K2-72 May be a 5 or 6-planet System

[ProtoJeb21]

Over the past few weeks, me and my collaborators over at Exoplanet Explorers (shutcheon, Vidar87, Libmar96, and @Cabbink) have been cranking out candidate planet discoveries like crazy. By now there's probably well over two dozen high sigma candidates - aka worlds that have a high statistical probability of being real. A good portion of these have been multi-planet systems. To date, we've found four 4-planet, two 5-planet, one 3-planet, and at least three 2-planet systems. All of the five-planet systems were found by shutcheon with collaborative efforts by me and other members of the group I mentioned. The trick to finding these multi-planet systems is by analyzing the data of stars with at least one confirmed planet or known candidate. This has worked with one confirmed planet system before - K2-82, where shutcheon found two extra Earth-sized candidates. Now it has worked again with K2-72.

Shutcheon managed to find a very likely transit event around epoch 2151 in the light curve of K2-72 (EPIC 206209135) lasting about 3 hours. He was able to find an orbital period of 32.54 days for the planet, putting it within the habitable zone. Once I returned home from school I raced to check the data for the star, and not only did I find shutcheon's K2-72f, but I also found evidence of a K2-72g! This world is the least likely, but appears to have a year of at least 52.989 days. This also puts it in the habitable zone, albeit in the outer edge. I'd say that this find is probably one of the greatest ever done by my group.

But wait, things get better! Using stellar size data from Martinez et al., I was able to figure out that planets K2-72c and K2-72e are much more promising than what was listed on ExoFOP. While 72c is in the habitable zone, it looks to more likely be a Venus analogue. This makes planet 72e, along with candidates 72f and 72g, potentially habitable! Now, I will list the parameters of the planets below. Space Engine representations of the planets coming soon!

• HOST STAR K2-72: 0.359 R_Sol, 0.361 M_Sol, 3,370^oK, 0.0149 L_Sol, spectral type M2.7V, habitable zone from 0.1164 to 0.1677 AU.
• K2-72b: 1.121 R_E, year of 5.5774 days, 0.0438 AU, 425^oK. Hot desert planet, likely tidally heated and locked.
• K2-72d: 0.998 R_E, year of 7.759 days, 0.0546 AU, 381^oK. Hot desert planet, likely tidally heated and locked.
• K2-72c: 1.278 R_E, year of 15.187 days, 0.0855 AU, 302^oK. In the optimistic habitable zone, but likely a hellish Venus analogue.
• K2-72e: 1.469 R_E, year of 24.167 days, 0.1163 AU, 261^oK. On the inner edge of the habitable zone; potentially habitable Super-Earth!
• K2-72f: 1.357 R_E, year of 32.54 days, 0.14209 AU, 233^oK. Smack in the middle of the habitable zone; best potentially habitable candidate of the system!
• K2-72g: 1.211 R_E, year of 52.989 days, 0.19668 AU, 201^oK. Rather cool potentially habitable candidate!

By the way, if anyone's wondering why I'm posting this on a different thread before the Daily Round-up, it's because this discovery is too big to put on My Exoplanet Discoveries thread. I also really wanted to share this with the KSP forums.

EDIT: The discussion thread on Exoplanet Explorers https://www.zooniverse.org/projects/ianc2/exoplanet-explorers/talk/821/366881

Edited June 15, 2017 by ProtoJeb21

[Spaceception]

Alright, that definitely looks like a larger TRAPPIST 1 analog.

Red dwarf parent

Large number of Rocky planets

No gas giants

And potentially 4 habitable planets, just like in TRAPPIST 1!

Edited June 15, 2017 by Spaceception

[ProtoJeb21]

6 minutes ago, Spaceception said:

Alright, that definitely looks like a larger TRAPPIST 1 analog. 

Maybe, maybe not. It seems like K2-72g is a false positive. Or there might be some other undetected (as of now) planet in the system.

[NSEP]

Im coming closer to the point where i believe that Alien life is instead of rare, quite common in the Universe. We are just quite lucky to have big brains and thumbs to build civilization.

Amazing!