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Proceedings Paper

Astrometric detection of exo-Earths in the presence of stellar noise
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Paper Abstract

Astrometry from space is capable of making extremely precise measurements of the positions of stars, at angular precision of well below 1 micro-arcsecond (uas) at each visit. Hundreds of visits over a period of five years could achieve a relative astrometric precision for the mission of below 0.05 uas; this is well below the astrometric signature of 0.3 uas for a Sun-Earth system at a distance of 10 pc. The Sun's photometric fluctuations on time scales from days to years are dominated by the rotation and evolution of stellar surface features (sunspots and faculae). This flux variability is a source of astrophysical noise in astrometric as well as radial velocity (RV) measurements of the star. In this paper we describe a dynamic starspot model that produces flux variability which is consistent with the measured photometric power spectra of the Sun and several other stars. We use that model to predict the jitter in astrometric and RV measurements due to starspots. We also employ empirical stellar activity models to estimate the astrometric jitter of a much larger sample of stars. The conclusion of these simulations is that astrometric detection of planets in the habitable zones of solar-type stars is not severely impacted by the noise due to starspots/faculae, down to well below one Earth mass.

Paper Details

Date Published: 28 July 2008
PDF: 11 pages
Proc. SPIE 7013, Optical and Infrared Interferometry, 70132K (28 July 2008); doi: 10.1117/12.787904
Show Author Affiliations
Joseph Catanzarite, Jet Propulsion Lab. (United States)
Nicholas Law, California Institute of Technology (United States)
Michael Shao, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 7013:
Optical and Infrared Interferometry
Markus Schöller; William C. Danchi; Françoise Delplancke, Editor(s)

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