access to metals, to electricity, or fire for metallurgy. Nonetheless, these worlds will still be beautiful blue planets circling an orange star — and maybe life’s inventiveness to get to a technology stage will surprise us.”
Kepler 62 is a class K star somewhat smaller and cooler than the Sun. According to the CfA’s models, Kepler 62e should be cloudier than the Earth, while the cooler Kepler 62f would need to take advantage of the greenhouse effect from carbon dioxide in the atmosphere to keep it warm enough for the ocean to remain liquid. Harvard’s Dimitar Sasselov notes in this CfA news release that discoveries like this raise the prospect of other stars with not one but two planets in the habitable zone. That conjures up what until recently was our view of the Solar System, when not so many decades ago we used to believe Venus and Mars might each be habitable worlds.
I think Sasselov is right to linger over this thought. These may be water worlds and most likely would not develop technological civilizations, but imagine a system where two worlds with continents and oceans, worlds much like Earth, existed close to each other in the habitable zone, each highly visible to the other. Surely the inhabitants of planets like these, with the prospect of a truly colonizable world this close, would be impelled to make the crossing.
The other planets around this star? Kepler 62 b, c and d are 1.31, 0.54 and 1.95 times the size of the Earth, respectively, all orbiting the star too tightly to be in the habitable zone. For more, see this University of Washington news release. Kaltenegger and Sasselov’s work is to be published in The Astrophysical Journal, while Agol is second author of the discovery paper published online in Science today as Borucki et al., “Kepler-62: A Five-Planet System with Planets of 1.4 and 1.6 Earth Radii in the Habitable Zone” (abstract).
With these kind of news releases, it is worth bearing in mind what Greg Laughlin wrote here:
(emphasis mine)
A paper suggesting that simple life is likely to emerge on any wet, rocky planet. However more complicated lifeforms probably evolve only by (rare) chance:
http://journalofcosmology.com/Abiogenesis107.html
Partial summary:
“The origin of life and evolution of prokaryotes is therefore deterministic and probable (necessity), while the evolution of more complex eukaryotic life is stochastic and improbable (chance). These bioenergetic principles are likely to apply throughout the universe.”
Shouldn’t that be “not one but two planets….”?
Thanks for catching that, Alex! Now fixed.
Thus far the bias in size trends to Super Terretrials and Low Mass Neptune Planets in the habitable zone. Obcourse I was wandering if they were ever going to find something in the habitable zone that humans could land on that only required modified scuba equiment, and did not require recombinant transportation devices owing to high gravity.
K 62f, seems to be that diamond the Kepler was looking for.
Even if this the best match of earth Kepler finds, I would consider their mission a sucess. For they have would clarified the matter of Habitable worlds frequency enourmously. Thus:
Earth-sized planets in the Habitable Zone are not abundant relative to other planets out there. They’re a minority, so on average most solar systems probably do not have one
Kepler is now nearing 4 years of operation. There is still a chance they
will find a True Earth analouge in the next 2 years. But note how long
it took to find even this one. IF Kepler finds no more terrestrials within the habitablity zone I still lean towards the closest True Earth analouge being the range of 275LY-300LY away
Does Kepler search for planets in F type stars too, It would put Mars
orbital distances in the habitable zone.
One interesting point is that if there are two planets HZ, even if on only one life has developed, it should be possible for it to spread to the other via exogenesis.
While in our system both Venus and Mars(and perhaps Europa) offer little prospect for life to thrive(even if it would endure in some form), a ocean world would allow for development of separate diverse ecosystem.
Rob Flores
“Kepler is now nearing 4 years of operation”
Rob, while Kepler is nearing 4 years, we should keep in mind that we are still to see the up-to date results. The planets discovered are from earlier data, not the one that was recently gathered as far as I know.
Before someone here enlightened me I always thought bigger planets would have greater than Earth gravity; I guess this is not necessarily so.
I am extremely interested in the gravity on these exoplanets- it is hard to get people excited about a place where they would break both legs if they stumbled and climbing a small hill is an ironman challenge.
A little less gravity and a larger surface IS exciting. Even an ocean planet fires the imagination- if the gravity is the same or lower than Earth.
“-simple life is likely to emerge on any wet, rocky planet”
Perfect for Earth megafauna and flora to invade. On such a world we can grow a second Earth (if that “simple life” is not lethal to us). We could eventually have thousands (millions?) of versions of Earth. Heinlein described a similar progression in Starship Troopers.
Both planets have pretty high surface gravities, if they have the same density as the Earth. Even if the density is close to that of Mars, the cooler of the two would be able to retain some Helium and maybe even some Hydrogen.
Smaller of the two.
Earth density: p = 5.5 gm/cm^3, g = 1.6
Venus density: p = 5.2 gm/cm^3, g = 1.5
Mars density: p= 3.9 gm/cm^3, g = 1.1
It’s sad when the PR starts talking about life and intelligence on a water world; pathetic, considering the paucity of data on these two planets.
If I want bad Science Fiction, I’ll turn to the Skiffy Channel.
Greg Laughlin ‘s words above should be the first paragraph of every PR on “habitable” worlds.
Since they don’t know the density of the planet, how do they know it would be a world completely covered in a deep ocean? Couldn’t a super-earth have some dry land, just like the earth?
I take the opposite view from GaryChurch about life-bearing planets. It should be hands off them, for both moral and scientific reasons. Moral because we shouldn’t do to them what we’ve already done too much of to the Earth. Scientific because they would be places where we could learn about principles of biology (what’s common? what’s unique?) that study only of Earth can’t tell us.
On principle I wouldn’t trust anything published in the Journal of Cosmology. Let’s just say that site has an interesting reputation. For that matter, it also gets an entry in this list of “potential, possible, or probable predatory scholarly open-access journals”.
I presume that the Kepler mission waits for 3 transits, Plus a ground verification. We now have and idea of Earth like worlds around K, M stars which constitute about 80% of all stars, They’re Not abundant.
Its true that I am going with Earth Like definition that is restrictive, RE .80-RE 1.20, in the habitable Zone, Not Tide Locked. I don’t think K 62f is
Earth Like, because It does not come close to an enviroment possible on the SURFACE of the Earth, based on the data we have and current theories on
the charateristics of HZ planets
But I agree It seems to be a Terrestrial world.
Mr. Wojciech J
is correct that the data is not all in, and we may yet be
surprised. What a gift it would be if it turns out that G and F
stars make plenty of Earth Like Worlds, and less Near Neptune Sized
planets. But I am skeptical because the results so far are not what was
expected, which means the models for planetary formation BEFORE,
the Kepler mission do not match reality.
Does Kepler indicate how likely alien planets that are
somewhat off the equatorial plane of it’s sun. Our solar system seems
to have a very orderly set of orbits, I am wondering if this is rare.
Excuse the ignorance, but why are earth analogs called “eta-earths” ?
By the way, the article says that Kepler-62e receives 20% more irradiation than earth. With such a larger radius, it is likely to have a dense atmosphere and I would not declare it in HZ.
Kepler-62f looks interesting, a sort of earth.
@GaryChurch,
For educated guesses at densities and gravities of such planets, see :
http://www.sciences.univ-nantes.fr/lpgnantes/index.php?option=com_content&view=article&id=144:modelisation-de-la-structure-interne-des-super-terres&catid=4&Itemid=13&lang=en
@ GaryChurch ,
“I am extremely interested in the gravity on these exoplanets- it is hard to get people excited about a place where they would break both legs if they stumbled and climbing a small hill is an ironman challenge. ”
I used to think that way and think how hard it would be to live at >1 g.
However, there is currently an ongoing giant experiment where people, thanks to obesity, live at 1.5, 1.6 and more g. This shows that it is possible and actually easier than one thinks.
There are also the super obese that probably live well above 2 g.
Assuming Kepler 62-e made of silicate, the mass would be ~3 Me with a gravity of 1.5 g. someone that weighs 80kg on earth would weigh 120kg there. This is quite possible and I’m sure you know many people like that.
I meant Kepler 62-f, not 62-e which is much bigger.
Dave: There is a limit to how high a mountain or continent can be above the ‘baseline’ before the pressure of the land melts the underlying rock, and it subsides. The numbers are pretty uncertain, but Olympus Mons on Mars is believed to be close to that limit. Above 20-30 km or so, any mountain / island / continent would subside.
So, if the ocean is 50-100 km deep, we think no dry land is possible
This is a great discovery. To think of the waves rolling under an orange sun, maybe alien plankton or alien fishes or alien ‘dolphins’. A real place happening now. If we could get that far, we could put down a nice floating city there. Maybe dredge up enough rock to make artificial islands. Mix our fishes with the local life. Grow a strong colony. Eventually forgetting our origins.
To andy, the paper is a good summary of a current school of thought about the origins of life, and cites research by mainstream scientists. Granted the Journal of Cosmology also appears give space to a wide range of opinion/speculation. Not sure what is meant by a “predatory journal”.
To NS: This “school of thought” is primarily Nick Lane’s, and does not have a lot of followers in the scientific mainstream. If you wanted to be ungenerous, you might call it (and that journal, both) a nutjob.
There aren’t a lot of data or even convincing arguments either way, but in my opinion the opposite makes a lot more sense: Abiogenesis is rare and stochastic. The development of more and more complex life following it is inevitable through the mechanism of evolution.
FrankH and Andy are right on the money about the wild speculation associated with these annoncements. It’s not science, it’s wishful thinking. It is pure conjecture to assume these planets are water worlds based upon computer modeling. If they could show us the spectrographic fingerprint of free oxygen in the atmospheres’ of these planets their suppositions would be far more reasonable, but they can’t…so now the tabloid press will report “Earth twins found!”
Remember, it was only 20-25 years ago that “very knowledgeable scientists” said that gas giant planets could only form in the colder, outer reaches of solar systems, for example, based upon their computer modeling. “Hot Jupiter” by its name alone implies oxymoron and should suggest to all of us to be very very skeptical when absorbing bold statements about the transit of two planets about their sun 1200 lyr away.
Rob Flores:
I do not think that is true at all. Earth sized planets in Earth sized orbits are simply not being detected, yet, because of lack of sensitivity. I think there are still experts speculating that nearly every solar system has at least one.
For our solar system, as well as for the exoplanets for which we have decent masses, the masses tend to scale as roughly R^2 (not the R^3 one would naively expect for undifferentiated bodies). Since the surface gravity just scales as M/R^2, this means these new planets would have surface gravities the same as the earth. So, no need for Great Mambo Chickens ( to steal science writer Ed Regis’s great phrase).
“-these new planets would have surface gravities the same as the earth. ”
Hmmm. Sounds too good to be true. But if so Coolstar, I will have to pack a bag in case I get the call. But being a couple thousand light years away is a……problem. It would take awhile to get there at .05C. Even if they froze me that is a long time for a starship to sleep.
Alastair McKinstry, I wish to amend your statement that about that limit to how high a mountain range can be. You are applying it to a world that has a homogenous composition at a particular distance from its core. I am wondering if in many worlds, particularly tidally locked ones, there is a significant difference in the density of rock and ice on one hemisphere compared to the other.
You also didn’t address Dave’s question as to why these worlds must be water worlds. As a world get’s bigger, it becomes harder to loose its volatiles, and even if it is just water of primordial mineral hydration, released to the surface by volcanism, the layer of water there on a larger planet would be proportionately larger, and thus thicker for bigger planets.
“This “school of thought” is primarily Nick Lane’s, and does not have a lot of followers in the scientific mainstream.”
I find Nick Lane’s ideas to be highly convincing. His book on mitochondria is an excellent introduction to his ideas about endosymbiosis, which are based on Martin’s “hydrogen hypothesis” concept of the endosymbiosis that resulted in the Eukaryote. If the hydrogen hypothesis is correct (and I think it is), Nick Lane is correct that it was a wildly improbable event that likely occurred only once in the history of this galaxy, at least.
Like Nick Lane (and others), I think the Earth is the only planet with complex life in the Milky Way.
Rob Flores wrote:
“I presume that the Kepler mission waits for 3 transits, Plus a ground verification. We now have and idea of Earth like worlds around K, M stars which constitute about 80% of all stars, They’re Not abundant.”
this not what the Studies Indicate about Earth-size planets Around M dwarf stars in Kepler Field,Did you ever read it?
The Radius Distribution of Small Planets Around Cool Stars:
http://arxiv.org/pdf/1303.3013v1.pdf
The Occurrence Rate of Small Planets around Small Stars
http://arxiv.org/pdf/1302.1647v2.pdf
A revised estimate of the occurrence rate of terrestrial planets in the habitable zones around kepler m-dwarfs
http://arxiv.org/pdf/1303.2649v1.pdf
Ever the most conservative estimation About Earth-size planets in HZ around M dwarf stars (by Kepler data and other instruments like HARPS-S) indicate that at LEAST 15% (could be ever 53%) of M stars in the galaxy have Earth-size planets in HZ (for our Galaxy Milky way 300-75 billion M dwarf stars(75% of stars of galaxy) would be about at least (for 15%) 45-11,25 billion of such planets)
Where did take data than this planets are not abundant? because far as I know isn’t what I’ve in the data publish by the scientist that work on the Kepler mission.
Far as I Know Nothing scientifically indicate the Statement that you said:
“We now have and idea of Earth like worlds around K, M stars which constitute about 80% of all stars, They’re Not abundant.”
@coolstar
not really. On the surface of an exoplanet, a given mass m1 (lets say myself) will be attracted by the force
F = GM*m1/R^2
where M is a mass of an exoplanet, R is its radius and G is a constant that has something to do with apples as far as I have heard. This gives
m1*g = GM*m1/R^2
where g is an accceleration on the surface of an exoplanet, which gives
g=GM/R^2
if we express this in proportion to our Earth (all variables indexed by ” e”) we have
g/g_e=(M/M_e)*(R_e/R)^2
or taking into account that M = V * rho = 4/3 * pi * R^3 * rho we have
g/g_e = (R/R_e)^3*(rho/rho_e)*(R_e/R)^2=(R/R_e)*(rho/rho_e)
or
g/g_e = (R/R_e)*(rho/rho_e)
which states that with constant rho (or rho = rho_e e.g. silicate planet) the relative acceleration on the surface of an exoplanet should be equal to the relative radius R/R_e.
So in the case of Kepler 62f we should have 40% larger acceleration than on Earth provided that K62f has the same density as our sweet home
Waterworlds are certainly more appealing than lifeless plains of shattered rock. I always thought that if we ever do make it to another earth-like planet, it will fall to naval architects to design ways to help humans explore it.
@Eniac
“I do not think that is true at all. Earth sized planets in Earth sized orbits are simply not being detected, yet, because of lack of sensitivity.”
Then you would have to explain why “lack of sensitivity” only affects longer period planets : Kepler has no problem at all detecting earth size planets and smaller around a variety of stars. For lower luminosity stars, many more periods than 3 have been covered at HZ distances since launch and the result is the same : the number of earth size planets drops as one gets towards the HZ. Even warm jupiters (jupiters around the HZ) look more common.
@Enzo
“lack of sensitivity” let me explain it: like the scientist of mission already said the stars in Kepler field are too noise(Kepler-37 is rare opposite case,the star is too quite,that they ever detect a moon size planet around such star) , they need at least till 2016 to accomplish the Mission of detection of Earth-size planet around a sun-like star,that need more that 3 transit to “catch” such Earth-size planet in HZ,Earth-size planets and ever small with short orbital period around a variety of stars is what Kepler had been detected, and this planets have many transit already on the Kepler Data, this is why Kepler have not problem in detect such planets,and there is loads of Kepler data come and to be analyzed yet, till now 22 months of Kepler data have been analyzed.
@Enzo wrote:
“For lower luminosity stars, many more periods than 3 have been covered at HZ distances since launch and the result is the same : the number of earth size planets drops as one gets towards the HZ. Even warm jupiters (jupiters around the HZ) look more common.”
I don’t know where you take conclusion the jupiters around the HZ of lower luminosity stars are more common the Earth-size in HZ,like I post here before, this is not what the Kepler data tell us,Earth-size and super-earth size planets are quite common around such stars, jupiters around low luminosity stars are quite rare
Clearly earth-sized planets can be considered abundant, as the Kepler data already indicate that a majority of M type stars have planets of approximately earth’s diameter. So, I think we are largely past the point of debating whether earth-sized planets are abundant or not– at least when it comes to stars smaller than the Sun. Even if only 1% of stars like the Sun have an earth-sized planet in the HZ, then that leaves many millions of potential spots for life to arise within our galaxy alone.
An interesting and often neglected point when talk of life on these new planets comes up is the fact that we still have no idea whether the transition from non-life to life is difficult versus easy. If the transition that we know occurred on our planet is indeed a chemical fluke (still consistent with the data we have), then there is not likely to be even one other independently evolved single-celled organism within billions of light years of earth! Planets like the ones just discovered by Kepler would be sterile as an autoclave despite there presence in the habitable zone of their star. Personally, the idea of a sterile universe is unappealing to me, but it is still consistent with the data and the notion certainly provides a compelling solution to the Fermi paradox or the “Great Silence.”
To Aberlard Lindsey, thanks for the pointer to the hydrogen hypothesis paper.
While I wouldn’t go so far as to say that complex life arose only once in the Milky Way, I suspect it’s a chancy evolutionary event and may not be common.
Despite various disagreements, like everyone here I hope we’ll actually find life on other worlds within our own lifetimes. Even a single such discovery would give us enormously greater information on how likely it is that life appears, develops complexity, etc.
A very simple – and accurate – way to estimate a planet’s surface gravity with respect to Earth’s is by multiplying the ratios of the planetary radii and densities:
gPlanet = (rPlanet/rEarth) * (dPlanet/dEarth)
or
using km for the radius and g/cm^3 for the density
gPlanet = (rPlanet/6371) * (dPlanet/5.52)
This is faster and less prone to simple math errors than the Physics textbook version.
Here are some worked examples. Compare to the real values.
Mars: (3390/6371) * (3.93/5.52) = 0.379
Moon: (1737/6371) * (3.35/5.52) = 0.165
Venus: (6062/6371) * (5.25/5.52) = 0.905
TPF-710 (7005/6371) * (5.15/5.52) = 1.026 (wait, the TPF was canceled? Never mind)
@Daniel,
” A revised estimate of the occurrence rate of terrestrial planets in the habitable zones around kepler m-dwarfs
http://arxiv.org/pdf/1303.2649v1.pdf”
I actually went through this paper and, on page 5, it says:
“In an optimistic scenario, the inner edge of the HZ boundary can
be obtained by the “recent Venus” limit which is based on the observations of Venus by Magellan spacecraft, suggesting that liquid water has been absent from the surface of Venus for at least 1 Gyr (Solomon & Head 1991) or earlier.”
Note that no water for AT LEAST 1 Gyr does not mean water up to 1 Gyr ago. It then proceeds to extend the HZ as if Venus had water on the surface 1 Gyr ago. This is not justified on the basis of the information reported.
Which a much deeper HZ (from 0.75 AU), he then gets the result of lots of planets in HZ.
I do agree though on extending the HZ outwards, mainly because the atmosphere can keep a planet warmer.
The problem is that there are so few planets detected by Kepler with an equilibrium temperature of 260-270 K or less that it is really difficult to extrapolate.
Note that, for low luminosity stars, Kepler has observed many periods well beyond the definition of HZ.
Regarding Kepler-62e and the Hz. Well who knows of course, but I would point out that there has been some interesting work done in recent years on ‘land planets’ that suggests that worlds with low water content can potentially be habitable a long way in from the classical Hz (with a few other caveats). These would not look anything like Earth, and would be fiercely hot and dry and their subsolar point, but still hold ice )and some water) at the poles (or the antisolar point if they were tidally locked). Think a hotter, bigger Mars.
Here’s one recent paper, there are others
http://arxiv.org/abs/1303.7079
P
@loggain Unfortunately (or, actually, FORTUNATELY) , that’s NOT what the data shows. For a LOT of planets, inside our solar system and out, M scales as R^2.06, more or less. This has been the starting point for first approximation conversions of R to M (since there are a LOT more planets now known with good values of R, as opposed to M, thanks mostly to Kepler). Your analysis is only correct for planets that have the same equation of state in the interiors as the earth, which does not seem to be the case (not even in the solar system, but you have to leave out Jupiter. Not unreasonable for planets as a whole since Jupiter mass planets are rare.). Yeah, I was surprised too. Goes to show that naive answers, while great for the back of a napkin, aren’t always correct.
As an additional note (you can add this to the above Paul, thanks): Jon Swift’s work and that of his co-authors at Cal Tech shows pretty convincingly (at least to this astronomer) that most planets in the HZ of M dwarfs are NOT silicate, since they likely formed beyond the frost line. So, even if they have masses, radii, gravities, etc. similar to that of the earth, that does not make them earth-LIKE. This of course does not rule out the possibility that they might support life of some kind. Though Kepler is getting closer, its team will tell you that they haven’t yet found the holy grail: an earth analog in the HZ of a solar type star (believe me, you’ll know, when and if they do!).
@Daniel RE: sensitivity
We are talking about earth size planets in the HZ, right ? Just want to make sure : there’s no doubt that Kepler has found heaps of earth size planets.
So, the bar has been moved to 6 periods, right ? (Kepler launched in 3/09).
They recently published data is for Q14, 3.5 yr of observations. Let’s say 3 to compensate for some set up time after launch. Three years are 1095 days which are 6 periods for planets that orbit in 1095/6=182 days .
Now, if you see my post here :
http://oklo.org/2012/03/11/lights-in-the-sky/#comments
Kepler has already observed 6 periods of all the stars of mass < 0.75 solar masses. You can verify it by plugging the numbers in the equations in the post. That is a lot of stars. For these stars, according to the 6 period test, we should find heaps of earths in the HZ. We just got Kepler 62-f and maybe few other candidates to verify.
Also, these stars are smaller than the sun and so the signal to noise ratio of a transit is higher (bigger proportion of the disc).
RE : warm jupiters
I said jupiters in HZ, not jupiters in HZ near low luminosity stars, even though it could be interpreted that way.
See the plot with a large number of jupiters with periods of 1-300 days around various stars :
http://oklo.org/2012/11/10/the-mmen/
It includes all jupiters known from Kepler and radial velocity.
Again, there are many. The same can't be said of earth size planets in the HZ.
Daniel Please:
Go back re-read my Entry
I wrote “EARTH LIKE” not EARTH SIZED.
I know there are Earth Sized planets found by Kepler, around
M stars in the HZ, but those are tide locked and most are subject to flares.
I am talking about Near Twin of Earths, in the HZ, Not Tide Locked.
As far I can recall, K 62f, is the closest among the M,K dwarfs.
And it is ONLY ONE. and not a true twin, but a terrestrial with the potential
for life. My view is narrow I admit, but I want to know how likely is it
to find a colonizable planet around any particular K,G,F star. And by
colonizable I don’t mean a body like Mars, or Titan I mean shirt sleve
and minimal life support needs, Colonizable.
Have I missed the other CONFIRMED planets, that are Near Twins of Earth in the HZ and Not Tide Locked?
Maybe the question needs to be inverted, what will Kepler tell us if the
only planet discovered by Kepler that remotely comes close to Earth is K 62f
What conclusion could one make?
Enzo:
This is easy: The longer the period, the lower the number of transits, and the lower the sensitivity. At this point of time, Earth is still outside of Kepler’s detection range, if I am not mistaken. In coming years, as more data comes in, it may or may not be included. As I understand, this was one of Kepler’s design goals, but unexpectedly higher noise has made it a bit of a reach.
@coolstar, loggain, FrankH
Regarding mass/radius relationship, you might be interested in the following post on astronomer Greg Laughlin’s blog :
http://oklo.org/2013/04/07/3138/
@Eniac
“This is easy: The longer the period, the lower the number of transits, and the lower the sensitivity. At this point of time, Earth is still outside of Kepler’s detection range, if I am not mistaken. In coming years, as more data comes in, it may or may not be included. As I understand, this was one of Kepler’s design goals, but unexpectedly higher noise has made it a bit of a reach.”
The new bar for earth detection has been raised to 6 periods.
As I have posted above, Kepler has already observed 6 periods for planets with a period of 182 days or less. This means for all the stars with mass < 0.75 sun (almost all K and M observable) 6 periods of a potential eta earth in HZ have been observed already.
I have not seen this flood of eta earths, just a handful of potential ones.
G stars might be a special case but it doesn't look good so far. They too show a lot of compact systems.
@Rob Flores
First, There is not Earth-LIKE planets Detect by Kepler because Kepler Is not Capable of such Thing we have some Earth-size in star HZ nothing beyond of it,because for we if a Planet is Earth-like we Need a telescope to image this planets (like a Starshade or/and TPF (that been cancelled)),study other properties of the planet Like atmosphere,rotational period, the planet axis and so on.that is the Kepler case
Second how do we know that all planet in HZ around M Dwarf are tidal lock ? Mercury in our solar system isn’t,and the Kepler team that work with cool stars did talk about it in the last conference where the present the scientific papers that I post here, ever so, there is still a chance of complex multicellular life forms (ever intelligent life forms) in this planets.this is been ever discuss many times here before on centauri dreams:
https://centauri-dreams.org/?p=6713
Simulations of the Atmospheres of Synchronously Rotating Terrestrial
Planets Orbiting M Dwarfs: Conditions for Atmospheric Collapse and
the Implications for Habitability
http://crack.seismo.unr.edu/ftp/ftp/pub/gillett/joshi.pdf
I talk about life in other planets, and not exact copies of planets like Earth
Well M dwarf has your negative and positives points, but Still a very fascinating case for Astrobiology, ever with the possible Tidal lock, strong stellar flare so on,there many ways that a planet can support life ever with all this extreme conditions (for our human standards anyway)
Enzo wrote:
“RE : warm jupiters
I said jupiters in HZ, not jupiters in HZ near low luminosity stars, even though it could be interpreted that way.
See the plot with a large number of jupiters with periods of 1-300 days around various stars :
http://oklo.org/2012/11/10/the-mmen/
It includes all jupiters known from Kepler and radial velocity.
Again, there are many. The same can’t be said of earth size planets in the HZ.”
I agree Expect in 2 points: Jupiter Are minority in the Kepler Data (as you can see here: http://www.nasa.gov/mission_pages/kepler/news/kepler-461-new-candidates.html ) in Radial velocity Jupiter a common because radial velocity are sensible to detect them,but not to Earth-size planets much less in the HZ , so Earth-size planets can’t be take on account in radial velocity and as you can see in Kepler data small planets are much more common the Jupiters ever in HZ (you can check in other Kepler graphics) ,Kepler still not sensible enough for Earth-size planets around sun-like stars as Eniac explain to you and the Kepler team the work on the Mission till 2016 at least
@Enzo
you maybe right with respect to the scarcity of earth analogs, but as far as I understand it contradicts a little bit the Kepler team statements. They claim officially that the detection of Earth twin is still ahead of them.
see: http://www.youtube.com/watch?v=0V8vKKt9-j8 (about 1:03:45)
in this youtube movie you will also see an interesting chart (about 0:25:45). It seems that there are about dozen of candidates in the HZ of G an K stars. Superearths maybe – unfortunately they do not show this on the chart.
@coolstar
certainly you maybe right if the density of the planet falls with its size. Maybe it is so. I am not sure however if our large sample of exoplanets with measured density is large enough to claim anything about that. Enzos link to GL blog seems to confirm this lack of knowledge.
anyway thanks Enzo for sharing!