A candidate short-period sub-Earth orbiting Proxima Centauri

Faria, J. P.; Mascareño, A. Suárez; Figueira, P.; Silva, A. M.; Damasso, M.; Pepe, F.; Santos, N. C.; Rebolo, R.; Cristiani, S.; Adibekyan, V.; Alibert, Yann; Allart, R.; Barros, S. C. C.; Cabral, Alexandre; D’Odorico, V.; Marcantonio, P. Di; Dumusque, X.; Ehrenreich, D.; Hernández, J. I. González; Hara, N.; Lillo-Box, J.; Curto, G. Lo; Martins, C. J. A. P.; Mégevand, D.; Mehner, A.; Micela, G.; Molaro, P.; Nunes, Nelson J.; Πάλλη, Ε.; Poretti, E.; Sousa, S. G.; Sozzetti, A.; Tabernero, H. M.; Udry, S.; Osorio, M. R. Zapatero

doi:10.1051/0004-6361/202142337

Cited by 88 publications

(52 citation statements)

References 80 publications

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“…On the same subject, more recent works (e.g. Hara et al 2019 andFaria et al 2022), discuss the issue that orbital eccentricities fitted using only RVs could be spurious, as a consequence of an inappropriate modelling or not optimal data quality relative to the low semi-amplitude of the signal. Hara et al (2019) showed how one can get a wrong inference of the eccentricity without including an uncorrelated jitter term in the model and, more importantly, an incorrect result without a proper modelling of correlated signals, such as stellar activity.…”

Section: Discussionmentioning

confidence: 99%

“…Hara et al (2019) showed how one can get a wrong inference of the eccentricity without including an uncorrelated jitter term in the model and, more importantly, an incorrect result without a proper modelling of correlated signals, such as stellar activity. Faria et al (2022) showed how the value of the eccentricity of Proxima d depends on the method used to extract the RVs from ESPRESSO spectra, with a better constraint obtained using a technique based on template matching. In our analysis, we included uncorrelated jitter terms, we showed that the result is independent from the model used to fit the correlated stellar activity signal, and we tested our finding against different RV extraction methods applied to HARPS spectra.…”

Section: Discussionmentioning

confidence: 99%

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A quarter century of spectroscopic monitoring of the nearby M dwarf Gl 514. A super-Earth on an eccentric orbit moving in and out of the habitable zone

Damasso¹,

Perger²,

Almenara³

et al. 2022

Preprint

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Context. Statistical analyses based on Kepler data show that most of the early-type M dwarfs host multi-planet systems consisting of Earth to sub-Neptune sized planets with orbital periods up to ∼250 days, and that at least one such planet is likely located within the habitable zone. M dwarfs are therefore primary targets to search for potentially habitable planets in the solar neighbourhood. Aims. We investigated the presence of planetary companions around the nearby (7.6 pc) and bright (V = 9 mag) early-type M dwarf Gl 514, analysing 540 radial velocities collected over nearly 25 years with the HIRES, HARPS, and CARMENES spectrographs. Methods. The data are affected by time-correlated signals at the level of 2-3 m s −1 due to stellar activity, that we filtered out testing three different models based on Gaussian process regression. As a sanity cross-check, we repeated the analyses using HARPS radial velocities extracted with three different algorithms. We used HIRES radial velocities and Hipparcos-Gaia astrometry to put constraints on the presence of long-period companions, and we analysed TESS photometric data. Results. We found strong evidence that Gl 514 hosts a super-Earth on a likely eccentric orbit, residing in the conservative habitable zone for nearly 34% of its orbital period. The planet Gl 514 b has minimum mass m b sin i b = 5.2 ± 0.9 M ⊕ , orbital period P b = 140.43 ± 0.41 days, and eccentricity e b = 0.45 +0.15 −0.14 . No evidence for transits is found in the TESS light curve. There is no evidence for a longer period companion in the radial velocities and, based on astrometry, we can rule out a ∼ 0.2 M Jup planet at a distance of ∼ 3 − 10 au, and massive giant planets/brown dwarfs out to several tens of au. We discuss the possible presence of a second low-mass companion at a shorter distance from the host than Gl 514 b. Conclusions. Gl 514 b represents an interesting science case to study the habitability of planets on eccentric orbits. We advocate for additional spectroscopic follow-up to get more accurate and precise planetary parameters. Further follow-up is also needed to investigate sub m s −1 and shorter period signals.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A quarter century of spectroscopic monitoring of the nearby M dwarf Gl 514. A super-Earth on an eccentric orbit moving in and out of the habitable zone

Damasso¹,

Perger²,

Almenara³

et al. 2022

Preprint

Self Cite

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“…The masses of the lowest-mass planets (which are also from the NASA Exoplanet Archive) in the systems are indicated by the color bar at the right side of the upper panel. A low-mass planet recently discovered around Proxima Centauri (Faria et al 2022) was included in the plots.…”

Section: Summary and Discussionmentioning

confidence: 99%

A Super-Earth Orbiting Near the Inner Edge of the Habitable Zone around the M4.5-dwarf Ross 508

Harakawa,

Takarada,

Kasagi

et al. 2022

Preprint

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We report the near-infrared radial-velocity (RV) discovery of a super-Earth planet on a 10.77day orbit around the M4.5 dwarf Ross 508 (J mag = 9.1). Using precision RVs from the Subaru Telescope IRD (InfraRed Doppler) instrument, we derive a semi-amplitude of 3.92 +0.60 −0.58 m s −1 , corresponding to a planet with a minimum mass msini = 4.00 +0.53 −0.55 M ⊕ . We find no evidence of significant signals at the detected period in spectroscopic stellar activity indicators or MEarth photometry. The planet, Ross 508 b, has a semimajor-axis of 0.05366 +0.00056 −0.00049 au. This gives an orbit-averaged insolation of ≈1.4 times the Earth's value, placing Ross 508 b near the inner edge of its star's habitable zone. We have explored the possibility that the planet has a high eccentricity and its host is accompanied by an additional unconfirmed companion on a wide orbit. Our discovery demonstrates that the near-infrared RV search can play a crucial role to find a low-mass planet around cool M dwarfs like Ross 508.

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“…Planets have been detected around very low mass (VLM) stars, defined as stars with masses 0.3 M , yet still above the hydrogen-burning limit at ∼ 0.08 M , below which the brown dwarf regime begins (Liebert & Probst 1987). Particularly fasci-nating are the cases of TRAPPIST-1, a ∼ 0.085 M star in the Solar neighborhood with a system of 7 rocky planets (Gillon et al 2017), and Proxima Centauri, the closest star to the Sun with a mass of ∼ 0.12 M , which hosts a terrestrial planet, a super-Earth candidate, and a newly discovered sub-Earth candidate (Anglada-Escudé et al 2016;Damasso et al 2020, Faria et al 2022. In general, data from the Kepler spacecraft show that the occurrence rate of small planets (with a radius of 1.0 − 2.8 R ⊕ ) is 3.5 times higher for M dwarfs than FGK stars (Mulders et al 2015).…”

Section: Introductionmentioning

confidence: 99%

A giant planet shaping the disk around the very low mass star CIDA 1

Curone,

Izquierdo,

Testi

et al. 2022

Preprint

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Context. Exoplanetary research has provided us with exciting discoveries of planets around very low mass (VLM) stars (0.08 M M 0.3 M ; e.g., TRAPPIST-1 and Proxima Centauri). However, current theoretical models still strive to explain planet formation in these conditions and do not predict the development of giant planets. Recent high-resolution observations from the Atacama Large Millimeter/submillimeter Array (ALMA) of the disk around CIDA 1, a VLM star in Taurus, show substructures hinting at the presence of a massive planet. Aims. We aim to reproduce the dust ring of CIDA 1, observed in the dust continuum emission in ALMA Band 7 (0.9 mm) and Band 4 (2.1 mm), along with its 12 CO (J = 3 − 2) and 13 CO (J = 3 − 2) channel maps, assuming the structures are shaped by the interaction of the disk with a massive planet. We seek to retrieve the mass and position of the putative planet, through a global simulation assessing planet-disk interaction to quantitatively reproduce protoplanetary disk observations of both dust and gas emission in a self-consistent way. Methods. We model the protoplanetary disk with a set of hydrodynamical simulations, hosting an embedded planet with a starting mass between 0.1 and 4.0 M Jup initially located at a distance between 9 and 11 au from the central star. We compute the dust and gas emission using radiative transfer simulations, and, finally, we obtain the synthetic observations treating the images as the actual ALMA observations. Results. Our models indicate that a planet with a minimum mass of ∼ 1.4 M Jup orbiting at a distance of ∼ 9 − 10 au can explain the morphology and location of the observed dust ring at Band 7 and Band 4. We match the flux of the dust emission observation with a dust-to-gas mass ratio in the disk of ∼ 10 −2 . We are able to reproduce the low spectral index (∼ 2) observed where the dust ring is detected, with a ∼ 40 − 50% fraction of optically thick emission. Assuming a 12 CO abundance of 5 × 10 −5 and a 13 CO abundance 70 times lower, our synthetic images reproduce the morphology of the 12 CO (J = 3 − 2) and 13 CO (J = 3 − 2) observed channel maps where the cloud absorption allowed a detection. From our simulations, we estimate that a stellar mass M = 0.2 M and a systemic velocity sys = 6.25 km s −1 are needed to reproduce the gas rotation as retrieved from molecular line observations. Applying an empirical relation between planet mass and gap width in the dust, we predict a maximum planet mass of ∼ 4 − 8 M Jup . Conclusions. Our results suggest the presence of a massive planet orbiting CIDA 1, thus challenging our understanding of planet formation around VLM stars.

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A candidate short-period sub-Earth orbiting Proxima Centauri

Cited by 88 publications

References 80 publications

A quarter century of spectroscopic monitoring of the nearby M dwarf Gl 514. A super-Earth on an eccentric orbit moving in and out of the habitable zone

A quarter century of spectroscopic monitoring of the nearby M dwarf Gl 514. A super-Earth on an eccentric orbit moving in and out of the habitable zone

A Super-Earth Orbiting Near the Inner Edge of the Habitable Zone around the M4.5-dwarf Ross 508

A giant planet shaping the disk around the very low mass star CIDA 1

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