Sunday, October 28, 2012

A Potential Super-Earth Orbiting KIC 3732035?



There have been many exciting developments in the study of alien worlds this month, not the least of which being discovery announcements for a new world next door in the triple star system Alpha Centuari and another, much further away within a hierarchical quadruple star system that has been re-christened 'PH1'. This latter case is the first confirmed exoplanet from PlanetHunters and was first  noted by veteran project members Kian Jek and Robert Gagliano! For more on its discovery and characterization check out the official PlanetHunters Blog.

These events have driven a flood of activity on PH Talk. Many are new users assessing light curves for the first time, but some are individuals dropping by to check up on past favorites. Such was the case with 'Trenton1979' and his bump given to the thread for Kepler target KIC 3732035.



 A possible exoplanet candidate was noted here over a year ago in the entry for Quarter 1. An updated check reveals that at least five plausible transits exist in the public data set that can be culled from the noise, occurring at an interval of ~139 days.


The host star is a Type G of estimated 5786(K) and 0.9 radius compared to our sun, found at a magnitude of 14.2 in the Kepler FOV.

Kian Jek's observations:

"The light curve was detrended, preserving the transits and folded. During this process, it was discovered that the 2nd transit at 292 was problematic, as it was ill-defined, too shallow and short in duration, so it was removed. With the remaining 5 transits, I was able to get a reasonably good transit curve fit above (original polyfit in green)."
"The transit duration still comes out a little on the long side, at 10.83 hr, given that a central transit of a 0.864x Rsol star is 8.33 hr, so it's possible the stellar radius is wrong, or we are looking at an eccentric orbit. The radius of the planet, assuming a 0.864x Rsol star, is around super-Earth size, at 2.11x RE, and an orbit of 0.51AU. Mass of the planet estimated (very roughly) to be 9.6x ME. The Teq is approximately 328 to 335K, which is very hot, but water is still liquid, so technically this planet is in the HZ, although its orbit lies between Mercury and Venus, and if it has an atmosphere, could turn out to be much hotter than this."

Although no clear centroid shifts appear to accompany these transits, they are shallow and thus proper follow up by observatories would be required to completely rule out the possibility that this is a false positive caused by a faint background binary.

More transits seem to be present in the Q10-Q13 data; if accurate on the radius this target is amongst the smallest potential exoplanet candidates characterized at PH Talk so far!


Unlisted RR Lyrae type ab with Blahzko Modulations - KIC 3448777


KIC 34487- The Kepler current release data for quarters 12 and 13 shows Blahzko modulations in the time plot.

A 1901 Astrophysical Journal paper by Pickering provides a list of sixty four new variables, one of which — a star in the constellation Lyra — was found using the method above on a plate from July 13, 1899. Examination of this plate by one of Pickering’s staff, Williamina Fleming, revealed a short-period, high amplitude star (aavso.org). In nine years, she (Fleming) catalogued more than 10,000 stars. During her work, she discovered 59 gaseous nebulae, over 310 variable stars, and 10 novae. In 1907, she published a list of 222 variable stars she had discovered (wikipedia).
RR Lyrae variables are periodic variable stars, commonly found in globular clusters, and often used as standard candles to measure galactic distances.” It is roughly estimated that out of the 200 billion stars in our Milky Way galaxy only 85,000 may be RR Lyrae stars. “They are extensively used in globular cluster studies, and also used to study chemical properties of older stars.” (wikipedia) More on RR Lyrae stars at earthsky.org.
The Kepler spacecraft is monitoring a section of our galaxy that consists of approximately 150,000 stars. In a science paper J.M. Benkő et al dated 22 July 2010, the Kepler science team has identified only 29 of them as RR Lyrae stars, and of those only 14 exhibit Blazhko modulations.

It now appears that Planet Hunters has found another RR Lyrae star with Blazhko modulation making a total of 15 with Blazhko modulation.

Q12/13 phased curve for KIC 3448777


UKIRT image of KIC 3448777 at center


Daryll LaCourse:
That is one heck of a light curve! Below are the Short and Long cadence masks taken from the target pixel files for Q12. Looks like they went with a single-pixel optimal aperture centered around coordinate y981x197:
SC

Full View

LC

 Full View


KIC 3448777 is an unlisted RR Lyrae type ab star that was first identified indirectly by Planet Hunters forum Talk member Thomas Lee Jacobs in the second quarter of 2011 as a nearby contaminator of the light curve for KIC  3448787 shown below:


The phased curve for the contaminated light curve displayed the characteristics for a RRL star which was further analyzed and confirmed by forum Talk member and co-discoverer Kian Jek. Here are some excerpts from the forum Talk thread:

Tom128 (Thomas Lee Jacobs)
Reminds one of an RR Lyrae pattern. Not listed if it is.



Default_user 

about 1 year ago
kianjin (Kian Jek)
Amplitude is too low to be an RR Lyrae type AB, but could be an RRL type C. Right spectral class. Ragged nature of light curve however casts some doubt and suggests possible contamination but background field looks clear.

UPDATE: Oh - I know why the light curve is so crappy and not because of contamination - Q2 was imaged by mod.out 2.3 and therefore a victim of the #fp16 glitch!

Default_user
about 1 year ago
Tom128
Very interesting Kianjin. Does that mean the RR Lyrae-like pattern is a product of the glitch as well ?

Default_user
about 1 year ago
kianjin
No, I was pretty sure the RRL pattern is in the star itself, just masked by errors in photometry and/or postprocessing. Here's how the undetrended but Kepler processed light curve looks like, Q1 to Q3:



It's strange that Q1 doesn't show any pulsations. Q2 is definitely distorted by the fp16 problem, but even Q3 has some funky distortions of its own.
So what I did was to take the raw flux from Q3 alone, detrended it myself and here's what I got - an RRL-like light curve complete with Blazhko modulation!



I'm pretty sure this is what the star should look like, and here's the final phased waveform:



I would wager a guess that it's an RR Lyrae type C. That's because the amplitude of the pulsations is less than 1%, although it has all the other characteristics, spectral class, Blazhko modulation of typical RR Lyraes.
So in the end, you were right, Tom, well done, and a great find!

Default_user
about 1 year ago
Tom128
Outstanding analysis Kianjin and we netted an unlisted one as well! KID 3448787
Default_user
about 1 year ago
zookeeper (moderator) (Chris Linttot)

Just a quick note to say I've emailed a friend who is one of the authors on the Blenko list : http://arxiv.org/abs/1007.3928 - I'll report back if I get any response.

Default_user
about 1 year ago
zookeeper (moderator)
Good news! I've heard back from our friends in the Kepler team, and this star is interesting and indeed new to them, so this is another #discovery for Planet Hunters! Congratulations, Tom128 for spotting it, and Klanjin for the analysis. They're going to do a detailed analysis - indeed, they've already started - and keep us informed. Obviously if it makes a paper then full credit will go to you two.

Some extra details; the reason that the variation appears and disappears between quarters might be because it's a background star; this would explain the small amplitude and if the processing used on different quarters included different parts of the image then that would explain why it comes and goes.
They also say "Any new RRLs - especially the modulated ones - are of great value and very much appreciated! Kepler provides excellent light curves and delivers surprising new discoveries on #RRLyrae stars." so do tag anything you find.

As Robert Szabo, one of the scientists says : 'Congratulations to this precious discovery'.

You can follow this star on the forum Talk thread here.

Sunday, October 21, 2012

The Sound of PH1's Light Curve



 Planet Hunters Q2 Kepler light curve for eclipsing binary KIC 4862625
 that PH1 is transiting.  

 Edit: You can listen to PH1 sonification here.


Forum Talk member TroyW put together a sonfication of the Kepler light curve for KIC 4862625 (quarters 1-9) that the new circumbinary planet- PH1 is transiting through. This is what the light curve sounds like. You can hear the light drops. Though harder to discern, PH1 may possibly be heard just after the main eclipse drop, but before the secondary eclipse- two short audible tweets for PH1 and the secondary. The cricket- like sounds in the background are star variability.

     Artist's conception of PH1 copyright Dirk Terrell 2012
 


Troy is the developer of the Amateur Kepler Observatory (AKO) and he posts his finds on Planet Hunters forum Talk. 



Saturday, October 20, 2012

Unlisted UV Ceti Flare Star - KIC 7123391


Forum Talk members have identified a possible unlisted  UV Ceti flare star in the Q7 light curves.

Tom Jacobs:
 
Q7 flares KIC 7123391 This one has a similar outburst in Q8 near D795
No magnitude reading on star. Close in neighbors in sky view but look extremely weak.

Q8 time plot:



Daryll LaCourse:
 
Thanks for flagging this Tom; those look pretty powerful! Star type is listed as Unknown but perhaps it is an M dwarf.

Kian Jek:
Possible, there's hardly any color info on this star but the J-K value of 0.996 suggests a Teff under 4000K. that's about right for a UV Ceti type flare star.


You can follow this star here.





Unlisted RR Lyrae Type C - KIC 2831097


Forum Talk member cappella has identified a possible unlisted RR Lyrae type C star.

Kian Jek:



Could this be an RRc? There is a GO (Kepler Guest Observer program) designation for it, perhaps someone at KASC is already looking at this. But still, Type A subgiant, low metallicity, period 0.2 to 0.5d, amplitude of +/- 10%, slightly sinusoidal profile. For comparison this is the phased plot for KIC 5520878, a known RRc:



Your can follow this star here.

Wednesday, October 17, 2012

Behind the Scenes - PH1 at Planet Hunters


http://www.boulder.swri.edu/~terrell/kepler_quadruple_1024.jpg
 Artist's conception of PH1 copyright Dirk Terrell 2012

If you just woke up from a deep sleep, Planet Hunters has recently published a science paper titled
" A Transiting Circumbinary Planet in a Quadruple Star System " named PH1 for Planet Hunters first confirmed planet. A very popular topic. If you search Google and type in key words PH1 and Planet Hunters over 55K hits will show up this week. Not a bad few days work of publicity for this very interesting find. There is something captivating about regular people finding exotic exoplanet systems. Kian Jek and Robert Gagliano are credited for the discovery.

 



  Robert Gagliano 












.

Kepler Science Conference December 2011- Right to Left 
Kian Jek, Dr. Frank Drake, Daryll LaCourse,
Dr. Svetlana Berdyugina

Photograph by Thomas Lee Jacobs

Kian and Robert have made other published finds at Planet Hunters such as a planet candidate orbiting KIC 4552729. The uncovering of PH1 that is orbiting KIC 4862625 all began on the Planet Hunters Science Thread:

Finally - an EB with a planet?

Started by kianjin (Kian Jek)


8 months ago
robert gagliano
Kian, what about the dip in Q2.3 at d106......could that be it? Thanks.


8 months ago
kianjin in response to robert gagliano
You are right - looking at the raw flux, there appear to be 3 matching dips, at BJD 237.79, 374.5 and 511.11. (subtract 131.511 to get the PH timings). The duration appears to be consistent, ~12 hrs.


8 months ago
kianjin
I removed all the EB primary/secondary eclipses, leaving only this third transit.


As can be seen, the periodicity is pretty good. However, the stacked transit curve looks a little lop-sided. It could possibly be due to the fact that transit 2 was interrupted by a primary eclipse. Maybe we need to see one or two more transits to be absolutely sure?

Kian posted again on the Discussion page for the suspected candidate where other members chimed in. That's how it works at Planet Hunters, everyone can voice their views.


kianjin (Kian Jek) 8 months ago
 
First spotted by Robert Gagliano, this could be a circumbinary planet. Three rounded dips are visible.

The EB primary/secondary eclipses were removed, leaving only this third transit:

and obtaining this phased curve:






As can be seen, the periodicity is pretty good. However, the stacked transit curve looks a little lop-sided. It could possibly be due to the fact that transit 2 was interrupted by a primary eclipse. Maybe we need to see one or two more transits to be absolutely sure?
The currently measured transit duration of 13.1hr appears to be too long for a central transit of this primary, but it is possible that the planet, a ~3 RE object, based on the transit depth, is in an eccentric orbit.


8 months ago
ajamyajax
'Well done' from a humble PH'er! I will enjoy reading the scientific paper that hopefully follows. :))
Some general info for others interested:
http://en.wikipedia.org/wiki/Circumbinary_planet



8 months ago
Sika56 
Amazing! Thanks.



6 months ago
arvintan
I think there's another possible transit at 381.6-382.2. Just open the image in a new tab.



6 months ago
ajamyajax in response to arvintan
arvintan:
I think there's another possible transit at 381.6-382.2. Just open the image in a new tab.
Took a look and that appears to be the third transit on Kianjin's chart above. Sorry about that.



6 months ago
arvintan in response to ajamyajax
@ajamyajax
Are you sure? Coz I think the deep one in 379 is the third transit in Kian's chart. If you work you're way back from 379 with the 136.64 day period, you'll get the other two. But if you take the one I proposed, you're not gonna get any good hits.



6 months ago
ajamyajax
Ok I'll look again, maybe I'm wrong. Gotta rush off right now but will chart later. And appreciate your centroid check on the new multi-EB one. Our trying to 'get it right' seems like good science to me. :)



6 months ago
ajamyajax in response to arvintan
arvintan:
@ajamyajax
Are you sure? Coz I think the deep one in 379 is the third transit in Kian's chart. If you work you're way back from 379 with the 136.64 day period, you'll get the other two. But if you take the one I proposed, you're not gonna get any good hits.
Arvintan, now I get it! At least I hope. You mean the area marked with a blue box in the chart below, right? I agree with the similar rounded appearance, this one could be yet another transit. But due to its shallow nature could also be tough to prove without a number of eclipses.. If you see them however, let me know if you need a chart to help establish a period there.

p1
Default_user
6 months ago
arvintan
@ajamyajax
Yes, that's the one. I tried looking for other similar dips but couldn't find one. Should be the case if the planet calc says it's supposed to have a period of somewhere around 872 days for a 2.1 rE planet at 1.725 AU.
And yes, any science with teamwork in it is good science. A pleasure to work with you, sir. :)

Default_user
6 months ago
JKD
likely an EB with p ~20d having a third object around with p ~136.5d


kianjin 2 days ago
 
I wasn't 'allowed' to post these earlier on because we needed to keep radio silence about this, but these plots were made sometime after July, shortly after the last batch of public data was released, to show the TTVs for the planetary object; the 4th and 5th transits in particular were delayed by significant times - up to 2 days.
These TTVs are also evidence that this planet was almost certainly bound to the binary and not a BG EB blend. There are more accurate figures published in the paper, but this was what we had back then:







Planet Hunters Offical Blog:

PH1 : A planet in a four-star system

Planet Hunters’s First Circumbinary Planet- A True Team Effort

The Road to Characterizing PH1: Visual-band Imaging

 

 

 


Sunday, October 14, 2012

Long Period Unlisted Eclipsing Binary - KID 7971363


KID 7971363 is an unlisted eclipsing binary star system flagged by Planet Hunters forum Talk members in Q7.

Kian Jek:
If the primary stellar data is accurate, we're looking at a 0.24x Sol companion, 26x RE, too large to be a brown dwarf. Let's hope we see a primary eclipse soon, but the eclipse duration of ~37.75 hr means a very long period > 10 years!
 You can follow this eclipsing binary here.

Saturday, October 13, 2012

Known Eclipsing Binary also a Heartbeat Binary - KIC 9965691


 KIC 9965691 is a known eclipsing binary star system that is also a Heartbeat binary.

Kian Jek:
 


Heartbeat binary- periodicity already recognized in Prsa v3 as published period is the heartbeat period.
 You can follow this Heartbeat eclipsing binary star system at Planet Hunters here.

Unlisted Planet Candidate KID 2581554


Planet Hunters forum Talk members have identified KID 2581554 as a planet candidate with a very short period.

Kian Jek:
The host is a heavily spotted Type K subgiant with a rapid rotation of ~8 days resulting in a lot of variation which made the 17 transits hard to isolate. There appear to be no correlated APOs. Transits were masked out by hand and the curve detrended:

The light curve is then folded by hand again to obtain a period of 47.148 and a rather good-looking transit curve:


The transit duration is very short because of the high impact parameter of 0.93. The transit depth corresponds to a 7.47x RE planet at a distance of 0.28AU and a Teq of 577K.
 UPDATE: Phased APO plot for Q5 and Q9:


You can follow the discussion for this planet at Planet Hunters here.



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