J/A+A/592/A13 HD 219828 radial velocity curve (Santos+, 2016)
An extreme planetary system around HD 219828 - One long-period super Jupiter to
a hot-Neptune host star.
Santos N.C., Santerne A., Faria J.P., Rey J., Correia A.C.M., Laskar J.,
Udry S., Adibekyan V., Bouchy F., Delgado-Mena E., Melo C., Dumusque X.,
Hebrard G., Lovis C., Mayor M., Montalto M., Mortier A., Pepe F.,
Figueira P., Sahlmann J., Segransan D., Sousai S.G.
<Astron. Astrophys. 592, A13 (2016)>
=2016A&A...592A..13S 2016A&A...592A..13S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Radial velocities
Keywords: planetary systems - techniques: spectroscopic -
techniques: radial velocities - stars: individual: HD219828
Abstract:
With about 2000 extrasolar planets confirmed, the results show that
planetary systems have a whole range of unexpected properties. This
wide diversity provides fundamental clues to the processes of planet
formation and evolution.
We present a full investigation of the HD 219828 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 HD 219828. The spectra
were used to characterise the star and its chemical abundances, as
well as to check for spurious, activity induced signals. 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=13.1-years) massive (msini=15.1M{Jup})
companion (HD 219828 c) in a very eccentric orbit (e=0.81). The same
data confirms the existence of a hot-neptune, HD 219828 b, with a
minimum mass of 21M☉ and a period of 3.83-days. The dynamical
analysis shows that the system is stable, and that the equilibrium
eccentricity of planet $b$ is close to zero. The HD 219828 system is
extreme and unique in several aspects. First, ammong all known
exoplanet systems it presents an unusually high mass ratio. We also
show that systems like HD 219828, 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 HD
219828 c 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 HD 219828 b is detected, we will be able to fully
characterise the system, including the relative orbital inclinations.
With a clearly known mass, HD 219828 c may become a benchmark object
for the range in between giant planets and brown dwarfs.
Description:
Radial velocity data used in the paper is presented, together with
error bars and the spectrograph used.
Objects:
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RA (ICRS) DE Designation(s)
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23 18 46.73 +18 38 44.6 HD 219828 = HIP 115100
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 37 114 Radial velocity data
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d BJD Baricentric Julian date (BJD-2400000)
14- 22 F9.5 km/s RV Radial velocity
24- 30 F7.5 km/s e_RV Uncertainty in Radial velocity
32- 37 A6 --- Inst Spectrograph used (ELODIE, HARPS or SOPHIE)
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Acknowledgements:
Nuno Santos, nuno.santos(at)astro.up.pt
(End) Nuno Santos [IA, Portugal], Patricia Vannier [CDS] 23-May-2016