KELT-18b: Puffy Planet, Hot Host, Probably Perturbed

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McLeod K. K., Rodriguez J. E., Oelkers R. J., Collins K. A., Bieryla A., Fulton B. J., ...Daha Fazla

ASTRONOMICAL JOURNAL, cilt.153, sa.6, 2017 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 153 Sayı: 6
  • Basım Tarihi: 2017
  • Doi Numarası: 10.3847/1538-3881/aa6d5d
  • Dergi Adı: ASTRONOMICAL JOURNAL
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Anahtar Kelimeler: methods: observational, planets and satellites: detection, planets and satellites: gaseous planets, stars: individual (BD+60 1538), techniques: photometric, techniques: radial velocities, PRECISION RADIAL-VELOCITIES, SPIN-ORBIT MISALIGNMENT, PRE-MAIN-SEQUENCE, TRANSITING PLANET, SHORT-PERIOD, JUPITER, STARS, ROTATION, MASS, TEMPERATURES
  • Ankara Üniversitesi Adresli: Evet

Özet

We report the discovery of KELT-18b, a transiting hot Jupiter in a 2.87-day orbit around the bright (V = 10.1), hot, F4V star BD+60 1538 (TYC 3865-1173-1). We present follow-up photometry, spectroscopy, and adaptive optics imaging that allow a detailed characterization of the system. Our preferred model fits yield a host stellar temperature of 6670 +/- 120 K and a mass of 1.524(-0.068)(+0.069) M circle dot, situating it as one of only a handful of known transiting planets with hosts that are as hot, massive, and bright. The planet has a mass of 1.18 +/- 0.11 M-J, a radius of 1.570(-0.036)(+0.042) R-J, and a density of 0.377 +/- 0.040 g cm (3), making it one of the most inflated planets known around a hot star. We argue that KELT-18b's high temperature and low surface gravity, which yield an estimated similar to 600 km atmospheric scale height, combined with its hot, bright host, make it an excellent candidate for observations aimed at atmospheric characterization. We also present evidence for a bound stellar companion at a projected separation of similar to 1100 au, and speculate that it may have contributed to the strong misalignment we suspect between KELT-18's spin axis and its planet's orbital axis. The inferior conjunction time is 2457542.524998 +/- 0.000416 (BJDTDB) and the orbital period is 2.8717510 +/- 0.0000029 days. We encourage Rossiter-McLaughlin measurements in the near future to confirm the suspected spin-orbit misalignment of this system.