Kepler News and Results

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Re: Kepler News and Results

Post by Galzi on 10th September 2012, 12:54 pm

A somewhat sobering update from Kepler scientists:

http://www.sciencenews.org/view/feature/id/343947/title/Planetary_Peekaboo

Kepler’s star field is overly rambunctious, with natural brightness fluctuations much greater than expected for stars like the sun, says Jon Jenkins of the SETI Institute in Mountain View, Calif. “It was a big surprise to us that the typical solarlike star is noisier than the sun,” says Jenkins, Kepler’s lead analytical guru. “The sun really isn’t a ‘solarlike star.’ ”

Quite interesting, just wondering the impact of this far larger stellar activity on life of potential habitable planets. Maybe we've been too much optimist in assigning "Solar-like" friendly qualities to stars with similar spectral type of the Sun.
On the other hand proposed missions like TESS and Plato should came back to the working board, either employing larger mirrors or planning longer observation runs to mitigate the lower SNR of planetary transits.

“We see the now-familiar rise in planet occurrence as you go to smaller planet sizes, down to two Earth radii,” said Andrew Howard of the University of Hawaii at Manoa. “And then something interesting happens: The occurrence actually falls.”

Let's hope this is due to the above cited SNR troubles. If the trend holds up that would be quite disappointing.

Marcy presented preliminary data at the astronomy meeting suggesting that planets begin to transition from bloated, watery mini-Neptunes to rocky Earths when they are somewhat smaller than two Earths. But he hasn’t surveyed enough planets to know for sure.
Since smaller planets tug less on a parent star, measuring the star’s wobbles requires a supersensitive, stable instrument. “The U.S. currently doesn’t have one,” says Marcy, who performs radial velocity follow-up measurements on the planets for which it is possible. “It’s a huge embarrassment.”

We're not going to characterize the large majority of small size Kepler planets for a while.

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Re: Kepler News and Results

Post by tommi59 on 10th September 2012, 1:20 pm

I already saw couple weeks ago the marcy data but the most if not all of the planets presented had significant mass loss and this can change a lot. .What if earth is the biggest planet with some land and other (slightly larger)are 100% water worlds -big disappointment but it could be true

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Re: Kepler News and Results

Post by jyril on 10th September 2012, 1:47 pm

Galzi wrote:On the other hand proposed missions like TESS and Plato should came back to the working board, either employing larger mirrors or planning longer observation runs to mitigate the lower SNR of planetary transits.

...which would mean much higher mission costs, something which is unthinkable in the current economical situation.

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Re: Kepler News and Results

Post by PlutonianEmpire on 10th September 2012, 6:03 pm

Kepler's supposed to be observing about 150,000 stars, right? Now, we've found about 2000 or 3000 or so planet candidates, right?

Whose smart idea was it to suggest that the MW has about 1.6 planets for every star? Shouldn't we have found a lot more planets by now?

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Re: Kepler News and Results

Post by Sirius_Alpha on 10th September 2012, 6:09 pm

Wasn't that from microlensing studies? (and thus, applicable to a very different parameter space than Kepler is probing)

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Re: Kepler News and Results

Post by tommi59 on 11th September 2012, 3:48 am

http://www.google.ie/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=3&cad=rja&sqi=2&ved=0CCoQFjAC&url=http%3A%2F%2Fkepler.nasa.gov%2Ffiles%2Fmws%2F2011marcy_geoffSciCon.pptx&ei=qvhOUJX1FNSQhQeh8IDoBw&usg=AFQjCNH-Mai5qP2G5bt1RmwnvmsKc5MhjA&sig2=JtQy4jMFVRM82ZFBGcKYzg

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Re: Kepler News and Results

Post by jyril on 11th September 2012, 4:47 am

PlutonianEmpire wrote:Kepler's supposed to be observing about 150,000 stars, right? Now, we've found about 2000 or 3000 or so planet candidates, right?

Whose smart idea was it to suggest that the MW has about 1.6 planets for every star? Shouldn't we have found a lot more planets by now?

The probability of transits drops rapidly as the distance of the planet from the star increases, so Kepler should detected only a tiny fraction of all planets unless the frequency of plants drops rapidly as the orbital distances increase.

The expected results are summarized here.

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Re: Kepler News and Results

Post by tommi59 on 11th September 2012, 5:58 am

Frequency of planets drops but not rapidly rather steady as the orbital distances increase


Last edited by tommi59 on 11th September 2012, 9:33 am; edited 1 time in total

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Re: Kepler News and Results

Post by Galzi on 11th September 2012, 7:43 am

tommi59 wrote:I already saw couple weeks ago the marcy data but the most if not all of the planets presented had significant mass loss and this can change a lot. .What if earth is the biggest planet with some land and other (slightly larger)are 100% water worlds -big disappointment but it could be true

Since the only example known of Earth-sized planet in the HZ (our Earth) is 71% covered by water, this cannot be excluded; however one sample doesn't allow to draw up valid statistics. I think that the quantity of water available in the HZ of a given star is a separate history for every different star system, so I'll allow myself to think somewhere exist abundant 1.2 Earth radius planets with even less water coverage than Earth.

tommi59 wrote:http://www.google.ie/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=3&cad=rja&sqi=2&ved=0CCoQFjAC&url=http%3A%2F%2Fkepler.nasa.gov%2Ffiles%2Fmws%2F2011marcy_geoffSciCon.pptx&ei=qvhOUJX1FNSQhQeh8IDoBw&usg=AFQjCNH-Mai5qP2G5bt1RmwnvmsKc5MhjA&sig2=JtQy4jMFVRM82ZFBGcKYzg

https://connect.arc.nasa.gov/p1lf9scrk1a/?launcher=false&fcsContent=true&pbMode=normal


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Heirarchal Tripple Systems from Kepler

Post by Lazarus on 8th October 2012, 5:02 pm

Starspot activity and rotation of the planet-hosting star Kepler-17
http://arxiv.org/abs/1210.1676

A larger starspot coverage than the Sun at solar maximum, no unambiguous evidence of star-planet interaction so far.

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Re: Kepler News and Results

Post by Sirius_Alpha on 15th October 2012, 11:28 am

~6% of solar type stars have 3 or more planets w/ Rp<1.5 Re and Porb<125 days (lissauer) #DPS12
http://twitter.com/PlanetDr

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temp

Post by Sirius_Alpha on 15th October 2012, 4:44 pm

And here I was thinking we had a few dozen.
Borucki at #dps12: there is not a single Earth-sized planet candidate in the habitable zone within the Kepler sample
https://twitter.com/ExoplanetApp

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temp

Post by Lazarus on 15th October 2012, 6:34 pm

That's... um... interesting.

Incidentally this thread has become a monster... I guess we could start a new one or split this or something?

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Re: Kepler News and Results

Post by Sirius_Alpha on 16th October 2012, 12:01 am

Lazarus wrote:Incidentally this thread has become a monster... I guess we could start a new one or split this or something?
Yeah I have given that some thought as well. I'll work on carving it up over the coming days.

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Re: Kepler News and Results

Post by Sirius_Alpha on 16th October 2012, 7:24 am

#Kepler PI Borucki: what is the freq of earths in the hab zone? Zero. #dps2012
Borucki: Right now we don't have phys evidence for such planets

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