Extrasolar Giant Planets and X‐Ray Activity

Kashyap, Vinay; Drake, J. J.; Saar, Steven H.

doi:10.1086/591922

Cited by 119 publications

(168 citation statements)

References 161 publications

(37 reference statements)

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“…For instance, Shkolnik et al (2003Shkolnik et al ( , 2008) report a planet-induced chromospheric activity on two stars with planets, HD 179949 and υ And, apparent from the night-to-night modulation of the CaII H and K chromospheric emission phased with the hot Jupiter's orbit. In addition, Kashyap et al (2008) claim that stars with close-in giant planets are on average more X-ray active than those with planets that are more distant, an observational result consistent with the hypothesis that giant planets in close proximity to the parent stars could influence stellar magnetic activity.…”

Section: Introductionsupporting

confidence: 64%

“…Table 3 shows the result of such an analysis, with the Spearman's ρ rank correlation for various combinations of stellar quantities and planetary parameters, for two samples. The first is composed of 19 stars with X-ray lumisonity from Kashyap et al (2008), and the second is composed of 13 stars with X-ray luminosities from Poppenhaeger et al (2010). The first interesting aspect of this analysis is a possible anticorrelation between the chromospheric activity indicator and the planetary semi-major axis in stars hosting planets with a pl ≤ 0.20 AU for both samples.…”

Section: Resultsmentioning

confidence: 99%

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Chromospheric activity of stars with planets

Martins

Chagas

Alves

et al. 2011

A&A

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Context. Signatures of chromospheric activity enhancement have been found for a dozen stars, pointing to a possible star-planet interaction. Nevertheless in the coronal activity regime, there is no conclusive observational evidence of such an interaction. Does star-planet interaction manifest itself only for a few particular cases, without having a major effect on stars with planets in general? Aims. We aim to add additional observational constraints to support or reject the major effects of star-planet interactions in stellar activity, based on Ca II chromospheric emission flux. Methods. We performed a statistical analysis of Ca II emission flux of stars with planets, as well as a comparison between Ca II and X-ray emission fluxes, searching for dependencies on planetary parameters. Results. In the present sample of stars with planets, there are no significant correlations between chromospheric activity indicator log(R HK ) and planetary parameters. Furthermore, the distribution of the chromospheric activity indicator for stars without planets is indistinguishable from the one with planets.

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Section: Introductionsupporting

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Chromospheric activity of stars with planets

Martins

Chagas

Alves

et al. 2011

A&A

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“…In the X-ray band, Kashyap et al (2008) show that stars with hot Jupiters are statistically brighter by up to a factor four than stars with distant planets. Krejčová & Budaj (2012) support the findings of Kashyap et al (2008) by means of a survey of Ca II H and K lines on planet hosting stars that traces a relationship betweeen stellar activity and planet-star separation, with closer hot Jupiters orbiting more active stars.…”

Section: Introductionmentioning

confidence: 99%

No X-rays from WASP-18

Pillitteri

Wolk

Sciortino

et al. 2014

A&A

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About 20% of the >1000 known exoplanets are Jupiter analogs orbiting very close to their parent stars. It is still under debate to what detectable level such hot Jupiters possibly affect the activity of the host stars through tidal or magnetic star-planet interaction. In this paper we report on an 87 ks Chandra observation of the hot Jupiter hosting star WASP-18. This system is composed of an F6 type star and a hot Jupiter of mass 10.4 M Jup orbiting in less than 20 hr around the parent star. On the basis of an isochrone fitting, WASP-18 is thought to be 600 Myr old and within the range of uncertainty of 0.5-2 Gyr. The star is not detected in X-rays down to a luminosity limit of 4 × 10 26 erg/s, which is more than two orders of magnitude lower than expected for a star of this age and mass. This value proves an unusual lack of activity for a star with an estimated age around 600 Myr. We argue that the massive planet can play a crucial role in disrupting the stellar magnetic dynamo created within its thin convective layers. Other additional 212 X-ray sources are detected in the Chandra image. We list them and briefly discuss their nature.

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“…The discovery of planetary systems by direct imaging nowadays is restricted to large separations >10−100 AU (Veras et al 2009) and favors higher mass planets. As of today nine exoplanetary systems have been directly imaged in the optical or near-infrared band, but only five of them are still embedded: GQ Lup (Neuhäuser et al 2005) and CT Cha (Schmidt et al 2008), but they are rather hosting a stellar companion as the companion masses are, because high as 21.5 M J and 17 M J , respectively; 2M1207 (Chauvin et al 2004(Chauvin et al , 2005a) hosting a 4 M J mass planet; UScoCTIO 108 (Kashyap et al 2008) hosting a 14 M J mass planet; β Pic (Lagrange et al 2009a,b) hosting an 8 M J mass planet. AB Pic (Chauvin et al 2005b), HR 8799 (Marois et al 2008) (triple system), SR 1845 (Biller et al 2006) and Fomalhaut (Kalas et al 2008) are mature planetary systems with ages of about 30 Myr, 60 Myr, 100 Myr, and 200 Myr.…”

Section: Introductionmentioning

confidence: 99%

Detectability of giant planets in protoplanetary disks by CO emission lines

Regály

Sándor

Dullemond

et al. 2010

A&A

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Context. Planets are thought to form in protoplanetary accretion disks around young stars. Detecting a giant planet still embedded in a protoplanetary disk would be very important and give observational constraints on the planet-formation process. However, detecting these planets with the radial velocity technique is problematic owing to the strong stellar activity of these young objects. Aims. We intend to provide an indirect method to detect Jovian planets by studying near infrared emission spectra originating in the protoplanetary disks around T Tauri stars. Our idea is to investigate whether a massive planet could induce any observable effect on the spectral lines emerging in the disks atmosphere. As a tracer molecule we propose CO, which is excited in the ro-vibrational fundamental band in the disk atmosphere to a distance of ∼2−3 AU (depending on the stellar mass) where terrestrial planets are thought to form. Methods. We developed a semi-analytical model to calculate synthetic molecular spectral line profiles in a protoplanetary disk using a double layer disk model heated on the outside by irradiation by the central star and in the midplane by viscous dissipation due to accretion. 2D gas dynamics were incorporated in the calculation of synthetic spectral lines. The motions of gas parcels were calculated by the publicly available hydrodynamical code FARGO which was developed to study planet-disk interactions. Results. We demonstrate that a massive planet embedded in a protoplanetary disk strongly influences the originally circular Keplerian gas dynamics. The perturbed motion of the gas can be detected by comparing the CO line profiles in emission, which emerge from planet-bearing to those of planet-free disk models. The planet signal has two major characteristics: a permanent line profile asymmetry, and short timescale variability correlated with the orbital phase of the giant planet. We have found that the strength of the asymmetry depends on the physical parameters of the star-planet-disk system, such as the disk inclination angle, the planetary and stellar masses, the orbital distance, and the size of the disk inner cavity. The permanent line profile asymmetry is caused by a disk in an eccentric state in the gap opened by the giant planet. However, the variable component is a consequence of the local dynamical perturbation by the orbiting giant planet. We show that a forming giant planet, still embedded in the protoplanetary disk, can be detected using contemporary or future high-resolution near-IR spectrographs like VLT/CRIRES and ELT/METIS.

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Extrasolar Giant Planets and X‐Ray Activity

Cited by 119 publications

References 161 publications

Chromospheric activity of stars with planets

Chromospheric activity of stars with planets

No X-rays from WASP-18

Detectability of giant planets in protoplanetary disks by CO emission lines

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