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CoRoT & Hayabusa: Starting the Week Right

If we ended last week on a high note with the successful deployment of the IKAROS sail, this week started equally well with the return of JAXA’s Hayabusa spacecraft, whose re-entry capsule has now been recovered from the Australian desert and is intact. We’ll learn once it gets back to Japan how much material from asteroid Itokawa it was able to acquire. But what an exciting finish to this mission, and what a accomplishment by JAXA to survive battery failures, communications problems, engine issues and more and bring this mission home.

The canister return is the fruit of a seven year journey that saw Hayabusa touch down on Itokawa back in 2005, and although the many glitches caused a three year delay in its return, Hayabusa may well offer us at least trace amounts of material from the asteroid, valuable in helping us understand not only the asteroid itself but also the early history of the solar system. We have so few instances of material recovered from space — Moon rocks, cometary dust (from the Stardust mission), solar wind particles (Genesis), and whatever Hayabusa bears — and we may now have new samples that have changed little since the beginning of our solar system. The return canister now awaits preparation and transit to the Sagamihara curation facility in Tokyo.

New CoRoT Planets (and a Brown Dwarf)

Meanwhile, we also launch the work week with more news from CoRoT, which has detected six new exoplanets and one brown dwarf. CoRoT works by measuring the decrease in a star’s light caused by the transit of a planet across its face as seen by the spacecraft, a method doubly valuable because it allows a determination of the planet’s radius. Follow-up Doppler studies can then make a determination of the mass of the object, and with mass and radius known, the mean density of the planet can be derived.

Image: CoRoT’s 15 exoplanets. Credit: CNES.

CoRoT’s new findings include CoRoT-8b, 70 percent of Saturn’s size and mass, and a string of ‘hot Jupiters’ — CoRoT-10b, CoRoT-11b, CoRoT-12b, CoRoT-13b and CoRoT-14b. The brown dwarf is CoRoT-15b, sixty times as massive as Jupiter. The extreme eccentricity of the orbit of CoRoT-10b sets it apart from the rest, while CoRoT-11b orbits a star that spins at a high rate. While our own Sun rotates approximately every 26 days, this star spins around its axis in less than two days. ESA’s Davide Gandolfi led the study of this world:

“This is the third exoplanet discovered around such a rapidly rotating star. Because of the fast rotation of its host star, such a planet could only have been discovered because it transits in front of it, thus only a transit-hunter, such as CoRoT, could have spotted it.”

CoRoT-11b represents deft work indeed, for a high rotational rate makes it difficult to achieve high-quality Doppler measurements that would reveal the presence of a planet. But the transit finding could then be corroborated by photometric and spectroscopic follow-up observations, allowing estimates of the planet’s mass — about twice that of Jupiter — and its radius, about 1.4 times that of Jupiter. Thus the transit technique (you can see the lightcurve below) allows us to home in on an exoplanet that Doppler studies alone wouldn’t have found, simply because the observational time required would have caused researchers to pick more likely targets.

Among the other planets, CoRoT-8b is noteworthy in being the smallest planet yet discovered by the CoRoT team after CoRoT-7b, a transiting ‘super-Earth.’ CoRoT-10b is intriguing because its eccentric orbit causes the amount of radiation it receives from its star to vary tenfold in intensity in short order. Current estimates are that the planet’s surface temperature may increase from 250 to 600 degrees Celsius in the space of its year, which lasts 13 Earth days.

Image: Phase-folded lightcurve of the transit of CoRoT-11b, as derived by superimposing all the transits observed in the lightcurve. The best-fit model (thick line) is plotted on top of it. Credit: D. Gandolfi [Gandolfi et al, 2010].

An upcoming paper on this work is Gandolfi et al., “Transiting exoplanets from the CoRoT space mission XII. CoRoT-11b: a transiting massive ‘hot Jupiter’ in a prograde orbit around a rapidly rotating F-type star,” submitted to Astronomy and Astrophysics.


Comments on this entry are closed.

  • bigdan201 June 14, 2010, 10:11

    Looks like alot of awesome work.

    Exoplanet discoveries are always intriguing. Science continues to prove that the universe is more varied and interesting than previously supposed. And exoplanet work is still in its early phases – there are surely many more planets which are undiscovered. Considering that we’ve been finding super-earths, it’s only a matter of time before we find an earth-like planet somewhere in the cosmos. Or perhaps it will be an earth-like exomoon around a gas giant. It will be some time before we can take precise enough observations to find earth-sized (or smaller) planets and moons, but the future looks very promising.

  • James M. Essig June 14, 2010, 12:37

    Hi Paul;

    I am ever a kid in a candy shop when it comes to finding new stars, brown dwarfs and the like.

    To put the number of stars, brown dwarfs and full scale planets in perspective, the number of such objects in the observable universe alone is roughly equal to the number od drops of water in the entirety of Earth’s oceans.

    Or one can look at it this way, since a 5 pound bag of Gold Medal brand fine grain baking flour has about one billion flour grains, the number of such bodies in the observable universe alone is equal to the number of such flour grains in 10 EXP 15 bags of such flour or about 2.5 trillion metric tons of such flour. If the flour was densely packed say to a density roughly equal to that of water at STP, the volume of this amount of flour would be about equal to a 13 kilometer by 13 kilometer by 13 kilometer cube of such compressed flour. Ever try to even visualize all of the flour dust grains that become airborne when you blow a mere dusting of such cooking flour off of you cooking apron.

    Anyhow, expect no end to the discovery of new stellar and full sized planetary objects. The fun has only just begun. I really enjoy logging on to Tau Zero almost as soon as I awake in the morning. I never no what to expect and every new observational announcement has it own unique and novel implications. This is very important since we will need a road map when we go interstellar.

  • Michael Spencer June 15, 2010, 7:00

    An interesting discussion, graceful as usual.

    I wonder about that plot, noticing that the curve is quite sharp on either side of the ‘dip’, and wondering what accounts for the rounded shape in the bottom of the curve. If that bottom shape reflects the planet leaving or entering, then I wonder why the same shape doesn’t appear at the top of the curve. I think I was expecting to see more of a vee shape.

    I bow to James’ valiant effort to make the quantity of stars accessible: those of us here already bow in reverence to the size of the universe, I suspect. That size– awing to every reader here, I suspect–is not, in my experience, communicable. The fact of it must be observed and internalized over some period of time, and even then, we are woefully unable to grasp the reality.

    Imagine, though, this: there are parts of the universe that we can see and will never be able to see. Now THAT gets the juices flowing, doesn’t it? Or this: across our great universe are trillions and trillions, all with families and jobs and kids (or whatever works for them, I suppose), all learning, all wondering all wanting a better future. We shall never know about them. Now THAT is pathos.

    Finally, to our Editor: recent WMAP work by Utane Sawangwit and Tom Shanks at Durham is nothing less than stunning. I wonder if it will be replicated.

  • Administrator June 15, 2010, 7:59

    Michael Spencer writes:

    Finally, to our Editor: recent WMAP work by Utane Sawangwit and Tom Shanks at Durham is nothing less than stunning. I wonder if it will be replicated.

    I need to look at the new WMAP studies, and will hope to have something on this in the near future. Thanks for the reminder!

  • James M. Essig June 15, 2010, 10:24

    Hi Michael Spencer;

    Thanks for the kind words and also, you took the words right out of my mouth. I could not agree with you more.

    Say on average that there exists one billion ETI persons per each of the possible 10 EXP 24 stars, brown dwarfs and planets within our observable universe alone, then the number of such ETI persons would be 10 EXP 33 or about equal to the number of flower grains in a STP water density, densely packed, portion of fine grain baking powder, having the volume of the Earth. Assuming that each such ETI person lives on the order of 1,000 years, the number of such ETI persons that will be born, conceived, or however they are procreated, over the following 10 billion years, in the currently observable portion of our universe alone, is a staggering 10 EXP 40, or the equivalent of the number of such flower grains in 10 million Earth volumes densely packed to water STP densities. This is about 30 times the mass of the Sun and about 10 times its volume.

    As a single age middle age guy who cannot help but notice the many attractive women walking or running along the side of the road as I am out driving and running errands, here in the Washington D.C. metro area, I relish the thought of the essentially unlimited number of beautiful human persons that our visible universe alone could and might support over the next several billion years. However, I would not recommend any “Avatar” like scenario of human exploitation of any of the numerous ETI peoples that might populate our universe, in fact, I could never take part in any such exploitation in good conscience. So, I relish the potential future we humans have to not only spread our civilization among the stars, but also the opportunity to enter into collaborative and fraternal friendship with what I hope are numerous ETI peoples.

    The visible universe however, is most likely, just a miniscule portion of the entire universe and our universe may be just one universe among enumerable universes, and so on.

    For the record, I am considering taking some planetary science classes at the local university where I received my undergraduate degree. I have never taken a course in planetary geology, but these latest Tau Zero threads on extra-solar planets, and stellar system mechanics have renewed my interest in the subject. Now I just need to scrape up enough funds to re-enroll.

  • Ron S June 15, 2010, 14:40

    Michael: “I wonder about that plot, noticing that the curve is quite sharp on either side of the ‘dip’, and wondering what accounts for the rounded shape in the bottom of the curve. If that bottom shape reflects the planet leaving or entering, then I wonder why the same shape doesn’t appear at the top of the curve. I think I was expecting to see more of a vee shape.”

    I had a suspicion of the reason for the rounded shape, so I gathered a bit of data for Corot-11 (http://exoplanet.eu/planet.php?p1=CoRoT-11&p2=b) and translated that to a radius ratio. Doing this gave ~1:9 ratio of apparent diameters. That is, during a full transit the planet blocks about 1% of the star’s surface which, unsurprisingly, corresponds closely to the normalized transit flux of 0.99 on the chart. The chart magnifies the absolute flux change.

    Stars exhibit limb darkening (http://en.wikipedia.org/wiki/Limb_darkening) where the flux from its edges is lower than from its center (from the observer’s vantage point). Therefore the absolute flux decline will increase as the transit progresses from beginning to mid-point, and then reverse symmetrically. This should result in the smooth curve shown, not a vee, although the error bars shown are quite large in comparison to the inferred curvature at the flux minimum.

    Disclaimer: I am not an expert in this subject.

  • andy June 15, 2010, 14:42

    Of these, CoRoT-8b is pretty interesting as it appears to be a “super-Neptune” with a mass similar to Saturn’s, with most of its mass in heavy elements rather like the previously-known planet HD 149026b. Figuring out how to assemble these planetary cores is going to be an interesting challenge.

  • ljk November 16, 2010, 9:00

    November 16, 2010 (JST) Identification of origin of particles brought back by Hayabusa The Japan Aerospace Exploration Agency (JAXA) has been engaged in collecting and categorizing particles in the sampler container* that were brought back by the instrumental module of the asteroid exploration spacecraft “Hayabusa.”

    Based on the results of the scanning electron microscope (SEM) observations and analyses of samples that were collected with a special spatula from sample catcher compartment “A”, about 1,500 grains were identified as rocky particles, and most of them were judged to be of extraterrestrial origin, and definitely from Asteroid Itokawa. Their size is mostly less than 10 micrometers, and handling these grains requires very special skills and techniques. JAXA is developing the necessary handling techniques and preparing the associated equipment for the initial (but more detailed) analyses of these ultra-minute particles.

    * The Hayabusa sampler container consists of 2 compartments that are called “Sample Catcher A and B. Attchement 1:Here is the criteria we used to conclude that most of the particles from sample catcher compartment “A” are judged to be definitely from Asteroid Itokawa Attchement 2:The special spatula observed by scanning electron microscope (SEM) Attchement 3:A picture of scraping out “Sample Catcher A ” by the special spatula Attchement 4:Utilized Scanning Electron Microscope (SEM) FE-SEM(S-4300SE/N) URL:


  • ljk September 24, 2011, 23:49

    Friday, Sep. 23, 2011


    In a galaxy not so far away….


    Special to The Japan Times

    “Japanese space engineers could just possibly be the most boring people on the face of the Earth,” laughed an aeronautics engineer working for JAXA (Japan Aerospace Exploration Agency), during a brief interview with The Japan Times.

    Lost in space: Yuko Takeuchi (front) plays Megumi Mizusawa in “Hayabusa,” a film about a Japanese unmaned spacecraft. FOX MEDIA CENTER

    The chat took place just after a major industry screening of the much touted, long-awaited movie “Hayabusa.” The film is about a successful Japanese space explorer vehicle that shot off in 2003, reached the asteroid Itokawa (named after professor Hideo Itokawa, the country’s revered father of rocket science) and brought back a stone sample from its surface.

    Full article here:


  • ljk February 1, 2012, 14:22

    Hayabusa 2 Mission Approved by Japanese Government

    by Paul Scott Anderson on January 31, 2012

    In 2010, the Japanese spacecraft Hayabusa completed an exciting although nail-biting mission to the asteroid Itokawa, successfully returning samples to Earth after first reaching the asteroid in 2005; the mission almost failed, with the spacecraft plagued by technical problems.

    The canister containing the microscopic rock samples made a soft landing in Australia, the first time that samples from an asteroid had been brought back to Earth for study.

    Now, the Japanese government has approved a follow-up mission, Hayabusa 2. This time the probe is scheduled to be launched in 2014 and rendezvous with the asteroid known as 1999 JU3 in mid-2018. Samples would again be taken and returned to Earth in late 2020.

    1999 JU3 is approximately 914 metres (3,000 feet) in diameter, a little larger than Itokawa, and is roughly spherical in shape, whereas Itokawa was much more oblong.

    As is common for any space agency, the Japanese Aerospace Exploration Agency (JAXA) is working with tight budgets and deadlines to make this next mission happen. There is a possibility of a back-up launch window in 2015, but if that deadline is also not met, the mission will have to wait another decade to launch.

    Full article here: