Surveying the Bright Stars by Optical Interferometry I: A Search for Multiplicity Among Stars of Spectral Types F - K

Abstract

We present the first results from an ongoing survey for multiplicity among the bright stars using the Navy Precision Optical Interferometer (NPOI). We first present a summary of NPOI observations of known multiple systems, including the first detection of the companion of $\beta$ Scuti with precise relative astrometry, to illustrate the instrument's detection sensitivity for binaries at magnitude differences $\Delta$$m$ $⪅$ 3 over the range of angular separation 3 - 860 milliarcseconds (mas). A limiting $\Delta$$m_{700}$ $\sim$ 3.5 is likely for binaries where the component spectral types differ by less than two. Model fits to these data show good agreement with published orbits, and we additionally present a new orbit solution for one of these stars, $\sigma$ Her. We then discuss early results of the survey of bright stars at $\delta$ $\ge$ -20$°$. This survey, which complements previous surveys of the bright stars by speckle interferometry, initially emphasizes bright stars of spectral types F0 through K2. We report observations of 41 stars of apparent visual magnitude $m_V$ $\le$ 4.30, all having been observed on multiple nights. Analysis of these data produces fitted angular separations, position angles, and component magnitude differences for six previously known visual binaries. Three additional systems were examined as possible binaries, but no conclusive detection could be made. No evidence of close stellar companions within our detection limit of $\Delta$$m$ $\approx$ 3 was found for the remaining 32 stars observed; however, uniform-disk angular diameters are reported for 11 of the resolved stars in this last group.

114 pages, 16 figures, 14 tables, accepted for publication in the Astrophysical Journal Supplement Series

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Cited by in corpus (8)

• Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer
• Precise calibration of the dependence of surface brightness-colour relations on colour and class for late-type stars
• Angular Diameters and Fundamental Parameters of Forty-Four Stars from the Navy Precision Optical Interferometer
• Dynamical parallax, physical parameters and evolutionary status of the components of the bright eclipsing binary α Draconis
• Thirty-Three New Stellar Angular Diameters from the NPOI, and Nearly 180 NPOI Diameters as an Ensemble
• Solar-like oscillations in $\gamma$ Cephei A as seen through SONG and TESS
• Simultaneous Six-way Observations from the Navy Precision Optical Interferometer
• Vintage NPOI: New and Updated Angular Diameters for 145 Stars