Upper limits on exosatellites around $β$ Pictoris b

arXiv (Cornell University)

Abstract

$β$ 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 $β$ 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$^{-1}$. The resultant set of radial velocities is analysed with a periodogram to search for candidate 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 P=1 day and 1 Jupiter at P=200 days, comparable to RV exomoon searches around other substellar companions. The RV limit is comparable with the astrometric exomoon limit at a period of 7 days and a mass of 150 Earth masses, where for longer periods the astrometric searches have lower mass limits. With an additional observing season, CRIRES+ can detect a planet/moon mass ratio of $10^{-3}$ (4 Earth masses) with a period of up to one day, and can detect a Neptune-mass moon at hundreds of Jupiter radii.

Authors 11

1. M. A. Kenworthy Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , Postbus 9513 , 2300 RA Leiden , The Netherlands

2. R. Landman Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , Postbus 9513 , 2300 RA Leiden , The Netherlands

3. Andrew M. Vanderburg

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics | Harvard & Smithsonian , 60 Garden Street , Cambridge , MA 02138 , USA

   Department of Physics and

4. J. E. Rodriguez

   Michigan State University

   Affiliation as printed

   Center for Data Intensive and Time Domain Astronomy , Department of Physics and Astronomy , Michigan State University , East Lansing , MI 48824 , USA

5. Jayne Birkby

   University of Oxford

   Affiliation as printed

   Astrophysics , University of Oxford , Denys Wilkinson Building , Keble Road , Oxford , OX1 3RH , UK

6. I. Macias

   University of Florida · Massachusetts Institute of Technology

   Affiliation as printed

   Department of Astronomy , University of Florida , Bryant Space Science Center , Stadium Road , Gainesville , FL 32611 , USA

   Department of Earth, Atmospheric, and Planetary Sciences , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , MA 02139 , USA

7. D. González Picos Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , Postbus 9513 , 2300 RA Leiden , The Netherlands

8. S. A. Jenkins

   Massachusetts Institute of Technology · Michigan State University

   Affiliation as printed

   Center for Data Intensive and Time Domain Astronomy , Department of Physics and Astronomy , Michigan State University , East Lansing , MI 48824 , USA

   Kavli Institute for Astrophysics and Space Research , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA

9. Evangelia Kleisioti Aachen Leiden Observatory

   Leiden University · Leiden Observatory · Delft University of Technology

   Affiliation as printed

   Faculty of Aerospace Engineering , Delft University of Technology , 2629 HS , Delft , The Netherlands

   Leiden Observatory , Leiden University , Postbus 9513 , 2300 RA Leiden , The Netherlands

10. T. Stolker Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory , Leiden University , Postbus 9513 , 2300 RA Leiden , The Netherlands

11. I. Koutalios Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory , Leiden University , Postbus 9513 , 2300 RA Leiden , The Netherlands