1998/06/19 by G. F. Benedict, G. Fritz Benedict, Barbara McArthur +15 · 8 citations
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Inertial Sensor and Navigation #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/300420
39 pages, 17 figures
arxiv created 1998/06/19 · openalex publication_date 1998/07/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/04
We have observed Proxima Centauri and Barnard's star with the Hubble Space T elescope Fine Guidance Sensor 3. Proxima Cen exhibits small-amplitude, periodic photometric variations. Once several sources of systematic photometric error are corrected, we obtain 2 mmag internal photometric precision. We identify two distinct behavior modes over the past 4 years: higher amplitude, longer period and smaller amplitude, shorter period. Within the errors, one period ( P ∼ 83 days) is twice the other. Barnard's star shows very weak evidence for periodicity on a timescale of approximately 130 days. If we interpret these periodic phenomena as rotational modulation of starspots, we identify three discrete spots on Proxima Cen and possibly one spot on Barnard's star. We find that the disturbances change significantly on timescales as short as one rotation period.