Astronomers from KU Leuven, Belgium, have shown that the interaction between the surface and the atmosphere of an exoplanet has major consequences for the temperature on the planet. This temperature, in turn, is a crucial element in the quest for habitable planets outside our Solar System.
CREDIT KU Leuven – Ludmila Carone and Leen Decin
In the quest for habitable planets outside our Solar System – also known as exoplanets – astronomers are currently focusing on rocky planets that don’t look like Earth. These planets orbit so-called M dwarfs – stars that are smaller than our Sun. In our universe, there are many more M dwarfs than there are sun-like stars, making it more likely that astronomers will discover the first habitable exoplanet around an M dwarf. Most planets orbiting these M dwarfs always face their star with the same side. As a result, they have permanent day and night sides. The day side is too hot to make life possible, while the night side is too cold.
Last year, KU Leuven researchers Ludmila Carone, Professor Rony Keppens, and Professor Leen Decin already showed that planets with permanent day sides may still be habitable depending on their ‘air conditioning’ system. Two out of three possible ‘air conditioning’ systems on these exoplanets use the cold air of the night side to cool down the day side. And with the right atmosphere and temperature, planets with permanent day and night sides are potentially habitable.
Whether the ‘air conditioning’ system is actually effective depends on the interaction between the surface of the planet and its atmosphere, Ludmila Carone’s new study shows.
Carone: “We built hundreds of computer models to examine this interaction. In an ideal situation, the cool air is transported from the night to the day side. On the latter side, the air is gradually heated by the star. This hot air rises to the upper layers of the atmosphere, where it is transported to the night side of the planet again.”
But this is not always the case: on the equator of many of these rocky planets, a strong air current in the upper layers of the atmosphere interferes with the circulation of hot air to the night side. The ‘air conditioning’ system stops working, and the planet becomes uninhabitable because the temperatures are too extreme.
Ludmila Carone: “Our models show that friction between the surface of the planet and the lower layers of the atmosphere can suppress these strong air currents. When there is a lot of surface friction, the ‘air conditioning’ system still works.”
The KU Leuven researchers created models in which the surface-atmosphere interaction on the exoplanet is the same as on Earth, and models in which there is ten times as much interaction as on Earth. In the latter case, the exoplanets had a more habitable climate. If planets with a well-functioning ‘air conditioning’ system also have the right atmosphere composition, there’s a good chance that these exoplanets are habitable.
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I hope that extrasolar astronomy will one day reach the point of allowing us to *actually* observe weather and climate patterns on other habitable worlds. Right now we can only play with computer models and we know that they don’t work well even with Earth itself, where we know reasonable values for most of the involved parameters.
Too true. We cannot model the Earth’s climate, even with the posibility of real data inputted (which they are not currently using).
If scientists believe these extremophile-exoplanets are still habitable even though one side BAKES in their associated suns to hundreds of degrees and the other side freezes to -hundreds, what makes scientists think that our earth would become uninhabitable with a few degrees of warming?
We need to find one that’s about -20F at the equator so we can send the Warmists there.
I wonder what Earth’s surface composition climate models use. A desert, meadow, jungle – who cares.
I have a partial answer, contained in essay Models All the way Down. The UK Had CM3 model contains no representation of the Andes Mountains in South America. Bit of a problem.
http://Www.eas.gatexh.edu/site/files/default/SmithTalkGT.pdf is the original source material per the footnote, as this comment may seem unbelievable.
Gatech, not gatext. Sorry for the link typo.
” The UK Had CM3 model contains no representation of the Andes Mountains in South America. Bit of a problem.”
Not quite true. It does, but the grid is so coarse as to make it practically useless. If you check you will find the that the altitude is fairly correct on the altiplano around Lake Titicaca which is a vast flat big plateau but way off in the surrounding ranges.
This problem (incidentally shared by all climate models) is one important reason that climate models are completely useless for simulating precipitation, where ground relief effects are vastly important.
Hmm. Interest notion – thanks for posting this one, Anthony. I’ll have to read the paper, though, before forming any thoughts on it. Seems to me that “ten times” the surface friction implies some rather radical differences in composition (less water for instance, to form large relatively flat regions).
BTW – the paper is free, though behind a bunch of link excavation. Direct link to the paper is: http://mnras.oxfordjournals.org/content/453/3/2412.full.pdf+html
On a tidally locked exo-planet, wouldn’t all the water be locked in night side glaciers?
if the day side is too hot and the night side too cold, shouldn’t there always be a transition region, however small, that is “just right”?
If the majority of m-dwarf exoplanets are of this permanent day/permanent night type, it suggests many of these planets could have habitable zones at the interfaces. in that case the size of the zone and presence of water would seem to be the key issues, so long as planetary “heating” or “air conditioning” doesn’t render the entire planet too hot or cold.
@ Area Man, I was thinking along the same lines, the article said this,
“In the quest for habitable planets outside our Solar System – also known as exoplanets – astronomers are currently focusing on rocky planets that don’t look like Earth. These planets orbit so-called M dwarfs – stars that are smaller than our Sun”.
I read that and thought, why are they not looking for planets that orbit around a sun that is close to the same as ours? ( G 4 I think) You know a planet that is more water like, the same temps etc and has an orbit the same as ours? I think the guys finding these “rocky planets and Jupiter like ” planets should be spending their funding on those possibilities rather than spending funds on useless places like those.
I wonder what the government would say if the scientists WOULD find a planet that has virtually the same composition, climate and sun as ours? ( Gee I almost starting to wonder if the real estate agents are holding back on us).
But sarc/cynicism off , would that interface between a hot and cold halves of the locked planet not be a zone of “extreme weather”? , ( oh sorry the warmist lingo took over there, btw there is a really good short story about that. It is SF of course but the story really get’s it right.)
Locked planets are what they find because of several transits a day. Instead of yearly events on planets like ours.
@Area Not sure how there would be much water recycling if 30% was constantly frozen. Pretty big Antarctica.
I would think that 100% of the water would be constantly frozen. There’s nothing to melt the ice that does form. So any water that falls in frozen form on the night side would never return to the day side.
And if you were able to observe climate and weather patterns on a very distant planet while standing on Earth are you witnessing what is happening now, the future or the past.
Having found a suitable planet to colonise it would be very disappointing to find it had actually been swallowed up some years before.
..and this Goldilocks star was stable for millions of years in order for life to evolve??
The smaller a sun is, the longer it stays in the main-sequence. The massive O-class suns age through the main-sequence and die quickly. Our G-class is ~4.5 billion years old, and has billions of years left. M-class have lifetimes that make G-class look like mayflies.
But the smaller a star is, the narrower the Goldilocks zone is, and the more likely tidal locking is. Hence the question: Can a tidally locked planet be habitable?
LD. That is the point of this paper. Tidal locking means one side always faces in. Like our moon. Their models say that under certain atmospheric conditions, possibly life could exist anyway if the orbit were in the Goldilocks zone.. Other papers on this same issue speculate the twilight zone between locked day and locked night might be habitable independent of atmospheric conditions. It is all just computer enhanced thought experiments. IMO, pretty useless speculation except for producing pretty useless Ph.Ds.
Unless this twilight zone was alternately baked and frozen by winds from alternating hemispheres.
I think it may not be safe to assume a long term stable zone in between a very hot place and a very cold place.
I suppose a “double planet” like our earth-moon system could be habitable. The two satellites would end up tidally locked to each other rather than to their star.
On a hot sunny day, walk barefoot from thick grass onto either hot asphalt or hot dry sand.
I would have thought the first approximation to a planet’s surface temperature would be given by the lapse rate.
Nah, lapse rate doesn’t control the surface temperature, just how the temperature changes as you leave the surface. E.g., you could have a lapse rate of 10 C/km, and the surface temperature could average 0 degrees, -100 degrees, or 100 degrees. By itself, the lapse rate doesn’t tell you much.
Actually, I think it acts as a feedback on surface temperature.
Here’s a story about how the lapse rate in the much denser atmosphere of Venus makes its surface temperature so high.
At a certain lapse rate, the atmosphere is stable and heat is removed from the planet’s surface by radiation and conduction. Past that rate, we get convection and heat is removed from the planet much more quickly. So, the lapse rate sets a rough maximum surface temperature.
Exactly.
Wonder why they don’t rotate. Well it’s easy enough to calculate a rocket that we could attach to the planet and blast it for a while to start the planet rotating.
Rishrac. Tidal locking is well known. Mercury is tidal locked to the Sun. Our Moon is tidal locked to Earth. That is why we we cannot see the Moon’s dark side except by going there. No rocket imaginable could overcome such gravitational forces. Cute comment, though.
It was meant to be. If you have a mental image of a rocket blasting away trying to turn a planet. ☺
ristvan July 15, 2016 at 3:13 pm
…Mercury is tidal locked to the Sun…..
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I had to look this one up for myself.
Of the several answers found, “no not Tidally Locked.”
Mercury
In 1965, the rotational period of Mercury was measured for the first time using the radar Doppler-spread [2]. Until then, it was generally believed that Mercury was synchronously tidally locked to the Sun, as the Moon has done to the Earth. Therefore, when the result of the experiment was published that the measured rotational period was 59±5 days, significantly shorter than the orbital period of Mercury (88 days), this immediately drew many physicists’ attention.
Colombo [3] was the first to point out that Mercury’s rotational period might actually be exactly two third of the orbital period, thus in sync with its revolution, only not by 1:1 but with 3:2 ratio. Mercury has the largest orbital eccentricity (e = 0.2056) among all the Solar planets (besides Pluto, e = 0.2482, which has been recently demoted to dwarf-planet status). Colombo claimed that since the distance between Mercury and the Sun varies significantly, the motion of Mercury must be regulated by the gravitational effect most heavily at perihelion. As shown in Figure 3, the only way to enforce a stabilized orientation of Mercury at its perihelion is to let it have the rotational period a multiple times of a half of the orbital period. Colombo also pointed out that the orbital angular velocity of Mercury at perihelion is
http://large.stanford.edu/courses/2007/ph210/kwon2/
Thanks, Carla – fascinating stuff.
Rocket? Well. Tidal Locking assumes there is no dedicated force trying to spin the planet and takes 100s of millions of years (if at all) so the net force is weak. A dedicated force operated over several years or decades is a different story.
The problem with operating a rocket in the atmosphere is that turbulence is created not propulsion. The propellant pushes the air, the propulsion pushes the rocket, in opposite directions. The net force on the planet is zero.
Now if the rocket was a nuclear engine at the end of a space elevator tether, and you pumped water up from the planet (for propellant mass), that is a different story.
At geosynchronous+ distances the rocket would exert six times the rotation torque it would on the ground of an airless planet.
Falcon 9 heavy produces 23,000 kN in air and 25,000 kN in vacuum.
Don’t have time to compute the effect but 1 year of Falcon 9 level propulsion should be able to spin the planet to at least a once a decade rotation rate.
We see the Moon’s dark side on every New Moon. The far side is NOT a “dark side.” Think about it.
Maybe we now have a real use for the mature high technologies of solar and wind turbines.
Tidally locked side facing the sun = reliable 24/7 solar power. Connect the solar power to turbine farms located on the dark side and blow all that cold air around to the hot side.
Result: temperature habitable planet. Finally! a constructive outcome from AGW technics.
Well until the solar panels rotate into the dark.
Sort of sums up the whole solar power issue.
Stop it. My ribs are hurting from the quaking.
Carla, good for you digging ever deeper.
I meant windchaser was correct
One of the problems with these kinds of planets are they are awfully close to their stars. Flares from these stars would not be good for living creatures.
Maybe one day astronomers will find the planet the IPCC has been making models of.
Good one, David! 🙂
Earth’s Albedo has varied between 24% and 50% in the last 3.0 billion years. Today it is 29.8% as in 29.8% of the sunlight received by the Earth is reflected directly back to space within 0.1 seconds and does contribute to Earth’s energy balance. It only takes less than 0.1 seconds for reflected sunlight to leave the Earth system at the speed of light.
Albedo has been as low as 24% in the Hothouse periods when most of the continents were concentrated at the equator – think Pangea 265 Mya super-continent centered at the equator or Cretaceous Earth at 94 Mya when the continents were concentrated at the equator and sea level was higher so that 30% of the continent were flooded by low Albedo shallow ocean.
This is Earth with 24% Albedo and global temperatures at +9.0C / +10.0C.
And then 50% Albedo as in Snowball Earth when 50% of the continents were at the South Pole and/or in direct contact with these continents. As in Glaciers build up at the South Pole to 5 kms high and spread by gravity to all the continents in contact with these South Pole continents. As in Earth with 50% Albedo and temperatures at -25.0C from today. As in, the sea ice even extended to 30 degree latitudes. Happened 4 different times in history with the last one peaking at 635 Mya.
Glaciers have 70% Albedos while every other Earth-situation is in the 25% category. Glaciers do not build up on ocean, (one can have sea ice) but it is when the continents/land are at the poles is when the big Albedo variances can happen.
Something as simple as the continental alignment can be +/- 35.0C on planet Earth.
If the Earth did not have a 23 degree tilt (or if it was just 20 degrees or something less), sorry the Earth would just be a permanent IceBall because the snow would NEVER melt at the poles in the summer and they would always be building up into 8 kms high glaciers and pushing towards the equator – ocean or not. IceBall Earth with anything less than a 20 degree tilt..
If the Earth had little ocean and was just mainly continents, sorry IceBall Earth once again. Water turns into ice at the poles, builds into glaciers and pushes toward the equator. Albedo at 50% and IceBall Earth again.
One can imagine 20 other situations where Albedo determines what the temperature of the planet is regardless of whether it is in the goldilocks zone or not. Less silicone, more iron etc.
Then there is the rotation rate. Anything more than 200 hours per rotation results in a completely baked out surface and a massive atmosphere and a Venus-like planetary surface. The planets which are likely tidally-locked to their Sun (probabaly very commone) are just hellish Venus-like planets regardless of the transition to the dark-side zone.
Earth is just a really lucky planet
Sure glad I was born here instead of on any of them.
Oh, wait…
Pure “Snowball-earth” states are unstable since volcanic ash would build up on the glaciers and lower the albedo until melting starts. Enough open seas must remain to keep the hydrological cycle going and allow new snow to accumulate on top of the ash.
Incidentally “completely baked out surface” can’t occur on a tidally locket planet. Volatiles baked out on the day side will accumulate on the night side. The question is whether the night side will be cold enough to freeze the volatiles permanently or not. Which is what this paper is all about really.
Antarctica has had 33 million years to accumulate a volcanic ash layer on top. Didn’t happen. Albedo between 70S-90S is 67%.
Antarctica gets new snow on a regular basis.
Thanks for the good summary of albedo, Bill.
If we really want to find planets suitable for our kind of life, we should be looking for a twin Earth with a twin moon.
Surface Composition? they are stretching their “calculations” a bit, the so called planets being discovered are questionable, I’m not saying there are no solar systems around stars, I’m saying the methods are flawed and imaginary.
Show us an Artistic impression at least ffs.
It’s modelonomy.
Once I read that a tidally locked planet would probably have no atmosphere. This is because the cold side would be so cold, that the atmosphere would freeze and fall to the ground as snow and stay there. So, even if there were a temperate zone, where liquid water could exist for a while, as soon as it either sublimates or evaporates, it would eventually be transported to the frozen cold side and stay there.
So the end result of such a planet, is no atmosphere and no liquid water.
I think it unlikely that a slow-rotation planet will have a magnetic field, and that a planet without a magnetic field can be considered “habitable” (I include Mars).
A close-in tidally locked planet around an M-star is actually rotating fairly rapidly.
“close-in” is probably not in the “Goldilocks” zone.
How much of this stuff do we have to pay for? Every time some graduate student has an epiphany at 4:20, it winds up in several thousand dollars involved in some study that shows nothing, just speculation to justify the grant.
Exactly. They already know what makes for basic climate. Why do they have to re-hash it? It’s not just the surface composition, but location, location, location. Different latitudes have different climates. Landlocked or not makes a huge difference. Altitude. Etc.
This is a 4-20, cannabis alert study.
Habitable Shabitable. When they find a planet that has ALL of these habitable characteristics (zones) then they should write an article. If your planet doesn’t have all these nobody will be there.
water habitable zone
ultraviolet habitable zone
photosynthetic habitable zone
ozone habitable zone
planetary rotation rate habitable zone
planetary obliquity habitable zone
tidal habitable zone
astrosphere habitable zone
electric wind habitable zone
cannabis habitable zone
Did the authors conclude that we live on a water cooled/warmed planet (depending on your latitude) or didn’t they arrive at that conclusion?
Why do we call them all ‘exoplanets’?
Seems rude.
When aliens hear us discussing aliens, they’ll think we’re talking about ourselves.
When we indicate ourselves, they’ll think we’re talking about them.
I’ll be able to communicate with aliens just fine, because I’ve always been confused by wind barbs and other fancy wind direction indicators without explicit arrow heads. Is it indicating where the wind is coming from or going? Why show the direction wind is coming from anyway? All you really care about is that ditch you’re about to be blown into, the arrow should be pointing at the ditch. Do clocks run backwards south of the Equator? Is the ozone hole an innie or an outie? When light switches close in the down position, are they dark switches? Why is the positive lead of this truck battery closest to the frame? What was that bright flash?
Reblogged this on | truthaholics and commented:
“The KU Leuven researchers created models in which the surface-atmosphere interaction on the exoplanet is the same as on Earth, and models in which there is ten times as much interaction as on Earth. In the latter case, the exoplanets had a more habitable climate. If planets with a well-functioning ‘air conditioning’ system also have the right atmosphere composition, there’s a good chance that these exoplanets are habitable.”
Perhaps life forms would evolve to take advantage of the huge energy source represented by having a huge amount of hot air and rock in one place, and a huge amount of cold air and rock always nearby.
If such life forms ever evolved intelligence, they would have huge energy sources readily available as well.
And imagine how convenient it would be to have your east windows an oven door, and your west windows a refrigerator!
Venus is “almost” tidally locked, yet the day/night sides have the same temp. Yes, it has a very thick atmosphere and efficient wind-circulating system, but since such an example is very close to us, it’s not inconceivable that an exoplanet w/a less-dense atmosphere could do the same.
For any life to get going it needs to be protected from radiation anyways. Shouldn’t they be looking for planets that have strong electromagnetic bands like Van Allen Belts are something?
Here’s a good article about some of the problems life might encounter near red dwarf stars.
http://www.astronomy.com/news/2011/01/hubble-finds-stellar-flares
An essential component to make Exoplanets habitable is water and GHG.
Without GHG you could end up with eternal inversion, where the upper parts of the atmosphere gets warmer and warmer, because it can not cool down by radiation, which is the only way a planet can cool.
In fact you could end up with a glowing hot upper atmosphere more or less independent of the surface of the planet.
For all the looking, I think we can make a planet that would suit our needs. But I think that as far far future hollow out the inside of a large asteroid and live in that. There would be no limit to how many. There’d be a lot of advantages. Large scale extinction would be less likely. And be able to move out of the way of hazards.
Hollowed-out asteriods are the future. Once we get sophisticated enough, we can build artificial hollow habitat structures in space. But we will start out with hollowed-out asteriods.
There are numerous advantage to using an asteroid instead of building structures. First, the thickness is a valuable asset in warding off energies since it doesn’t have an atmosphere. Second, micro meteors, again the thickness and density are a shield. A medium size rock would do a lot of damage to a man made structure.
While I generally oppose nuclear energy on the surface of this planet, that is not the case in an asteroid.
Asteriod material could be used as radiation shielding for artificial structures. Some asteriods are not very dense, described as “rubble piles” which could be broken up and used as fill for the artificial structures. Like blown-in insulation.
Humans definitely have to be protected from radiation in space, and they definitely have to have artificial “gravity” equivalent to the gravity on the Earth’s surface to be healthy, and large structures are required for both.
Asteriods that would be suitable for human habitation should be sized from two to five miles in diameter. The smaller, the better, to begin with, because they would be easier to handle.
Let’s say we find ourselves a good, solid asteriod about two miles in diameter and eight miles long. We go into the center of this asteriod and hollow out a cylinder one mile in diameter and the length of the asteriod. We now have a huge chamber inside a solid mile of asteriod. The mile of asteriod material in the walls will serve to block out harmful radiation from space.
The one mile diameter spec is the minimum size to use when spinning up the asteriod to create artificial gravity (centrifugal force) in the interior of the asteriod that is equivalent to the gravity on Earth, without giving humans motion sickness.
The one-mile-diameter asteriod habitat would be spun at one revolution per minute (imagine you are sitting on the end of the second hand on a clock that is one mile in diameter. That’s how fast you would be moving. You say, you don’t know what a second hand on a clock is? Oh, well.:)
This leads to my formula: 1+1=1 One mile in diameter, plus one revolution per minute, equals one Earth-equivalent “gravity”. 🙂
It is claimed that humans don’t experience any motion sickness at one rpm and would not be able to tell you were spinning while inside the habitat.
If that proved to be a problem, the solution would be to go bigger. A two mile diameter habitat could be spun at half the rate of the one mile habitat to get the same Earth-equivalent “gravity”.
I don’t know that any large-scale asteriod habitat searches have been done to date, but I’ll bet there are people looking at the question right now.
We just need cheap access to space, and the human race will be off to the races. The Breakout is getting closer.
Such large temperature differences would tend to produce hurricane-force winds.
Pangaea was NOT on the tropics–it was the entire sphere, about 2/3 of the diameter of today’s Earth, as proved by sea-floor spreading. Google expanding Earth and you should soon find one of the videos that demonstrates this.
These astronomers should stop playing with their computer and start observing daily weather. Change in a day’s minimum to maximum temperatures is not abrupt but gradual following the Earth’s rotation. If an exoplanet has one side at constant day and one side at constant night, there are certain longitudes at constant dawn. The temperature here is between the maximum and minimum. The temperature change would be gradual as one moves away from this Goldilocks zone.
“”” Most planets orbiting these M dwarfs always face their star with the same side. As a result, they have permanent day and night sides. The day side is too hot to make life possible, while the night side is too cold.”””
____________________________________________________________________________
What kind of magnetic field/magnetosphere could these non-rotating planets have to protect them from the M dwarf? Are their daytime atmospheres always being stripped off by the M dwarf’s stellar wind flow?
This image is a great perspective view on the magnetosphere of Jupiter (see image).
And because there might be others somewhere else in the galaxy, like us here, that also are looking for exoplanets.
Jupiter might likely be findable and viewable to them that are trying to find us….
Enjoy
http://lasp.colorado.edu/home/mop/files/2012/04/FluxTubes.jpg
Fluxtubes connecting the Galilean satellites to Jupiter, plus the aurora at the foot of their fluxtubes.
Credit: John Clarke & John Spencer
This webpage is a cornucopia of our solar systems planetary magnetospheres… and growing. One of the images depicts the spacecraft Juno trajectory thru this somewhat tricky magnetosphere.
http://lasp.colorado.edu/home/mop/graphics/graphics/
Brown dwarf compared to Jupiter for size.
BrownDwarfCompare-WISE-thumb-500×299-321750.jpg
Scientists Discover Smallest Known Star
http://www.iflscience.com/space/scientists-discover-smallest-known-star/
http://cdn.iflscience.com/images/d598ab3a-ce80-5e73-bb8c-e4d85996196d/extra_large-1464355874-1190-scientists-discover-smallest-known-star.jpg
Astronomers recently stumbled upon a teeny star called 2MASS J0523-1403 located just 40 light years away. It’s not only the smallest star discovered so far – it may also represent the smallest possible star. By studying stars such as this, scientists are starting to be able to answer the question: where do stars end and brown dwarfs begin?
Stars are burning balls of gas held together by gravity that are fuelled by the fusion of hydrogen atoms to helium in their cores. Stars come in a variety of sizes; the smallest stars, known as red dwarfs, can possess as little as 10% of the mass of our Sun, whereas the biggest stars (hypergiants) can be over 100 times as massive as the Sun. But just how small can an object be and still be defined as a star? This has mystified astronomers for years. All that was previously known is that objects below this limit don’t have enough mass to ignite the fusion of hydrogen in their cores. These objects are known as brown dwarfs.
Brown dwarfs are elusive objects that are thought to be the missing link between gas giants and low-mass stars such as red dwarfs. They’re generally around the size of Jupiter, but they don’t have enough mass to become a star. Unlike stars, brown dwarfs have no internal energy source.
http://www.stsci.edu/~inr/thisweek1/thisweek/browndwarf.jpg
Completing the Census of Ultracool Brown Dwarfs in the Solar Neighborhood using HST/WFC3
Brown dwarfs are objects that form in the same manner as stars, by gravitational collapse within molecular clouds, but which do not accrete sufficient mass to raise the central temperature above ~2 million Kelvin and ignite hydrogen fusion. As a result, these objects, which have masses less than 0.075 MSun or ~75 MJup, lack a sustained source of energy, and they fade and cool on relatively short astronomical (albeit, long anthropological) timescales. Following their discovery over a decade ago, considerable observational and theoretical attention has focused on the evolution of their intrinsic properties, particularly the details of the atmospheric changes. At their formation, most brown dwarfs have temperatures of ~3,000 to 3,500K, comparable with early-type M dwarfs, but they rapidly cool, with the rate of cooling increasing with decreasing mass. As temperatures drop below ~2,000K, dust condenses within the atmosphere, molecular bands of titanium oxide and vanadium oxide disappear from the spectrum to be replaced by metal hydrides, and the objects are characterised as spectral type L. Below 1,300K, strong methane bands appear in the near-infrared, characteristics of spectral type T. At present, the coolest T dwarfs known have temperatures of ~650 to 700K. At lower temperatures, other species, notably ammonia, are expected to become prominent, and a number of efforts have been undertaken recently to find examples of these “Y” dwarfs. ….
http://www.stsci.edu/~inr/thisweek1/thisweek/M-dwarf-planet.jpg
Investigating the nature of GJ 3470b, the missing link between super-Earths and Neptunes
M dwarfs are the most common stars in the galaxy and, with the continued accumulation of observations showing that the presence of planetary companions, they are also likely to the best candidates for finding nearby habitable planets. GJ 3470 is an early type M dwarf (spectral type M1.5) a mass approximately half that of the Sun lying at a distance of 25 parsecs lying in the constellation of Cancer. Early last year (February-April, 2012), the HARPS planet search team announced the discovery of a ~14 MEarth planetary companion with a 3.3371 day period orbit, corresponding to a semi-major axis of 0.035 Astronomical units, or 10% the size of Mercury’s orbit. The radial velocity semi-amplitude is less than 10 m/sec. Crucially, the planet transits the parent star, allowing its diameter to be measured as 4.2 Earth radii. With these parameters, the companion is more comparable with Uranus than with the “hot Neptune” systems like Gl 436b (a ~22 Earth-mass planet in a 2.64 day, 0.0278 AU orbit around the M2 dwarf, ~10 parsecs distant). Those parameters indicate a relatively low density, suggestive of a thick hydrogen/helium atmosphere and/or substantial water-ice content. The present program aims to obtain transit spectroscopy using the G141 grating on the WFC3-IR camera. The observations cover significant water features, whose detection might indicate that the former model is correct, and whose non-detection might argue for a water-rich interior content or high altitude hazes within the atmosphere.
http://www.stsci.edu/~inr/thisweek1/2013/thisweek035.html
Love all those size comparisons. Thanks, Carla.
And where did the Oort Cloud, Kuiper Belt and Asteroid Belt come from? Don’t forget about the debris in Earth’s orbit, with more and more being discovered every year!!! Should we be referring to the Asteroid belt as belonging to Jupiter, that somehow it’s location is not coincidental???
Rack em Up
Johnny Lang, “there aint no shame in beaten by a master,””
I get the first shot….see (my bold in text)
Warm Jupiters not as lonely as expected
http://phys.org/news/2016-07-jupiters-lonely.html
July 14, 2016
….Because of their proximity to their parent stars, they are warmer than our system’s cold gas giants—though not as hot as Hot Jupiters, which are typically closer to their parent stars than Mercury.
It has generally been thought that Warm Jupiters didn’t form where we find them today; they are too close to their parent stars to have accumulated large, gas-giant-like atmospheres. So, it appeared likely that they formed in the outer reaches of their planetary systems and migrated inward to their current positions, and might in fact continue their inward journey to become Hot Jupiters. On such a migration, the gravity of any Warm Jupiter would have disturbed neighbouring or companion planets, ejecting them from the system.
But, instead of finding “lonely”, companion-less Warm Jupiters, the team found that 11 of the 27 targets they studied have companions ranging in size from Earth-like to Neptune-like.
“And when we take into account that there is more analysis to come,” says Huang, “the number of Warm Jupiters with smaller neighbours may be even higher. We may find that more than half have companions.”..
On such exoplanets, wouldn’t the day side be bone dry.
Moist air moves from the day side to the night side where it cools to the point that water condenses out of it and falls as first water, then snow.
Depending on the topography, the water might run back to the day side, where it will evaporate and return to the night side where it will falls as both water and snow.
Repeat ad infinitum, each cycle there is less liquid water because some fraction of the water that migrates to the night side will always fall as snow.
Since the night side will always be in the shadow, there is nothing to melt the snow that has fallen.
Eventually, all the water will be trapped in glaciers on the night side.