Before we can do anything with the planets, we must know something about the stars that host them: KNOW THY STAR, KNOW THY PLANET! It is important to measure things like stellar radii, masses, temperatures, etc. in a homogeneous manner for occurrence rates.pic.twitter.com/L2gLOXQ0yY
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K2 (revitalized Kepler spacecraft) stared at a bunch of different fields along the ecliptic plane for ~80 days each in search of planets transiting their host star. To measure the transiting planet radius, we first need to know the host star radius.pic.twitter.com/qMxpcyPQSx
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The Ecliptic Plane Input Catalog (EPIC; Huber+ 2016) characterized about ~300,000 stars for K2 mostly using proper motions and colors. Then, something completely expected happened. Gaia DR2 came and changed everything...pic.twitter.com/nLWgCzWtji
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Gaia measured distances to 1.3 billion stars! But Gaia is not alone in the era of Big Astronomical Data™. Pan-STARRS DR2 is 1.6 petabytes of photometry, and LAMOST DR5 has over 9 million spectra!pic.twitter.com/HWloalVE4w
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We updated some of the photometry in the EPIC using Pan-STARRS, used the http://gaia-kepler.fun database to cross-match Gaia and K2 targets, and cross-matched the K2 targets with LAMOST to find ~27,000 K2 targets with a spectrum.pic.twitter.com/ofBlTwRTGu
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The LAMOST pipeline provides spectral types, temperatures, surface gravities, and metallicities for A, F, G, and K stars, but not M dwarfs. Luckily, I know a thing or two about M dwarfs (https://arxiv.org/abs/1905.05900 ).pic.twitter.com/jLh0OIcqQD
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Using the spectroscopic target photometry and parameters as a training set, we used machine learning to derive spectral types, temperatures, surface gravities, and metallicities for targets without a spectrum.pic.twitter.com/WTAc1dmvVG
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We used the Stefan-Boltzmann law to compute radii for AFGK stars, and absolute magnitude-radius relations from Mann+ 2015 for M dwarfs. In total we have new stellar parameters for 222,088 stars!pic.twitter.com/84nlRX5ZyI
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Using our new stellar parameters, we re-derived radii for 299 confirmed and 517 candidate planets and something magical happened: WE FOUND A DEFINITIVE PLANET RADIUS GAP FOR THE FIRST TIME IN A DATA SET OTHER THAN KEPLER!pic.twitter.com/IAlZkHbJhx
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This means that the Kepler result is not a fluke, and since K2 probes different regions in the Galaxy, this result is not exclusive to the Kepler field! Here's how the radius valley looks in relation to incident stellar flux (left), and compared Kepler (right).pic.twitter.com/zN5ka4wilO
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This result would not have been easily identifiable without a uniform set of stellar parameters.pic.twitter.com/nw5qHdkTsB
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Many thanks to
@jonKzink,@aussiastronomer,@AstroDressing, David R. Ciardi, and@JoshuaSchlieder for their important contributions to this paper!pic.twitter.com/Tl9tmNSHyDPrikaži ovu nit -
BUT WAIT.... THERE'S MORE! Go read "Scaling K2. II. Assembly of a Fully Automated C5 Planet Candidate Catalog Using EDI-Vetter", led by
@jonKzink! https://arxiv.org/abs/2001.11515 pic.twitter.com/I2nEfPQjmfPrikaži ovu nit -
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