Planet Detectability in the Alpha Centauri System
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Fecha
2018
Profesor/a Guía
Facultad/escuela
Idioma
en
Título de la revista
ISSN de la revista
Título del volumen
Editor
Institute of Physics Publishing
Nombre de Curso
Licencia CC
Licencia CC
Resumen
We use more than a decade of radial-velocity measurements for α Cen A, B, and Proxima Centauri from the High Accuracy Radial Velocity Planet Searcher, CTIO High Resolution Spectrograph, and the Ultraviolet and Visual Echelle Spectrograph to identify the M i sin and orbital periods of planets that could have been detected if they existed. At each point in a mass-period grid, we sample a simulated, Keplerian signal with the precision and cadence of existing data and assess the probability that the signal could have been produced by noise alone. Existing data places detection thresholds in the classically defined habitable zones at about M i sin of 53 M· for a Cen A, 8.4 M· for a Cen B, and 0.47 M· for Proxima Centauri. Additionally, we examine the impact of systematic errors, or "red noise" in the data. A comparison of white- and red-noise simulations highlights quasi-periodic variability in the radial velocities that may be caused by systematic errors, photospheric velocity signals, or planetary signals. For example, the red-noise simulations show a peak above white-noise simulations at the period of Proxima Centauri b. We also carry out a spectroscopic analysis of the chemical composition of the a Centauri stars. The stars have supersolar metallicity with ratios of C/O and Mg/Si that are similar to the Sun, suggesting that any small planets in the a Cen system may be compositionally similar to our terrestrial planets. Although the small projected separation of a Cen A and B currently hampers extreme-precision radial-velocity measurements, the angular separation is now increasing. By 2019, a Cen A and B will be ideal targets for renewed Doppler planet surveys.
Notas
Indexación: Scopus.
Palabras clave
Planetary systems, Planets and satellites: detection, Stars: fundamental parameters, Stars: individual (Alpha Centauri), Techniques: radial velocities
Citación
Astronomical Journal. Volume 155, Issue 1, January 2018, Article number 24