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Giant Outer Transiting Exoplanet Mass (GOTa EM) survey: VII. TOI-6041: A multi-planet system including a warm Neptune exhibiting strong transit-timing variations

Heidari, N. ; Davies, M.B. LU and Wolf, S. (2026) In Astronomy and Astrophysics 707.
Abstract
We present the characterisation of the TOI-6041 system, a bright (V = 9.84 ± 0.03) G7-type star hosting at least two planets. The inner planet, TOI-6041 b, is a warm Neptune with a radius of 4.55-0.17+0.18 R⊕, initially identified as a single-transit event in TESS photometry. Subsequent observations with TESS and CHEOPS revealed additional transits, enabling the determination of its 26.04945-0.00034+0.00033 orbital period and the detection of significant transit-timing variations (TTVs), exhibiting a peak-to-peak amplitude of about 1 hour. Radial-velocity (RV) measurements obtained with the APF spectrographs allowed us to place a 3ÏÂ upper mass limit of 28.9 M⊕ on TOI-6041 b. In addition, the RV data reveal a second companion, TOI-6041 c,... (More)
We present the characterisation of the TOI-6041 system, a bright (V = 9.84 ± 0.03) G7-type star hosting at least two planets. The inner planet, TOI-6041 b, is a warm Neptune with a radius of 4.55-0.17+0.18 R⊕, initially identified as a single-transit event in TESS photometry. Subsequent observations with TESS and CHEOPS revealed additional transits, enabling the determination of its 26.04945-0.00034+0.00033 orbital period and the detection of significant transit-timing variations (TTVs), exhibiting a peak-to-peak amplitude of about 1 hour. Radial-velocity (RV) measurements obtained with the APF spectrographs allowed us to place a 3ÏÂ upper mass limit of 28.9 M⊕ on TOI-6041 b. In addition, the RV data reveal a second companion, TOI-6041 c, on an 88 d orbit, with a minimum mass of 0.25 MJup. A preliminary TTV analysis suggested that the observed variations could be caused by gravitational perturbations from planet c; however, reproducing the observed amplitudes requires a relatively high eccentricity of about 0.3 for that planet. Our dynamical stability analysis indicates that such a configuration is dynamically viable and places a 1ÏÂ upper limit on the mass of TOI-6041 c at 0.8 MJup. An alternative is the presence of a third, low-mass planet located between planets b and c, or on an inner orbit relative to planet b -particularly near a mean-motion resonance with planet b -which could account for the observed variations. These findings remain tentative, and further RV and photometric observations are essential in to better constrain the mass of planet b and to refine the TTV modeling, thereby improving our understanding of the systema s dynamical architecture. © The Authors 2026. (Less)
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keywords
Planets and satellites: detection, Planets and satellites: dynamical evolution and stability, Exoplanets, Gravitation, Orbits, Satellites, Timing circuits, Exo-planets, Neptune, Orbital periods, Peak to peak amplitudes, Planets and satellites: detections, Planets and satellites: dynamical evolution and stabilities, Radial velocity, Radial velocity measurements, Timing variations, Transit timing, Photometry
in
Astronomy and Astrophysics
volume
707
article number
A134
publisher
EDP Sciences
external identifiers
  • scopus:105033014134
ISSN
0004-6361
DOI
10.1051/0004-6361/202556700
language
English
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yes
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8738da34-14b8-43c5-b81f-987c3dd588e7
date added to LUP
2026-04-01 13:13:00
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2026-04-01 13:13:16
@article{8738da34-14b8-43c5-b81f-987c3dd588e7,
  abstract     = {{We present the characterisation of the TOI-6041 system, a bright (V = 9.84 ± 0.03) G7-type star hosting at least two planets. The inner planet, TOI-6041 b, is a warm Neptune with a radius of 4.55-0.17+0.18 R⊕, initially identified as a single-transit event in TESS photometry. Subsequent observations with TESS and CHEOPS revealed additional transits, enabling the determination of its 26.04945-0.00034+0.00033 orbital period and the detection of significant transit-timing variations (TTVs), exhibiting a peak-to-peak amplitude of about 1 hour. Radial-velocity (RV) measurements obtained with the APF spectrographs allowed us to place a 3ÏÂ upper mass limit of 28.9 M⊕ on TOI-6041 b. In addition, the RV data reveal a second companion, TOI-6041 c, on an 88 d orbit, with a minimum mass of 0.25 MJup. A preliminary TTV analysis suggested that the observed variations could be caused by gravitational perturbations from planet c; however, reproducing the observed amplitudes requires a relatively high eccentricity of about 0.3 for that planet. Our dynamical stability analysis indicates that such a configuration is dynamically viable and places a 1ÏÂ upper limit on the mass of TOI-6041 c at 0.8 MJup. An alternative is the presence of a third, low-mass planet located between planets b and c, or on an inner orbit relative to planet b -particularly near a mean-motion resonance with planet b -which could account for the observed variations. These findings remain tentative, and further RV and photometric observations are essential in to better constrain the mass of planet b and to refine the TTV modeling, thereby improving our understanding of the systema s dynamical architecture. © The Authors 2026.}},
  author       = {{Heidari, N. and Davies, M.B. and Wolf, S.}},
  issn         = {{0004-6361}},
  keywords     = {{Planets and satellites: detection; Planets and satellites: dynamical evolution and stability; Exoplanets; Gravitation; Orbits; Satellites; Timing circuits; Exo-planets; Neptune; Orbital periods; Peak to peak amplitudes; Planets and satellites: detections; Planets and satellites: dynamical evolution and stabilities; Radial velocity; Radial velocity measurements; Timing variations; Transit timing; Photometry}},
  language     = {{eng}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{Giant Outer Transiting Exoplanet Mass (GOTa EM) survey: VII. TOI-6041: A multi-planet system including a warm Neptune exhibiting strong transit-timing variations}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202556700}},
  doi          = {{10.1051/0004-6361/202556700}},
  volume       = {{707}},
  year         = {{2026}},
}