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.

24 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 (20)

• 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
• Proxima's orbit around Alpha Centauri
• Improvements to stellar structure models, based on a grid of 3D convection simulations. II. Calibrating the mixing-length formulation
• Asteroseismology and Interferometry
• The radii and limb darkenings of Alpha Centauri A and B - Interferometric measurements with VLTI/PIONIER
• Models of alpha Centauri A and B with and without seismic constraints: time dependence of the mixing-length parameter
• 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
• Imaging low-mass planets within the habitable zone of α Centauri
• Planet Detectability in the Alpha Centauri System
• HD 202206 : A Circumbinary Brown Dwarf System
• ALMA observations of alpha Centauri: First detection of main-sequence stars at 3mm wavelength
• An astrometric planetary companion candidate to the M9 Dwarf TVLM 513-46546
• 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
• On the nature of the core of $\alpha$ Centauri A: the impact of the metallicity mixture
• ALMA's view of the Sun's nearest neighbours: The submm/mm SEDs of the alpha Centauri binary and a new source
• Coronal activity cycles in action - X-rays from alpha Centauri A/B
• $\alpha$ Centauri revisited: 2nd epoch ALMA observations

Cited by in corpus (14)

• 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