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Using HARPS-N to characterise the long-period planets in the PH-2 and Kepler-103 systems

Research output: Contribution to journalArticle

  • Sophie C. Dubber
  • Annelies Mortier
  • Chantanelle Nava
  • Luca Malavolta
  • Helen Giles
  • Adrien Coffinet
  • David Charbonneau
  • Andrew Vanderburg
  • Aldo S. Bonomo
  • Walter Boschin
  • Lars A. Buchhave
  • Andrew Collier Cameron
  • Rosario Cosentino
  • Xavier Dumusque
  • Adriano Ghedina
  • Avet Harutyunyan
  • Raphaelle D. Haywood
  • David Latham
  • Mercedes Lopez-Morales
  • Giusi Micela
  • Emilio Molinari
  • Francesco A. Pepe
  • David Phillips
  • Giampaolo Piotto
  • Ennio Poretti
  • Dimitar Sasselov
  • Alessandro Sozzetti
  • Stephane Udry

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Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Publication statusPublished - 12 Oct 2019


 We present confirmation of the planetary nature of PH-2b, as well as the first mass estimates for the two planets in the Kepler-103 system. PH-2b and Kepler-103c are both long-period and transiting, a sparsely-populated category of exoplanet. We use {\it Kepler} light-curve data to estimate a radius, and then use HARPS-N radial velocities to determine the semi-amplitude of the stellar reflex motion and, hence, the planet mass. For PH-2b we recover a 3.5-σ mass estimate of Mp=109+30−32 M⊕ and a radius of Rp=9.49±0.16 R⊕. This means that PH-2b has a Saturn-like bulk density and is the only planet of this type with an orbital period P>200 days that orbits a single star. We find that Kepler-103b has a mass of Mp,b=11.7+4.31−4.72 M⊕ and Kepler-103c has a mass of Mp,c=58.5+11.2−11.4 M⊕. These are 2.5σ and 5σ results, respectively. With radii of Rp,b=3.49+0.06−0.05 R⊕, and Rp,c=5.45+0.18−0.17 R⊕, these results suggest that Kepler-103b has a Neptune-like density, while Kepler-103c is one of the highest density planets with a period P>100 days. By providing high-precision estimates for the masses of the long-period, intermediate-mass planets PH-2b and Kepler-103c, we increase the sample of long-period planets with known masses and radii, which will improve our understanding of the mass-radius relation across the full range of exoplanet masses and radii.

    Research areas

  • astro-ph.EP

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