J/A+A/605/A103ivo://CDS.VizieR/J/A+A/605/A103doi:10.26093/cds/vizier.36050103CDSFeng F.Tuomi M.Jones H.R.A.2017-09-18T12:47:11Z2017-09-18T09:17:23ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frmultiple-starssolar-system-planetsradial-velocityg-starsWe explore the feasibility of detecting Earth analogs around Sun-like stars using the radial velocity method by investigating one of the largest radial velocities datasets for the one of the most stable radial-velocity stars HD20794. We proceed by disentangling the Keplerian signals from correlated noise and activity-induced variability. We diagnose the noise using the differences between radial velocities measured at different wavelength ranges, so-called "differential radial velocities", as well as the combination of radial velocities measured for other stars to account for instrumental effects. We apply this method to the radial velocities measured by HARPS, and identify four signals at 18, 89, 147 and 330d. The two signals at periods of 18 and 89d are previously reported and are better quantified in this work. The signal at a period of about 147d is reported for the first time, and corresponds to a super-Earth with a minimum mass of 4.59 Earth mass located 0.51AU from HD20794. We also find a significant signal at a period of about 330d corresponding to a super-Earth or Neptune in the habitable zone. Since this signal is close to the annual sampling period and significant periodogram power in some noise proxies are found close to this signal, further observations and analyses are required to confirm it. The analyses of the eccentricity and consistency of signals provide weak evidence for the existence of the previously reported 43d signal and a new signal at a period of about 11.9d with a semi amplitude of 0.4m/s. We find that the detection of a number of signals with radial velocity variations around 0.5m/s likely caused by low mass planet candidates demonstrates the important role of noise modeling in searching for Earth analogs.2017A&A...605A.103Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/605/A103CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/534/A58 : HD20794, HD85512, HD192310 HARPS radial velocities (Pepe+ 2011)J/ApJS/200/15 : HARPS-TERRA project. I. (Anglada-Escude+, 2012)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/605/A103https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/605/A103http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/605/A103https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/605/A103https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/605/A103http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/605/A103GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/605/A103/hd20794HARPS radial velocities for HD20794 and corresponding noise proxiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRJDReduced Julian Date (JD-2400000)dtime.epochdoubleRVRadial velocity variationm/sphys.veloc;arith.diffdoublee_RVrms uncertainty on radial velocitym/sstat.errordoubleBISBisector span of the cross-correlation functionm/sphys.velocdoubleFWHMCross-correlation function (CCF) FWHMkm/sspect.line.widthdoubleHalphaActivity index H-alphaspect.index;em.line.HalphadoublelogR'(HK)Activity index logR'(HK)meta.code;spect.index;em.opt.RdoubleNaD1Activity index Sodium NaD1spect.indexdoubleNaD2Activity index Sodium NaD2m/sspect.indexdouble3AP2-1Differential radial velocity 3AP2-1m/sphys.veloc;arith.diffdouble3AP3-2Differential radial velocity 3AP3-2m/sphys.veloc;arith.diffdouble6AP2-1Differential radial velocity 6AP2-1m/sphys.veloc;arith.diffdouble6AP3-2Differential radial velocity 6AP3-2m/sphys.veloc;arith.diffdouble6AP4-3Differential radial velocity 6AP4-3m/sphys.veloc;arith.diffdouble6AP5-4Differential radial velocity 6AP5-4m/sphys.veloc;arith.diffdouble6AP6-5Differential radial velocity 6AP6-5m/sphys.veloc;arith.diffdouble9AP2-1Differential radial velocity 9AP2-1m/sphys.veloc;arith.diffdouble9AP3-2Differential radial velocity 9AP3-2m/sphys.veloc;arith.diffdouble9AP4-3Differential radial velocity 9AP4-3m/sphys.veloc;arith.diffdouble9AP5-4Differential radial velocity 9AP5-4m/sphys.veloc;arith.diffdouble9AP6-5Differential radial velocity 9AP6-5m/sphys.veloc;arith.diffdouble9AP7-6Differential radial velocity 9AP7-6m/sphys.veloc;arith.diffdouble9AP8-7Differential radial velocity 9AP8-7m/sphys.veloc;arith.diffdouble9AP9-8Differential radial velocity 9AP9-8m/sphys.veloc;arith.diffdouble