Searching for spectroscopic binaries within transition disk objects

TL;DR

This study conducted high-resolution spectroscopic observations of 31 transition disk objects to identify spectroscopic binaries, finding a low binary fraction similar to non-transition disks, implying binaries may not significantly influence disk gaps.

Contribution

First spectroscopic survey of transition disks to measure binary fraction, showing no significant difference from non-transition disks, challenging binary-driven gap formation theories.

Findings

Detected one spectroscopic binary in the sample.

Binary fraction consistent with non-transition disks.

Close binaries unlikely to be the primary cause of disk gaps.

Abstract

Transition disks (TDs) are intermediate stage circumstellar disks characterized by an inner gap within the disk structure. To test whether these gaps may have been formed by closely orbiting, previously undetected stellar companions, we collected high-resolution optical spectra of 31 TD objects to search for spectroscopic binaries (SBs). Twenty-four of these objects are in Ophiuchus and seven are within the Coronet, Corona Australis, and Chameleon I star-forming regions. We measured radial velocities for multiple epochs, obtaining a median precision of 400 ms$^{-1}$. We identified double-lined SB SSTc2d J163154.7-250324 in Ophiuchus, which we determined to be composed of a K7($\pm$0.5) and a K9($\pm$0.5) star, with orbital limits of $a<$0.6 AU and $P<$150 days. This results in an SB fraction of 0.04$^{+0.12}_{-0.03}$ in Ophiuchus, which is consistent with other spectroscopic surveys of non-TD objects in the region. This similarity suggests that TDs are not preferentially sculpted by the presence of close binaries and that planet formation around close binaries may take place over similar timescales to that around single stars.