Multiplicity Study of Exoplanet Host Stars

The team | Latest results | Our current Projects | Our Publications | Student Thesis Work | Press Releases

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:

Detection of White Dwarf Companions of (potential) Exoplanet Host Stars

Left and middle Figure: VIRCAM/VISTA Ks-band images of TOI 2486, and CTOI 161478895. The intrinsic faintness of the white dwarf companions TOI 2486 C and CTOI 161478895 A in the near infrared spectral range is clearly visible in these images.

Right Figure: A (RGB)-color-composite image of TOI 388 (alias WASP-71) with its white dwarf companion TOI 388 B, made of y-, i-, and g-band images, taken by Pan-STARRS.

Reference: Mugrauer, M., Zander, J., & Michel, K.-U. (2022) "Gaia Search for stellar Companions of TESS Objects of Interest III" AN, e20224017

 Follow-up Observations of the Exoplanet host Binary System g Cep 

Figure.: AstraLux i'-band images of the exoplanet host star g Cep A, and its close stellar companion g Cep B (marked with a white arrow in each image), taken between 2014 and 2020. The AstraLux astrometry is used to obtain an accurate orbital solution for this binary star system and to determine its system parameters.

Reference: Mugrauer, M., Schlagenhauf, S., Buder, S., Ginski, C., Fernández, M., (2022) "Follow-up observations of the binary system g Cep" AN, 343, e224014

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 (Anton Pannekoek Institute for Astronomy)

• Ann-Kathrin Kollak (AIU Jena)

• Kai-Uwe Michel (AIU Jena)

• Ralph Neuhäuser (AIU Jena)

• Johanna Rück (AIU Jena)

• Saskia Schlagenhauf (AIU Jena)

• Nikolaus Vogt (Universidad de Valparaíso)

• Jule Zander (AIU Jena)

Former Team Members:

• Sven Buder

• Therese Heyne

• Tsevi Mazeh

• Friedemann Reum

• Tristan Röll

• Martin Seeliger

• Andreas Seifahrt

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)

• 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) & Our online image library of detected companions

Our Publications

• Mugrauer, M., Zander, J., & Michel, K.-U. (2022) "Gaia Search for stellar Companions of TESS Objects of Interest III" AN, e20224017

• Mugrauer, M., Schlagenhauf, S., Buder, S., Ginski, C., Fernández, M. (2022) "Follow-up observations of the binary system g Cep" AN, 343, e224014

• Mugrauer, M., & Michel, K.-U. (2021) "Gaia search for stellar companions of TESS Objects of Interest II" AN, 342, 840

• Michel, K.-U., & Mugrauer, M. (2021) "Search for (sub)stellar companions of exoplanet hosts by exploring the second ESA-Gaia data release" FrASS, 8, 14

• Mugrauer, M., & Michel, K.-U. (2020) "Gaia search for stellar companions of TESS Objects of Interest" AN, 341, 996

• Ginski, C., Mugrauer, M., Adam, C., et al. (2020) "How many suns are in the sky? A SPHERE multiplicity survey of exoplanet host stars I -- Four new close stellar companions including a white dwarf" A&A, 649, 156

• Mugrauer, M., Ginski, C., Vogt, N., et al. (2020) "How many suns are in the sky? Multiplicity surveys of exoplanet host stars" IAUS, 345, 316

• Mugrauer, M. (2019) "Search for stellar companions of exoplanet host stars by exploring the second ESA-Gaia data release" MNRAS, 490, 5088

• Mugrauer, M., Ginski, C., Vogt, N., et al. (2018) "Search for (Sub)Stellar Companions of Exoplanet Host Stars" dmss.conf, 21

• Cagigal, M. P., Valle, P. J., Cagigas, M. A., et al. (2017) "Covariance of lucky images: performance analysis" MNRAS, 464, 680

• Mugrauer, M., Buder, S., Reum, F., et al. (2017) "The Großschwabhausen binary survey" AN, 338, 61

• Mugrauer, M., & Dinçel, B. (2016) "Follow-up spectroscopic observations of HD 107148 B: A new white dwarf companion of an exoplanet host star" AN, 337, 627

• Ginski, C., Mugrauer, M., Seeliger, M., et al. (2016) "A lucky imaging multiplicity study of exoplanet host stars - II" MNRAS, 457, 2173

• Mugrauer, M., & Ginski, C. (2015) "High-contrast imaging search for stellar and substellar companions of exoplanet host stars" MNRAS, 450, 3127

• Mugrauer, M., Ginski, C., & Seeliger, M. (2014) "New wide stellar companions of exoplanet host stars" MNRAS, 439, 1063

• Ginski, C., Mugrauer, M., & Neuhäuser, R. (2014) "Lucky imaging multiplicity studies of exoplanet host stars" CoSka, 43, 410

• Ginski, C., Mugrauer, M., Seeliger, M., et al. (2013) "The multiplicity status of three exoplanet host stars" A&A, 559, A71

• Roell, T., Neuhäuser, R., Seifahrt, A., et al. (2012) "Extrasolar planets in stellar multiple systems" A&A, 542, A92

• Ginski, C., Mugrauer, M., Seeliger, M., et al. (2012) "A lucky imaging multiplicity study of exoplanet host stars" MNRAS, 421, 2498

• Mugrauer, M., Neuhäuser, R., Ginski, C., et al. (2010) "Multiplicity study of exoplanet host stars" HiA, 15, 694

• Mugrauer, M., & Neuhäuser, R. (2009) "The multiplicity of exoplanet host stars. New low-mass stellar companions of the exoplanet host stars HD 125612 and HD 212301" A&A, 494, 373

• Jang-Condell, H., Mugrauer, M., & Schmidt, T. (2008) "Disk Truncation and Planet Formation in γ Cephei" ApJL, 683, L191

• Neuhäuser, R., Mugrauer, M., Seifahrt, A., et al. (2008) "Astrometric and photometric monitoring of GQ Lupi and its sub-stellar companion" A&A, 484, 281

• Mugrauer, M., Seifahrt, A., Neuhäuser, R., et al. (2007) "Multiplicity Study of Exoplanet Host Stars: the HD 3651 AB System" IAUS, 240, 638

• Mugrauer, M., Neuhaeuser, R., Mazeh, T., et al. (2007) "Multiplicity study of Exoplanet host Stars" IAUS, 240, 329

• Neuhäuser, R., Seifahrt, A., Röll, T., et al. (2007) "Detectability of Planets in Wide Binaries by Ground-Based Relative Astrometry with AO" IAUS, 240, 261

• Mugrauer, M., Seifahrt, A., & Neuhäuser, R. (2007) "The multiplicity of planet host stars - new low-mass companions to planet host stars" MNRAS, 378, 1328

• Mugrauer, M., Neuhäuser, R., & Mazeh, T. (2007) "Spectroscopic confirmation of the companions GJ 3021 B and HD 27442 B, one new planet host triple-star system, and global statistics" A&A, 469, 755

• Seifahrt, A., Neuhäuser, R., & Hauschildt, P. H. (2007) "Near-infrared integral-field spectroscopy of the companion to GQ Lupi" A&A, 463, 309

• Neuhäuser, R., Mugrauer, M., Fukagawa, M., et al. (2007) "Direct detection of exoplanet host star companion γ Cep B and revised masses for both stars and the sub-stellar object" A&A, 462, 777

• Mugrauer, M., Seifahrt, A., Neuhäuser, R., et al. (2006) "HD3651B: the first directly imaged brown dwarf companion of an exoplanet host star" MNRAS, 373, L31

• Mugrauer, M., Neuhäuser, R., Mazeh, T., et al. (2006) "A search for wide visual companions of exoplanet host stars: The Calar Alto Survey" AN, 327, 321

• Mugrauer, M., & Neuhäuser, R. (2005) "GQ Lup and its common proper motion companion" AN, 326, 701

• Mugrauer, M., Neuhäuser, R., Seifahrt, A., et al. (2005) "Four new wide binaries among exoplanet host stars" A&A, 440, 1051

• Mugrauer, M., Neuhaeuser, R., Guenther, E., et al. (2005) "The multiplicity of exoplanet host stars" AN, 326, 629

• Mugrauer, M., & Neuhäuser, R. (2005) "Gl86B: a white dwarf orbits an exoplanet host star" MNRAS, 361, L15

• Neuhäuser, R., Guenther, E. W., Wuchterl, G., et al. (2005) "Evidence for a co-moving sub-stellar companion of GQ Lup" A&A, 435, L13

• Mugrauer, M., Neuhäuser, R., Guenther, E., et al. (2005) "Multiplicity of Exoplanet Hosts Stars" prpl.conf, 8026

• Mugrauer, M., Neuhäuser, R., Mazeh, T., et al. (2004) "A Direct Imaging Search for Wide (Sub)Stellar Companions around Rad-vel Planet Host Stars" ASPC, 321, 127

• Mugrauer, M., Neuhäuser, R., Mazeh, T., et al. (2004) "Astrometric confirmation of a wide low-mass companion to the planet host star HD 89744" AN, 325, 718

• Mugrauer, M., Neuhäuser, R., Mazeh, T., et al. (2004) "A low-mass stellar companion of the planet host star HD 75289" A&A, 425, 249

• Mugrauer, M., Neuhäuser, R., Mazeh, T., et al. (2004) "A Search for Wide (Sub)Stellar Companions Around Extrasolar Planet Host Stars" AIPC, 713, 31

Student Thesis Work

• Lara Dürrenberg: "Suche und Charakterisierung stellarer Begleiter von KOIs"

• Ann-Kathrin Kollak: "Suche nach stellaren Begleitern von (C)TOIs"

• Kai-Uwe Michel: "Search for (sub)stellar Companions of Exoplanet Hosts by using Data from the ESA-Gaia mission"

• Johanna Rück: "Suche nach stellaren Begleitern potentieller Planeten-Muttersterne"

• Saskia Schlagenhauf: "AstraLux Lucky-Imaging Observations of Exoplanet host Stars" 

• Jule Zander: "ESA-Gaia Search for stellar Companions of TESS Objects of Interest"

Press Releases

• FSU Jena press release 11/2019: "Distant worlds under many suns"

• Calar Alto press release 01/2007: "Double sun sunset no longer science fiction"

• ESO press release 10/2006: "The star, the dwarf and the planet"

• FSU Jena press release 07/2005: "Wie ein Planet zwischen zwei Sonnen entsteht und überlebt"