A Model-independent Mass and Moderate Eccentricity for β Pic b

Trent J. Dupuy, Timothy D. Brandt, Kaitlin M. Kratter, Brendan P. Bowler

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


We use a cross-calibration of Hipparcos and Gaia second data release astrometry for β Pic to measure the mass of the giant planet β Pic b (13 ± 3 ) in a comprehensive joint orbit analysis that includes published relative astrometry and radial velocities. Our mass uncertainty is somewhat higher than previous work because our astrometry from the Hipparcos-Gaia Catalog of Accelerations accounts for the error inflation and systematic terms that are required to bring the two data sets onto a common astrometric reference frame, and because we fit freely for the host-star mass (1.84 ± 0.05 M o ). This first model-independent mass for a directly imaged planet is inconsistent with cold-start models given the age of the β Pic moving group (22 ± 6 Myr) but consistent with hot- and warm-start models, concordant with past work. We find a higher eccentricity (0.24 ± 0.06) for β Pic b compared to previous orbital fits. If confirmed by future observations, this eccentricity may help explain inner edge, scale height, and brightness asymmetry of β Pic's disk. It could also potentially signal that β Pic b has migrated inward to its current location, acquiring its eccentricity from interaction with the 3:1 outer Lindblad resonance in the disk.

Original languageEnglish (US)
Article numberL4
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Jan 20 2019


  • astrometry
  • planetary systems
  • stars: individual (bet Pic)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'A Model-independent Mass and Moderate Eccentricity for β Pic b'. Together they form a unique fingerprint.

Cite this