J/ApJ/801/79ivo://CDS.VizieR/J/ApJ/801/79doi:10.26093/cds/vizier.18010079CDSRobertson P.Endl M.Henry G.W.Cochran W.D.MacQueen P.J.,Williamson M.H.2017-06-22T14:29:17Z2015-08-07T10:17:53ZCDS support team

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

cds-question@unistra.frinfrared-photometryvisible-astronomyphotometryradial-velocitym-starsWe present an in-depth analysis of stellar activity and its effects on radial velocity (RV) for the M2 dwarf GJ 176 based on spectra taken over 10yr from the High Resolution Spectrograph on the Hobby-Eberly Telescope. These data are supplemented with spectra from previous observations with the HIRES and HARPS spectrographs, and V- and R-band photometry taken over six years at the Dyer and Fairborn observatories. Previous studies of GJ 176 revealed a super-Earth exoplanet in an 8.8-day orbit. However, the velocities of this star are also known to be contaminated by activity, particularly at the 39-day stellar rotation period. We have examined the magnetic activity of GJ 176 using the sodium I D lines, which have been shown to be a sensitive activity tracer in cool stars. In addition to rotational modulation, we see evidence of a long-term trend in our Na I D index, which may be part of a long-period activity cycle. The sodium index is well correlated with our RVs, and we show that this activity trend drives a corresponding slope in RV. Interestingly, the rotation signal remains in phase in photometry, but not in the spectral activity indicators. We interpret this phenomenon as the result of one or more large spot complexes or active regions which dominate the photometric variability, while the spectral indices are driven by the overall magnetic activity across the stellar surface. In light of these results, we discuss the potential for correcting activity signals in the RVs of M dwarfs.2015ApJ...801...79Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/801/79CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/MNRAS/443/2561 : Trumpeting M dwarfs with CONCH-SHELL (Gaidos+, 2014)J/AJ/147/20 : Spectroscopy of 447 nearby M dwarfs (Newton+, 2014)J/MNRAS/431/2063 : UV/X-ray activity of M dwarfs within 10pc (Stelzer+, 2013)J/ApJ/767/95 : Improved parameters of smallest KIC stars (Dressing+, 2013)J/ApJ/764/3 : H{alpha} indices in M low-mass stars (Robertson+, 2013)J/AJ/145/102 : Spectroscopy of M dwarfs in the northern sky (Lepine+, 2013)J/A+A/549/A109 : HARPS XXXI. The M-dwarf sample (Bonfils+, 2013)J/A+A/546/A61 : Radial velocities for XHIP catalogue (de Bruijne+, 2012)J/A+A/541/A9 : M dwarfs activity & radial velocity (Gomes da Silva+, 2012)J/A+A/535/A55 : 4 stars with long-period planets (Dumusque+, 2011)J/MNRAS/403/1949 : UBV(RcIc)JHK photometry of HIP nearby stars (Koen+, 2010)J/A+A/505/859 : M dwarfs radial velocities (Zechmeister+, 2009)J/A+A/493/645 : Gl 176 radial velocities (Forveille+, 2009)J/A+A/469/309 : Late-type stars chromospheric activity (Cincunegui+, 2007)J/ApJS/141/503 : Radial Velocities for 889 late-type stars (Nidever+, 2002)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/801/79https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/801/79http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/801/79https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/801/79https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/801/79http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/801/79GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/801/79/table2Radial velocities and spectral activity indices for our HET/HRS spectra of GJ 176recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Date; minus 2450000dtime.epochdoubleRVel[-26/21] Radial velocity (1)m/sphys.veloc;pos.heliocentricfloate_RVel[4/10] Uncertainty in RVelm/sstat.error;spect.dopplerVelocfloatID1[0.1/0.15] The I_D_ index in 1{AA} window (2)phot.flux;arith.ratiodoublee_ID1[0.002/0.004] Uncertainty in ID1stat.errordoubleID0.5[0.08/0.13] The I_D_ index in 0.5{AA} window (2)phot.flux;arith.ratiodoublee_ID0.5[0.001/0.003] Uncertainty in ID0.5stat.errordoubleIHa[0.06/0.08] The I_H{alpha}_ indexphot.flux;arith.ratiodoublee_IHa[0.0009/0.0016] Uncertainty in IHastat.errordoubleICaI[0.02/0.03] The I_Ca I_ index for the CaI line at {lambda}=6572.795{AA}phot.flux;arith.ratiodoublee_ICaI[0.0006/0.0009] Uncertainty in ICaIstat.errordoubleJ/ApJ/801/79/table3Differential R-band photometry of GJ 176recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Date; minus 2450000dtime.epochdoubledRmag[-2.5/-2.4] Differential R band magnitude (G1)magphot.mag;em.opt.R;arith.diffdoublee_dRmag[0.0002/0.004] Uncertainty in dRmagmagstat.error;phot.magdoubleJ/ApJ/801/79/table4Differential V-band photometry of GJ 176recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Date; minus 2450000dtime.epochdoubledVmag[-2.1/-1.9] Differential V band magnitude (G1)magphot.mag;em.opt.V;arith.diffdoublee_dVmag[0.0001/0.009] Uncertainty in dVmagmagstat.error;phot.magdouble