A candidate Earth Analog in Kepler data revealed by deep learning

[HabPlanet]

HST Confirmation of a Candidate Earth Analogue from the Kepler Primary Mission

Investigators                                                                   
                                                                                   
    PI: Dr. Andrew Vanderburg             University of Texas at Austin 
   CoI: Dr. Laura Kreidberg                   Harvard University
   CoI: Chris Shallue                              Google AI
   CoI: David W Latham                        Smithsonian Institution Astrophysical Observatory      

Abstract                  

Quote

We request 21 orbits of HST observations to confirm the transit of a candidate Earth analog exoplanet recently detected in the Kepler data set. The candidate Earth-sized (Rp = 1.1 +/- 0.1 Re) planet orbits its Sun-like (0.97 Rsun) host star in a 365.4 day period, and if confirmed, would be the first true Earth analog around a Sun-like star known. Though our vetting finds no indication that the candidate signal is a false positive, we cannot completely rule out an instrumental origin for the signal without independent confirmation from HST. These HST observations are urgently needed to inform the 2020 Decadal Survey of occurrence rate of Earth analogs around  Sun-like stars, a crucial design input for the proposed LUVOIR and HabEx flagship missions.    

http://www.stsci.edu/hst/phase2-public/15685.pdf

http://www.stsci.edu/cgi-bin/get-proposal-info?id=15685&observatory=HST

http://archive.stsci.edu/proposal_search.php?mission=hst&id=15685

 

The reported visit target in the proposal is 2MASS-J19432996+5059289. In the Kepler target catalog, this star is called KIC 12266812. HST has completed the observation two weeks ago and the analysis is underway. 

Gaia DR2 parallax gives a distance of 1010~1030 light years and stellar radius (0.978 Rs) and effective temperature (5908 K) literally identical to our Sun.

The three transits and periods detected by Kepler seem identifiable and robust to my eyes. Based on HST's visit time and period reported in the proposal, the transits must have taken place during 485-487, 851-852, and 1216-1217 (BJD-2,454,833). The light curves below are obtained from Time Series Viewer. This is my own analysis on KIC 12266812, yielding a transit depth at around ~120 ppm and duration around 10 hours. 

https://drive.google.com/drive/u/0/folders/1pG8fzxWzAJ0MU3NMSA7T55Mbh2BurIIL

If confirmed, this planet will be the most similar planet to Earth, literally an Earth twin with identical size, orbital period, orbital distance, insolation, host star, and maybe even biosphere, although the result from HST observation takes about three years to publish. 

Edited May 17, 2019 by HabPlanet
Pictures

[HebaruSan]

51 minutes ago, HabPlanet said:

a 365.4 day period

That's... amazing!

[Scotius]

And if we find a sizeable moon orbiting this planet one day...

[GearsNSuch]

5 hours ago, HebaruSan said:

a 365.4 day period

 

1 hour ago, Scotius said:

And if we find a sizeable moon orbiting this planet one day...

 

Must've turned the telescope around backwards.

[ProtoJeb21]

I just re-calculated the parameters for the star and candidate using Gaia DR2 data and V and K magnitudes on ExoFOP, and the system looks even more incredible now. 

- Stellar Radius: 1.0095 (+/-0.0245)x Sun

- Stellar Mass: 0.9935 (+/-0.0065)x Sun

- Stellar Temperature: 5758 (+/-82) K

- Luminosity: 1.00505x Sun

- Semi-major Axis: 0.998102 AU

- Equilibrium Temp: 255 K (the same as Earth!)

- Insolation: 1.009x Earth

KIC 12266812 and the planet candidate are just about identical to the Sun and Earth. Later today, I’ll take a look at the system with LcViewer and see if, maybe, there are other small planets in the system. 

[StrandedonEarth]

Wow. Is there a space mirror about 510 LY away out in that direction? 

[HabPlanet]

4 hours ago, ProtoJeb21 said:

- Stellar Radius: 1.0095 (+/-0.0245)x Sun

- Stellar Mass: 0.9935 (+/-0.0065)x Sun

- Stellar Temperature: 5758 (+/-82) K

- Luminosity: 1.00505x Sun

- Semi-major Axis: 0.998102 AU

- Equilibrium Temp: 255 K (the same as Earth!)

- Insolation: 1.009x Earth

Wow, just WOW! This is crazy. The 485.9 transit is shallower and shorter than others and the 1216.8 transit is deeper and longer than others, and they differ by a factor of 2. I wonder if this could be attributed to instrumental noise or two different planets transiting coincidently. Three transits have depths of ~84 ppm, ~129 ppm and ~177 ppm respectively, and the combined depth is ~116 ppm. 

Adopting your stellar radius would yield 1.19 (+0.31/-0.21) Re

Adopting Berger et al (2018) would yield 1.15 (+0.37/-0.24) Re

Considering the uncertainty, both overlap well.

47 minutes ago, StrandedonEarth said:

Wow. Is there a space mirror about 510 LY away out in that direction? 

It would be funny if a galactic civilization created a mirror Earth and put it right at 100π pc (because Gaia DR2 parallax gives 313.172 (+2.296/-2.270) parsec for this star) as a sign of something for humans to discover....

Edited May 17, 2019 by HabPlanet

[HabPlanet]

4 hours ago, ProtoJeb21 said:

Later today, I’ll take a look at the system with LcViewer and see if, maybe, there are other small planets in the system. 

There are a few possible transits at 466.7, 838.3, 842.0, 870.5, 900.6, 1195.6, and 1258.6

[electricpants]

holy cow, no way! this is almost like what happened with laythe...

 

to quote the kerbal astronomical society:

"When Laythe was first discovered, it was not entered in the records because the scientist in charge thought he was looking at Kerbin.

Luckily this error was corrected when a plucky intern informed him that 'telescopes don’t work that way'."

[Bill Phil]

Nice.

We’ve found Jupiter analogs in the past but I think the main limitation to finding Earth analogs is technology. With better scopes we should be able to get a lot of information about other stars.

[TheTripleAce3]

Next time someone asks what the law of large numbers is I'm showing them this thread.

[ProtoJeb21]

Bad news: for some reason, I can’t downlod original Kepler data from MAST (the Mikulski Archive for Space Telescopes), so until I can fix that issue, I won’t be able to get to my KIC 12266812 analysis. 

[HabPlanet]

1 hour ago, ProtoJeb21 said:

Bad news: for some reason, I can’t downlod original Kepler data from MAST (the Mikulski Archive for Space Telescopes), so until I can fix that issue, I won’t be able to get to my KIC 12266812 analysis. 

I have the normalized pdcsap flux and time in google folder, if that's what you're looking for.

[HabPlanet]

It is important to note that at current stage we should treat this TCE as nothing more than just a candidate.

First, the parameter space between 350 and 380 orbital days has the highest false alarm rate. All false alarms cluster at 370 days in Kepler data, so it naturally produces a peak of candidate planets and TCEs.

Second, Kepler team's official automatic vetting system, Robovetter, did not detect this TCE in DR25 and previous DRs, although Robovetter also missed a lot of other TCEs. 

Third, in the inverted run, where light curve is inverted so any detected TCE has to be false alarm produced by noise, false alarms can be indistinguishable from true transit even to human eyes. They also cluster at 370 days.

Fourth, only three transits are detected, but the chance of instrumental and stellar noise alignments three times are significantly greater than alignments of five times. 

Edited May 18, 2019 by HabPlanet

[KerikBalm]

That seems incredibly close to Earth's parameters... how far away is it?

[Mitchz95]

"Captain's log, stardate 2713.5. In the distant reaches of our galaxy, we have made an astonishing discovery: Earth-type radio signals coming from a planet which apparently is an exact duplicate of the Earth. It seems impossible, but there it is."

Edited May 26, 2019 by Mitchz95

[RealKerbal3x]

2 hours ago, Mitchz95 said:

"Captain's log, stardate 2713.5. In the distant reaches of our galaxy, we have made an astonishing discovery: Earth-type radio signals coming from a planet which apparently is an exact duplicate of the Earth. It seems impossible, but there it is."

We’ve got the start of a possible killer Star Trek episode here

[Hypercosmic]

Finally, an Earthlike planet candidate to look forward to, after a bunch of fat balls, sunbather planets, and red dwarf dwellers. If this planet is confirmed with no significant changes, it will be on the same class as Kepler-62f, Kepler-186f, and Kepler-442b, as some of the planets with the best chances of being habitable.

For the note, I never really understand articles that include planets like Proxima b or TRAPPIST-1e for planets with the best chances of being Earthlike. Hugging their respective red dwarf stars is pretty much a big no. Not because they get tidal locked, but the extreme radiation (TRAPPIST-1e) and flares (Proxima b) should pretty much ensure that these worlds are either ocean worlds, if their density is low, or airless desert worlds, if their density is high.

Edited May 27, 2019 by Hypercosmic