New C0 K2 Transits
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Here are some new transits using Al Schmitt's LcViewer and 7,743 Campaign 0 light curves for the K2 project. Andrew Vanderburg (Harvard-Smithsonian Center for Astrophysics) has graciously provided Al with his latest corrected light curve files.
202059223 ( t @ 1944 )
202059348 ( t @ 1954.5 )
202059435 ( t @ 1968 )
202059435 ( t @ 1962 )
202060523 ( t @ 1947, 1963.5 )
202060631 ( t @ 1954 )
202060710 ( t @ 1940 )
202060921 ( t @ 1971.2 )
202061000 ( t @ 1943,1948.7,1954.7,1960.5,1966.4 )
202064253 ( t @ 1944.9,1966.1)
202066910 ( t @ 1961.6 )
202067380 ( t @ 1953.5 )
202067846 ( t @ 1949.0 )
202067861 ( t @ 1945.7 )
2020 67932 ( t @ 1964.0 )
202068141 ( t @ 1962.5 )
202068365 ( t @ 1952.7 )
202068780 ( t @ 1949.9 )
202068795 ( t @ 1947.9 )
202068800 ( t @ 1942.2 )
202071394 ( t @ 1943.1)
202071448 ( t @ 1947.2 )
202071635 ( 5 transits )
202071645 ( 3 transits )
202071690 ( t @ 1960 )
202071902 ( t @ 1958.6 )
202083828 ( t @ 1942.1,1956.7 )
202084588 ( t @ 1959.6,1967.3 )
202071448 ( t @ 1947.2 )
202074603 ( t @ 1963.3 )
202081111 ( t @1961.9 )
202073476 ( t @ 1957.8 )
202088569 ( t @ 1952.5 )
202085656 ( t @1959.6 )
202086291 ( multiple t's )
202088428 ( t @ 1949.2 )
202090723 ( 5 transits )
202091179 ( t @ 1950, 1966 )
202091295 ( multiple t's )
202092915 ( t @ 1948.8 )
202093020 ( multiple t's )
202126847 ( multiple t's )
202126849 ( multiple t's )
202126887 ( t @1944.2, 1957.1, 1969.9 )
202126852 ( multiple t's )
202135998 ( t @ 1967.8 )
202136151 ( multiple t's )
202136212 ( t @ 1953.5 )
202137209 ( multiple t's )
202137560 ( t @ 1970 )
202137562 ( t @ 1950 )
202137580 ( t @ 1963 )
202137637 ( multiple t's )
202159332 ( t @ 1960.3 )Posted
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by
troyw
I checked all the curves with more than 2 transits for TTVs and did not find anything obvious.
Posted
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by
ajamyajax
EPIC 202090723: maybe just pulsations in a heartbeat style LC, but worth noting is the folded transit looks planetary in shape and depth. So hopeful we have another PC here. (And no TTV as Troy already noted.)
s1=1944.675 p1=6.15 d1=0.19 (4.56 hours)
K2 corrected light curve data credit: Vanderburg & Johnson (2014)
Posted
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by
Dolorous_Edd
in response to ajamyajax's comment.
Listed under GO0111 DETECTION OF EARTH-SIZE PLANETS USING K2
Though optimal aperture a bit problematic
https://www.cfa.harvard.edu/~avanderb/k2c0/ep202072704.html
Stars 3 and 5 could fall within it
N | Cat | ID/Name | RA/Lon | Dec/Lat | X | Y
1 | http://archive.stsci.edu/k2/epic/search.php | 202090723 | 90.2285| 23.9386| 150.0| 150.0
2 | http://archive.stsci.edu/k2/epic/search.php | 209178636 | 90.2308| 23.9369| 111.1| 118.8
3 | http://archive.stsci.edu/k2/epic/search.php | 209179402 | 90.2231| 23.9398| 237.8| 171.8
4 | http://archive.stsci.edu/k2/epic/search.php | 209179651 | 90.2336| 23.9408| 65.6| 190.2
5 | http://archive.stsci.edu/k2/epic/search.php | 209179781 | 90.2220| 23.9414| 256.0| 199.8
6 | http://archive.stsci.edu/k2/epic/search.php | 209179612 | 90.2364| 23.9407| 19.0| 187.3
Posted
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Shellface
in response to ajamyajax's comment.
EPID 202090723: Though the out-of-transit variations do not appear to be well-phased with the period (and thus probably not to do with the companion), the transits appear to be "bracketed" by decreases in flux towards the transit that I can't really explain.
There appears to only be one (smeared) star in-aperture. The star's colours are late-F.
Posted
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ajamyajax
in response to Shellface's comment.
Re the changes in flux: here are several other possible 'heartbeat binaries' with more data (K1), that do something similar. Maybe a grazing binary, partial eclipse, then a heated-up gas after contact sequence(?)
Posted
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Shellface
in response to ajamyajax's comment.
Though architecturally unlikely, that seems like a vaguely plausible explanation. Still, a more quantitative look at the lightcurve is probably necessary.
Posted
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ajamyajax
Re: "Still, a more quantitative look at the lightcurve is probably necessary."
Thanks for remaining objective. Not to be trite but what it really is, is what matters most.
Posted
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by
JKD
202082150 - 1955.74BKJD - dFLUX ~1.5%, looks promising, even when in a glitch area
In the meantime I’ve also found one with dFLUX of ~4.2% at exactly the same position.
=> GLITCHPosted
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by
JKD
202083828 ( t @ 1942.1,1956.7 )
3 transits - 1942.16 - 1956.71 - 1971.26 (BKJD)
p=14.55dPosted
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ajamyajax
Well, been trying to catch up with (fwiw) my plots of a few more of our repeating transit events and possible K2 planet candidates... Most are probably stellar eclipses but hopefully still a PC or two in these, if the stars are small enough.. Also after getting through the K2 data, I do want to get back to helping our science team identify more possible PCs in the K1 data, long period or otherwise. I already have another maybe a MPC in the works -- that Planet Hunters seem to have spotted. But we'll see how it goes. And always the optimist, we'll see what more we can find here. 😉
Posted
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ajamyajax
EPIC 202136151: chance for a pc here with a less than one percent drop in flux. The fit does look stellar, but might have some ttv. And maybe an odd/even offset there also but limited data a factor, as always with these. Also maybe a secondary or albedo-type transit present, see note below.
s1=1943.655 p1=6.39 d1=0.14 (3.36 hours)
ttv1 = [1943.655,1950.0396,1956.424,1962.82,1969.215]
(my alt eb test found one possible transit around 1953.24 BJD, but maybe too deep for an albedo eclipse and could be a glitch.)
s2=1946.85 p2=6.39 d2=0.11
K2 corrected light curve data credit: Vanderburg & Johnson (2014)
Posted
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Shellface
in response to ajamyajax's comment.
EPID 202136151: Source is highly blended, with 3 visible stars in the Kepler image that is corroborated by 2MASS along with an additional faint star. Unlikely to be a planet, and too difficult to meaningfully follow-up.
Posted
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EPIC 202060921 has a nice U-shaped transit @ 1971.3 BKJD with a transit duration of 7.8 hrs....possible pc?
https://www.cfa.harvard.edu/~avanderb/k2c0/ep202060921.html
Posted
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Shellface
It has a depth of ~11% (~0.11). The radius ratio of the two components is the square root of the second number, so it has ~a third of the radius of the primary. I'm not even going to check the colours…
A U-shaped transit means that the transiter crosses close to the centre of the transited's disk (it has a low impact parameter). It doesn't tell you anything in particular about the size of the transiter, whereas the transit depth does.
(Apologies if I'm rather blunt, it's 1 in the morning)
Posted
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ajamyajax
EPIC 202126852: looks like another under 1% drop in flux candidate. It also could have TTV, but sparse transit data makes it difficult to be sure or line those up. And my odd/even plot here could be affected by this as well.
s1=1941.083 p1=2.79155 d1=0.095 (2.28 hours)
ttv1 = [1941.083,1943.88,1946.6791,1949.468,1952.257,1955.0465,1957.834,1960.624,1963.424,1966.212,1969.0013,1971.7898]
Posted
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Shellface
in response to ajamyajax's comment.
You and your darn TTVs…
EPID 202126852: Despite being a nondescript 11th magnitude star, this object has a Henry Draper number (262389) and even a Hipparcos number (32209), along with a SIMBAD entry. This gives me a fair bit more information to work with.
A combination of four of the star's colour indexes (B-V, V-K, J-H, H-K) gives a spectral type of F5 ± 2. Its Hipparcos parallax is negative to 1σ (a negative parallax is non-sensical, so this is due to measurement error, probably due to the faintness of the star), but the star nevertheless has a large proper motion, which suggests a large galactic velocity. If the star is a dwarf - which is the most likely evolutionary state for an F-type star - then the expected parallax would be ~3.3 mas, which is about 2σ from the HIP parallax, which is probably acceptable. More evolved states for the star would place it at lower parallax, bringing the friction closer to zero.
Stars with high galactic velocities are almost unanimously old. Old stars are metal-poor, and giant planets need metals to form. This is a rather large red flag for this PC, but at the same time it makes it valuable if it is real. Assuming the star is a dwarf, the companion radius is ~1.4 Rjup, but the transit appears to be grazing so this is a lower limit.
When I plugged this into EXOFAST, the fit resulted in a moderately metal-poor (Fe/H = -0.3) F-star approaching the end of the main sequence. The impact parameter of the transit is 0.9, so the entire transit is ingress/egress. The modelled companion radius is 1.6 Rjup, which is again a ~lower limit.
So… yes, this seems like a valid PC. I expect the modelled stellar parameters are mildly incorrect (the turn-off age for a 1.27 Msol star is ~5 Gyr, which is younger than the thick disk), but a planet seems plausible. There are no visibly coherent out-of-transit variations, so the companion is at least low-mass. The brightness of the star eases follow-up, so this is a good planet candidate.
Posted
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ajamyajax
in response to Shellface's comment.
Awesome! About any papers, suggest an e-mail to Dr. Schwamb (Megan) or Dr. Fischer (Debra) if you need to know. They could answer this best, in my humble opinion. Me, I just post away and let nature take its course (grin), i.e. if our friends are interested in the system they will find our work eventually. And best regards and great working with you SF! So unless I notice or hear about something else K2-wise, I am on to K1 systems now (for a few days anyway).
Posted
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by
JKD
202126877 - #transit at 1955.434 BKJD, transit duration ~5.88hrs, deltaFlux ~6%
the transit is close before the known glitch area at 1955.7 BKJD
see also https://www.cfa.harvard.edu/~avanderb/k2c0/ep202126877.htmlPosted
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by
ProtoJeb21
I found two interesting transits of the star EPIC 202059086 using LcViewer. Transit 1 occurs at BKJD 1950.326550 with a duration of 2.94 hours and a depth of 21303 ppm. Transit 2 occurs at BKJD 1964.036200, lasts for 2.942400 hours, and has a depth of 19848 ppm. Both are V-shaped, which is a promising sign. I was not able to find any stellar parameters except for a Kepler magnitude of about 18.000. Based on the decent amount of noise in the data and the high magnitude of the star, I can infer that EPIC 202059086 is either a distant giant star or an ultracool M-dwarf similar to TRAPPIST-1.
Screenshots of the two transit events (I altered the zoom view so that they're easier to see):
Posted
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Artman40
Can it be noise? I see similar signal in day 1962.
Posted
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by
ProtoJeb21
in response to Artman40's comment.
The signal at day 1962, as seen with LcViewer, occurs right after a brief spike in brightness, so I assume it's a star spot. It also has no defined bottom - that is, when zoomed in, the two bottom data points of the dip are not connected. That, and it doesn't match the two other potential transit events I found. It has a duration of 3.432 hours and a depth of 12237 ppm. This is about 0.5 hours longer and 7000-9000 ppm shallower than the dips I found.
It might be possible that the two signals I found are noise, but the majority of stellar noise in the data is smaller and more frequent. Quite a lot of said noise occurs between days 1953.75 and 1958.25.
Here are the two possible transits phase folded:
Posted
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by
ProtoJeb21
Some other interesting signals I've found in C0 data:
EPIC 202059193, single transit. It's even more symmetrical when phase folded than the transits shown above.
EPIC 202059223, a rather long and deep transit-like event. Its duration of about 9.3 hours makes it seem less likely to be a false positive, but I'm not too certain.
EPIC 202059347, two transit-like events that could be caused by a planet orbiting every 14.60865 days. Both dips look v-shaped, which is promising.
EPIC 202059348, a large but short (~3.92 hours) transit-like event. I'm surprised to find that it hasn't been cataloged as a K2 candidate yet.
Posted
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by
zoo3hans
in response to ProtoJeb21's comment.
EPIC 202059348 people have posted about this star here : https://talk.planethunters.org/#/subjects/APH000075v
Posted
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ProtoJeb21
I recently found what might be a small rocky planet orbiting every 22.4748 days around the star EPIC 202059403. I'm not too sure if its a set of transits or just regular stellar noise, but both events are almost identical in depth and duration. If the radius of the star was known, I could see if the transit duration matched up with the orbital period I found. However, I'm going to try and work backwards to see if I can calculate stellar radius and/or mass just by transit duration and orbital period.
Posted