A LOW STELLAR OBLIQUITY FOR WASP-47, A COMPACT MULTIPLANET SYSTEM WITH A HOT JUPITER AND AN ULTRA-SHORT PERIOD PLANET

作者：Sanchis Ojeda Roberto^*; Winn Joshua N; Dai Fei; Howard Andrew W; Isaacson Howard; Marcy Geoffrey W; Petigura Erik; Sinukoff Evan; Weiss Lauren; Albrecht Simon; Hirano Teruyuki; Rogers Leslie

来源：Astrophysical Journal Letters, 2015, 812(1): L11.

DOI：10.1088/2041-8205/812/1/L11

• planet
• star interactions
• planetary systems
• planets and satellites: formation
• stars: rotation

We have detected the Rossiter-Mclaughlin effect during a transit of WASP-47b, the only known hot Jupiter with close planetary companions. By combining our spectroscopic observations with Kepler photometry, we show that the projected stellar obliquity is lambda = 0 degrees +/- 24 degrees. We can firmly exclude a retrograde orbit for WASP-47b, and rule out strongly misaligned prograde orbits. Low obliquities have also been found for most of the other compact multiplanet systems that have been investigated. The Kepler-56 system, with two close-in gas giants transiting their subgiant host star with an obliquity of at least 45 degrees, remains the only clear counterexample.

• 出版日期2015-10-10