Detection and Doppler monitoring of K2-285 (EPIC 246471491), a system of four transiting planets smaller than Neptune

Palle, E.; Nowak, G.; Luque, R.; Hidalgo, D.; Barragán, O.; Prieto-Arranz, J.; Hirano, T.; Fridlund, M.; Gandolfi, D.; Livingston, J.; Dai, F.; Morales, J. C.; Lafarga, M.; Albrecht, S.; Alonso, R.; Amado, P. J.; Caballero, J. A.; Cabrera, J.; Cochran, W. D.; Csizmadia, Sz; Deeg, H.; Eigmüller, Ph; Endl, M.; Erikson, A.; Fukui, A.; Guenther, E. W.; Grziwa, S.; Hatzes, A. P.; Korth, J.; Kürster, M.; Kuzuhara, M.; Montañes Rodríguez, P.; Murgas, F.; Narita, N.; Nespral, D.; Pätzold, M.; Persson, C. M.; Quirrenbach, A.; Rauer, H.; Redfield, S.; Reiners, A.; Ribas, I.; Smith, A. M.S.; Van Eylen, V.; Winn, J. N.; Zechmeister, M.

Detection and Doppler monitoring of K2-285 (EPIC 246471491), a system of four transiting planets smaller than Neptune

Mark

Palle, E. ; Nowak, G. ; Luque, R. ; Hidalgo, D. ; Barragán, O. ; Prieto-Arranz, J. ; Hirano, T. ; Fridlund, M. ; Gandolfi, D. and Livingston, J. , et al. (2019) In Astronomy and Astrophysics 623.

Abstract: Context. The Kepler extended mission, also known as K2, has provided the community with a wealth of planetary candidates that orbit stars typically much brighter than the targets of the original mission. These planet candidates are suitable for further spectroscopic follow-up and precise mass determinations, leading ultimately to the construction of empirical mass-radius diagrams. Particularly interesting is to constrain the properties of planets that are between Earth and Neptune in size, the most abundant type of planet orbiting Sun-like stars with periods of less than a few years. Aims. Among many other K2 candidates, we discovered a multi-planetary system around EPIC 246471491, referred to henceforth as K2-285, which contains four... (More); Context. The Kepler extended mission, also known as K2, has provided the community with a wealth of planetary candidates that orbit stars typically much brighter than the targets of the original mission. These planet candidates are suitable for further spectroscopic follow-up and precise mass determinations, leading ultimately to the construction of empirical mass-radius diagrams. Particularly interesting is to constrain the properties of planets that are between Earth and Neptune in size, the most abundant type of planet orbiting Sun-like stars with periods of less than a few years. Aims. Among many other K2 candidates, we discovered a multi-planetary system around EPIC 246471491, referred to henceforth as K2-285, which contains four planets, ranging in size from twice the size of Earth to nearly the size of Neptune. We aim here at confirming their planetary nature and characterizing the properties of this system. Methods. We measure the mass of the planets of the K2-285 system by means of precise radial-velocity measurements using the CARMENES spectrograph and the HARPS-N spectrograph. Results. With our data we are able to determine the mass of the two inner planets of the system with a precision better than 15%, and place upper limits on the masses of the two outer planets. Conclusions. We find that K2-285b has a mass of M_b = 9.68_-1.37^+1.21 M_· and a radius of R_b = 2.59_-0.06^+0.06 R_·, yielding a mean density of ρ_b = 3.07_-0.45^+0.45 g cm^-3, while K2-285c has a mass of M_c = 15.68_-2.13^+2.28 M_·, radius of R_c = 3.53_-0.08^+0.08 R_·, and a mean density of ρ_c = 1.95_-0.28^+0.32 g cm^-3. For K2-285d (R_d = 2.48_-0.06^+0.06 R_·) and K2-285e (R_e = 1.95_-0.05^+0.05 R_·), the upper limits for the masses are 6.5 M_· and 10.7 M_·, respectively. The system is thus composed of an (almost) Neptune-twin planet (in mass and radius), two sub-Neptunes with very different densities and presumably bulk composition, and a fourth planet in the outermost orbit that resides right in the middle of the super-Earth/sub-Neptune radius gap. Future comparative planetology studies of this system would provide useful insights into planetary formation, and also a good test of atmospheric escape and evolution theories.
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Please use this url to cite or link to this publication: https://lup.lub.lu.se/record/9d00c746-e1c4-4efa-8956-ccb933ac8e05

author

Palle, E. ; Nowak, G. ; Luque, R. ; Hidalgo, D. ; Barragán, O. ; Prieto-Arranz, J. ; Hirano, T. ; Fridlund, M. ; Gandolfi, D. and Livingston, J. , et al. (More)

Palle, E. ; Nowak, G. ; Luque, R. ; Hidalgo, D. ; Barragán, O. ; Prieto-Arranz, J. ; Hirano, T. ; Fridlund, M. ; Gandolfi, D. ; Livingston, J. ; Dai, F. ; Morales, J. C. ; Lafarga, M. ; Albrecht, S. ; Alonso, R. ; Amado, P. J. ; Caballero, J. A. ; Cabrera, J. ; Cochran, W. D. ; Csizmadia, Sz ; Deeg, H. ; Eigmüller, Ph ; Endl, M. ; Erikson, A. ; Fukui, A. ; Guenther, E. W. ; Grziwa, S. ; Hatzes, A. P. ; Korth, J. ^LU ; Kürster, M. ; Kuzuhara, M. ; Montañes Rodríguez, P. ; Murgas, F. ; Narita, N. ; Nespral, D. ; Pätzold, M. ; Persson, C. M. ; Quirrenbach, A. ; Rauer, H. ; Redfield, S. ; Reiners, A. ; Ribas, I. ; Smith, A. M.S. ; Van Eylen, V. ; Winn, J. N. and Zechmeister, M. (Less)

publishing date

2019-03-01

type

Contribution to journal

publication status

published

keywords

Planetary systems, Planets and satellites: atmospheres, Planets and satellites: detection, Planets and satellites: dynamical evolution and stability, Planets and satellites: fundamental parameters

in

Astronomy and Astrophysics

volume

623

article number

A41

publisher

EDP Sciences

external identifiers

scopus:85062772173

ISSN

0004-6361

DOI

10.1051/0004-6361/201834001

language

English

LU publication?

no

additional info

id

9d00c746-e1c4-4efa-8956-ccb933ac8e05

date added to LUP

2023-02-02 10:42:20

date last changed

2023-02-21 10:18:24

@article{9d00c746-e1c4-4efa-8956-ccb933ac8e05,
  abstract     = {{<p>Context. The Kepler extended mission, also known as K2, has provided the community with a wealth of planetary candidates that orbit stars typically much brighter than the targets of the original mission. These planet candidates are suitable for further spectroscopic follow-up and precise mass determinations, leading ultimately to the construction of empirical mass-radius diagrams. Particularly interesting is to constrain the properties of planets that are between Earth and Neptune in size, the most abundant type of planet orbiting Sun-like stars with periods of less than a few years. Aims. Among many other K2 candidates, we discovered a multi-planetary system around EPIC 246471491, referred to henceforth as K2-285, which contains four planets, ranging in size from twice the size of Earth to nearly the size of Neptune. We aim here at confirming their planetary nature and characterizing the properties of this system. Methods. We measure the mass of the planets of the K2-285 system by means of precise radial-velocity measurements using the CARMENES spectrograph and the HARPS-N spectrograph. Results. With our data we are able to determine the mass of the two inner planets of the system with a precision better than 15%, and place upper limits on the masses of the two outer planets. Conclusions. We find that K2-285b has a mass of M<sub>b</sub> = 9.68<sub>-1.37</sub><sup>+1.21</sup> M<sub>·</sub> and a radius of R<sub>b</sub> = 2.59<sub>-0.06</sub><sup>+0.06</sup> R<sub>·</sub>, yielding a mean density of ρ<sub>b</sub> = 3.07<sub>-0.45</sub><sup>+0.45</sup> g cm<sup>-3</sup>, while K2-285c has a mass of M<sub>c</sub> = 15.68<sub>-2.13</sub><sup>+2.28</sup> M<sub>·</sub>, radius of R<sub>c</sub> = 3.53<sub>-0.08</sub><sup>+0.08</sup> R<sub>·</sub>, and a mean density of ρ<sub>c</sub> = 1.95<sub>-0.28</sub><sup>+0.32</sup> g cm<sup>-3</sup>. For K2-285d (R<sub>d</sub> = 2.48<sub>-0.06</sub><sup>+0.06</sup> R<sub>·</sub>) and K2-285e (R<sub>e</sub> = 1.95<sub>-0.05</sub><sup>+0.05</sup> R<sub>·</sub>), the upper limits for the masses are 6.5 M<sub>·</sub> and 10.7 M<sub>·</sub>, respectively. The system is thus composed of an (almost) Neptune-twin planet (in mass and radius), two sub-Neptunes with very different densities and presumably bulk composition, and a fourth planet in the outermost orbit that resides right in the middle of the super-Earth/sub-Neptune radius gap. Future comparative planetology studies of this system would provide useful insights into planetary formation, and also a good test of atmospheric escape and evolution theories.</p>}},
  author       = {{Palle, E. and Nowak, G. and Luque, R. and Hidalgo, D. and Barragán, O. and Prieto-Arranz, J. and Hirano, T. and Fridlund, M. and Gandolfi, D. and Livingston, J. and Dai, F. and Morales, J. C. and Lafarga, M. and Albrecht, S. and Alonso, R. and Amado, P. J. and Caballero, J. A. and Cabrera, J. and Cochran, W. D. and Csizmadia, Sz and Deeg, H. and Eigmüller, Ph and Endl, M. and Erikson, A. and Fukui, A. and Guenther, E. W. and Grziwa, S. and Hatzes, A. P. and Korth, J. and Kürster, M. and Kuzuhara, M. and Montañes Rodríguez, P. and Murgas, F. and Narita, N. and Nespral, D. and Pätzold, M. and Persson, C. M. and Quirrenbach, A. and Rauer, H. and Redfield, S. and Reiners, A. and Ribas, I. and Smith, A. M.S. and Van Eylen, V. and Winn, J. N. and Zechmeister, M.}},
  issn         = {{0004-6361}},
  keywords     = {{Planetary systems; Planets and satellites: atmospheres; Planets and satellites: detection; Planets and satellites: dynamical evolution and stability; Planets and satellites: fundamental parameters}},
  language     = {{eng}},
  month        = {{03}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{Detection and Doppler monitoring of K2-285 (EPIC 246471491), a system of four transiting planets smaller than Neptune}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/201834001}},
  doi          = {{10.1051/0004-6361/201834001}},
  volume       = {{623}},
  year         = {{2019}},
}

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Detection and Doppler monitoring of K2-285 (EPIC 246471491), a system of four transiting planets smaller than Neptune