skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet

Abstract

Kepler-10b was the first rocky planet detected by the Kepler satellite and confirmed with radial velocity follow-up observations from Keck-HIRES. The mass of the planet was measured with a precision of around 30%, which was insufficient to constrain models of its internal structure and composition in detail. In addition to Kepler-10b, a second planet transiting the same star with a period of 45 days was statistically validated, but the radial velocities were only good enough to set an upper limit of 20 M{sub ⊕} for the mass of Kepler-10c. To improve the precision on the mass for planet b, the HARPS-N Collaboration decided to observe Kepler-10 intensively with the HARPS-N spectrograph on the Telescopio Nazionale Galileo on La Palma. In total, 148 high-quality radial-velocity measurements were obtained over two observing seasons. These new data allow us to improve the precision of the mass determination for Kepler-10b to 15%. With a mass of 3.33 ± 0.49 M{sub ⊕} and an updated radius of 1.47{sub −0.02}{sup +0.03} R{sub ⊕}, Kepler-10b has a density of 5.8 ± 0.8 g cm{sup –3}, very close to the value predicted by models with the same internal structure and composition as the Earth. We were also ablemore » to determine a mass for the 45-day period planet Kepler-10c, with an even better precision of 11%. With a mass of 17.2 ± 1.9 M{sub ⊕} and radius of 2.35{sub −0.04}{sup +0.09} R{sub ⊕}, Kepler-10c has a density of 7.1 ± 1.0 g cm{sup –3}. Kepler-10c appears to be the first strong evidence of a class of more massive solid planets with longer orbital periods.« less

Authors:
; ; ; ; ; ;  [1];  [2]; ; ;  [3];  [4]; ; ;  [5]; ; ; ;  [6];  [7] more »; « less
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. INAF - Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese (Italy)
  3. SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews Fife KY16 9SS (United Kingdom)
  4. Dipartimento di Fisica e Astronomia "Galileo Galilei," Universita'di Padova, Vicolo dell'Osservatorio 3, I-35122 Padova (Italy)
  5. Observatoire Astronomique de l'Université de Genève, 51 ch. des Maillettes, CH-1290 Versoix (Switzerland)
  6. INAF - Fundacin Galileo Galilei, Rambla Jos Ana Fernandez Prez 7, E-38712 Brea Baja (Spain)
  7. Centro de Astrofìsica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal)
Publication Date:
OSTI Identifier:
22365690
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; DENSITY; GLOBAL ASPECTS; MASS; RADIAL VELOCITY; SATELLITES; STARS; STATISTICS

Citation Formats

Dumusque, Xavier, Buchhave, Lars A., Latham, David W., Charbonneau, David, Dressing, Courtney D., Gettel, Sara, Lopez-Morales, Mercedes, Bonomo, Aldo S., Haywood, Raphaëlle D., Cameron, Andrew Collier, Horne, Keith, Malavolta, Luca, Ségransan, Damien, Pepe, Francesco, Udry, Stéphane, Molinari, Emilio, Cosentino, Rosario, Fiorenzano, Aldo F. M., Harutyunyan, Avet, Figueira, Pedro, E-mail: xdumusque@cfa.harvard.edu, and and others. The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet. United States: N. p., 2014. Web. doi:10.1088/0004-637X/789/2/154.
Dumusque, Xavier, Buchhave, Lars A., Latham, David W., Charbonneau, David, Dressing, Courtney D., Gettel, Sara, Lopez-Morales, Mercedes, Bonomo, Aldo S., Haywood, Raphaëlle D., Cameron, Andrew Collier, Horne, Keith, Malavolta, Luca, Ségransan, Damien, Pepe, Francesco, Udry, Stéphane, Molinari, Emilio, Cosentino, Rosario, Fiorenzano, Aldo F. M., Harutyunyan, Avet, Figueira, Pedro, E-mail: xdumusque@cfa.harvard.edu, & and others. The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet. United States. doi:10.1088/0004-637X/789/2/154.
Dumusque, Xavier, Buchhave, Lars A., Latham, David W., Charbonneau, David, Dressing, Courtney D., Gettel, Sara, Lopez-Morales, Mercedes, Bonomo, Aldo S., Haywood, Raphaëlle D., Cameron, Andrew Collier, Horne, Keith, Malavolta, Luca, Ségransan, Damien, Pepe, Francesco, Udry, Stéphane, Molinari, Emilio, Cosentino, Rosario, Fiorenzano, Aldo F. M., Harutyunyan, Avet, Figueira, Pedro, E-mail: xdumusque@cfa.harvard.edu, and and others. Thu . "The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet". United States. doi:10.1088/0004-637X/789/2/154.
@article{osti_22365690,
title = {The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet},
author = {Dumusque, Xavier and Buchhave, Lars A. and Latham, David W. and Charbonneau, David and Dressing, Courtney D. and Gettel, Sara and Lopez-Morales, Mercedes and Bonomo, Aldo S. and Haywood, Raphaëlle D. and Cameron, Andrew Collier and Horne, Keith and Malavolta, Luca and Ségransan, Damien and Pepe, Francesco and Udry, Stéphane and Molinari, Emilio and Cosentino, Rosario and Fiorenzano, Aldo F. M. and Harutyunyan, Avet and Figueira, Pedro, E-mail: xdumusque@cfa.harvard.edu and and others},
abstractNote = {Kepler-10b was the first rocky planet detected by the Kepler satellite and confirmed with radial velocity follow-up observations from Keck-HIRES. The mass of the planet was measured with a precision of around 30%, which was insufficient to constrain models of its internal structure and composition in detail. In addition to Kepler-10b, a second planet transiting the same star with a period of 45 days was statistically validated, but the radial velocities were only good enough to set an upper limit of 20 M{sub ⊕} for the mass of Kepler-10c. To improve the precision on the mass for planet b, the HARPS-N Collaboration decided to observe Kepler-10 intensively with the HARPS-N spectrograph on the Telescopio Nazionale Galileo on La Palma. In total, 148 high-quality radial-velocity measurements were obtained over two observing seasons. These new data allow us to improve the precision of the mass determination for Kepler-10b to 15%. With a mass of 3.33 ± 0.49 M{sub ⊕} and an updated radius of 1.47{sub −0.02}{sup +0.03} R{sub ⊕}, Kepler-10b has a density of 5.8 ± 0.8 g cm{sup –3}, very close to the value predicted by models with the same internal structure and composition as the Earth. We were also able to determine a mass for the 45-day period planet Kepler-10c, with an even better precision of 11%. With a mass of 17.2 ± 1.9 M{sub ⊕} and radius of 2.35{sub −0.04}{sup +0.09} R{sub ⊕}, Kepler-10c has a density of 7.1 ± 1.0 g cm{sup –3}. Kepler-10c appears to be the first strong evidence of a class of more massive solid planets with longer orbital periods.},
doi = {10.1088/0004-637X/789/2/154},
journal = {Astrophysical Journal},
number = 2,
volume = 789,
place = {United States},
year = {Thu Jul 10 00:00:00 EDT 2014},
month = {Thu Jul 10 00:00:00 EDT 2014}
}
  • Since the discovery of Kepler-10, the system has received considerable interest because it contains a small, rocky planet which orbits the star in less than a day. The system's parameters, announced by the Kepler team and subsequently used in further research, were based on only five months of data. We have reanalyzed this system using the full span of 29 months of Kepler photometric data, and obtained improved information about its star and the planets. A detailed asteroseismic analysis of the extended time series provides a significant improvement on the stellar parameters: not only can we state that Kepler-10 ismore » the oldest known rocky-planet-harboring system at 10.41 ± 1.36 Gyr, but these parameters combined with improved planetary parameters from new transit fits gives us the radius of Kepler-10b to within just 125 km. A new analysis of the full planetary phase curve leads to new estimates on the planetary temperature and albedo, which remain degenerate in the Kepler band. Our modeling suggests that the flux level during the occultation is slightly lower than at the transit wings, which would imply that the nightside of this planet has a non-negligible temperature.« less
  • Early time-series photometry from NASA's Kepler spacecraft has revealed a planet transiting the star we term Kepler-4, at R.A. = 19{sup h}02{sup m}27.{sup s}68, {delta} = +50{sup 0}08'08.''7. The planet has an orbital period of 3.213 days and shows transits with a relative depth of 0.87 x 10{sup -3} and a duration of about 3.95 hr. Radial velocity (RV) measurements from the Keck High Resolution Echelle Spectrometer show a reflex Doppler signal of 9.3{sup +1.1} {sub -1.9} m s{sup -1}, consistent with a low-eccentricity orbit with the phase expected from the transits. Various tests show no evidence for any companionmore » star near enough to affect the light curve or the RVs for this system. From a transit-based estimate of the host star's mean density, combined with analysis of high-resolution spectra, we infer that the host star is near turnoff from the main sequence, with estimated mass and radius of 1.223{sup +0.053} {sub -0.091} M {sub sun} and 1.487{sup +0.071} {sub -0.084} R {sub sun}. We estimate the planet mass and radius to be {l_brace}M {sub P}, R {sub P}{r_brace} = {l_brace}24.5 {+-} 3.8 M {sub +}, 3.99 {+-} 0.21 R {sub +}{r_brace}. The planet's density is near 1.9 g cm{sup -3}; it is thus slightly denser and more massive than Neptune, but about the same size.« less
  • We infer the period (P) and size (R{sub p} ) distribution of Kepler transiting planet candidates with R{sub p} ≥ 1 R {sub ⊕} and P < 250 days hosted by solar-type stars. The planet detection efficiency is computed by using measured noise and the observed time spans of the light curves for ∼120,000 Kepler target stars. We focus on deriving the shape of planet periods and radius distribution functions. We find that for orbital periods P > 10 days, the planet frequency dN{sub p} /dlog P for 'Neptune-size' planets (R{sub p} = 4-8 R {sub ⊕}) increases with periodmore » as ∝P {sup 0.7±0.1}. In contrast, dN{sub p} /dlog P for 'super-Earth-size' (2-4 R {sub ⊕}) as well as 'Earth-size' (1-2 R {sub ⊕}) planets are consistent with a nearly flat distribution as a function of period (∝P {sup 0.11±0.05} and ∝P {sup –0.10±0.12}, respectively), and the normalizations are remarkably similar (within a factor of ∼1.5 at 50 days). Planet size distribution evolves with period, and generally the relative fractions for big planets (∼3-10 R {sub ⊕}) increase with period. The shape of the distribution function is not sensitive to changes in the selection criteria of the sample. The implied nearly flat or rising planet frequency at long periods appears to be in disagreement with the sharp decline at ∼100 days in planet frequency for low-mass planets (planet mass m{sub p} < 30 M {sub ⊕}) recently suggested by the HARPS survey. Within 250 days, the cumulative frequencies for Earth-size and super-Earth-size planets are remarkably similar (∼28% and 25%), while Neptune-size and Jupiter-size planets are ∼7% and ∼3%, respectively. A major potential uncertainty arises from the unphysical impact parameter distribution of the candidates.« less
  • We report a detailed characterization of the Kepler-19 system. This star was previously known to host a transiting planet with a period of 9.29 days, a radius of 2.2 R {sub ⊕}, and an upper limit on the mass of 20 M {sub ⊕}. The presence of a second, non-transiting planet was inferred from the transit time variations (TTVs) of Kepler-19b over eight quarters of Kepler photometry, although neither the mass nor period could be determined. By combining new TTVs measurements from all the Kepler quarters and 91 high-precision radial velocities obtained with the HARPS-N spectrograph, using dynamical simulations wemore » obtained a mass of 8.4 ± 1.6 M {sub ⊕} for Kepler-19b. From the same data, assuming system coplanarity, we determined an orbital period of 28.7 days and a mass of 13.1 ± 2.7 M {sub ⊕} for Kepler-19c and discovered a Neptune-like planet with a mass of 20.3 ± 3.4 M {sub ⊕} on a 63-day orbit. By comparing dynamical simulations with non-interacting Keplerian orbits, we concluded that neglecting interactions between planets may lead to systematic errors that can hamper the precision in the orbital parameters when the data set spans several years. With a density of 4.32 ± 0.87 g cm{sup −3} (0.78 ± 0.16 ρ {sub ⊕}) Kepler-19b belongs to the group of planets with a rocky core and a significant fraction of volatiles, in opposition to low-density planets characterized only by transit time variations and an increasing number of rocky planets with Earth-like density. Kepler-19 joins the small number of systems that reconcile transit timing variation and radial velocity measurements.« less
  • The ongoing High Accuracy Radial velocity Planet Search (HARPS) has found that 30%-50% of G and K dwarfs in the solar neighborhood host planets with M{sub pl} {approx}< M{sub Nep} in orbits of P {<=} 50 days. At first glance, this high overall occurrence rate seems at best to be marginally consistent with the planet frequency measured during Q0-Q2 of the Kepler mission, whose 1235 detected planetary candidates naively imply that {approx}15% of main-sequence dwarfs harbor a short-period planet with R{sub pl} < 4 R{sub Circled-Plus }. A rigorous comparison between the two surveys is difficult, however, as they observemore » different stellar populations, measure different planetary physical properties, and are subject to radically different sampling plans. In this article, we report the results of a Monte Carlo study which seeks to partially overcome this apparent discrepancy by identifying plausible planetary population distributions which can jointly conform to the results of the two surveys. We find that, given the HARPS occurrence rate, either a population subject to a mass-density relationship extrapolated from our solar system or a population concurrently consisting of dense silicate-iron planets and low-density gaseous worlds can produce total numbers of planet candidates consistent with those actually detected by Kepler. However, these two mass-to-radius relationships (M-Rs) resolve the apparent occurrence rate discrepancy with different mass and period distributions, enabling future observations to rule out M-Rs that do not fully describe the observed planet population in a global sense. Extracting information of this nature from the transit-radial-velocity comparison has significant implications for the interpretation of planet occurrence rates: if a multi-valued M-R, which allows planets of similar mass to have significantly different radii, emerges from observational data, then multiple formation mechanisms are likely at work. In this event, HARPS may be detecting a large population of dense low-mass planets, while Kepler detects a large population of gaseous sub-Neptunes.« less