Doppler Monitoring of the WASP-47 Multiplanet System

We present precise Doppler observations of WASP-47, a transiting planetary system featuring a hot Jupiter with both inner and outer planetary companions. This system has an unusual architecture and also provides a rare opportunity to measure planet masses in two different ways: the Doppler method, and the analysis of transit-timing variations (TTV). Based on the new Doppler data, obtained with the Planet Finder Spectrograph on the Magellan/Clay 6.5 m telescope, the mass of the hot Jupiter is 370+/- 29 {M}_\oplus . This is consistent with the previous Doppler determination as well as the TTV determination. For the inner planet WASP-47e, the Doppler data lead to a mass of 12.2+/- 3.7 {M}_\oplus , in agreement with the TTV-based upper limit of <22 M_⊕ (95% confidence). For the outer planet WASP-47d, the Doppler mass constraint of 10.4+/- 8.4 {M}_\oplus is consistent with the TTV-based measurement of {15.2}_-7.6^+6.7 {M}_\oplus .

This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.