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dc.contributor.authorCameron, A Collieren
dc.contributor.authorFord, EBen
dc.contributor.authorShahaf, Sen
dc.contributor.authorAigrain, Sen
dc.contributor.authorDumusque, Xen
dc.contributor.authorHaywood, RDen
dc.contributor.authorMortier, Anneliesen
dc.contributor.authorPhillips, DFen
dc.contributor.authorBuchhave, Len
dc.contributor.authorCecconi, Men
dc.contributor.authorCegla, Hen
dc.contributor.authorCosentino, Ren
dc.contributor.authorCretignier, Men
dc.contributor.authorGhedina, Aen
dc.contributor.authorGonzalez, Men
dc.contributor.authorLatham, DWen
dc.contributor.authorLodi, Men
dc.contributor.authorLopez-Morales, Men
dc.contributor.authorMicela, Gen
dc.contributor.authorMolinari, Een
dc.contributor.authorPepe, Fen
dc.contributor.authorPiotto, Gen
dc.contributor.authorPoretti, Een
dc.contributor.authorQueloz, Didieren
dc.contributor.authorSan Juan, Jen
dc.contributor.authorSegransan, Den
dc.contributor.authorSozzetti, Aen
dc.contributor.authorSzentgyorgyi, Aen
dc.contributor.authorThompson, Sen
dc.contributor.authorUdry, Sen
dc.contributor.authorWatson, Cen
dc.date.accessioned2021-05-24T23:30:41Z
dc.date.available2021-05-24T23:30:41Z
dc.date.issued2021-08en
dc.identifier.issn0035-8711
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/322902
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 $\sim~6.6$ 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.publisherOxford University Press
dc.rightsAll rights reserved
dc.subjectmethods: statisticalen
dc.subjecttechniques: radial velocitiesen
dc.subjecttechniques: spectroscopicen
dc.subjectSun: photosphereen
dc.subjectplanets and satellites: generalen
dc.titleSeparating planetary reflex Doppler shifts from stellar variability in the wavelength domainen
dc.typeArticle
prism.endingPage1717
prism.issueIdentifier2en
prism.publicationDate2021en
prism.publicationNameMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETYen
prism.startingPage1699
prism.volume505en
dc.identifier.doi10.17863/CAM.70358
dcterms.dateAccepted2021-05-02en
rioxxterms.versionofrecord10.1093/mnras/stab1323en
rioxxterms.versionAM
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2021-08en
dc.contributor.orcidMortier, Annelies [0000-0001-7254-4363]
dc.contributor.orcidQueloz, Didier [0000-0002-3012-0316]
dc.identifier.eissn1365-2966
rioxxterms.typeJournal Article/Reviewen
pubs.funder-project-idSCIENCE & TECHNOLOGY FACILITIES COUNCIL (ST/N002997/1)
cam.orpheus.successMon May 31 07:30:28 BST 2021 - Embargo updated*
rioxxterms.freetoread.startdate2021-05-12


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