A low stellar obliquity for WASP-47, a compact multiplanet system with a hot Jupiter and an ultra-short period planet

Abstract

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 $\lambda =0^{\circ }\pm 24^{\circ }$. 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${}^{\circ }$, remains the only clear counterexample.

5 pages, 2 figures, Accepted for publication on ApJL, comments welcome

References in corpus (15)

• The K2 Mission: Characterization and Early results
• Prospects for the Characterization and Confirmation of Transiting Exoplanets via the Rossiter-McLaughlin Effect
• The Mass of KOI-94d and a Relation for Planet Radius, Mass, and Incident Flux
• WASP-47: A Hot Jupiter System with Two Additional Planets Discovered by K2
• Five Planets Orbiting 55 Cancri
• Kepler constraints on planets near hot Jupiters
• Determining stellar macroturbulence using asteroseismic rotational velocities from Kepler
• A Study of the Shortest-Period Planets Found With Kepler
• The Exoplanet Orbit Database II: Updates to exoplanets.org
• Alignment of the stellar spin with the orbits of a three-planet system
• Photometric Amplitude Distribution of Stellar Rotation of Kepler KOIs-Indication for Spin-Orbit Alignment of Cool Stars and High Obliquity for Hot Stars
• Obliquities of Kepler Stars: Comparison of Single- and Multiple-Transit Systems
• Detecting the spin-orbit misalignment of the super-Earth 55 Cnc e
• The Dynamics of the Multi-planet System Orbiting Kepler-56
• Rossiter-McLaughlin Observations of 55 Cnc e

Cited by in corpus (36)

• State of the Field: Extreme Precision Radial Velocities
• Stellar obliquities in exoplanetary systems
• The discoveries of WASP-91b, WASP-105b and WASP-107b: two warm Jupiters and a planet in the transition region between ice giants and gas giants
• Hot Jupiters with relatives: discovery of additional planets in orbit around WASP-41 and WASP-47
• DREAM I. Orbital architecture orrery
• Evidence for Hidden Nearby Companions to Hot Jupiters
• Precise Masses in the WASP-47 System
• The discovery and mass measurement of a new ultra-short-period planet: EPIC~228732031b
• Effects of Unseen Additional Planetary Perturbers on Compact Extrasolar Planetary Systems
• Planet Formation in Disks with Inclined Binary Companions: Can Primordial Spin-Orbit Misalignment be Produced?
• Stellar Spin-Orbit Alignment for Kepler-9, a Multi-transiting Planetary system with Two Outer Planets Near 2:1 Resonance
• Ultra Short Period Planets in K2: SuPerPiG Results for Campaigns 0-5
• The TESS-Keck Survey II: An Ultra-Short Period Rocky Planet and its Siblings Transiting the Galactic Thick-Disk Star TOI-561
• GJ 1252 b: A 1.2 $R_{\oplus }$ planet transiting an M3-dwarf at 20.4 pc
• Mass and Eccentricity Constraints in the WASP-47 Planetary System from a Simultaneous Analysis of Radial Velocities & Transit Timing Variations
• Investigating the architecture and internal structure of the TOI-561 system planets with CHEOPS, HARPS-N and TESS
• DREAM II. The spin-orbit angle distribution of close-in exoplanets under the lens of tides
• A Multi-Planet System Transiting the $V$ = 9 Rapidly Rotating F-Star HD 106315
• The Aligned Orbit of WASP-148b, the Only Known Hot Jupiter with a Nearby Warm Jupiter Companion, from NEID and HIRES
• The warm Neptunes around HD 106315 have low stellar obliquities
• Absolute densities, masses, and radii of the WASP-47 system determined dynamically
• Mass Constraints of the WASP-47 Planetary System from Radial Velocities
• Doppler Monitoring of the WASP-47 Multiplanet System
• A new dynamical modeling of the WASP-47 system with CHEOPS observations
• Spin-orbit alignments for Three Transiting Hot Jupiters: WASP-103b, WASP-87b, & WASP-66b
• A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system
• How do External Companions Affect Spin-Orbit Misalignment of Hot Jupiters?
• On a Possible Solution to the Tidal Realignment Problem for Hot Jupiters
• Stellar Obliquities & Planetary Alignments (SOPA) I. Spin-Orbit measurements of Three Transiting Hot Jupiters: WASP-72b, WASP-100b, & WASP-109b
• Exterior Companions to Hot Jupiters Orbiting Cool Stars are Coplanar
• Evidence for Primordial Alignment: Insights from Stellar Obliquity Measurements for Compact Sub-Saturn Systems
• Revisiting WASP-47 with ESPRESSO and TESS
• Stellar obliquities and magnetic activities of Planet-Hosting Stars and Eclipsing Binaries based on Transit Chord Correlation
• Revisiting the Architecture of the KOI-89 System
• Evidence for Primordial Alignment II: Insights from Stellar Obliquity Measurements for Hot Jupiters in Compact Multiplanet Systems
• Evidence for the Late Arrival of Hot Jupiters in Systems with High Host-star Obliquities