An extreme planetary system around HD219828. One long-period super Jupiter to a hot-neptune host star

Abstract

With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. We present a full investigation of the HD219828 system, a bright metal-rich star for which a hot neptune has previously been detected. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD219828. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. We announce the discovery of a long period (P=13.1years) massive (msini=15.1MJup) companion (HD219828c) in a very eccentric orbit (e=0.81). The same data confirms the existence of a hot-neptune, HD219828b, with a minimum mass of 21 MEarth and a period of 3.83days. The dynamical analysis shows that the system is stable. The HD219828 system is extreme and unique in several aspects. First, among all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like HD219828, with a hot neptune and a long-period massive companion are more frequent than similar systems with a hot jupiter instead. This suggests that the formation of hot neptunes follows a different path than the formation of their hot jovian counterparts. The high mass, long period, and eccentricity of HD219828c also make it a good target for Gaia astrometry as well as a potential target for atmospheric characterisation, using direct imaging or high-resolution spectroscopy. Astrometric observations will allow us to derive its real mass and orbital configuration. If a transit of HD219828b is detected, we will be able to fully characterise the system, including the relative orbital inclinations. With a clearly known mass, HD219828c may become a benchmark object for the range in between giant planets and brown dwarfs.

arXiv commentAstronomy & Astrophysics, in press

References in corpus (73)

• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• A Survey of Stellar Families: Multiplicity of Solar-Type Stars
• Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 20945
• Accurate masses and radii of normal stars: modern results and applications
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Spectroscopic [Fe/H] for 98 extra-solar planet-host stars: Exploring the probability of planet formation
• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• The Theory of Brown Dwarfs and Extrasolar Giant Planets
• Defining and cataloging exoplanets: The exoplanet.eu database
• The HARPS search for southern extra-solar planets XXXI. The M-dwarf sample
• Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program.Galactic stellar populations and planets
• Formation of Hot Planets by a combination of planet scattering, tidal circularization, and Kozai mechanism
• Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets
• Basic physical parameters of a selected sample of evolved stars
• The signature of orbital motion from the dayside of the planet tau Bootis b
• The fast spin-rotation of a young extrasolar planet
• Dynamics of the giant planets of the solar system in the gaseous proto-planetary disk and relationship to the current orbital architecture
• Parametrizing the exoplanet eccentricity distribution with the Beta distribution
• SWEET-Cat: A catalogue of parameters for Stars With ExoplanETs I. New atmospheric parameters and masses for 48 stars with planets
• Planetary detection limits taking into account stellar noise. I. Observational strategies to reduce stellar oscillation and granulation effects
• SOPHIE velocimetry of Kepler transit candidates XVII. The physical properties of giant exoplanets within 400 days of period
• The CORALIE survey for southern extra-solar planets IX. A 1.3-day period brown dwarf disguised as a planet
• Giant planets orbiting metal-rich stars show signatures of planet-planet interactions
• WASP-121 b: a hot Jupiter in a polar orbit and close to tidal disruption
• Search for brown-dwarf companions of stars
• PASTIS: Bayesian extrasolar planet validation. I. General framework, models, and performance
• Rotation periods of late-type dwarf stars from time-series high-resolution spectroscopy of chromospheric indicators
• Long-term tidal evolution of short-period planets with companions
• A pair of planets around HD 202206 or a circumbinary planet?
• Statistics of Long Period Gas Giant Planets in Known Planetary Systems
• Chromospheric activity as age indicator
• Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars
• The HARPS search for southern extra-solar planets XIX. Characterization and dynamics of the GJ876 planetary system
• SOPHIE+: First results of an octagonal-section fiber for high-precision radial velocity measurements
• HAT-P-26b: A Low-Density Neptune-Mass Planet Transiting a K Star
• Constraining planet structure from stellar chemistry: the cases of CoRoT-7, Kepler-10, and Kepler-93
• Li depletion in solar analogues with exoplanets: Extending the sample
• The SOPHIE search for northern extrasolar planets III. A Jupiter-mass companion around HD 109246
• Exploring the alpha-enhancement of metal-poor planet-hosting stars. The Kepler and HARPS samples
• The HARPS search for southern extra-solar planets XXXV. The interesting case of HD41248: stellar activity, no planets?
• Parent Stars of Extrasolar Planets. X. Lithium Abundances and vsini Revisited
• Advances in exoplanet science from Kepler
• C, S, Zn and Cu abundances in planet-harbouring stars
• Gas giant planets as dynamical barriers to inward-migrating super-Earths
• Discovery and Rossiter-McLaughlin Effect of Exoplanet Kepler-8b
• Correcting the spectroscopic surface gravity using transits and asteroseismology. No significant effect on temperatures or metallicities with ARES+MOOG in LTE
• Oxygen abundances in G- and F-type stars from HARPS
• Highlights in the Study of Exoplanet Atmospheres
• Orbital and physical properties of planets and their hosts: new insights on planet formation and evolution
• HD45364, a pair of planets in a 3:2 mean motion resonance
• Evidence against the young hot-Jupiter around BD +20 1790
• Evidence for a spectroscopic direct detection of reflected light from 51 Peg b
• The SOPHIE search for northern extrasolar planets VIII. A warm Neptune orbiting HD164595
• Do stellar magnetic cycles influence the measurement of precise radial velocities?
• A new Neptune-mass planet orbiting HD 219828
• The HARPS search for southern extra-solar planets. XXXIV. A planetary system around the nearby M dwarf GJ163, with a super-Earth possibly in the habitable zone
• High precision Symplectic Integrators for the Solar System
• Secular evolution of a satellite by tidal effect. Application to Triton
• The frequency of giant planets around metal-poor stars
• The ELODIE survey for northern extra--solar planets I. 6 new extra--solar planet candidates
• The California Planet Survey IV: A Planet Orbiting the Giant Star HD 145934 and Updates to Seven Systems with Long-Period Planets
• Tidal dissipation in multi-planet systems and constraints to orbit-fitting
• A planetary system with gas giants and super-Earths around the nearby M dwarf GJ 676A. Optimizing data analysis techniques for the detection of multi-planetary systems
• On the long-term correlation between the flux in the Ca II H & K and Halpha lines for FGK stars
• On the Age of Stars Harboring Transiting Planets
• The Lick-Carnegie Exoplanet Survey: HD32963 -- A New Jupiter Analog Orbiting a Sun-like Star
• The Kepler-454 System: A Small, Not-rocky Inner Planet, a Jovian World, and a Distant Companion
• Stellar Activity and Exclusion of the Outer Planet in the HD 99492 System
• The HARPS search for southern extra-solar planets XXXVI: Five new long-period giant planets and a system update
• Exoplanet hosts reveal lithium depletion: Results from a homogeneous statistical analysis
• The HARPS search for southern extra-solar planets: XXVIII. Two giant planets around M0 dwarfs
• Consequences of spectrograph illumination for the accuracy of radial-velocimetry
• An extreme planetary system around HD219828. One long-period super Jupiter to a hot-neptune host star

Cited by in corpus (15)

• The Super Earth-Cold Jupiter Relations
• The GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data
• Dynamically hot Super-Earths from outer giant planet scattering
• Truly eccentric. I. Revisiting eight single-eccentric planetary systems
• The HD 137496 system: A dense, hot super-Mercury and a cold Jupiter
• The Spitzer search for the transits of HARPS low-mass planets - I. No transit for the super-Earth HD 40307b
• An extreme planetary system around HD219828. One long-period super Jupiter to a hot-neptune host star
• The Spitzer search for the transits of HARPS low-mass planets - II. Null results for 19 planets
• The GAPS Programme with HARPS-N@TNG XII: Characterization of the planetary system around HD108874
• The SOPHIE search for northern extrasolar planets. XVIII: Six new cold Jupiters, including one of the most eccentric exoplanet orbits
• Chemical composition of stars with massive planets
• An Edge-On Orbit for the Eccentric Long-Period Planet HR 5183 b
• Discovery of a cold giant planet and mass measurement of a hot super-Earth in the multi-planetary system WASP-132
• The young planetary system K2-25: constraints on companions and starspots
• Effects of Outer Giant Planets on In Situ Formation of Inner Super-Earths