English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We have measured transit times for HD 189733b passing in front of its bright(V = 7.67) chromospherically active and spotted parent star. Nearly continuousbroadband optical photometry of this system was obtained with the MOST(Microvariability & Oscillations of STars) space telescope during 21 days inAugust 2006, monitoring 10 consecutive transits. We have used these data tosearch for deviations from a constant orbital period which can indicate thepresence of additional planets in the system that are as yet undetected byDoppler searches. There are no transit timing variations above the level of${\pm}45$ s, ruling out super-Earths (of masses $1 - 4 M_{\earth}$) in the 1:2and 2:3 inner resonances and planets of 20 $M_{\earth}$ in the 2:1 outerresonance of the known planet. We also discuss complications in measuringtransit times for a planet that transits an active star with large star spots,and how the transits can help constrain and test spot models. This hasimplications for the large number of such systems expected to be discovered bythe CoRoT and Kepler missions.

MOST Spacebased Photometry of the Transiting Exoplanet System HD 189733: Precise Timing Measurements for Transits Across an Active Star