Close stellar conjunctions of<i>α</i>Centauri A and B until 2050

Kervella, P.; Mignard, F.; Mérand, A.; Thévenin, F.

doi:10.1051/0004-6361/201629201

Cited by 55 publications

(88 citation statements)

References 49 publications

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“…These new measurements are independent of model atmospheres for the prediction of LD correction coefficients as they are now measured. Together with the parallax and masses recently reported by Kervella et al (2016), as well as spectroscopic studies, the determined radii complete the calibration of the fundamental parameters of both components of α Centauri (Table 5).…”

Section: Discussionsupporting

confidence: 56%

“…To read the tables from the different authors, we adopt the following turbulence and metallicity parameters for α Cen A and B from Jofré et al (2015) and Heiter et al (2015) The surface gravity parameter of α Cen A and B can be deduced from the combination of these masses and our radius measurements, and we obtain log g = 4.53 ± 0.03). They are however one to two orders of magnitude more accurate thanks mainly to the improved masses from Kervella et al (2016).…”

Section: Comparison With Literature Models and The Sunmentioning

confidence: 99%

“…The recently determined parallax of the α Cen system by Kervella et al (2016) of π = 747.17 ± 0.61 mas allows us to convert the measured LD angular diameters (using the power law LD) into linear radii. We adopt the IAU convention (Prša et al 2016) for the nominal solar radius (R N = 695 700 km), leading to the following conversion relation between the linear radius and the angular diameter:…”

Section: Linear Radii Of α Cen a And Bmentioning

confidence: 99%

“…Measured radii and seismic oscillation frequencies provide complementary constraints for stellar structure and evolution models (Creevey et al 2007;Cunha et al 2007;Metcalfe et al 2015). The triple system α Centauri (WDS J14396-6050AB, GJ559AB) is our closest stellar neighbor, at a distance of only d = 1.3384 ± 0.0011 pc for the main components A and B (π = 747.17 ± 0.61 mas; Kervella et al 2016). The third member is Proxima (M5.5V, GJ551).…”

Section: Introductionmentioning

confidence: 99%

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The radii and limb darkenings of α Centauri A and B

Kervella

Bigot

Gallenne

et al. 2017

A&A

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The photospheric radius is one of the fundamental parameters governing the radiative equilibrium of a star. We report new observations of the nearest solar-type stars α Centauri A (G2V) and B (K1V) with the VLTI/PIONIER optical interferometer. The combination of four configurations of the VLTI enable us to measure simultaneously the limb darkened angular diameter θ LD and the limb darkening parameters of the two solar-type stars in the near-infrared H band (λ = 1.65 µm). We obtain photospheric angular diameters of θ LD (A) = 8.502 ± 0.038 mas (0.43%) and θ LD (B) = 5.999 ± 0.025 mas (0.42%), through the adjustment of a power law limb darkening model. We find H band power law exponents of α(A) = 0.1404 ± 0.0050 (3.6%) and α(B) = 0.1545 ± 0.0044 (2.8%), which closely bracket the observed solar value (α = 0.15027). Combined with the parallax π = 747.17 ± 0.61 mas previously determined, we derive linear radii of R A = 1.2234 ± 0.0053 R (0.43%) and R B = 0.8632 ± 0.0037 R (0.43%). The power law exponents that we derive for the two stars indicate a significantly weaker limb darkening than predicted by both 1D and 3D stellar atmosphere models. As this discrepancy is also observed on near-infrared limb darkening profile of the Sun, an improvement of the calibration of stellar atmosphere models is clearly needed. The reported PIONIER visibility measurements of α Cen A and B provide a robust basis to validate the future evolutions of these models.

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Section: Discussionsupporting

confidence: 56%

Section: Comparison With Literature Models and The Sunmentioning

confidence: 99%

Section: Linear Radii Of α Cen a And Bmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The radii and limb darkenings of α Centauri A and B

Kervella

Bigot

Gallenne

et al. 2017

A&A

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“…Proxima Centauri, a red dwarf, is well-known as the nearest star to the Sun, with a distance of 1.3008±0.0006 pc (Kervella et al 2016). Proxima Centauri and αCentaur-iAandB are in a hierarchical triple star system.…”

Section: Introductionmentioning

confidence: 99%

Searching for the Transit of the Earth-mass Exoplanet Proxima Centauri b in Antarctica: Preliminary Result

Liu

Jiang

Huang

et al. 2017

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ProximaCentauri is known as the closest star to the Sun. Recently, radial velocity (RV) observations revealed the existence of an Earth-mass planet around it. With an orbital period of ∼11 days, Proxima Centauri b is probably in the habitable zone of its host star. We undertook a photometric monitoring campaign to search for its transit, using the Bright Star Survey Telescope at the Zhongshan Station in Antarctica. A transit-like signal appearing on 2016 September 8 has been tentatively identified. Its midtime, T C =2,457,640.1990±0.0017 HJD, is consistent with the predicted ephemeris based on the RV orbit in a 1σ confidence interval. Time-correlated noise is pronounced in the light curve of ProximaCentauri, affecting the detection of transits. We develop a technique, in a Gaussian process framework, to gauge the statistical significance of a potential transit detection. The tentative transit signal reported here has a confidence level of 2.5σ. Further detection of its periodic signals is necessary to confirm the planetary transit of ProximaCentaurib. We plan to monitor ProximaCentauri in the next polar night at DomeA in Antarctica, taking advantage of continuous darkness. Kipping et al. reported two tentative transit-like signals of ProximaCentaurib observed by the Microvariability and Oscillation of Stars space telescope in 2014 and 2015. The midtransit time of our detection is 138minutes later than that predicted by their transit ephemeris. If all of the signals are real transits, the misalignment of the epochs plausibly suggests transit timing variations of ProximaCentaurib induced by an outer planet in this system.

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Observing Exoplanets with the James Webb Space Telescope

Beichman¹,

Greene²

2018

Handbook of Exoplanets

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The census of exoplanets has revealed an enormous variety of planets orbiting stars of all ages and spectral types: planets in orbits of less than a day to frigid worlds in orbits over 100 AU; planets with masses 10 times that of Jupiter to planets with masses less than that of Earth; searingly hot planets to temperate planets in the Habitable Zone. The challenge of the coming decade is to move from demography to physical characterization. The James Webb Space Telescope (JWST) is poised to open a revolutionary new phase in our understanding of exoplanets with transit spectroscopy of relatively short period planets and coronagraphic imaging of ones with wide separations from their host stars. This article discusses the wide variety of exoplanet opportunities enabled by JWST's sensitivity and stability, its high angular resolution, and its suite of powerful instruments. These capabilities will advance our understanding of planet formation, brown dwarfs, and the atmospheres of young to mature planets.

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Close stellar conjunctions ofαCentauri A and B until 2050

Cited by 55 publications

References 49 publications

The radii and limb darkenings of α Centauri A and B

The radii and limb darkenings of α Centauri A and B

Searching for the Transit of the Earth-mass Exoplanet Proxima Centauri b in Antarctica: Preliminary Result

Observing Exoplanets with the James Webb Space Telescope

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