The extended chromosphere of CoRoT-2A

Czesla, S.; Schröter, Sebastian; Wolter, Uwe; Essen, C. von; Huber, K. F.; Schmitt, J. H. M. M.; Reichart, D.; Moore, J. P.

doi:10.1051/0004-6361/201118042

Cited by 30 publications

(31 citation statements)

References 46 publications

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“…The matter that forms a prominence probably comes from the evaporation of the chromosphere induced by magnetic heating that is localized close to Robinson 1989a,b). Prominence-like structures were also observed in CoRoT-2 (Czesla et al 2012). …”

Section: Configuration Of the Stellar Coronal Fieldmentioning

confidence: 80%

On the correlation between stellar chromospheric flux and the surface gravity of close-in planets

Lanza

2014

A&A

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Aims. The chromospheric emission of stars with close-in transiting planets has been found to correlate with the surface gravity of their planets. Stars with low-gravity planets have on average a lower chromospheric flux. Methods. We propose that this correlation is due to the absorption by circumstellar matter that comes from the evaporation of the planets. Planets with a lower gravity have a greater mass-loss rate, which leads to a higher column density of circumstellar absorption and in turn explains the lower level of chromospheric emission observed in their host stars. We estimated the required column density and found that planetary evaporation can account for it. We derived a theoretical relationship between the chromospheric emission as measured in the core of the Ca II H&K lines and the planet gravity.Results. We applied this relationship to a sample of transiting systems for which both the stellar Ca II H&K emission and the planetary surface gravity are known and found a good agreement, given the various sources of uncertainties and the intrinsic variability of the stellar emissions and planetary evaporation rates. We consider implications for the radial velocity jitter applied to fit the spectroscopic orbits and for the age estimates of planetary systems based on the chromospheric activity level of their host stars.

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Section: Configuration Of the Stellar Coronal Fieldmentioning

confidence: 80%

On the correlation between stellar chromospheric flux and the surface gravity of close-in planets

Lanza

2014

A&A

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“…The Ca  H and K emission line cores also show variability before the ingress, which is probably unrelated to the transit. While an earlier ingress either due to planetary material or an extended stellar chromosphere is conceivable (e.g., Czesla et al 2012;Haswell et al 2012), intrinsic variability, independent of the transit, appears to be a more plausible interpretation in view of the flare observed later. In any case, it remains difficult to distinguish between effects caused by the transiting planetary disk and intrinsic stellar variability in our data set.…”

Section: The Center-to-limb Variationmentioning

confidence: 99%

The center-to-limb variation across the Fraunhofer lines of HD 189733

Czesla

Klocová

Khalafinejad

et al. 2015

A&A

Self Cite

115

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The center-to-limb variation (CLV) describes the brightness of the stellar disk as a function of the limb angle. Across strong absorption lines, the CLV can vary quite significantly. We obtained a densely sampled time series of high-resolution transit spectra of the active planet host star HD 189733 with UVES. Using the passing planetary disk of the hot Jupiter HD 189733 b as a probe, we study the CLV in the wings of the Ca  H and K and Na  D 1 and D 2 Fraunhofer lines, which are not strongly affected by activity-induced variability.In agreement with model predictions, our analysis shows that the wings of the studied Fraunhofer lines are limb brightened with respect to the (quasi-)continuum. The strength of the CLV-induced effect can be on the same order as signals found for hot Jupiter atmospheres. Therefore, a careful treatment of the wavelength dependence of the stellar CLV in strong absorption lines is highly relevant in the interpretation of planetary transit spectroscopy.

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“…The highlights of this additional science are: i) the first mass measurement of a brown dwarf using Doppler boosting in the CoRoT-3 system (Mazeh and Faigler 2010), ii) the first asteroseismic analysis of red giants (Kallinger et al 2010;Hekker et al 2009;Mosser et al 2010), iii) the characterization of the stellar population (Gazzano et al 2010;Sebastian et al 2012;Guenther et al 2012a), iv) the classification of stellar variability (Debosscher et al 2009), v) the search for transit timing variations in the light curves of CoRoT-1 b and CoRoT-9 b (Csizmadia et al 2010;Borkovits et al 2011), vi) the measurement of spectroscopic transits for estimating the orbital alignment of the planet with respect to the stellar spin axis in the systems CoRoT-1, 2, 3 and 11 (Pont et al 2010;Bouchy et al 2008;Czesla et al 2012;Triaud et al 2009;Gandolfi et al 2012)...…”

Section: Conclusion and Futurementioning

confidence: 99%

CoRoT: Harvest of the exoplanet program

Moutou¹,

Deleuil²,

Guillot³

et al. 2013

Icarus

105

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One of the objectives of the CoRoT mission is the search for transiting extrasolar planets using highprecision photometry, and the accurate characterization of their fundamental parameters. The CoRoT satellite consecutively observes crowded stellar fields since February 2007, in high-cadence precise photometry; periodic eclipses are detected and analysed in the stellar light curves. Then complementary observations using ground-based facilities allows establishing the nature of the transiting body and its mass. CoRoT has acquired more than 163 000 light curves and detected about 500 planet candidates. A fraction of them (5%) are confirmed planets whose masses are independently measured. Main highlights of the CoRoT discoveries are: i) the variety of internal structures in close-in giant planets, ii) the characterisation of the first known transiting rocky planet, CoRoT-7 b, iii) multiple constraints on the formation, evolution, role of tides in planetary systems.

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The extended chromosphere of CoRoT-2A

Cited by 30 publications

References 46 publications

On the correlation between stellar chromospheric flux and the surface gravity of close-in planets

On the correlation between stellar chromospheric flux and the surface gravity of close-in planets

The center-to-limb variation across the Fraunhofer lines of HD 189733

CoRoT: Harvest of the exoplanet program

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