Detection of Planetary and Stellar Companions to Neighboring Stars via a Combination of Radial Velocity and Direct Imaging Techniques

Abstract

The sensitivity of radial velocity (RV) surveys for exoplanet detection are extending to increasingly long orbital periods, where companions with periods of several years are now being regularly discovered. Companions with orbital periods that exceed the duration of the survey manifest in the data as an incomplete orbit or linear trend, a feature that can either present as the sole detectable companion to the host star, or as an additional signal overlain on the signatures of previously discovered companion(s). A diagnostic that can confirm or constrain scenarios in which the trend is caused by an unseen stellar, rather than planetary, companion is the use of high-contrast imaging observations. Here, we present RV data from the Anglo-Australian Planet Search (AAPS) for twenty stars that show evidence of orbiting companions. Of these, six companions have resolved orbits, with three that lie in the planetary regime. Two of these (HD~92987b and HD~221420b) are new discoveries. Follow-up observations using the Differential Speckle Survey Instrument (DSSI) on the Gemini South telescope revealed that five of the twenty monitored companions are likely stellar in nature. We use the sensitivity of the AAPS and DSSI data to place constraints on the mass of the companions for the remaining systems. Our analysis shows that a planetary-mass companion provides the most likely self-consistent explanation of the data for many of the remaining systems.

13 pages, 6 figures, 4 tables, accepted for publication in the Astronomical Journal (submitted 25 Feb 2019; accepted 28 April 2019). Machine readable tables and Posteriors from the RadVel fits are available here: http://stephenkane.net/rvfits.tar

References in corpus (17)

• The Gaia mission
• The Dartmouth Stellar Evolution Database
• One or more bound planets per Milky Way star from microlensing observations
• No large population of unbound or wide-orbit Jupiter-mass planets
• An Earth-sized Planet in the Habitable Zone of a Cool Star
• Efficient fitting of multiplanet Keplerian models to radial velocity and astrometry data
• Most Sub-Arcsecond Companions of Kepler Exoplanet Candidate Host Stars are Gravitationally Bound
• Constraining Orbital Parameters Through Planetary Transit Monitoring
• The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets
• The Jupiter Twin HD 154345b
• A Direct Imaging Survey of Spitzer detected debris disks: Occurrence of giant planets in dusty systems
• High-resolution Multi-band Imaging for Validation and Characterization of Small Kepler Planets
• Assessing the Effect of Stellar Companions from High-Resolution Imaging of Kepler Objects of Interest
• Speckle Imaging Excludes Low-Mass Companions Orbiting the Exoplanet Host Star TRAPPIST-1
• Stellar Companions to the Exoplanet Host Stars HD 2638 and HD 164509
• Exclusion of Stellar Companions to Exoplanet Host Stars
• Discovery of a Compact Companion to a Nearby Star

Cited by in corpus (24)

• Gaia Early Data Release 3: The Gaia Catalogue of Nearby Stars
• Cool Jupiters greatly outnumber their toasty siblings: Occurrence rates from the Anglo-Australian Planet Search
• 3-D selection of 167 sub-stellar companions to nearby stars
• Solar System Physics for Exoplanet Research
• True masses of the long-period companions to HD 92987 and HD 221420 from Hipparcos-Gaia astrometry
• The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 day Orbit with the Automated Planet Finder Telescope
• The Pan-Pacific Planet Search. VIII. Complete results and the occurrence rate of planets around low-luminosity giants
• Frequency of Planets in Binaries
• The Masses of a Sample of Radial-Velocity Exoplanets with Astrometric Measurements
• Joint Radial Velocity and Direct Imaging Planet Yield Calculations: I. Self-consistent Planet Populations
• In the Presence of a Wrecking Ball: Orbital Stability in the HR 5183 System
• Updated characterization of long-period single companion by combining radial velocity, relative astrometry, and absolute astrometry
• Precise dynamical masses of new directly imaged companions from combining relative astrometry, radial velocities, and Hipparcos-Gaia eDR3 accelerations
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Year, Highly Eccentric Orbit
• Speckle Imaging Characterization of Radial Velocity Exoplanet Systems
• Multi techniques approach to identify and/or constrain radial velocity sub-stellar companions
• Luminaries in the Sky: The TESS Legacy Sample of Bright Stars. I. Asteroseismic detections in naked-eye main-sequence and sub-giant solar-like oscillators
• Radial velocity confirmation of a hot super-Neptune discovered by TESS with a warm Saturn-mass companion
• Observational constraints on the formation and evolution of Neptune-class exoplanets
• The California Legacy Survey II. Occurrence of Giant Planets Beyond the Ice line
• An Edge-On Orbit for the Eccentric Long-Period Planet HR 5183 b
• Stability analysis of three exoplanet systems
• Precise Masses and Orbits for Nine Radial Velocity Exoplanets
• SPORES-HWO. II. Companion Mass Limits and Updated Planet Properties for 120 Future Exoplanet Imaging Targets from 35 yr of Precise Doppler Monitoring