J/A+A/640/A48 K2-32 and K2-233 light and RV curves (Lillo-Box+, 2020)
Masses for the seven planets in K2-32 and K2-233.
Four diverse planets in resonant chain and the first young rocky worlds.
Lillo-Box J., Lopez, T., Santerne A., Nielsen L.D., Barros S.C.C.,
Deleuil M., Acuna L., Mousis O., Sousa S.G., Adibekyan V., Armstrong D.J.,
Barrado D., Bayliss D., Brown D.J.A., Demangeon O.D.S., Dumusque X.,
Figueira P., Hojjatpanah S., Osborn H.P., Santos N.C., Udry S.
<Astron. Astrophys. 640, A48 (2020)>
=2020A&A...640A..48L 2020A&A...640A..48L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry ;
Radial velocities
Keywords: planets and satellites: terrestrial planets, composition -
techniques: radial velocities - techniques: photometric
Abstract:
High-precision planetary densities are key pieces of information
necessary to derive robust atmospheric properties for extrasolar
planets. Measuring precise masses is the most challenging part of this
task, especially in multi-planetary systems. The ESO-K2 collaboration
focuses on the follow-up of a selection of multi-planetary systems
detected by the K2 mission using the HARPS instrument with this goal
in mind.
In this work, we measure the masses and densities of two
multi-planetary systems: a four-planet near resonant chain system
(K2-32) and a young (∼400Myr old) planetary system consisting of
three close-in small planets (K2-233).
We obtained 199 new HARPS observations for K2-32 and 124 for K2-233
covering a long baseline of more than three years. We performed a
joint analysis of the radial velocities and K2 photometry with PASTIS
to precisely measure and constrained the properties of these planets,
focusing on their masses and orbital properties.
We find that K2-32 is a compact scaled-down version of the Solar
System's architecture, with a small rocky inner planet
(Me=2.1-1.1+1.3M{earth}, Pe∼4.35-days) followed by an inflated
Neptune-mass planet (Mb=15.0-1.7+1.8M{earth}, Pb∼8.99-days)
and two external sub-Neptunes (Mc=8.1±2.4M{earth}, Pc∼20.66-days;
Md=6.7±2.5M{earth}, Pd∼31.72-days). K2-32 becomes one of the few
multi-planetary systems with four or more planets known where all have
measured masses and radii. Additionally, we constrain the masses of
the three planets in the K2-233 system through marginal detection of
their induced radial velocity variations. For the two inner Earth-size
planets we constrain their masses at a 95% confidence level to be
smaller than Mb<11.3M{earth} (Pb∼2.47-days), Mc<12.8M{earth}
(Pc∼7.06-days). The outer planet is a sub-Neptune size planet with an
inferred mass of Md=8.3-4.7+5.2M{earth} (Md<21.1M{earth},
Pd∼24.36-days).
Our observations of these two planetary systems confirm for the first
time the rocky nature of two planets orbiting a young star, with
relatively short orbital periods (<7-days). They provide key
information for planet formation and evolution models of telluric
planets. Additionally, the Neptune-like derived masses of the three
planets, K2-32 b, c, d, puts them in a relatively unexplored regime of
incident flux and planet mass, which is key for transmission
spectroscopy studies in the near future.
Description:
Radial velocity observations with HARPS instrument and K2
high-precision photometry were analysed jointly to provide a
self-consistent measurement of the physical and orbital properties of
the planets.
Objects:
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RA (2000) DE Designation(s)
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16 49 42.26 -19 32 34.15 K2-32 = EPIC 205071984
15 21 55.20 -20 13 53.99 K2-233 = EPIC 249622103
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
k2-32lc.dat 36 3534 K2 photometry extracted and detrended for K2-32
k2-32rv.dat 43 168 Radial velocity data set for K2-32
k2-233lc.dat 36 3886 K2 photometry extracted and detrended for K2-233
k2-233rv.dat 43 126 Radial velocity data set for K2-233
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See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
Byte-by-byte Description of file: k2-233lc.dat k2-32lc.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD Barycentric Julian date
16- 25 F10.8 --- Flux K2 detrended and normalised relative flux
27- 36 F10.8 --- e_Flux K2 uncertainty of relative flux
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Byte-by-byte Description of file: k2-233rv.dat k2-32rv.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD Barycentric Julian date
16- 26 F11.8 km/s RV Radial velocity corrected for instrument offset
28- 37 F10.8 km/s e_RV Radial velocity uncertainty
39- 43 A5 --- Inst Instrument
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Acknowledgements:
Jorge Lillo-Box, Jorge.Lillo(at)cab.inta-csic.es
(End) Jorge Lillo-Box [CAB], Patricia Vannier [CDS] 29-May-2020