The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc

Luque, R.; Fulton, B. J.; Kunimoto, Michelle; Amado, P. J.; Gorrini, P.; Hellier, C.; Henry, Gregory W.; Molaverdikhani, Karan; Morello, Giuseppe; Peña-Moñino, L.; Pozuelos, F. J.; Shan, Yutong; Anglada‐Escudé, G.; Béjar, V. J. S.; Bergond, G.; Boyle, A. W.; Caballero, J. A.; Charbonneau, David; Ciardi, David R.; Dufoer, Sjoerd; Espinoza, N.; Everett, Mark E.; Fischer, Debra A.; Hatzes, A. P.; Henning, Th.; Hesse, Katharine; Howard, Andrew W.; Howell, Steve B.; Isaacson, Howard; Jeffers, S. V.; Jenkins, Jon M.; Kane, Stephen R.; Kemmer, J.; Khalafinejad, S.; Kidwell, Richard C.; Kossakowski, D.; Latham, David W.; Lillo-Box, J.; Lissauer, Jack J.; Montes, D.; Orell-Miquel, J.; Πάλλη, Ε.; Pollacco, D.; Quirrenbach, A.; Reffert, S.; Reiners, A.; Ribas, I.; Ricker, G.; Rogers, Leslie; Sanz-Forcada, J.; Schlecker, Martin; Schweitzer, A.; Seager, Sara; Shporer, Avi; Stassun, Keivan G.; Stock, S.; Tal-Or, L.; Ting, Eric B.; Trifonov, T.; Vanaverbeke, Sigfried; Vanderspek, R.; Villaseñor, J.; Winn, Joshua N.; Winters, Jennifer G.; Osorio, M. R. Zapatero

doi:10.1051/0004-6361/202243834

Cited by 15 publications

(1 citation statement)

References 178 publications

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“…4. According to our estimations, the new model can be applied to CSs in the vicinity of old-star exoplanets (such as discussed by Luque et al 2022) that have no large magnetospheres, to rarefied exospheres or astrospheres, as well as to CSs in the proximity of planets/stars that can be distorted by the gravity force and magnetic shear.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Impact of Heavy Ions on the Structure of Current Sheets in the Gravity Field of Exoplanets and Stars

Kislov

Malova

Khabarova

et al. 2023

ApJ

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Boundary current sheets (CSs) can be formed in collisionless space plasmas in the environment of exoplanets and cold stars. Usually they represent curved surfaces carrying the electric current analogous to the well-known planetary ionospheres, magnetopauses, or stellar coronas surrounding celestial bodies. At smaller local scales, some of them can be imagined as planar current layers of a finite scale located parallel to the surface of a celestial object and, correspondingly, perpendicular to the direction of the gravitational force. In some cases, this force crossed with magnetic field can influence the dynamics of charged particles in CSs and substantially change the structure of both the current layer and the magnetic field. We have generalized our prior model, taking into account a multi-ion plasma composition and a magnetic field configuration with a shear. It is shown that, due to the drift motion of plasma particles in the crossed gravitational and magnetic fields, the structure of CSs becomes more complex, accruing asymmetric and shifted profiles of the current and plasma densities that depend on dominating current carriers and the characteristics of the magnetic shear. We discuss possible applications of the results to the interpretation of observations of boundary layers in different space plasmas.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Impact of Heavy Ions on the Structure of Current Sheets in the Gravity Field of Exoplanets and Stars

Kislov

Malova

Khabarova

et al. 2023

ApJ

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A detailed analysis of the Gl 486 planetary system

Caballero

González-Álvarez

Brady

et al. 2022

A&A

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Context. The Gl 486 system consists of a very nearby, relatively bright, weakly active M3.5 V star at just 8 pc with a warm transiting rocky planet of about 1.3 R ⊕ and 3.0 M ⊕ that is ideal for both transmission and emission spectroscopy and for testing interior models of telluric planets. Aims. To prepare for future studies, we thoroughly characterise the planetary system with new accurate and precise data collected with state-ofthe-art photometers from space and spectrometers and interferometers from the ground. Methods. We collected light curves of seven new transits observed with the CHEOPS space mission and new radial velocities obtained with MAROON-X at the 8.1 m Gemini North and CARMENES at the 3.5 m Calar Alto telescopes, together with previously published spectroscopic and photometric data from the two spectrographs and TESS. We also performed near-infrared interferometric observations with the CHARA Array and new photometric monitoring with a suite of smaller telescopes (AstroLAB, LCOGT, OSN, TJO). This extraordinary and rich data set was the input for our comprehensive analysis. Results. From interferometry, we measure a limb-darkened disc angular size of the star Gl 486 at θ LDD = 0.390 ± 0.018 mas. Together with a corrected Gaia EDR3 parallax, we obtain a stellar radius R = 0.339 ± 0.015 R . We also measure a stellar rotation period at P rot = 49.9 ± 5.5 d, an upper limit to its XUV (5-920 Å) flux with new Hubble/STIS data, and, for the first time, a variety of element abundances (Fe, Mg, Si, V, Sr, Zr, Rb) and C/O ratio. Besides, we impose restrictive constraints on the presence of additional components, either stellar or substellar, in the system. With the input stellar parameters and the radial-velocity and transit data, we determine the radius and mass of the planet Gl 486 b at R p = 1.343 +0.063 −0.062 R ⊕ and M p = 3.00 +0.13 −0.13 M ⊕ , with relative uncertainties in planet radius and mass of 4.7 % and 4.2 %, respectively. From the planet parameters and the stellar element abundances, we infer the most probable models of planet internal structure and composition, which are consistent with a relatively small metallic core with respect to the Earth, a deep silicate mantle, and a thin volatile upper layer. With all these ingredients, we outline prospects for Gl 486 b atmospheric studies, especially with forthcoming James Webb Space Telescope observations.

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HD 191939 revisited: New and refined planet mass determinations, and a new planet in the habitable zone

Orell-Miquel¹,

Nowak²,

Murgas³

et al. 2023

A&A

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HD 191939 (TOI-1339) is a nearby (d = 54 pc), bright (V = 9 mag), and inactive Sun-like star (G9 V) known to host a multi-planet transiting system. Ground-based spectroscopic observations confirmed the planetary nature of the three transiting sub-Neptunes (HD 191939 b, c, and d) originally detected by TESS and were used to measure the masses for planets b and c with 3σ precision. These previous observations also reported the discovery of an additional Saturn-mass planet (HD 191939 e) and evidence for a further, very long-period companion (HD 191939 f). Here, we report the discovery of a new non-transiting planet in the system and a refined mass determination of HD 191939 d. The new planet, HD 191939 g, has a minimum mass of 13.5±2.0 M⊕ and a period of about 280 days. This period places the planet within the conservative habitable zone of the host star, and near a 1:3 resonance with HD 191939 e. The compilation of 362 radial velocity measurements with a baseline of 677 days from four different high-resolution spectrographs also allowed us to refine the properties of the previously known planets, including a 4.6σ mass determination for planet d, for which only a 2σ upper limit had been set until now. We confirm the previously suspected low density of HD 191939 d, which makes it an attractive target for attempting atmospheric characterisation. Overall, the planetary system consists of three sub-Neptunes interior to a Saturn-mass and a Uranus-mass planet plus a high-mass long-period companion. This particular configuration has no counterpart in the literature and makes HD 191939 an exceptional multi-planet transiting system with an unusual planet demographic worthy of future observation.

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The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc

Cited by 15 publications

References 178 publications

Impact of Heavy Ions on the Structure of Current Sheets in the Gravity Field of Exoplanets and Stars

Impact of Heavy Ions on the Structure of Current Sheets in the Gravity Field of Exoplanets and Stars

A detailed analysis of the Gl 486 planetary system

HD 191939 revisited: New and refined planet mass determinations, and a new planet in the habitable zone

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