Multiplicity Study of Exoplanet Host Stars

Abstract:

A key aspect in the diversity of exoplanets is the multiplicity of their host stars.

As described by theories stellar companions of exoplanet host stars can significantly influence the formation process of planets around these stars as well as the long-term evolution of their orbits. On the one hand, in close binary systems, planet formation and long-term stable orbits of planets are restricted to the close vicinity (only a few astronomical units) around the host stars. On the other hand, in wide binary systems, the orbital evolution of the star system itself, for example under the influence of galactic tides or perturbations from other passing stars, can significantly affect the orbits of exoplanets around their host stars.

How planets form and evolve in multiple star systems is a very important question in modern astrophysics, since a large fraction of the stars in our galaxy are members of binary or even higher order multiple star systems. Furthermore, the efficiency of planet formation in these systems also affects the total number of planets in the Milky Way.

In order to detect such stellar systems with exoplanets, we have initiated several surveys to search for stellar companions of exoplanet host stars, using either seeing-limited, lucky-, or high-contrast adaptive optics imaging, as well as data releases of the European Space Agency (ESA) Gaia mission. With these different surveys, we are able to cover the entire detection space for possible stellar companions around the exoplanet host stars and can thus accurately determine the multiplicity rate of these stars, and characterize the properties of their companions. Eventually, our efforts will allow us to determine the true impact of stellar multiplicity on planet formation and evolution.

Latest Results:

Detected White Dwarf Companions of (Community) TESS Objects of Interest

Left Figure: Images of (C)TOIs with white dwarf companions, detected in the course of our Gaia multiplicity survey of (Community) TESS Objects of Interest. Right Figure: The absolute magnitude MG plotted against Teff of the components of all star systems with detected white dwarf companions. The grey dashed line shows the main sequence, the black dotted lines the evolutionary mass tracks of DA white dwarfs with masses of 0.5 and 0.6 M☉. The primaries of the systems are shown as red circles, the white dwarf secondaries as blue circles, respectively.

Reference: Mugrauer et al. (2024) "Gaia Search for Stellar Companions of TESS Objects of Interest V", AN in press

The Impact of stellar Multiplicity on the Properties of Exoplanets and their Host Stars

Left Figure: Cumulative distribution function of the mass of single and multiple star planets. Middle Figure: Cumulative distribution function of the semi-major axis of single and multiple (super-)Jupiters. Right Figure: Cumulative distribution function of the mass of single and multiple exoplanet host stars.

Reference: Mugrauer et al. (2024) "The impact of stellar multiplicity on the formation and evolution of planets" eas conf, 715

The Team

Principle Investigator

  • Markus Mugrauer (AIU Jena)

Team Members:

  • Christian Adam (Centro de Astronomía de la Universidad de Antofagasta)
  • Lara Dürrenberg (FSU Jena)
  • Matilde Fernández Hernández (IAA-CSIC)
  • Christian Ginski (University of Galway)
  • Kai-Uwe Michel (AIU Jena)
  • Ralph Neuhäuser (AIU Jena)
  • Saskia Schlagenhauf (Armagh Observatory and Planetarium)
  • Lara Pietsch (AIU Jena)

Former Team Members:

  • Sven Buder
  • Therese Heyne
  • Ann-Kathrin Kollak
  • Tsevi Mazeh
  • Friedemann Reum
  • Tristan Röll
  • Johanna Rück
  • Martin Seeliger
  • Andreas Seifahrt
  • Nikolaus Vogt
  • Jule Zander

Our current Projects:
  • Long-term Multiplicity Survey of northern Exoplanet host Stars with the Lucky-Imager AstraLux at CAHA/2.2m (started in 2008) → for results see publications below
  • Long-term Multiplicity Survey of southern Exoplanet host Stars using the extreme Adaptive Optics SPHERE/VLT (started in 2016) → for results see publications below
  • Multiplicity Study of Exoplanet Hosts using Data of the ESA-Gaia mission (started in 2018) → for results see publications below & VizieR catalogues of detected companions (Link1, Link2, Link3)
  • ESA-Gaia Search for stellar companions of TESS Objects of Interest (started in 2020) → for results see publications below & VizieR catalogues of detected companions (Link1, Link2, Link3, Link4, Link5) & Online image library of detected companions

Our Publications:

Student Thesis Work:
  • Dürrenberg, L. (2023) "Suche und Charakterisierung stellarer Begleiter von KOIs"
  • Kollak, A.-K. (2022) "Suche nach stellaren Begleitern von (C)TOIs"
  • Michel, K.-U. (2021) "Search for (sub)stellar Companions of Exoplanet Hosts by using Data from the ESA-Gaia mission"
  • Pietsch, L. (2024) "Suche und Charakterisierung stellarer Begleiter von (C)TOIs"
  • Rück, J. (2022) "Suche nach stellaren Begleitern potentieller Planeten-Muttersterne"
  • Schlagenhauf, S. (2022) "AstraLux Lucky-Imaging Observations of Exoplanet host Stars"
  • Zander, J. (2021) "ESA-Gaia Search for stellar Companions of TESS Objects of Interest"

Press Releases: