TOI–1278 B: SPIRou Unveils a Rare Brown Dwarf Companion in Close-in Orbit around an M Dwarf

Artigau, Étienne; Hébrard, G.; Cadieux, Charles; Vandal, Thomas; Cook, Neil J.; Doyon, René; Gagné, Jonathan; Moutou, C.; Martioli, Eder; Frasca, A.; Jahandar, Farbod; Lafrenière, David; Malo, Lison; Donati, J.‐F.; Cortés-Zuleta, P.; Boisse, I.; Delfosse, X.; Fouqué, P.; Morin, J.; Rowe, Jason F.; Marino, G.; Papini, Riccardo; Ciardi, David R.; Lund, Michael B.; Martins, J. H. C.; Pelletier, Sonia; Arnold, L.; Bouchy, F.; Forveille, T.; Santos, N. C.; Bonfils, X.; Figueira, P.; Fausnaugh, Michael; Ricker, G.; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Ting, Eric B.; Torres, Guillermo; Silva, João Gomes da

doi:10.3847/1538-3881/ac096d

Cited by 23 publications

(7 citation statements)

References 103 publications

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“…For TOI-1278, the algorithm typically converges in three steps, with a typical residual uncertainty that decreases by a factor ∼30 between steps. The per-epoch RV uncertainty with the LBL is 9.4 m s −1 , which is a two-fold improvement compared to the previous published values, which were measured with a CCF (see Table 1 in Artigau et al 2021). The TOI-1278 Keplerian fit values are consistent with those published albeit with significantly reduced uncertainties; this target is currently the subject of ongoing monitoring with SPIRou and its extended RV monitoring will be presented in a future publication.…”

Section: Iterations Of the Line-by-line Algorithmmentioning

confidence: 61%

“…For RV-stable targets (with planetary and activity signals at the few meters per second level), the algorithm converges in one or two steps. To test the convergence in the presence of a large RV signal, we revisited the TOI-1278 data set presented in Artigau et al (2021) where an 18 M Jup brown dwarf imparts a K ∼ 2300 m s −1 RV signal on its M0V host. The RV excursions for the system are at about half of the FWHM of stellar lines.…”

Section: Iterations Of the Line-by-line Algorithmmentioning

confidence: 99%

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Line-by-line Velocity Measurements: an Outlier-resistant Method for Precision Velocimetry

Artigau

Cadieux

Cook

et al. 2022

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We present a new algorithm for precision radial velocity (pRV) measurements, a line-by-line (LBL) approach designed to handle outlying spectral information in a simple but efficient manner. The effectiveness of the LBL method is demonstrated on two data sets, one obtained with SPIRou on Barnard’s star, and the other with the High Accuracy Radial velocity Planet Searcher (HARPS) on Proxima Centauri. In the near-infrared, the LBL provides a framework for meters-per-second-level accuracy in pRV measurements despite the challenges associated with telluric absorption and sky emission lines. We confirm with SPIRou measurements spanning 2.7 yr that the candidate super-Earth on a 233 day orbit around Barnard’s star is an artifact due to a combination of time sampling and activity. The LBL analysis of the Proxima Centauri HARPS post-upgrade data alone easily recovers the Proxima b signal and also provides a 2σ detection of the recently confirmed 5 day Proxima d planet, but argues against the presence of the candidate Proxima c with a period of 1900 days. We provide evidence that the Proxima c signal is associated with small, unaccounted systematic effects affecting the HARPS-TERRA template-matching radial velocity extraction method for long-period signals. Finally, the LBL framework provides a very effective activity indicator, akin to the FWHM derived from the cross-correlation function, from which we infer a rotation period of 92.1 − 3.5 + 4.2 days for Proxima.

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Section: Iterations Of the Line-by-line Algorithmmentioning

confidence: 61%

Section: Iterations Of the Line-by-line Algorithmmentioning

confidence: 99%

Line-by-line Velocity Measurements: an Outlier-resistant Method for Precision Velocimetry

Artigau

Cadieux

Cook

et al. 2022

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“…The SPIRou data reduction was performed using the 0.7.194 version of the APERO pipeline (Cook et al, in prep). Basic APERO steps have been described in a number of contributions (Artigau et al 2021;Cristofari et al 2021;Martioli et al 2022). In brief, the major APERO modules are as follows:…”

Section: Cfht/spiroumentioning

confidence: 99%

TESS discovery of a sub-Neptune orbiting a mid-M dwarf TOI-2136

Gan¹,

Soubkiou²,

Wang³

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present the discovery of TOI-2136 b, a sub-Neptune planet transiting a nearby M4.5V-type star every 7.85 days, identified through photometric measurements from the TESS mission. The host star is located 33 pc away with a radius of R* = 0.34 ± 0.02 R⊙, a mass of 0.34 ± 0.02 M⊙ and an effective temperature of 3342 ± 100 K. We estimate its stellar rotation period to be 75 ± 5 days based on archival long-term photometry. We confirm and characterize the planet based on a series of ground-based multi-wavelength photometry, high-angular-resolution imaging observations, and precise radial velocities from CFHT/SPIRou. Our joint analysis reveals that the planet has a radius of 2.20 ± 0.17 R⊕ and a mass of 6.4 ± 2.4 M⊕. The mass and radius of TOI-2136 b is consistent with a broad range of compositions, from water-ice to gas-dominated worlds. TOI-2136 b falls close to the radius valley for M dwarfs predicted by thermally driven atmospheric mass loss models, making it an interesting target for future studies of its interior structure and atmospheric properties.

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“…method to mitigate tellurics in PRVs for stabilized spectrographs such as HARPS and SPIRou (Artigau et al 2021;Cretignier et al 2021). 3.…”

Section: Extracting Rvs and Correcting For The Telluric Absorptionmentioning

confidence: 99%

“…This is equivalent to knowing the line depths to some degree (though not perfectly) prior to the final RV extraction, a fairly common situation in reality (e.g.,Artigau et al 2021). 15 We use the LMFIT package in Python with the L-BFGS algorithm, which we observed to have the best convergence properties for our calculations.…”

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confidence: 99%

Characterizing and Mitigating the Impact of Telluric Absorption in Precise Radial Velocities

Wang

Latouf

Plavchan

et al. 2022

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Precise radial velocity (PRV) surveys are important for the search for Earth analogs around nearby bright stars, which induce a small stellar reflex motion with an RV amplitude of ∼10 cm s−1. Detecting such a small RV signal poses challenges to instrumentation, data analysis, and the precision of astrophysical models to mitigate stellar jitter. In this work, we investigate an important component in the PRV error budget—the spectral contamination from the Earth’s atmosphere (tellurics). We characterize the effects of telluric absorption on the RV precision and quantify its contribution to the RV error budget over time and across a wavelength range of 350 nm–2.5 μm. We use simulated solar spectra with telluric contamination injected, and we extract the RVs using two commonly adopted algorithms: dividing out a telluric model before performing cross-correlation or forward modeling the observed spectrum incorporating a telluric model. We assume various degrees of cleanness in removing the tellurics. We conclude that the RV errors caused by telluric absorption can be suppressed to close to or even below 1–10 cm s−1 in the blue optical region. At red through near-infrared wavelengths, however, the residuals of tellurics can induce an RV error on the meter-per-second level even under the most favorable assumptions for telluric removal, leading to significant systematic noise in the RV time series and periodograms. If the red-optical or near-infrared becomes critical in the mitigation of stellar activity, systematic errors from tellurics can be eliminated with a space mission such as EarthFinder.

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TOI–1278 B: SPIRou Unveils a Rare Brown Dwarf Companion in Close-in Orbit around an M Dwarf

Cited by 23 publications

References 103 publications

Line-by-line Velocity Measurements: an Outlier-resistant Method for Precision Velocimetry

Line-by-line Velocity Measurements: an Outlier-resistant Method for Precision Velocimetry

TESS discovery of a sub-Neptune orbiting a mid-M dwarf TOI-2136

Characterizing and Mitigating the Impact of Telluric Absorption in Precise Radial Velocities

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