Planet Hunters Talk

202072282: possible HB with small luminous companion

  • ajamyajax by ajamyajax

    202072282 looks interesting because of a possible low impact heartbeat binary signature. This LC suggests to me that the companion could be small and luminous (by the transit depth and v-shape). So maybe a brown dwarf system here. The other possibility is blending of a larger bg system. And maybe a luminous gas giant is less likely if the hb signature is real, but there still appears to be a small-ish possible transit to consider.

    s1=1945.34 p1=5.957 or 5.968 d1=0.31 (7.44 hours)

    F1
    T1

    http://talk.planethunters.org/#/subjects/APH00008ps

    K2 corrected light curve data credit: Vanderburg & Johnson (2014)

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  • Dolorous_Edd by Dolorous_Edd

    Few stars within optimal aperture, so a bit problematic

    https://www.cfa.harvard.edu/~avanderb/k2c0/ep202072282.html

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  • andrew418 by andrew418

    The signal is definitely coming from the brightest star in the center of the aperture (the one marked with the green dot). (By the way, feel free to shoot me an email if you have a question about multiple stars in an aperture -- I try to keep up with everything going on, but I'm sure I'm missing some.)

    I don't know if I believe that's actually an eclipse though. It looks pretty significantly asymmetric. I'm no expert by any means on this type of star, but I'd believe that the dips are also just pulsations.

    Best,
    Andrew

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  • ajamyajax by ajamyajax in response to andrew418's comment.

    Thank you Andrew. What you say makes sense, I see how these could just be pulsations (the period was a bit squishy).

    And Shellface, many thanks to you as well!! Very valuable posts and contributions by you here. Just saying I appreciate your help also when time permits.

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  • Shellface by Shellface

    And Shellface, many thanks to you as well!! Very valuable posts and contributions by you here. Just saying I appreciate your help also when time permits.

    Aw, shucks. I'm happy to help here, especially now we can do analysis on completely fresh data.

    Anyway. I… don't really know what is going on here. First off, the star - despite being a normal point source in both Tycho and 2MASS - has somewhat conflictory colours, but they ultimately point towards a late-A star. This gives me no clear explanation for the sinusoidal variations in the lightcurve (they have reasonable amplitude and period for solar-type oscillations, but early stars like this one cannot experience such a thing). Because the variations have almost 1/5th of the period of the transits (which I do believe are real, stellar variations would likely not behave in a periodic manner like this) it seems insensible to ignore the former as they may be inherently related.

    The transits seem pretty normal, as the asymmetry appears to be due to them all falling on the early rising limb of the sinusoidal variations. If they are on the A-type star and that star is a dwarf, the transits correspond to a companion radius of ~1.2 Rjup, which is pretty reasonable. There are even hints of phased out-of-transit variations behind the shorter ones (notice how the peaks on either side of a transit are higher than the others)

    Since the star is so early, it will likely not be possible to fully characterise the planet candidate if it is real, but the peculiar nature of this lightcurve does warrant a proper analysis. There are… what, three known Hot Jupiters around A-type stars? Any vaguely convincing candidates are worth looking into!

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  • Dolorous_Edd by Dolorous_Edd

    Maybe will be helpful, maybe not

    Target is listed under GO0100

    PROBING THE PLANETARY POPULATION OF HIGH-MASS STARS

    http://keplerscience.arc.nasa.gov/K2/docs/Campaigns/C0/GO0100_Johnson.pdf

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