The Ups and Downs of Alpha Centauri
Thomas R. Ayres

TL;DR
This study reports on the long-term coronal activity cycles of Alpha Centauri A and B using X-ray observations, revealing an 8.2-year cycle for B and a prolonged low state for A, comparable to solar activity patterns.
Contribution
The paper provides the first detailed long-term X-ray activity cycles for Alpha Centauri A and B, including a potential 19-year cycle for A, based on multi-year Chandra, XMM-Newton, and ROSAT data.
Findings
Alpha Centauri B has an 8.2-year X-ray activity cycle.
Alpha Centauri A was in a low activity state, similar to solar minima.
A possible 19-year cycle for Alpha Centauri A is suggested.
Abstract
The following is a progress report on the long-term coronal activity of Alpha Centauri A (HD128620: G2V) and B (HD128621: K1V). Since 2005, Chandra X-ray Observatory has carried out semiannual pointings on AB, mainly with the High Resolution Camera (HRC-I), but also on two occasions with the Low-Energy Transmission Grating Spectrometer (LETGS), fully resolving the close pair in all cases. During 2008-2013, Chandra captured the rise, peak, and initial decline of B's coronal luminosity. Together with previous high states documented by ROSAT and XMM-Newton, the long-term X-ray record suggests a period of 8.2+/-0.2 yr, compared to 11 yr for the Sun; with a minimum-to-peak contrast of 4.5, about half the typical solar cycle amplitude. Meanwhile, the A component has been mired in a Maunder-Minimum-like low state since 2005, initially recognized by XMM. But now, A finally appears to be…
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Taxonomy
TopicsStellar, planetary, and galactic studies · Solar and Space Plasma Dynamics · Gamma-ray bursts and supernovae
