Video chat about the new Kepler planets

By Phil Plait | December 21, 2011 7:00 am

Yesterday, astronomers announced the discovery of a compact solar system orbiting a distant star, with two of the planets being very close to the size of the Earth.

My friend Fraser Cain, from Universe Today, put together a video chat Q&A about the discovery with me, Nancy Atkinson from UT, Emily Lakdawalla from the Planetary Society Blog, and Alan Boyle from the MSNBC Cosmic Log blog. We talked about the discovery, how it was made, what it means for exoplanetary science, and a few other topics just for good measure.

Fraser did this using Google+ Hangout, the social network’s video chat software. They rolled out a new feature just a few days ago where a few people can chat on camera, and the whole thing can be broadcast on G+ at the same time. Not only that, but, obviously, it can be recorded and uploaded to YouTube as well. This is brand new stuff, and not widely available just yet, so we had some issues with it (notably Fraser’s window never was displayed on the main screen; the images he displays at 13 minutes in can be found on the Kepler website).

Since I’ve got you here, there’s one very cool thing I’d like to expand on. Later in the video, we chatted about the physical characteristics of the Kepler-20 system, including how the planets’ orbits were tilted, and how you can determine that from the Kepler data. I poked around on the web afterwards, and found that the Kepler site has an amazing feature; an interactive display of all the confirmed planets they’ve found. For example, here’s the one for Kepler-20-f, the outermost of the five planets in the system, and the one closest to the size of Earth.

You can watch an animation of it going around the star, with a display of how it blocks the light. You can also see how the orbit is slightly tilted to the line of sight, and how it cuts a chord across the star. It’s truly a splendid way to show folks what they’ve found, and I highly suggest playing around with it (though it may be slow due to heavy use right now). When it loads, click the button labeled "Perspective" and then click "go to view from Earth". That’ll show you how a transit works pretty well.

From those pages, I found that these planets do orbit their star almost — but not quite — edge-on. An orbital inclination of 90° would be edge-on, and the planets, in order from the star, have tilts of 86.5, 88.4, 89.6, 87.5, and 88.7°. I was surprised to see that there is a spread of even as much as 3°. I wonder why? The planets probably formed farther out and migrated in toward the star; we know planetary migration happens for many (if not all) solar systems when they’re young, including our own. As these planets got closer, they could interact more strongly via gravity. Maybe that amplified their tilts somewhat. Or maybe I’m totally wrong in thinking the tilts should all be aligned in the first place.

We’re still new at this game, so there’s a lot left to learn. But that, my friends, is where the fun is. May we have lots more fun systems like Kepler-20 to investigate.

CATEGORIZED UNDER: Astronomy, Cool stuff

Comments (22)

  1. Rick

    I enjoyed this format Phil….thanks to you and your friends for keeping us informed.

  2. Messier Tidy Upper

    Cheers! :-)

    One very minor nit – really wish they included spectral class under stellar properties &, ideally, also had distances liste din light years as well.

  3. Messier Tidy Upper

    ^ For the linked interactive display of all the confirmed planets they’ve found, specifically Kepler 20-f.

    Er, does anyone know what the Kepler 20 stars spectral class is and care to enlighten us please?

    (To my way of thinking, nothing tells you more about a star more quickly and effectively than its spectral class. A simple combination of one english capital letter, one numeral, and one Roman numeral tell you so much instantly.)

    PS. Seconds #1 Rick here . :-)

  4. llewelly

    Here is something I have never understood. Why do some astronomers
    expect a relationship between the mass of a planet, and its distance
    from its primary?

    It seems to me that the expectation ought to be that there is no
    relationship.

  5. Lime

    According to my Exoplanet app the host star is a G 8 …

  6. Dave

    Giant planets need to form where there is more gas, which is farther out in the disk. Rocky planets in principle could form anywhere, but probably form where there’s less stuff or else they’d become giants. So you might expect systems to look kind of like ours, with giants farther out and rocky objects closer to the star. But then, once planets form, they can jostle for position and rearrange their order so what we see as the order now might not be the primordial order.

  7. dcsohl

    Messier Tidy Upper@3: If you go to the Kepler Input Catalog search page, you can search for Kepler-20 by its KIC ID of 6850504. The search results tell me it has a surface temperature of 5342 Kelvins, which is consistent with a spectral class of G9 V or K0 V … somewhere right around there.

    The search results also give a radius of 70% of our own Sun, which is not consistent with a G9 V spectral class. But I’d be far more confident in the temperature estimation than in the radius. Or maybe there’s something odd about the star… but the temperature is still the leading indicator of these things.

    llewelly@4: Modern theories of planetary system formation rely, of course, on our own system. These theories naturally lead to small rocky worlds close in, gas giants at a middling distance, and small icy worlds far out. These theories are being tested now by the discovery of exoplanets, but these theories still define what we expect to find out there.

    True, we’ve found many many systems with mega-Jupiters orbiting closer to the primary than Mercury does, but these are simply the easiest systems to find. As our detection methods get better, we’ll get a better idea of whether hot mega-Jupiters are the outliers or whether our own system is the outlier…

  8. llewelly

    Phil: “I get sick reading in cars.”

    I am reminded of when the suggestion of sending an ordinary citizen to
    space in the space shuttle was raised back in the early 1980s, in the
    L5 Society magazine. Some people suggesting sending Isaac Asimov
    … who had flown in a commercial airline only a few times, and
    insisted he would never do it again.

  9. llewelly

    “But then, once planets form, they can jostle for position and rearrange their order so what we see as the order now might not be the primordial order.”

    Sure, we’ve been hearing that for years now – and to me it implies
    that there ought to be little or no correlation between size and
    distance. Yet remarks from many astronomers keep implying that people
    might expect otherwise.

  10. Gah! I didn’t find out about it until it was long over!
    (/pout)

  11. Jess Tauber

    The Super Jup’er lights are gonna find me
    Shining with their Sun
    Circling having fun
    Causing occulta-tion

    (apologies to ABBA)

  12. Carp!
    35 mins in and it stopped! Just as Phil was talking about orbital inclinations, too!
    I wonder if G+ hangouts could allow the “question asker” to join the video chat during his/her question? That would be an improvement. At least insomuch as the questioner doesn’t get on a soapbox and harangue the other guests…

    This could well spell the end of Ustream for us astronomy types. Waaaaay cool! Let’s do ths on a regular weekly basis! Like “Monday Night Football” it might be “Friday Night Astronomy” or something… Just not on the same night as Nova… (Being the imaginative sort) I can imagine guests like Neil DeG Tyson, Dr. Hawking, Dr. Pamela Gay, Mike Brown, the list goes on!

    It’d be awesome too if iPhone FaceTime users could join in. Then we could have reportage from conferences or major NASA launches.

  13. dcsohl

    G+ Hangouts are limited to 20 maximum participants.

    I’ve recently, however, become aware of a new service called Buzzumi that allows exactly the sort of thing that #12 has in mind. They have four different “chat” formats, one of which, “Interview” is described as “You and up to one hundred guests. Everyone can chat via text; only you and guests you select have video and audio.” I do not know if there is any option to record the chat for later.

    I’m not a Buzzumi employee nor have I even used the service, so all this should be taken with a grain of salt. But there are a lot of options out there besides G+ Hangouts that don’t require participation in the Google Empire, and can enable some of us plebs to participate as well. :)

  14. A Hangout on Air is limited to 8 participants, but an unlimited number of people can view it. A regular Hangout can have 10 people, but nobody can watch it.

    So the Hangout we did yesterday was “On Air”, which allowed hundreds of people to watch the live stream as we did it. People were commenting and chatting as the video was happening.

    Although other tools like Buzzumi are cool, I think we’re going to keep using the Google option because it integrates so well with the other services we use, like Youtube.

    I don’t understand the “plebes” comment. We’ve had non-stop participation in our Google+ Hangouts. Now that we have Hangouts on Air capability, everyone can at least watch and comment.

  15. Josh K

    That was wonderful. Phil, I’ve tried to catch some of the other chats on UStream, but have terrible timing and am never able to catch them. I LOVE that you can record these and embed them. I’d still like to watch it live, though, and post some questions.

    Good work to Fraser for putting it all together. I Fraser was camera shy or something. Hopefully, Google can fix the feature and allow Hangout to cycle through all the web cams.

  16. Small point – Kepler-20f isn’t the furthest out (as you must realise from the graphic showing large-small-large-small-large). It’s d that’s the outermost one: the order is b, e, c, f, d. I think the reason is that the lettering follows the order of discovery as confirmed planets, and there was a period when b, c, d were confirmed but not yet e and f.

    Surprised none of you had heard of BLENDER – the Kepler team have published quite a bit on it, and several of the previous discoveries (e.g. 10c, 11g) used it.

  17. Messier Tidy Upper

    @5. Lime : ” According to my Exoplanet app the host star is a G 8 …”

    & also :

    @7. dcsohl :

    Messier Tidy Upper@3: If you go to the Kepler Input Catalog search page, you can search for Kepler-20 by its KIC ID of 6850504. The search results tell me it has a surface temperature of 5342 Kelvins, which is consistent with a spectral class of G9 V or K0 V … somewhere right around there.

    Thanks for that both of you – very much appreciated. :-)

    The search results also give a radius of 70% of our own Sun, which is not consistent with a G9 V spectral class. But I’d be far more confident in the temperature estimation than in the radius. Or maybe there’s something odd about the star… but the temperature is still the leading indicator of these things.

    Could that be related to that stars age and evolution given that main-sequence stars gradually become more luminous and perhaps larger over time? Our Sun was once only about two-thirds of its current brightness (eg. Cambrian “faint sun paradox” ) but, I think, was still classed as a G2 V star at that time. Or was it?

    Note also that Alpha Centauri A shares our Sun’s spectral class yet is significantly larger and brighter than our Sun is.

    Alternatively, is Kepler 20 affected by having unusual metallicity composition?

    *****

    “Our Sun’s brightness is gradually increasing by about 10 % every billion years.”
    – McNab, David & Younger, James, ‘The Planets’, BBC Worldwide,1999. / “The Planets” final episode – ‘Destiny” , BBC TV, screened circa 1995-2005 in Australia.

  18. FYI People watch the Kepler-20 talk by Nick Gautier (and every other talk from the Kepler Science Conference) here: http://keplergo.arc.nasa.gov/ScienceKepSciCon1.shtml

    Gautier’s talk is located at session C

  19. dcsohl

    Fraser,

    My bad — I only saw the group of you onscreen and was unaware of other people commenting on the talk as it was happening. I don’t use G+; their hostility towards pseudonymity and inconsistent enforcement of “real names” effectively disadvantages already vulnerable groups (like battered women and political dissidents in tyrannical states). I refuse to participate in such a service.

    But that’s beside the point here. I was attempting to point out alternatives and why they might be better, but I guess they’re not better, so never mind.

  20. In the video chat, two issues came up that I can comment on:
    1. How are the newly discovered planets confirmed?
    Kepler team has been using this terminology: a “confirmation” is accomplished by Earth-based observations of stellar spectrum to detect alternating red-shift/blue-shift caused by gravitational tugging on the star by a planet. This is known as the “radial velocity” (RV) method which is the planet-finding method used by astronomers to find most of the discovered planets to date. When the RV method is not possible (with very small planets or ones too far from the star to have big enough gravitational effect), the Kepler scientists use software to rule out every possible source of a “false positive”. When confidence is high enough in this technique (well over 99% certain), the Kepler team deems it safe to say that the planet discovery is “validated” (as opposed to confirmed).

    2. What is BLENDER software?
    I don’t know a lot of details, but BLENDER was created to rigorously rule out false positives, by comparing the observed light curve with theoretical light curves of various conditions that might be false positives, the main type being a binary star (two stars orbiting each other) that appears very close to the star under observation, and masquerading as a planet due to similarity in shape of light curve produced.

  21. David from North Fork

    Are there adjusted units of distance for exoplanet orbits around stars so that 1 in those units is the distance from that star that gives the same amount of light that the Earth gets from the Sun?

  22. Matt B.

    I don’t understand how the Kepler-20-f could block almost 1% of the star’s light if it’s only 1% as wide as the star. It would have to be about 10% as wide, making it a gas giant, not rocky planet.

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