Precision Millimeter Astrometry of the $\alpha$ Centauri AB System

Abstract

$\alpha$ Centauri A is the closest solar-type star to the Sun and offers the best opportunity to find and ultimately to characterize an Earth-sized planet located in its Habitable Zone (HZ). Here we describe initial results from an ALMA program to search for planets in the $\alpha$ Cen AB system using differential astrometry at millimeter wavelengths. Our initial results include new absolute astrometric measurements of the proper motion, orbital motion, and parallax of the $\alpha$ Cen system. These lead to an improved knowledge of the physical properties of both $\alpha$ Cen A and B. Our estimates of ALMA's relative astrometric precision suggest that we will ultimately be sensitive to planets of a few 10s of Earth mass in orbits from 1-3 AU, where stable orbits are thought to exist.

arXiv comment24 pages, 11 figures. Accepted for publication in the Astronomical Journal. Full versions of Tables 6, 7 and 12 available in the source material

References in corpus (51)

• Astropy: A Community Python Package for Astronomy
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Long-Term Stability of Planets in Binary Systems
• The Ages of Stars
• Asteroseismology of Solar-Type and Red-Giant Stars
• Stellar and substellar companions of nearby stars from Gaia DR2 - Binarity from proper motion anomaly
• Gaia FGK Benchmark Stars: Effective temperatures and surface gravities
• Proxima's orbit around Alpha Centauri
• Stellar Diameters and Temperatures III. Main Sequence A, F, G, & K Stars: Additional high-precision measurements and empirical relations
• Chromospheric activity catalogue of 4454 cool stars. Questioning the active branch of stellar activity cycles
• Measuring precise radial velocities on individual spectral lines. I. Validation of the method and application to mitigate stellar activity
• A public HARPS radial velocity database corrected for systematic errors
• Improvements to stellar structure models, based on a grid of 3D convection simulations. II. Calibrating the mixing-length formulation
• The diameters of Alpha Centauri A and B - A comparison of the asteroseismic and VINCI/VLTI views
• Asteroseismology and Interferometry
• Constraining the difference in convective blueshift between the components of alpha Cen with precise radial velocities
• P-mode observations on Alpha Cen A
• The acoustic spectrum of alpha Cen A
• Asteroseismology and calibration of alpha Cen binary system
• Starspot Jitter in Photometry, Astrometry and Radial Velocity Measurements
• The radii and limb darkenings of Alpha Centauri A and B - Interferometric measurements with VLTI/PIONIER
• Classically and Asteroseismically constrained 1D Stellar Evolution Models of $\alpha$ Centauri A and B using Empirical Mixing Length Calibrations
• Models of alpha Centauri A and B with and without seismic constraints: time dependence of the mixing-length parameter
• On the uncertain nature of the core of $\mathbf{\alpha }$ Cen A
• Close stellar conjunctions of alpha Centauri A and B until 2050 - An mK = 7.8 star may enter the Einstein ring of alpha Cen A in 2028
• Long-Term Stability of Planets in the $\alpha$ Centauri System
• Parallax and masses of alpha Centauri revisited
• Imaging low-mass planets within the habitable zone of α Centauri
• Benchmark ages for the Gaia benchmark stars
• Core properties of alpha Cen A using asteroseismology
• Orbital inclination and mass of the exoplanet candidate Proxima c
• Planet Detectability in the Alpha Centauri System
• $\alpha$ Centauri A in the far infrared
• Long-Term Stability of Tightly Packed Multi-Planet Systems in Prograde, Coplanar, Circumstellar Orbits within the $\alpha$ Centauri AB System
• Detection of Alpha Centauri at radio wavelengths: chromospheric emission and search for star-planet interaction
• HD 202206 : A Circumbinary Brown Dwarf System
• ALMA observations of alpha Centauri: First detection of main-sequence stars at 3mm wavelength
• The chemical composition of $\alpha$ Cen AB revisited
• An astrometric planetary companion candidate to the M9 Dwarf TVLM 513-46546
• On the structure of the Sun and alpha Centauri A and B in the light of seismic and non-seismic constraints
• Searching for Planets Orbiting Alpha Centauri A with the James Webb Space Telescope
• Activity and telluric contamination in HARPS observations of Alpha Centauri B
• Long-Term Stability of Planets in the $\alpha$ Centauri System, II: Forced Eccentricities
• Testing the entropy calibration of the radii of cool stars: models of alpha Centauri A and B
• The Solar and $\alpha$ Centauri A and B models improved by opacity enhancement - a possible explanation for the oversize cool stars
• ALMA's view of the Sun's nearest neighbours: The submm/mm SEDs of the alpha Centauri binary and a new source
• On the nature of the core of $\alpha$ Centauri A: the impact of the metallicity mixture
• Coronal activity cycles in action - X-rays from alpha Centauri A/B
• $\alpha$ Centauri revisited: 2nd epoch ALMA observations

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• Stellar and substellar companions from Gaia EDR3 -- Proper motion anomaly and resolved common proper motion pairs
• Setting the stage for the search for life with the Habitable Worlds Observatory: Properties of 164 promising planet survey targets
• EMISSA -- Exploring Millimeter Indicators of Solar-Stellar Activity I. The Initial mm-cm Main Sequence Star Sample
• An Early Catalog of Planet Hosting Multiple Star Systems of Order Three and Higher
• Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of $\alpha$ Cen A. I. Observations, Orbital and Physical Properties, and Exozodi Upper Limits
• Milankovitch Cycles for a Circumstellar Earth-analog within $\alpha$ Centauri-like Binaries
• Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of $\alpha$ Cen A. II. Binary Star Modeling, Planet and Exozodi Search, and Sensitivity Analysis
• Correlating Intrinsic Stellar Parameters with Mg II Self-Reversal Depths
• A Case Study of Interstellar Material Delivery: α Centauri
• Astrometric radial velocities for nearby stars
• The assembly, characterization, and performance of SISTINE
• SPORES-HWO. II. Companion Mass Limits and Updated Planet Properties for 120 Future Exoplanet Imaging Targets from 35 yr of Precise Doppler Monitoring
• Searching for Axion-Like Particles with X-ray Observations of Alpha Centauri
• Ground to Dust: Collisional Cascades and the Fate of Kardashev II Megaswarms