[P-AE16] 系外惑星

[PAE16-10] Spitzer and ground-based follow-up of the young transiting multi-planet system V1298 Tau

*John Livingston¹、Trevor David²、Gudmundur Stefansson³、Elisabeth Newton⁴、Allyson Bieryla⁵、Shreyas Vissapragada⁶、Samuel Hadden⁵、Erik Petigura⁷、Eric Mamajek⁸、Lynne Hillenbrand⁶、David Ciardi⁶、Charles Beichman⁶、Luisa Rebull⁶、John Stauffer⁶、Varoujan Gorjian⁶、Heather Knutson⁶、Akihiko Fukui¹、Norio Narita¹、Motohide Tamura¹ (1.University of Tokyo、2.Flatiron Institute、3.Princeton University、4.Dartmouth College、5.Harvard-Smithsonian、6.California Institute of Technology、7.University of California, Los Angeles、8.Jet Propulsion Laboratory)

キーワード：Exoplanets, Young associations, Multi-planet systems, Transit photometry

We report on Spitzer IRAC2 and ground-based transit observations of the young (23 Myr) transiting multi-planet system V1298 Tau in the foreground of the Taurus-Auriga star-forming region. We find the transit depths at 4.5 microns of planets b, c, and d are consistent to within ~1-sigma of that measured at 0.42-0.90 microns from Kepler observations acquired during Campaign 4 of the K2 mission. The K2 data were acquired in early 2015 and were affected by a data gap as well as likely spot-crossings. We see no evidence for spot-crossings in the Spitzer light curves, consistent with the expectation of a lower spot-to-photosphere contrast at mid-IR wavelengths relative to the optical. Our revised ephemerides shrink the transit midpoint uncertainties from hours to minutes in mid-2021, when observations with JWST might be obtained. Our observations provide the first multi-wavelength view of the V1298 Tau system, an important benchmark for investigating the atmospheric properties of a moderately irradiated giant exoplanet shortly after its formation. Additionally, we publish individual transit times from K2, Spitzer, and our ground-based observations, along with dynamical investigations of transit timing variations. We measure very low dynamical masses consistent with the picture of low density young planets still undergoing significant radial contraction.