Special Session SS12  13 July 2023

Planets not orbiting main sequence stars

News: Please, note that this sessions will consist of invited talks only, each one followed by discussion. THERE WILL BE NO CONTRIBUTED TALKS, but e-posters are very welcome! If you have already submitted your abstract for a contributed talk, please, convert it to e-poster. Thanks!

Aims and scope

Extrasolar planetary science does not end when host stars leave the main sequence! Studies of planetary systems found within off-main sequence stellar environments represent an under-explored yet essential area of research within exoplanet science, which provides chemical and dynamical information not attainable in main-sequence planetary systems. Detections of planets around giant, subgiant and subdwarf stars furnish information about properties of planetary systems around descendants of intermediate mass stars. In addition, each detection of a planetary system around a sufficiently evolved, post-main sequence star provides a "snapshot" of the changes in its dynamical configuration powered by evolution of the parent star. Mounting detections of the debris disks (over 60), the broken-up remnants of minor planets (over 1,000), and recent evidence for the surviving major planets around white dwarfs (at distances ranging from 0.02 au to 2,500 au), reveal how evolving stars transform planetary systems at the endpoint of stellar evolution. This field has now become mature enough to enable a broad discussion involving planet detections, the evolution of planetary system architectures, population synthesis, and a variety of theoretical studies.

Planets and sub-stellar mass stellar remnants orbiting neutron stars form another, small population of bodies associated with remnants of stellar evolution, and provide crucial information about second-generation rocky body formation. The rarity of neutron star planetary systems is still unclear, and there have been several recent surveys attempting to address this outstanding issue that are worth discussing.

Another emerging population of planets that are not bound to the main sequence or post-main sequence stars are the "free-floating planets" discovered in young stellar associations, in the Galactic field, and by microlensing surveys -- not to mention their smaller cousins, Oumuamua and Borisov, which have passed through the Solar System. Such planets appear to be very abundant, but more surveys and theoretical work are needed to fully understand their origins, evolution and statistics.

This session will be devoted to the evolution of planetary systems driven by the transformation of the main sequence host stars to giants and then, finally, to the white dwarf stars. We will also review the influence of stellar evolution on the long-term survival of life. Another part of the proposed session will discuss the free-floating planets, their origins, and their relationship to planets bound to main sequence and post-main sequence stars. We expect this session to provide a broad synthesis of the current state of the field of planets off the main sequence, and to establish main directions for future research.



  • Searches for subgiant/giant planets
  • Theory: (RGB to AGB)
  • Theory: (CE evolution, post-AGB, pre-WD phase)


  • Hot subdwarfs
  • WD atmospheric pollution
  • WD disks


  • Searches for WD planets
  • Searches for NS planets
  • The origin of free-floating planets

Invited speakers

  • Sam Grunblatt (Johns Hopkins University, USA)
  • Paula Izquierdo (University of Warwick, UK)
  • Uri Malamud (Technion, Israel)
  • Nuria Miret Roig (University of Vienna, Austria)
  • Alex Mustill (Lund University, Sweden)
  • Jason Nordhaus (Rochester Institute of Technology, USA)
  • Zach Vanderbosch (Caltech, USA)
  • Valerie van Grootel (University of Liege)

Scientific organisers

Isabelle Baraffe (University of Exeter, UK), Martin Dominik (University of St Andrews, UK), Boris Gaensicke (University of Warwick, UK), Andrzej Niedzielski (Nicolaus Copernicus University, Poland), Roberto Silvotti (INAF, Osservatorio Astrofisico di Torino, Italy), Dimitri Veras (University of Warwick, UK), Eva Villaver (CSIC-INTA, Centro de Astrobiologia, Spain), Alex Wolszczan (chair, Penn State University, USA)


Alex Wolszczan, e-mail: alex @ astro.psu.edu

Updated on Thu Mar 23 15:50:43 CET 2023