ARMADA. I. Triple Companions Detected in B-type Binaries α Del and ν Gem

Tyler Gardner, John D. Monnier, Francis C. Fekel, Gail Schaefer, Keith J.C. Johnson, Jean Baptiste Le Bouquin, Stefan Kraus, Narsireddy Anugu, Benjamin R. Setterholm, Aaron Labdon, Claire L. Davies, Cyprien Lanthermann, Jacob Ennis, Michael Ireland, Kaitlin M. Kratter, Theo Ten Brummelaar, Judit Sturmann, Laszlo Sturmann, Chris Farrington, Douglas R. GiesRobert Klement, Fred C. Adams

Research output: Contribution to journalArticlepeer-review

Abstract

Ground-based optical long-baseline interferometry has the power to measure the orbits of close binary systems at ∼10 μas precision. This precision makes it possible to detect "wobbles"in the binary motion due to the gravitational pull from additional short-period companions. We started the ARrangement for Micro-Arcsecond Differential Astrometry (ARMADA) survey with the Michigan Infra-Red Combiner (MIRC)/MIRC-X instrument at the Center for High Angular Resoloution Astronomy (CHARA) array for the purpose of detecting giant planets and stellar companions orbiting individual stars in binary systems. We describe our observations for the survey, and introduce the wavelength calibration scheme that delivers precision at the tens of microarcseconds level for <0.″2 binaries. We test our instrument performance on a known triple system, κ Peg, and show that our survey is delivering a factor of 10 better precision than previous similar surveys. We present astrometric detections of tertiary components to two B-type binaries: a 30 day companion to α Del, and a 50 day companion to ν Gem. We also collected radial velocity data for α Del with the Tennessee State University Automated Spectroscopic Telescope at Fairborn Observatory. We are able to measure the orbits and masses of all three components in these systems. We find that the previously published radial velocity orbit for the inner pair of ν Gem is not consistent with our visual orbit. The precision achieved for these orbits suggests that our ARMADA survey will be successful at discovering new compact triple systems to A/B-type binary systems, leading to better statistics of hierarchical system architectures and formation history.

Original languageEnglish (US)
Article number40
JournalAstronomical Journal
Volume161
Issue number1
DOIs
StatePublished - Jan 2021

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint

Dive into the research topics of 'ARMADA. I. Triple Companions Detected in B-type Binaries α Del and ν Gem'. Together they form a unique fingerprint.

Cite this