Radial-velocity variability of the Sun as a star with HARPS and HARPS-N
| Main Authors: | Haywood, Raphaëlle D, Collier Cameron, Andrew, Dumusque, Xavier, Glenday, Alex, Latham, David W, Lovis, Christophe, Maldonado, Jesus, Micela, Giusi, Molinari, Emiliano, Mortier, Annelies, Pepe, Francesco, Phillips, David F, Udry, Stephane |
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| Format: | info Proceeding Journal |
| Terbitan: |
, 2016
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/55693 |
Daftar Isi:
- Since we can resolve the surface of the Sun directly, we can explore the origin of radial-velocity variations induced by individual solar surface features such as faculae/plage, sunspots and granulation. I will present my recent investigation of the radial-velocity variations of the Sun as a star, based on high-resolution HARPS spectra of reflected sunlight and simultaneous images from the Solar Dynamics Observatory. We found that faculae are the dominant source of activity-induced radial-velocity variations, via suppression of convective blueshift. We investigated possible proxies for activity-induced radial-velocity variations and found that optical lightcurves can only provide a partial representation of these signals; the full-disc magnetic flux, however, is an excellent tracer. In addition to this dataset, the HARPS-N spectrograph has been operating with a new solar telescope feed since 2015 July. I will present results from the first year observations, which show radial-velocity variations of up to 7-8 m/s. Identifying proxies for solar radial-velocity variations is key to understanding the radial-velocity variability of other Sun-like stars, and is also essential for other investigations such as exoplanet detection surveys.