Gaia search for stellar companions of TESS Objects of Interest II

Abstract

We present the latest results of our ongoing multiplicity study of (Community) TESS Objects of Interest, using astro-and photometric data from the ESA-Gaia mission, to detect stellar companions of these stars and to characterize their properties. In total, 107 binary, 5 hierarchical triple star systems, as well as one quadruple system were detected among 585 targets surveyed, which are all located at distances closer than about 500 pc around the Sun. As proven with their accurate Gaia EDR3 astrometry, the companions and the targets are located at the same distance and share a common proper motion, as it is expected for components of gravitationally bound stellar systems. The companions exhibit masses in the range between about 0.09 M ⊙ and 4.5 M ⊙ and are most frequently found in the mass range between 0.15 and 0.6 M ⊙ . The companions are separated from the targets by about 120 up to 9,500 au and their frequency is the highest and constant within about 500 au while it continually decreases for larger separations. Beside mainly early to mid M dwarfs, also five white dwarf companions were identified in this survey, whose true nature was revealed by their photometric properties.

Gaia search for stellar companions of TESS Objects of Interest III

“…For comparison, we show the Gaia EDR3 detection limit, determined by Mugrauer & Michel (2021) among (C)TOIs, which agrees well with the detection limit of the survey, presented here. Only at small angular separations below about 0.6 arcsec, it appears to be too conservative.…”

“…The magnitude differences of all detected companions plotted against their angular separations to the associated (C)TOIs. The Gaia detection limit among (C)TOIs, found by Mugrauer & Michel (2021), is shown as a dotted line for comparison. The expected average magnitude differences for companions with 0.1 or 0.6 $$$ {M}_{\odot } $$$ are drawn as gray dashed horizontal lines…”

“…As started in Mugrauer & Michel (2021) the search for companions, presented here, uses astro‐ and photometric data from the Gaia EDR3, acquired with the instruments of the ESA‐Gaia satellite during the first 34 months of its mission. This data release contains astrometric solutions, that is, positions ($$$ \alpha $$$, $$$ \delta $$$), parallaxes $$$ \pi $$$, and proper motions ($$$ {\mu}_{\alpha}\cos \left(\delta \right) $$$, $$$ {\mu}_{\delta } $$$) of about 1.5 billion sources down to a limiting magnitude of 21 mag in the G‐band, that is, white light observations, taking advantage of the full spectral sensitivity of the used CCD‐detectors.…”

“…The selection of targets did not include 603 (C)TOIs with dips in their light curves, which could already be classified as false‐positive detections by the follow‐up observations performed in the ExoFOP‐TESS. In addition, 585 (C)TOIs, whose multiplicity had already been investigated by Mugrauer & Michel (2021) using the Gaia EDR3, were also excluded as targets.…”

“…In our survey, stellar companions of (C)TOIs are detected and their properties are determined with astro‐ and photometry, originally from the 2nd data release (Gaia DR2 from hereon, Gaia Collaboration et al 2018) and later from the early version of the 3rd data release (Gaia EDR3 from hereon, Gaia Collaboration et al 2021) of the ESA‐Gaia mission. The first results of the survey were presented by Mugrauer & Michel (2020) and Mugrauer & Michel (2021), who have already examined the multiplicity of 1976 (C)TOIs, which are all listed in the (C)TOI release of the Exoplanet Follow‐up Observing Program for TESS (ExoFOP‐TESS) by the beginning of December 2020. In the meantime, many of these (C)TOIs, which were revealed as members of multiple star systems in the course of our survey, have already been proven to be exoplanet host stars through follow‐up observations, for example, TOI 129, TOI 130, TOI 421, TOI 451, TOI 488, TOI 737, TOI 811, TOI 833,TOI 1098, TOI 1201, TOI 1259, TOI 1333, TOI 1411, TOI 1634, TOI 1759, and TOI 1860, which are listed in the Extrasolar Planets Encyclopaedia (see Schneider et al 2011, and references therein).…”