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dc.contributor.authorCameron, A Collier
dc.contributor.authorFord, E B
dc.contributor.authorShahaf, S
dc.contributor.authorAigrain, S
dc.contributor.authorDumusque, X
dc.contributor.authorHaywood, R D
dc.contributor.authorMortier, A
dc.contributor.authorPhillips, D F
dc.contributor.authorBuchhave, L
dc.contributor.authorCecconi, M
dc.contributor.authorCegla, H
dc.contributor.authorCosentino, R
dc.contributor.authorCrétignier, M
dc.contributor.authorGhedina, A
dc.contributor.authorGonzález, M
dc.contributor.authorLatham, D W
dc.contributor.authorLodi, M
dc.contributor.authorLópez-Morales, M
dc.contributor.authorMicela, G
dc.contributor.authorMolinari, E
dc.contributor.authorPepe, F
dc.contributor.authorPiotto, G
dc.contributor.authorPoretti, E
dc.contributor.authorQueloz, D
dc.contributor.authorJuan, J San
dc.contributor.authorSégransan, D
dc.contributor.authorSozzetti, A
dc.contributor.authorSzentgyorgyi, A
dc.contributor.authorThompson, S
dc.contributor.authorUdry, S
dc.contributor.authorWatson, C
dc.identifier.citationCameron , A C , Ford , E B , Shahaf , S , Aigrain , S , Dumusque , X , Haywood , R D , Mortier , A , Phillips , D F , Buchhave , L , Cecconi , M , Cegla , H , Cosentino , R , Crétignier , M , Ghedina , A , González , M , Latham , D W , Lodi , M , López-Morales , M , Micela , G , Molinari , E , Pepe , F , Piotto , G , Poretti , E , Queloz , D , Juan , J S , Ségransan , D , Sozzetti , A , Szentgyorgyi , A , Thompson , S , Udry , S & Watson , C 2021 , ' Separating planetary reflex Doppler shifts from stellar variability in the wavelength domain ' , Monthly Notices of the Royal Astronomical Society , vol. 505 , no. 2 , pp. 1699–1717 .
dc.identifier.otherPURE: 274344340
dc.identifier.otherPURE UUID: dd808674-65aa-4399-a3e8-51f78415823e
dc.identifier.otherJisc: ba88270beef4417b99e809e2c27f29f9
dc.identifier.otherORCID: /0000-0002-8863-7828/work/94669196
dc.identifier.otherWOS: 000672803400013
dc.descriptionACC acknowledges support from the Science and Technology Facilities Council (STFC) consolidated grant number ST/R000824/1 and UKSA grant ST/R003203/1.en
dc.description.abstractStellar magnetic activity produces time-varying distortions in the photospheric line profiles of solar-type stars. These lead to systematic errors in high-precision radial-velocity measurements, which limit efforts to discover and measure the masses of low-mass exoplanets with orbital periods of more than a few tens of days. We present a new data-driven method for separating Doppler shifts of dynamical origin from apparent velocity variations arising from variability-induced changes in the stellar spectrum. We show that the autocorrelation function (ACF) of the cross-correlation function used to measure radial velocities is effectively invariant to translation. By projecting the radial velocities on to a subspace labelled by the observation identifiers and spanned by the amplitude coefficients of the ACF’s principal components, we can isolate and subtract velocity perturbations caused by stellar magnetic activity. We test the method on a 5-year time sequence of 853 daily 15-minute observations of the solar spectrum from the HARPS-N instrument and solar-telescope feed on the 3.58-m Telescopio Nazionale Galileo. After removal of the activity signals, the heliocentric solar velocity residuals are found to be Gaussian and nearly uncorrelated. We inject synthetic low-mass planet signals with amplitude K = 40 cm s−1 into the solar observations at a wide range of orbital periods. Projection into the orthogonal complement of the ACF subspace isolates these signals effectively from solar activity signals. Their semi-amplitudes are recovered with a precision of ∼ 6.6 cm s−1, opening the door to Doppler detection and characterization of terrestrial-mass planets around well-observed, bright main-sequence stars across a wide range of orbital periods.
dc.relation.ispartofMonthly Notices of the Royal Astronomical Societyen
dc.rightsCopyright ©2021 The Author(s). Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.en
dc.subjectMethods: statisticalen
dc.subjectPlanets and satellites: generalen
dc.subjectSun: photosphereen
dc.subjectTechniques: radial velocitiesen
dc.subjectTechniques: spectroscopicen
dc.subjectQB Astronomyen
dc.titleSeparating planetary reflex Doppler shifts from stellar variability in the wavelength domainen
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews.School of Physics and Astronomyen
dc.contributor.institutionUniversity of St Andrews.St Andrews Centre for Exoplanet Scienceen
dc.description.statusPeer revieweden

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