HD 28471: a near-resonant compact multiplanet system with a possible cold giant planet

Fuente: arXiv
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Autores principales: Stevenson, A. T., Haswell, C. A., Barnes, J. R., Standing, M. R., Barstow, J. K., Ross, Z. O. B., Freckelton, A. V., Staab, D.
Formato: Preprint
Publicado: 2025
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author Stevenson, A. T.
Haswell, C. A.
Barnes, J. R.
Standing, M. R.
Barstow, J. K.
Ross, Z. O. B.
Freckelton, A. V.
Staab, D.
author_facet Stevenson, A. T.
Haswell, C. A.
Barnes, J. R.
Standing, M. R.
Barstow, J. K.
Ross, Z. O. B.
Freckelton, A. V.
Staab, D.
contents We present radial velocity measurements of the star HD 28471, observed by HARPS at the ESO 3.6 m telescope over a baseline of $\sim19$ years. We have searched for planetary companions to HD 28471 using kima, a trans-dimensional diffusive nested sampling algorithm where the number of planetary signals is explored as a free parameter. We detect a compact system of three planets, with signals in the preferred solution corresponding to orbits of $P\sim3.16,~6.12,~\textrm{and }11.68$ d. These planets lie firmly in the super-Earth and sub-Neptune mass regime, with (minimum) masses of $3.7, 5.7, \textrm{and }4.9$ M$_{\oplus}$, respectively. A long-period ($\sim1500$ d) signal is also strongly detected. Assessment of activity indicator periodicities and RV correlations suggests that the three short-period signals are genuine planets, but casts doubt upon the nature of the long-period signal. The origin may be a short stellar magnetic cycle, though additional data are required to fully sample the periodicity without intervening offsets. HD 28471 b exhibits a more eccentric orbit than the other planets, which may be due to dynamical interaction, or a result of RV variation from an as-yet-undetected 4th planet interior to this compact system. The detected planets lie close to a resonant configuration, indicating that the system may retain features of its natal configuration, with convergent migration potentially responsible for evolving the planets onto such short-period orbits.
format Preprint
id arxiv_https___arxiv_org_abs_2508_18000
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle HD 28471: a near-resonant compact multiplanet system with a possible cold giant planet
Stevenson, A. T.
Haswell, C. A.
Barnes, J. R.
Standing, M. R.
Barstow, J. K.
Ross, Z. O. B.
Freckelton, A. V.
Staab, D.
Earth and Planetary Astrophysics
We present radial velocity measurements of the star HD 28471, observed by HARPS at the ESO 3.6 m telescope over a baseline of $\sim19$ years. We have searched for planetary companions to HD 28471 using kima, a trans-dimensional diffusive nested sampling algorithm where the number of planetary signals is explored as a free parameter. We detect a compact system of three planets, with signals in the preferred solution corresponding to orbits of $P\sim3.16,~6.12,~\textrm{and }11.68$ d. These planets lie firmly in the super-Earth and sub-Neptune mass regime, with (minimum) masses of $3.7, 5.7, \textrm{and }4.9$ M$_{\oplus}$, respectively. A long-period ($\sim1500$ d) signal is also strongly detected. Assessment of activity indicator periodicities and RV correlations suggests that the three short-period signals are genuine planets, but casts doubt upon the nature of the long-period signal. The origin may be a short stellar magnetic cycle, though additional data are required to fully sample the periodicity without intervening offsets. HD 28471 b exhibits a more eccentric orbit than the other planets, which may be due to dynamical interaction, or a result of RV variation from an as-yet-undetected 4th planet interior to this compact system. The detected planets lie close to a resonant configuration, indicating that the system may retain features of its natal configuration, with convergent migration potentially responsible for evolving the planets onto such short-period orbits.
title HD 28471: a near-resonant compact multiplanet system with a possible cold giant planet
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2508.18000