Precision Millimeter Astrometry of the α Centauri AB System


Top left panel: Astrometric measurements and best fit orbit of α Cen B relative to α Cen A. The red dots represent the Hipparcos and ALMA data, while the light blue dots show the other measurements. Top right panel: enlargement of the 2019 ALMA measurements. In both panels, the cyan disks represent the model positions corresponding to the Hipparcos and ALMA points.

α 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 α 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 α Cen system.

These lead to an improved knowledge of the physical properties of both α 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.

Rachel Akeson, Charles Beichman, Pierre Kervella, Edward Fomalont, G. Fritz Benedict

Comments: 24 pages, 11 figures. Submitted to ApJ
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2104.10086 [astro-ph.SR] (or arXiv:2104.10086v1 [astro-ph.SR] for this version)
Submission history
From: Rachel Akeson [view email]
[v1] Tue, 20 Apr 2021 16:14:37 UTC (1,560 KB)
https://arxiv.org/abs/2104.10086
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