Issue |
A&A
Volume 677, September 2023
|
|
---|---|---|
Article Number | A122 | |
Number of page(s) | 20 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202346476 | |
Published online | 13 September 2023 |
The GAPS programme at TNG
XLVI. Deep search for low-mass planets in late-dwarf systems hosting cold Jupiters★,★★
1
INAF – Osservatorio Astrofisico di Torino,
via Osservatorio 20,
10025
Pino Torinese, Italy
e-mail: matteo.pinamonti@inaf.it
2
Observatoire de Genève, Université de Genève,
51 Chemin des Maillettes,
1290
Sauverny, Switzerland
3
INAF – Osservatorio Astronomico di Palermo,
piazza del Parlamento 1,
I-90134
Palermo, Italy
4
INAF – Osservatorio Astrofisico di Catania,
via S. Sofia 78,
95123
Catania, Italy
5
INAF – Osservatorio Astronomico di Trieste,
via G. B. Tiepolo 11,
34143
Trieste, Italy
6
INAF – Osservatorio Astronomico di Brera,
via E. Bianchi 46,
23807
Merate, Italy
7
INAF – Osservatorio Astronomico di Padova,
vicolo dell’Osservatorio 5,
35122
Padova, Italy
8
Dipartimento di Fisica, Università di Roma “Tor Vergata”,
via della Ricerca Scientifica 1,
00133
Roma, Italy
9
Max Planck Institute for Astronomy,
Kõnigstuhl 17,
69117
Heidelberg, Germany
10
Dipartimento di Fisica e Astronomia, Università di Firenze,
Largo Enrico Fermi 5,
50125
Firenze, Italy
11
Fundación Galileo Galilei – INAF,
Ramble José Ana Fernandez Pérez 7,
38712
Breña Baja, TF, Spain
12
INAF – Osservatorio Astronomico di Roma,
via Frascati 33,
00078
Monte Porzio Catone, Italy
13
Instituto de Astrofísica de Canarias (IAC),
38205
La Laguna, Tenerife, Spain
14
INAF – Osservatorio Astronomico di Capodimonte,
Salita Moiariello 16,
I80131,
Napoli, Italy
15
INAF – Osservatorio di Cagliari,
via della Scienza 5,
I09047
Selargius, Italy
16
Dipartimento di Fisica e Astronomia, Università di Padova,
via Marzolo 8,
35131
Padova, Italy
Received:
21
March
2023
Accepted:
7
June
2023
Context. With the growth of comparative exoplanetology, it is increasingly clear that the relationship between inner and outer planets plays a key role in unveiling the mechanisms governing formation and evolution models. For this reason, it is important to probe the inner region of systems hosting long-period giants in search of undetected lower mass planetary companions.
Aims. We aim to present the results of a high-cadence and high-precision radial velocity (RV) monitoring of three late-type dwarf stars hosting long-period giants with well-measured orbits in order to search for short-period sub-Neptunes (SN, M sin i < 30 M⊕).
Methods. Building on the results and expertise of our previous studies, we carried out combined fits of our HARPS-N data with literature RVs. We used Markov chain Monte Carlo (MCMC) analyses to refine the literature orbital solutions and search for additional inner planets, applying Gaussian process regression techniques to deal with the stellar activity signals where required. We then used the results of our survey to estimate the frequency of sub-Neptunes in systems hosting cold Jupiters, f(SN|CJ), and compared it with the frequency around field M dwarfs, f(SN).
Results. We identify a new short-period, low-mass planet orbiting GJ 328, GJ 328 c, with Pc = 241.8-1.7+1.3 days and Mc sin i = 21.4-3.2+3.4M⊕. We moreover identify and model the chromospheric activity signals and rotation periods of GJ 649 and GJ 849, around which no additional planet is found. Then, taking into account also planetary system around the previously analysed low-mass star BD-11 4672, we derive an estimate of the frequencies of inner planets in such systems. In particular, f(SN|CJ) = 0.25-0.07+0.58 for mini-Neptunes (10 M⊕ < M sin i < 30 M⊕, P < 150 d), marginally larger than f(SN). For lower mass planets (M sin i < 10 M⊕) instead f(SN|CJ) < 0.69, which is compatible with f(SN).
Conclusions. In light of the newly detected mini-Neptune, we find tentative evidence of a positive correlation between the presence of long-period giant planets and that of inner low-mass planets, f(SN|CJ) > f(SN). This might indicate that cold Jupiters have an opposite influence in the formation of inner sub-Neptunes around late-type dwarfs as opposed to their solar-type counterparts, boosting the formation of mini-Neptunes instead of impeding it.
Key words: techniques: radial velocities / stars: individual: GJ 328 / stars: individual: GJ 649 / stars: individual: GJ 849 / stars: activity / planets and satellites: detection
The complete time series of all spectroscopic data used in this work is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/677/A122
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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