Star: om nom nom! Planet: Aieee!

By Phil Plait | May 20, 2010 10:23 am

600 light years away, in the constellation of Auriga, there is a star in some ways similar to our Sun. It’s a shade hotter (by about 800° C), more massive, and older. Oddly, it appears to be laced with heavy elements: more oxygen, aluminum, and so on, than might be expected. A puzzle.

Then, last year, it was discovered that this star had a planet orbiting it. A project called WASP – Wide Area Search for Planets, a UK telescope system that searches for exoplanets — noticed that the star underwent periodic dips in its light. This indicates that a planet circles the star, and when the planet gets between the star and us, it blocks a tiny fraction of the starlight.

The planet is a weirdo, for many reasons… but it won’t be weird for too much longer. That’s because the star is eating it.

What WASP 12b may look likeWhat WASP 12b may look like.

OK, first, the planet. Called WASP 12b, it was instantly pegged as an oddball. The orbit is only 1.1 days long! Compare that to our own 365 day orbit, or even Mercury’s 88 days to circle the Sun. This incredibly short orbital period means this planet is practically touching the surface of its star as it sweeps around at over 220 km/sec (130 miles/sec)! That also means it must be very hot; models indicate that the temperature at its cloud tops would be in excess of 2200°C (4000° F).

Not only that, but other numbers were odd, too. WASP 12b was found to be a bit more massive and bigger than Jupiter; about 1.8 times its size and 1.4 times its mass. That’s too big! Models indicate that planets this massive have a funny state of matter in them; they are so compressible that if you add mass, the planet doesn’t really get bigger, it just gets denser. In other words, you could double Jupiter’s mass and its size wouldn’t increase appreciably, but since the mass goes up, so would its density.

But WASP 12b isn’t like that. In fact, it has a lower density than Jupiter, and is a lot bigger! Something must be going on… and when you see a lot of weird things all sitting in one place, it makes sense to assume they’re connected. In this case it’s true: that planet is frakking hot, and that’s at the heart of this mess. Heating a planet that much would not exactly be conducive to its well-being. When you heat a gas it expands, which would explain WASP 12b’s big size. It’s puffy! But being all bloated that close to a star turns out to be bad for your health.

Astronomers used Hubble to observe the planet in the ultraviolet and found clear signs of all sorts of heavy elements, including sodium, tin, aluminum, magnesium, and manganese, as well as, weirdly, ytterbium*. Moreover, they could tell from the data that these elements existed in a cloud surrounding the planet, like an extended atmosphere going outward for hundreds of thousands of kilometers.

That’s a long way from the planet. Any atom of, say, manganese that far from the planet would be caught in a tug-of-war between the gravity of the planet and the star… and the star would win. The gravity of the star is drawing material off the planet in a vast stream, or, in other words, the planet is getting slowly eaten by its star. If astronomers ever get around to giving this planet an actual name, I suggest Sarlacc.

This explains the peculiar high abundance of heavy metals in the star I mentioned at the beginning of this post; they come from the planet! But not for long. Given the mass of the planet and the density of the stream, it looks like it has roughly ten million years left. At that point, supper’s over: there won’t be anything left for the star to eat. In reality it’s hard to say exactly what will happen; there may be a rocky/metal core to the planet that will survive. But even that is so close to the star that it will be a molten blob of goo. The way orbits work, the way the dance of gravity plays out over time, the planet itself may actually be drawn inexorably closer to its star. Remember, too, the star is old, and will soon start to expand into a red giant. So the planet is falling and the star is rising; eventually the two will meet and the planet will meet a fiery death.

All in all, it sucks to be WASP 12b.

But it’s cool to be an astronomer! Only 15 years ago we had no idea that there were other planets orbiting Sunlike stars, and now we know of over 400, and a lot of them are really, really bizarro. When I was a kid I watched Star Trek and read a lot of science fiction, and I remember thinking that the planets in them were too weird; there was no way anything like them could actually exist.

Ha! The Universe, as usual, is smarter and more clever than we are. There’s a lot of strange out there, and the more we look, the more we find.



* Admit it: you didn’t even know that was an element.


Yes, I know, Star Wars fanbois, that that would be a better name for the star and not the planet, since Sarlacc was the creature that did the digesting, and was not itself digested. But if the star were Sarlacc, the planet would have to be named Boba Fett, and that’s just silly.

Artwork credit: NASA, ESA, and G. Bacon (STScI)

CATEGORIZED UNDER: Astronomy, Cool stuff

Comments (74)

  1. wright1

    Just… wow. I’ve heard of “roaster” gas giants; maybe this is their ultimate fate? And just how does a gas giant form and then get that close to its primary to begin with? Incredible.

  2. Sometimes I wish objects such as these were a tad closer to the solar system, not so astronomers and science buffs would have a better view, but so the general public could see for themselves how (anthropic principled…) lucky we are to have this relatively stable place to live.

    But then I suppose we’d just squabble over which god was the one dooming WASP 12b to a fiery death.

  3. Now this is cool. Thanks, Phil!

    Also, in the endnotes, it’s Boba Fett, not Bobba Fett. That’s Boba’s cousin from Tennessee. ;-) [/fanboy]

  4. Magrathea

    I disagree, I did know what ytterbium was , even if high school is 20 years away in the past ;)

  5. Doug Little

    If the star is old and the planet only has 10,000,000 years left. It must have either been extremely large in the past or the planet has slowly spiraled in over time to its current digestible position, does this make sense or am I missing something?

  6. armillary

    I dub thee planet Marshmallow.

  7. Kendall

    Wonder if the lack of density is due to the opposite tugs of gravity and centrifugal force, pulling the matter in the planet in opposite directions….

  8. Brian

    Re footnote1: Anyone who ever memorized Tom Lehrer’s “The Elements” would have heard of ytterbium. It rhymes with erbium.

    Re footnote2: Naming a planet Boba Fett might be silly, but I bet you could organize a letter-writing campaign to make it happen that would swamp the IAU.

  9. IVAN3MAN AT LARGE

    wright1(#1):

    And just how does a gas giant form and then get that close to its primary to begin with?

    A “hot Jupiter” planet is hypothesized to form at a distance from the star beyond the frost line, where the planet can form from rock, ice, and gases. The planet then migrates inward towards its star where it eventually enters a stable orbit.

  10. Cool. And, for the record, I DID know that ytterbium was an element. :P

  11. Kim

    Best headline ever.

  12. starwars fangrl

    Re footnote2: Naming the planet Boba Fett would indeed be silly, mostly because it would be inaccurate. Fett escapes the Sarlacc (something you need to read the Star Wars books to know), which is something I highly doubt Wasp12b can manage.

  13. DennyMo

    “This explains the peculiar high abundance of heavy metals in the star I mentioned at the beginning of this post; they come from the planet!”

    I assume “high abundance” is a very relative term. Isn’t a planet streaming material into a star kinda like putting a drop of food coloring into Lake Michigan. Yeah, the lake has more/different color than it did before, but “high abundance”? Our instrumentation is really that good to detect such tiny variances from such a distance?

    I keep confusing ytterbium with yttrium…

    Edit – OK, I read the linked article, especially the bits on COS. I’m familiar with spectroscopy, got a team of folks in the lab downstairs who do it for me all the time. But it’s still mind-boggling that COS is sensitive enough to detect what it did with this planet.

  14. Now that is a diet I don’t care to try.

  15. Amy J

    Question from a non-astronomer (and generally non-scientist) regarding the heavier elements in the star… If there were a similar planetary snack for our sun, would we notice a difference here on earth? Would it change the effects of sunlight/heat/etc. that we experience?

  16. DrFlimmer

    I am with Kim (#12). I was laughing out loud for quite some time when I read that headline! At least I knew immediately what you were going to tell us! :-D Aieee!

  17. Christine P.

    Love the headline, Phil!

  18. JillW

    “Sarlacc” would be a better name for the star, as it’s the one doing the eating.

    However, I like armillary’s name for the planet… Marshmallow. Which would mean the star should be named Campfire.

  19. Dave

    The line “and when you see a lot of weird things all sitting in one place, it makes sense to assume they’re connected” sounds a bit like you’re contradicting your recent post on earthquakes (post hoc, ergo propter hoc)

    How are the Internet trolls supposed to tell the difference? :-)

  20. Torbjörn Larsson, OM

    So delicious!

    “I felt a great disturbance in the Force, as if millions of planets cried out in terror and were silenced over millions of years. I fear something terrible has happened, is happening and will happen.”

    Admit it: you didn’t even know that was an element.

    Oh yes, I did! Evidently my physics geekiness overpower your astronomy geekiness.

    “- Element library, my dear Watson.”

  21. Torbjörn Larsson, OM

    But then I suppose we’d just squabble over which god was the one dooming WASP 12b to a fiery death.

    Not so. The planet is hot, spicy (with unusual elements), ball-like and edible.

    It can only be the FSM.

  22. I did my high school project on WASP-12b. I was granted observing time at the Nordic Optical Telescope (2.6m) on La Palma last december and I made a successful V-band observation of the transit. It’s nice to know that new things are being discovered about my favorite exoplanet and that my observation might be of value (it was actually used in http://arxiv.org/abs/1003.2763 )

    Here’s the link to my project blog:
    http://extrasolar-planets.blogspot.com/

    And here’s the link to the latest draft of the report:
    http://docs.google.com/fileview?id=0B4apkV6IUFkKMGVmNTA5NmItYTI0ZC00MGIyLTkxZTktYzRjZGYyMDE2MTc5&hl=en&pli=1

    I’m 19 btw.

  23. Do you think that Wasp 12b asks the other planets, “Does the heat from this sun make me look fat?”

  24. KCN

    I like what armillary named it: Marshmallow, but I think Bacon would be an even better name. Think ‘extra crispy’. :-)

  25. Torbjörn Larsson, OM

    Fat? Why would

    hot; models

    care? They can eat their star breakfast and still loose weight after dinner!

  26. Poor Poor Wasp 12b (or Boba fett). I am in mourning. More so, since it is already dead and gone, isn’t it? Since we are seeing events from 600 million years ago. I suppose even the mean old Sarlacc is gone.

    The anthropomorphizing of these planets and stars is starting to get too much for my sensitive nature.

  27. MoonShark

    I knew about ytterbium. Named for its discovery in the Swedish town of Ytterby. But then, I study chemistry and take an interest in the periodic table ;)

    Check it out. http://theodoregray.com/periodictable/Elements/070/index.s9.html

  28. Gunnar

    But wouldn’t that planet be within the star’s Roche limit? How could it even form that close to the star? Does being within that limit have a lot to do with the fact that the planet is being “eaten” by the star?

  29. The video stole some of my planned post about ytterbium, it’s discovery in rocks from Ytterby, along its fellows erbium and terbium also named after the town, but I’ll add that inbetween the three in the periodic table we find holmium named after nearby Stockholm, and thulium, named after Scandinavia. (Dysprosium is in that neighbourhood too, but that’s just a silly name.)

  30. Woody Tanaka

    @Non-Believer: “More so, since it is already dead and gone, isn’t it? Since we are seeing events from 600 million years ago. I suppose even the mean old Sarlacc is gone. ”

    No, it’s 600 light years away, not 600 million light years away… presumably Sarlacc and Boba Fett are still there.

  31. Ray

    @13,

    Sorry, but Lucas is pretty clear that books aren’t canon. Boba Fett remains in the stomach of the Sarlacc.

  32. Ray

    Phil, you say the orbit of Boba Fett is 1.1 days and that the planet may go 10 million years before its been “eaten” away. But how long can the planet stay in orbit that close to the star before it spirals in?

  33. John

    Of course I knew it was an actuall element. Data mentions it on the episode when they go back in time and find his head in a gold mine shaft……

  34. Does anybody remember V838 Monocerotis, the star that flared up in 2002 and made those fantastic light echoes that Hubble imaged? One of the hypotheses for why it flared up multiple times was that the star ate one or more of its planets!

     Light Echo  Illuminates Dust Around Supergiant Star V838 Monocerotis (V838 Mon)
    Source: Hubblesite.org

  35. jcm

    A slow painful dead!

  36. Oh darn. I hate it when I don’t read carefully. Thanks for pointing it out Woody Tanaka.

  37. Left_Wing_Fox

    A question. I know that when a star tries to fuse iron late in it’s life cycle Bad Things Happen. What effect would swallowing the molten iron core of a planet tis big have on the star’s lifecycle?

  38. Thameron

    If this planet is so close to have such a short orbit then why hasn’t it been torn apart by tidal forces? How close would it have to be to be torn apart that way? Also why would the instances of those elements be particularly high in the star when both the star and planet presumably formed out of the the same protostellar cloud of dust and gas?

  39. Allen

    I knew ytterbium was an element thanks to Tom Lehrer and his (must now be out-dated) song “The Elements. Check it out!

  40. Chief

    You can check out the following site for videos on each element in the table. some of the elements are really cool to work with.

    http://www.periodicvideos.com/index.htm

  41. Brody

    I wonder if there are star consumption denialists posting trolls to message boards on that planet about the religious thinking of star consumption alarmists…

  42. lordbubonicus

    @Gunnar (#29): If it is inside the Roche limit, which seems plausible (I’d need to do a quick calculation to check), then it almost certainly didn’t form there. It’s more likely that it formed outside the ‘snow line’, then migrated inwards, possibly through interactions with a circumstellar disc, or possibly through Kozai oscillations. Once it got close enough to the star, tidal interactions will have started to play a role and pull it in even further.

    @Thameron (#39): Because that doesn’t happen instantaneously. The planet has to be within the Roche limit for it to start happening/filling its Roche lobe (and as I said, I’d need to do a quick calculation to check that). There’s an idea as well that when the planet gets close enough it loses mass like this, which can cause it to move outwards again or stop it filling its Roche lobe. It then moves in again, and the cycle starts over. It’s an interesting idea.

    I’m intrigued by this. I’ll have to have a read through the paper, and see if it impacts on what I’m writing at the moment.

  43. TheCritic

    Kendall, just so you don’t have to wonder too long. The reason he made that statement in the article “When you heat a gas it expands, which would explain WASP 12b’s big size.” That explains the density. Also, in terms of being pulled in all directions. When a planet gets into a gravity battle like that with a star, it normally becomes tidally locked. Meaning that the side of the planet facing the star never changes. The planet doesn’t rotate.

  44. Keith Harwood

    Thameron @39. The planet *is* being torn apart by tidal forces.

    Star and planet are formed from the same cloud, but the proportions of elements in each are different. Planet got rid of much of its hydrogen in early life, star kept its. Planet concentrated its heavy metals, star didn’t. Star is in the process of swallowing a heavy metal pill. All its own heavy metals are distributed throughout its interior. The new stuff is at the surface or in orbit around it, where we can see it.

  45. TMB

    @Left_Wing_Fox: The problem in that case isn’t that the stars have iron, it’s that they’ve run out of lighter elements to fuse. So adding a bit more heavy elements doesn’t affect things (especially since they’ll go on the surface, whereas the fusion is happening deep in the core).

    [TMB]

  46. John Paradox

    RE: ytterbium, and Tom Lehrer. Shout!Factory is releasing a combination CD of Lehrer’s songs, and a DVD of him in concert.
    I also found this video that highlights each element as it is sung – up to the last known at the time of the song.

  47. I did so know that ytterbium was an element. It’s not as cool as yttrium, which is used in YAG lasers, something that i never got for xmas, no matter how much i begged.

    “No, we are not going to get you a laser that can mow your friends down like dried autumn wheat.”

    “but they are weak, and deserving of contempt”

    “no”

  48. Actually if it’s tidally locked it IS rotating…just at the right rate as to keep the one side facing inwards. But yes, I knew what you meant. :)

  49. Messier Tidy Upper

    Amazing news & great post there – Thanks Bad Astronomer. :-)

    Reminds me of this part from a talk I gave on exoplanets :

    ***

    [Discussing categories of exoplanets eg. pulsar planets, eccentric orbiters, “SuperEarth’s”, etc .. )

    II) Hot Jupiters : (a.k.a. ‘Pegasids’, a.k.a. “Roasters”)

    • These are (more or less) Jupiter mass planets found – to general amazement – orbiting in weeks or less rather than years next to their primary stars. These have been relatively numerous and some star systems have more than one or boast other exoplanets orbiting beyond them. Some have considerably larger, more metal rich cores or puffed up atmospheres and a few are known to be actually evaporating!

    A recent study suggests all HotJoves closer than 0.15 AU (24 million km) will eventually be destroyed by this catastrophic evaporation. eg. 51 Pegasi b, Tau Bootis b, HD 209458 b …

    ***

    & now add this “Sarlacc /Boba Fett” example too as the most notable such world yet! ;-)

    I suspect some of the lowest mass *very* hot (& IMHON very badly misnamed) “SuperEarths” such as Gliese 581 e & COROT-Exo-7 b are what’s left (temporarily?) of such fevapourating or being sucked away Hot Jupiters.

    PS. Yes I did know about Ytterbium already too. ;-)

  50. Messier Tidy Upper

    Supeluminous (ie. beyond just brilliant) artists illustration there too – congrats & thanks to whoever painted that. :-)

    Wikipedia Links to the planets I mentioned are here

    http://en.wikipedia.org/wiki/COROT-7b &
    http://en.wikipedia.org/wiki/Gliese_581_e

    These low-mass close-orbiting – star grazing exoplanets living perilous and ceventually doomed lives being blow-torched by their suns are occassionally termed “SuperEarths” although they are very strange and far more like super-Mercurys or something totally without analogue in our own solar system than anything even remotely “earth-like”.

    While on this topic & other examples it is also worth checking out the one for an earlier and also veryspectacular example of HD 209458 b “Osiris’ :

    ***

    HD 209458 b or “Osiris” : In 1999 this became the first Hot Jupiter found by the transiting technique – detecting a transit of the planet like transits of Mercury & Venus in own solar system and the first to have atmosphere detected – a huge cloud of hydrogen and sodium was found to be “boiling” off this exoplanets surface. This led to its nickname by astronomers of “Osiris” after a dismembered Egyptian God. HD 209458 b is located in Pegasus 150 light years away and circles its star every 3.5 days.

    See : http://en.wikipedia.org/wiki/HD_209458_b

    & the largest (?) puffiest exoplanet aka the “Balsawood planet” :

    TrES-4 “Balsawood planet” : Very recently discovered (October 2007) this Hot Jupiter is the record-holder for largest diameter being 70 % larger than Jupiter’s radius but with a density of just 0.2 grams per cubic centimeter making its density equivalent to balsawood and thus less dense than Saturn. If there was an ocean big enough to float this planet – like Saturn would do so. It would also sizzle being around, 1,330 degrees Celsius (1,600 Kelvin) from orbiting its star in 3 and half days. It was discovered through transiting and directly measured by a team from the Lowell Observatory as part of the Trans-Atlantic Exoplanet Survey (hence TrES) and presents a problem for the theorists being much larger than current models can explain. The Balsawood planet is 1,400 light years distant.

    (http://en.wikipedia.org/wiki/TrES-4)

    & one the BA posted on that orbits like a comet and ahs been nickname dthe Icarus planet for getting too close to its star :

    HD 80606 b “Icarus planet / Comet orbit Planet” : The most eccentrically orbiting exoplanet discovered in 2009. “HD 80606b is a gas giant planet four times the mass of Jupiter that orbits a star 190 light years from Earth. The planet’s orbit is incredibly elliptical, with a whopping eccentricity value of 0.927 — meaning the orbit is elongated like a rubber band being fought over by jealous children. See :

    http://blogs.discovermagazine.com/badastronomy/2009/01/28/weather-sizzles-on-a-planet-that-kisses-its-star/

    Of course that’s just for starters – I passionately love the whole new exoplanets field and thinking about all these strange and astounding new found worlds that we’re discovering more and more in number and detail. :-)

  51. Orthos

    I AM SINISTAR.
    BEWARE, I LIVE.
    I HUNGER!
    RUN, COWARD!! RUN RUN RUN!!!
    ROOOWWWWWWWAAAAAAAAAARRRR!!!!

  52. RM

    Very cool! But why is it so weird that ytterbium has been found? Just because it’s such a heavy metal? What are the detection limits on their equipment?

  53. Brian G

    @32
    Do you have a source for that? All the books are canon so therefore Fett lived and escaped the Sarlacc.

  54. Ytterbium? Sure we did. I even remember Isaac Asimov’s essay about the discovery of it and its relatives, and his irritation that half-a-dozen or so elements got named after an otherwise boring Swedish hamlet.

  55. Ray

    @54,

    Lucas has given several interviews where his view is clear. The movies occupy his universe, and the books and such occupy a different one.

    In July 2001, Lucas gave his opinion on the matter of what is canon in Star Wars during an interview with Cinescape magazine:
    “ There are two worlds here,” explained Lucas. “There’s my world, which is the movies, and there’s this other world that has been created, which I say is the parallel universe – the licensing world of the books, games and comic books. They don’t intrude on my world, which is a select period of time, [but] they do intrude in between the movies. I don’t get too involved in the parallel universe. ”

    http://en.wikipedia.org/wiki/Star_Wars_canon

  56. mike burkhart

    How about calling the planet doomsday and the star death star .Yes acording the Star Wars novel series the bounty hunter wars Boba Fet used a grenade to blast his way out of the sarlac, all of his armor disolved.We maybe seeing the future of Earth.

  57. Divergence of B

    220 km/sec? That’s starting to move into a relativistic region. Though I assume the errors in measurement are greater than the 0.25% length contraction, yes?

  58. Lucas

    I still think dinosaurs are living in the center of that burnt ball.

  59. Peter F

    Not sure how/why the subject even came up in these comments, but as a lifelong Star Wars fan, I don’t consider anything but Star Wars and its one sequel, Empire Strikes Back, to be “canon”.

  60. Ben

    @32, 58: Granted, the movies take precedence over the books. And as soon as you show me something from the movies that contradicts the events of the books, I’ll agree with you.

  61. Brian Too

    I wonder how the temperature gradient of the planet’s interior works. On Earth, the deeper you go, the hotter it gets. With this place, there’s so much solar radiation pumping in, I wonder if this is reversed? Maybe it’s cooler the closer to the centre you go?

    What a place, it’s like something from Dante’s Inferno.

  62. Stargleam

    Barely fifteen years old, high school sophomore, read Discover magazine all the time, love the blogs, had to memorize the first hundred-something elements for chemistry class. Of course I knew ytterbium was an element. And yes, I spelled it without looking. =]

  63. atrius

    I’m failing to see how the universe being surprisingly strange makes it either ‘smart’ or ‘clever’.

  64. dartigen

    I always thought ytterbium was some sort of chemistry joke because it sounded so absurd, and the only time I ever saw it was on the periodic table.

    And yes, naming the planet Boba Fett would be a misnomer – Boba escaped the Sarlaac. This planet is definitely not doing that.

    Maybe call the star Galactus? I mean, it is eating a world…not sure if it’s got anything to do with survival, but the world-eating is enough.

  65. Gunnar

    Have any planetary systems yet been detected that include at least one planet comparable in size to ours and whose orbit is entirely within the so-called “goldilocks” zone of their primaries so they could potentially support life as we know it? If not, which is the most likely reason for that: (1) Such systems are most likely exceedingly rare, (2) planets comparable to ours both in terms of mass and distance from their stars would be exceedingly hard (if not impossible) to detect with the means currently at our disposal, or (3) both of the above?

  66. John Baxter

    Of course I knew about ytterbium–Tom Lehrer taught me about the elements–in the auditorium at MIT.

  67. Messier Tidy Upper

    @68. Gunnar Says:

    Have any planetary systems yet been detected that include at least one planet comparable in size to ours and whose orbit is entirely within the so-called “goldilocks” zone of their primaries so they could potentially support life as we know it?

    Not yet as far as I know & I follow this area pretty closely.

    There is the pulsar planet system which has one world about four times the mass of Earth about half an AU (ie. half Earth’s orbit) from its neutron star sun.

    See : http://en.wikipedia.org/wiki/PSR_B1257%2B12

    There are also a couple of stars with exoplanets in roughly earth-like or Mars-like orbits but these are gas giant or superjovian exoplanets – Pollux the brightest star known to host an exoplanet is an example of this (http://en.wikipedia.org/wiki/Pollux_(star) ) as is HD 17092 b another red giant star.

    If not, which is the most likely reason for that: (1) Such systems are most likely exceedingly rare, (2) planets comparable to ours both in terms of mass and distance from their stars would be exceedingly hard (if not impossible) to detect with the means currently at our disposal, or (3) both of the above?

    I’d probably have to say a bit of both of the above although we’re certainly getting closer to making such a discovery as technology and amount of data gathered builds up. :-)

    I don’t know whether such systems are exceedingly rare but they certainly are NOT typical of the exoplanetary systems we’ve discovered so far.

    Many of the exoplanets we’ve located are Hot Jupiter’s which migrated inwards from where they were formed and quite probably rendered their ssytems without rocky earth-like worlds in Earth-like orbits as a result because theywould have disrupted their systems protoplanetary disks and perhaps swallowed or ejected any Earth-like protoplanets.

    Even more of the exoplanets are in eccentric (more oval or elliptical) orbits which also cuases potential problems for any Earth-like worlds making their existence either unlikely or if they do exist likely to also be highly eccentric orbits taking such hypothetical worlds outside the habitable zone for much of their orbits.

    A few planets have been found in circular orbits (outside the Hot Jupiters whose orbits are usually circularised by gravitational tidal factors) and afew systems with promising Jupiter analogues – Jupiter like planets staying at steady Jupiter like distances are known and are thus promising candidates for finding other earth’s.

  68. Messier Tidy Upper

    Hmm … Pollux link there not working apparently. :-(

    Trying again : http://en.wikipedia.org/wiki/Pollux_(star)

    I’m sure I remember the BA posting on HD 17092 b but I haven’t been able to find it via the search engine here. My own summary of it is :

    ***

    25. HD 17092 b : Jovian-type planet orbiting its orange giant star in 360 days which generated media interest for having an “earth-like” orbit. In reality, however, there is very little earth-like about it! For starters, the orbit is actually a bit further than Earth’s being about 1.3 AU given the greater (2.3 solar) mass of the star which consequently “drives” the exoplanet along its orbit much faster. More importantly, this world’s type of sun this is vastly different being a K0-type giant with a vastly greater diameter, surface area and luminosity. Calculations show this planets temperature would be around 500 degrees Celsius – hot enough to melt lead or zinc. Moreover, the exoplanet itself “weighs” over four Jupiter masses and is vastly different from being a rocky Earth-like planet! HD 17092 was the 10th orange or red giant star discovered to have planets orbiting it.

    ***

  69. This made it to the Rachel Maddow show:

    “[Geeky news] isn’t all excitement and fun – sometimes it’s about weird things that happen in space that if you athropomorphise them they make you feel sad about your family”

    http://www.msnbc.msn.com/id/26315908/#37346876

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