J/ApJ/800/135 HARPS-N radial velocities of KOI-69 (Dressing+, 2015) ================================================================================ The mass of Kepler-93b and the composition of terrestrial planets. Dressing C.D., Charbonneau D., Dumusque X., Gettel S., Pepe F., Collier Cameron A., Latham D.W., Molinari E., Udry S., Affer L., Bonomo A.S., Buchhave L.A., Cosentino R., Figueira P., Fiorenzano A.F.M., Harutyunyan A., Haywood R.D., Johnson J.A., Lopez-Morales M., Lovis C., Malavolta L., Mayor M., Micela G., Motalebi F., Nascimbeni V., Phillips D.F., Piotto G., Pollacco D., Queloz D., Rice K., Sasselov D., Segransan D., Sozzetti A., Szentgyorgyi A., Watson C. =2015ApJ...800..135D ================================================================================ ADC_Keywords: Stars, double and multiple ; Radial velocities ; Planets Keywords: planetary systems; planets and satellites: composition; stars: individual: Kepler-93 = KOI 69 = KIC 3544595; techniques: radial velocities Abstract: Kepler-93b is a 1.478+/-0.019R_{Earth}_ planet with a 4.7day period around a bright (V=10.2), astroseismically characterized host star with a mass of 0.911+/-0.033M_{sun}_ and a radius of 0.919+/-0.011R_{sun}_. Based on 86 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 32 archival Keck/HIRES observations, we present a precise mass estimate of 4.02+/-0.68M_{Earth}_. The corresponding high density of 6.88+/-1.18g/cm3 is consistent with a rocky composition of primarily iron and magnesium silicate. We compare Kepler-93b to other dense planets with well-constrained parameters and find that between 1 and 6M_{Earth}_, all dense planets including the Earth and Venus are well-described by the same fixed ratio of iron to magnesium silicate. There are as of yet no examples of such planets with masses >6M_{Earth}_. All known planets in this mass regime have lower densities requiring significant fractions of volatiles or H/He gas. We also constrain the mass and period of the outer companion in the Kepler-93 system from the long-term radial velocity trend and archival adaptive optics images. As the sample of dense planets with well-constrained masses and radii continues to grow, we will be able to test whether the fixed compositional model found for the seven dense planets considered in this paper extends to the full population of 1-6M_{Earth}_ planets. Description: We obtained 86 spectra of Kepler-93 using the HARPS-N spectrograph (R~115000) on the 3.57m Telescopio Nazionale Galileo (TNG) at the Observatorio del Roque de los Muchachos. We acquired 38 and 49 HARPS-N observations of Kepler-93 during the 2013 and 2014 observing seasons, respectively (see table 1). Our full data set included RVs from four seasons of archival HIRES observations (2009 July-2012 September; see Marcy et al., 2014, J/ApJS/210/20) and two seasons of HARPS-N observations (2013 June-2014 October). Objects: ------------------------------------------------------------- RA (ICRS) DE Designation(s) (P=Per (d)) ------------------------------------------------------------- 19 25 40.39 +38 40 20.4 Kepler-93 = KOI-69 (P=4.72674) ------------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 51 86 HARPS-N radial velocity observations of Kepler-93 -------------------------------------------------------------------------------- See also: V/133 : Kepler Input Catalog (Kepler Mission Team, 2009) J/ApJS/211/2 : Revised properties of Q1-16 Kepler targets (Huber+, 2014) J/ApJS/210/20 : Small Kepler planets radial velocities (Marcy+, 2014) J/ApJS/210/19 : Kepler planetary candidates. IV. 22 months (Burke+, 2014) J/A+A/566/A103 : Kepler planet host candidates imaging (Lillo-Box+, 2014) J/ApJS/208/16 : Kepler transit timing observations. VIII. (Mazeh+, 2013) J/ApJ/767/127 : Asteroseismic solutions for 77 Kepler stars (Huber+, 2013) J/A+A/547/A36 : Chemical abundances of 87 KOIs (Adibekyan++, 2012) J/PASP/124/1279 : Q3 Kepler's combined photometry (Christiansen+, 2012) J/AJ/144/24 : The Kepler-INT survey (Greiss+, 2012) J/AJ/142/112 : KIC photometric calibration (Brown+, 2011) J/ApJ/736/19 : Kepler planetary candidates. II. (Borucki+, 2011) J/A+A/449/723 : Atmospheres of stars with planets (Gilli+, 2006) J/A+A/438/251 : Abundances in stars with giant planets (Beirao+, 2005) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 14 F14.6 d BJD Barycentric Julian Date; UTC 16- 23 F8.2 m/s RVel [27331/27356] Radial velocity 25- 28 F4.2 m/s e_RVel [0.7/2.2] Uncertainty in RVel 30- 35 F6.2 m/s BS [-41.2/-22.2] Bisector span 37- 41 F5.2 [-] logR'HK [-5.1/-4.9] The logR'_HK_ chromospheric activity value 43- 46 F4.2 [-] e_logR'HK [0/0.03] Uncertainty in logR'HK 48- 51 I4 s Exp [900/1800] Exposure Time -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 03-Jul-2015