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15 results on '"do Nascimento, J.-D."'

2. Seismic and spectroscopic analysis of 9 bright red giants observed by Kepler

Author

Coelho, H R, primary, Miglio, A, additional, Morel, T, additional, Lagarde, N, additional, Bossini, D, additional, Chaplin, W J, additional, Degl’Innocenti, S, additional, Dell’Omodarme, M, additional, Garcia, R A, additional, Handberg, R, additional, Hekker, S, additional, Huber, D, additional, Lund, M N, additional, Mathur, S, additional, Prada Moroni, P G, additional, Mosser, B, additional, Serenelli, A, additional, Rainer, M, additional, do Nascimento, J D, additional, Poretti, E, additional, Mathias, P, additional, Valle, G, additional, Dal Tio, P, additional, and Duarte, T, additional

Published
2023
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3. A Hale-like Cycle in the Solar Twin 18 Scorpii

Author

do Nascimento, J.-D., primary, Barnes, S. A., additional, Saar, S. H., additional, de Mello, G. F. Porto, additional, Hall, J. C., additional, Anthony, F., additional, de Almeida, L., additional, Velloso, E. N., additional, da Costa, J. S., additional, Petit, P., additional, Strugarek, A., additional, Wargelin, B. J., additional, Castro, M., additional, Strassmeier, K. G., additional, and Brun, A. S., additional

Published
2023
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5. Stellar rotations and the disentanglement of the Galactic thin and thick discs.

Author

da Silva, M P, Alves-Brito, A, and do Nascimento, J D

Subjects
STELLAR rotation, DWARF stars, LOW mass stars, STELLAR populations, STARS, GALAXY formation, AGE of stars
Abstract

The kinematics, mean α-elements, and ages of the stars reveal two distinct disc populations observed in the Solar neighbourhood. Although several studies have been carried out to characterize abundances of chemical elements and kinematic identifications in these populations, there are few studies that dealt with the analysis of stellar rotation and characteristics of populations focused on low-mass stars of the F and G types. In this work, we propose a new approach to classify stellar populations from the thin and thick disc for F and G dwarf stars by relating chemical abundance and rotation (v  sin  i) of these stars in the rotational–chemical–plane (v  sin  i –[α/Fe]–[Fe/H] plot). Our results show that the two rotational-chemical sequences disentangled, high- and low-[α/Fe] components, present properties (α-enhanced, ages, kinematics, space velocity gradients, local density ratio) closely linked to the stars of the chemically and kinematically defined as thin and thick disc components. This study has an impact on calibrations that relate ages to rotation (gyro-chronology) as well as age to chemical abundances (chemochronology), as well as sheds light on the understanding of the processes of Galactic disc formation. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Seismic and spectroscopic analysis of nine bright red giants observed by Kepler.

Author

Coelho, H R, Miglio, A, Morel, T, Lagarde, N, Bossini, D, Chaplin, W J, Degl'Innocenti, S, Dell'Omodarme, M, Garcia, R A, Handberg, R, Hekker, S, Huber, D, Lund, M N, Mathur, S, Prada Moroni, P G, Mosser, B, Serenelli, A, Rainer, M, do Nascimento, J D, and Poretti, E

Subjects
RED giants, ASTRONOMICAL photometry, PARALLAX, CARBON isotopes, SPACE telescopes, DATA release
Abstract

Photometric time series gathered by space telescopes such as CoRoT and Kepler allow to detect solar-like oscillations in red giant stars and to measure their global seismic constraints, which can be used to infer global stellar properties (e.g. masses, radii, and evolutionary states). Combining such precise constraints with photospheric abundances provides a means of testing mixing processes that occur inside red-giant stars. In this work, we conduct a detailed spectroscopic and seismic analysis of nine nearby (d < 200 pc) red giant stars observed by Kepler. Both seismic constraints and grid-based modelling approaches are used to determine precise fundamental parameters for those evolved stars. We compare distances and radii derived from Gaia Data Release 3 parallaxes with those inferred by a combination of seismic, spectroscopic, and photometric constraints. We find no deviations within errors bars, however the small sample size and the associated uncertainties are a limiting factor for such comparison. We use the period spacing of mixed modes to distinguish between ascending red-giants and red clump stars. Based on the evolutionary status, we apply corrections to the values of Δν for some stars, resulting in a slight improvement to the agreement between seismic and photometric distances. Finally, we couple constraints on detailed chemical abundances with the inferred masses, radii, and evolutionary states. Our results corroborate previous studies that show that observed abundances of lithium and carbon isotopic ratio are in contrast with predictions from standard models, giving robust evidence for the occurrence of additional mixing during the red-giant phase. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Far beyond the sun: II. Probing the stellar magnetism of the young Sun ι Horologii from the photosphere to its corona

Author

Amazo-Gómez, E M, primary, Alvarado-Gómez, J D, additional, Poppenhaeger, K, additional, Hussain, G A J, additional, Wood, B E, additional, Drake, J J, additional, do Nascimento, J D, additional, Anthony, F, additional, Sanz-Forcada, J, additional, Stelzer, B, additional, Del Sordo, F, additional, Damasso, M, additional, Redfield, S, additional, Donati, J F, additional, König, P C, additional, Hébrard, G, additional, and Miles-Páez, P A, additional

Published
2023
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8. Far beyond the Sun − II. Probing the stellar magnetism of the young Sun ι Horologii from the photosphere to its corona.

Author

Amazo-Gómez, E M, Alvarado-Gómez, J D, Poppenhäger, K, Hussain, G A J, Wood, B E, Drake, J J, do Nascimento, J-D, Anthony, F, Sanz-Forcada, J, Stelzer, B, Del Sordo, F, Damasso, M, Redfield, S, Donati, J F, König, P C, Hébrard, G, and Miles-Páez, P A

Subjects
STELLAR activity, STELLAR rotation, STELLAR magnetic fields, SPACE telescopes, LIGHT curves, SOLAR flares, SOLAR atmosphere, POWER spectra
Abstract

A comprehensive multiwavelength campaign has been carried out to probe stellar activity and variability in the young Sun-like star ι-Horologii. We present the results from long-term spectropolarimetric monitoring of the system by using the ultra-stable spectropolarimeter/velocimeter HARPS at the ESO 3.6-m telescope. Additionally, we included high-precision photometry from the NASA Transiting Exoplanet Survey Satellite (TESS) and observations in the far- and near-ultraviolet spectral regions using the STIS instrument on the NASA/ESA Hubble Space Telescope (HST). The high-quality data set allows a robust characterization of the star's rotation period, as well as a probe of the variability using a range of spectroscopic and photometric activity proxies. By analysing the gradient of the power spectra (GPS) in the TESS light curves, we constrained the faculae-to-spot driver ratio (⁠|$\rm S_{fac}/S_{spot}$|⁠) to 0.510 ± 0.023, which indicates that the stellar surface is spot dominated during the time of the observations. We compared the photospheric activity properties derived from the GPS method with a magnetic field map of the star derived using Zeeman–Doppler imaging (ZDI) from simultaneous spectropolarimetric data for the first time. Different stellar activity proxies enable a more complete interpretation of the observed variability. For example, we observed enhanced emission in the HST transition line diagnostics C  iv and C  iii , suggesting a flaring event. From the analysis of TESS data acquired simultaneously with the HST data, we investigate the photometric variability at the precise moment that the emission increased and derive correlations between different observables, probing the star from its photosphere to its corona. [ABSTRACT FROM AUTHOR]

Published
2023
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11. TOI-1452 b: SPIRou and TESS Reveal a Super-Earth in a Temperate Orbit Transiting an M4 Dwarf

Author

Cadieux, Charles, primary, Doyon, René, additional, Plotnykov, Mykhaylo, additional, Hébrard, Guillaume, additional, Jahandar, Farbod, additional, Artigau, Étienne, additional, Valencia, Diana, additional, Cook, Neil J., additional, Martioli, Eder, additional, Vandal, Thomas, additional, Donati, Jean-François, additional, Cloutier, Ryan, additional, Narita, Norio, additional, Fukui, Akihiko, additional, Hirano, Teruyuki, additional, Bouchy, François, additional, Cowan, Nicolas B., additional, Gonzales, Erica J., additional, Ciardi, David R., additional, Stassun, Keivan G., additional, Arnold, Luc, additional, Benneke, Björn, additional, Boisse, Isabelle, additional, Bonfils, Xavier, additional, Carmona, Andrés, additional, Cortés-Zuleta, Pía, additional, Delfosse, Xavier, additional, Forveille, Thierry, additional, Fouqué, Pascal, additional, da Silva, João Gomes, additional, Jenkins, Jon M., additional, Kiefer, Flavien, additional, Kóspál, Ágnes, additional, Lafrenière, David, additional, Martins, Jorge H. C., additional, Moutou, Claire, additional, do Nascimento, J.-D., additional, Ould-Elhkim, Merwan, additional, Pelletier, Stefan, additional, Twicken, Joseph D., additional, Bouma, Luke G., additional, Cartwright, Scott, additional, Darveau-Bernier, Antoine, additional, Grankin, Konstantin, additional, Ikoma, Masahiro, additional, Kagetani, Taiki, additional, Kawauchi, Kiyoe, additional, Kodama, Takanori, additional, Kotani, Takayuki, additional, Latham, David W., additional, Menou, Kristen, additional, Ricker, George, additional, Seager, Sara, additional, Tamura, Motohide, additional, Vanderspek, Roland, additional, and Watanabe, Noriharu, additional

Published
2022
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12. TOI-1759 b: A transiting sub-Neptune around a low mass star characterized with SPIRou and TESS

Author

Martioli, E., primary, Hébrard, G., additional, Fouqué, P., additional, Artigau, É., additional, Donati, J.-F., additional, Cadieux, C., additional, Bellotti, S., additional, Lecavelier des Etangs, A., additional, Doyon, R., additional, do Nascimento, J.-D., additional, Arnold, L., additional, Carmona, A., additional, Cook, N. J., additional, Cortes-Zuleta, P., additional, de Almeida, L., additional, Delfosse, X., additional, Folsom, C. P., additional, König, P.-C., additional, Moutou, C., additional, Ould-Elhkim, M., additional, Petit, P., additional, Stassun, K. G., additional, Vidotto, A. A., additional, Vandal, T., additional, Benneke, B., additional, Boisse, I., additional, Bonfils, X., additional, Boyd, P., additional, Brasseur, C., additional, Charbonneau, D., additional, Cloutier, R., additional, Collins, K., additional, Cristofari, P., additional, Crossfield, I., additional, Díaz, R. F., additional, Fausnaugh, M., additional, Figueira, P., additional, Forveille, T., additional, Furlan, E., additional, Girardin, E., additional, Gnilka, C. L., additional, Gomes da Silva, J., additional, Gu, P.-G., additional, Guerra, P., additional, Howell, S. B., additional, Hussain, G. A. J., additional, Jenkins, J. M., additional, Kiefer, F., additional, Latham, D. W., additional, Matson, R. A., additional, Matthews, E. C., additional, Morin, J., additional, Naves, R., additional, Ricker, G., additional, Seager, S., additional, Takami, M., additional, Twicken, J. D., additional, Vanderburg, A., additional, Vanderspek, R., additional, and Winn, J., additional

Published
2022
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13. Activity and Rotation of Nearby Field M Dwarfs in the TESS Southern Continuous Viewing Zone

Author

Newton, E.R., Agüeros, M.A., Machado, J.M., Anthony, F., Do Nascimento, J.-D., Wood, M.L., Núñez, A., Curtis, J.L., Rampalli, R., Mann, A.W., and Thao, P.C.

Abstract

The evolution of magnetism in late-type dwarfs remains murky, as we can only weakly predict levels of activity for M dwarfs of a given mass and age. We report results from our spectroscopic survey of M dwarfs in the Southern Continuous Viewing Zone (CVZ) of the Transiting Exoplanet Survey Satellite (TESS). As the TESS CVZs overlap with those of the James Webb Space Telescope, our targets constitute a legacy sample for studies of nearby M dwarfs. For 122 stars, we obtained at least one R ≈ 2000 optical spectrum with which we measure chromospheric Hα emission, a proxy for magnetic field strength. The fraction of active stars is consistent with what is expected for field M dwarfs; as in previous studies, we find that late-type M dwarfs remain active for longer than their early-type counterparts. While the TESS light curves for ≈20% of our targets show modulations consistent with rotation, TESS systematics are not well enough understood for confident measurements of rotation periods (P rot) longer than half the length of an observing sector. We report periods for 12 stars for which we measure P rot ≲ 15 days or find confirmation for the TESS-derived P rot in the literature. Our sample of 21 P rot, which includes periods from the literature, is consistent with our targets being spun-down field stars. Finally, we examine the Hα-to-bolometric luminosity distribution for our sample. Two stars are rotating fast enough to be magnetically saturated, but are not, hinting at the possibility that fast rotators may appear inactive in Hα.

Published
2022
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14. OGLE-2019-BLG-0033/MOA-2019-BLG-035

Author

Herald, A., Udalski, A., Bozza, V., Rota, P., Bond, I. A., Yee, J. C., Sajadian, S., Mróz, P., Poleski, R., Skowron, J., Szymański, M. K., Soszyński, I., Pietrukowicz, P., Kozłowski, S., Ulaczyk, K., Rybicki, K. A., Iwanek, P., Wrona, M., Gromadzki, M., Abe, F., Barry, R., Bennett, D. P., Bhattacharya, A., Fukui, A., Fujii, H., Hirao, Y., Itow, Y., Kirikawa, R., Kondo, I., Koshimoto, N., Matsubara, Y., Matsumoto, S., Miyazaki, S., Muraki, Y., Olmschenk, G., Ranc, C., Okamura, A., Rattenbury, N. J., Satoh, Y., Sumi, T., Suzuki, D., Silva, S. Ishitani, Toda, T., Tristram, P. J., Vandorou, A., Yama, H., Beichman, C. A., Bryden, G., Novati, S. Calchi, Carey, S., Gaudi, B. S., Gould, A., Henderson, C. B., Johnson, S., Shvartzvald, Y., Zhu, W., Dominik, M., Hundertmark, M., Jørgensen, U. G., Longa-Peña, P., Skottfelt, J., Tregloan-Reed, J., Bach-Møller, N., Burgdorf, M., D’Ago, G., Haikala, L., Hitchcock, J., Khalouei, E., Peixinho, N., Rahvar, S., Snodgrass, C., Southworth, J., Spyratos, P., Zang, W., Yang, H., Mao, S., Bachelet, E., Maoz, D., Street, R. A., Tsapras, Y., Christie, G. W., Cooper, T., de Almeida, L., do Nascimento, J.-D., Green, J., Han, C., Hennerley, S., Marmont, A., McCormick, J., Monard, L. A. G., Natusch, T., and Pogge, R.

Subjects
binaries: general, stars: low-mass, gravitational lensing: micro, brown dwarfs
Abstract

Context Brown dwarfs are transition objects between stars and planets that are still poorly understood, for which several competing mechanisms have been proposed to describe their formation. Mass measurements are generally difficult to carry out for isolated objects as well as for brown dwarfs orbiting low-mass stars, which are often too faint for a spectroscopic follow-up. \ud \ud Aims Microlensing provides an alternative tool for the discovery and investigation of such faint systems. Here, we present an analysis of the microlensing event OGLE-2019-BLG-0033/MOA-2019-BLG-035, which is caused by a binary system composed of a brown dwarf orbiting a red dwarf. \ud \ud Methods Thanks to extensive ground observations and the availability of space observations from Spitzer, it has been possible to obtain accurate estimates of all microlensing parameters, including the parallax, source radius, and orbital motion of the binary lens. \ud \ud Results Following an accurate modeling process, we found that the lens is composed of a red dwarf with a mass of M1 = 0.149 ± 0.010 M⊙ and a brown dwarf with a mass of M2 = 0.0463 ± 0.0031 M⊙at a projected separation of a⊥ = 0.585 au. The system has a peculiar velocity that is typical of old metal-poor populations in the thick disk. A percent-level precision in the mass measurement of brown dwarfs has been achieved only in a few microlensing events up to now, but will likely become more common in the future thanks to the Roman space telescope.

Published
2022

15. Estimating fundamental parameters of nearby M dwarfs from SPIRou spectra

Author

Cristofari, P I, primary, Donati, J-F, additional, Masseron, T, additional, Fouqué, P, additional, Moutou, C, additional, Delfosse, X, additional, Artigau, E, additional, Folsom, C P, additional, Carmona, A, additional, Gaidos, E, additional, do Nascimento, J-D, additional, Jahandar, F, additional, and Hébrard, G, additional

Published
2021
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