Upper limits on exosatellites around β Pictoris b

Journal article

Pictoris b is one of the closest known directly imaged gas giant exoplanets with an orbit that is almost edge-on to our line of sight, making it an ideal target for radial velocity monitoring to search for massive exomoons. We measure the radial velocity of Pictoris b over several epochs between October 2024 and March 2025 by using the cross-correlation of a template spectrum with absorption lines in the planet’s atmosphere, giving a mean precision of 160 m s. The resultant set of radial velocities is analysed with a periodogram to search for candidate radial velocity (RV) signals indicating a massive exomoon. Although we do not detect an exomoon signal in our data, our detection limits for a single moon are 80 Earth masses at d and 1 Jupiter at d, comparable to RV exomoon searches around other substellar companions. The RV limit is comparable with the astrometric exomoon limit at a period of 7 d and a mass of 150 , where for longer periods the astrometric searches have lower mass limits. With an additional observing season, the upgraded CRyogenic InfraRed Echelle Spectrograph (CRIRES+) can detect a planet/moon mass ratio of () with a period of up to one day, and can detect a Neptune-mass moon at hundreds of Jupiter radii.

Authors: Kenworthy, MA; Landman, R; Vanderburg, A; Rodriguez, JE; Birkby, JL

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 549
• Issue: 4
• Article number: stag1060
• Publication date: 2026-06-05
• Acceptance date: 2026-05-29
• DOI: 10.1093/mnras/stag1060
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: techniques: radial velocities; exoplanets; stars: individual: Beta Pictoris