An Ultraviolet Investigation of Activity on Exoplanet Host Stars

Shkolnik, Evgenya L.

doi:10.1088/0004-637x/766/1/9

Cited by 72 publications

(64 citation statements)

References 70 publications

(104 reference statements)

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“…The discovery paper (Anderson et al 2012) has found a 16-day rotational modulation and weak Ca ii H+K for the host star. A recent study led by Shkolnik (2013) furthermore derived a high far-UV fractional luminosity log(L FUV /L bol ) = −4.546 ± 0.079 based on the NASA Galaxy Evolution Explorer (GALEX) measurements. The possible absence of high-altitude absorbers would indicate that there is no strong thermal inversion.…”

Section: Near-infrared Thermal Emission From the Dayside Atmosphere Omentioning

confidence: 99%

Observed spectral energy distribution of the thermal emission from the dayside of WASP-46b

Chen

Boekel

Wang

et al. 2014

A&A

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Aims. We aim to construct a spectral energy distribution (SED) for the emission from the dayside atmosphere of the hot Jupiter WASP-46b and to investigate its energy budget. Methods. We observed a secondary eclipse of WASP-46b simultaneously in the g r i z JHK bands using the GROND instrument on the MPG/ESO 2.2 m telescope. Eclipse depths of the acquired light curves were derived to infer the brightness temperatures at multibands that cover the SED peak. Results. We report the first detection of the thermal emission from the dayside of WASP-46b in the K band at 4.2σ level and tentative detections in the H (2.5σ) and J (2.3σ) bands, with flux ratios of 0.253 +0.063 −0.060 %, 0.194 ± 0.078%, and 0.129 ± 0.055%, respectively. The derived brightness temperatures (2306 +177 −187 K, 2462 +245 −302 K, and 2453 +198 −258 K, respectively) are consistent with an isothermal temperature profile of 2386 K, which is significantly higher than the dayside-averaged equilibrium temperature, indicative of very poor heat redistribution efficiency. We also investigate the tentative detections in the g r i bands and the 3σ upper limit in the z band, which might indicate the existence of reflective clouds if these tentative detections do not arise from systematics.

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Section: Near-infrared Thermal Emission From the Dayside Atmosphere Omentioning

confidence: 99%

Observed spectral energy distribution of the thermal emission from the dayside of WASP-46b

Chen

Boekel

Wang

et al. 2014

A&A

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“…It has been speculated that similar effects, albeit on a weaker scale, may occur for stars with Hot Jupiters (Cuntz et al 2000;Lanza 2008). Observational studies have been performed on individual systems (Shkolnik et al 2005(Shkolnik et al , 2008Pillitteri et al 2011;Miller et al 2012) as well as on larger samples of planet-hosting stars (Kashyap et al 2008;Poppenhaeger et al 2010;Shkolnik 2013), finding weak correlations of stellar activity with the presence of Hot Jupiters. Indications for higher v sin i values have also been reported (Pont 2009) for systems with Hot Jupiters compared with systems hosting smaller or more distant planets, NASA Sagan Fellow yielding first indications of a tidal influence of exoplanets on their host stars.…”

Section: Introductionmentioning

confidence: 99%

Indications for an influence of hot Jupiters on the rotation and activity of their host stars

Poppenhaeger

Wolk

2014

A&A

126

121

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Context. The magnetic activity of planet-hosting stars is an important factor for estimating the atmospheric stability of close-in exoplanets and the age of their host stars. It has long been speculated that close-in exoplanets can influence the stellar activity level. However, testing for tidal or magnetic interaction effects in samples of planet-hosting stars is difficult because stellar activity hinders exoplanet detection, so that stellar samples with detected exoplanets show a bias toward low activity for small exoplanets. Aims. We aim to test whether exoplanets in close orbits influence the stellar rotation and magnetic activity of their host stars. Methods. We developed a novel approach to test for systematic activity-enhancements in planet-hosting stars. We use wide (several 100 AU) binary systems in which one of the stellar components is known to have an exoplanet, while the second stellar component does not have a detected planet and therefore acts as a negative control. We use the stellar coronal X-ray emission as an observational proxy for magnetic activity and analyze observations performed with Chandra and XMM-Newton. Results. We find that in two systems for which strong tidal interaction can be expected the planet-hosting primary displays a much higher magnetic activity level than the planet-free secondary. In three systems for which weaker tidal interaction can be expected the activity levels of the two stellar components agree with each other. Conclusions. Our observations indicate that the presence of Hot Jupiters may inhibit the spin-down of host stars with thick outer convective layers. Possible causes for this effect include a transfer of angular momentum from the planetary orbit to the stellar rotation through tidal interaction, or differences during the early evolution of the system, where the host star may decouple from the protoplanetary disk early because of a gap opened by the forming Hot Jupiter.

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“…As a striking counterexample, the extreme WASP-18 system, which contains a ≃ 10M Jup planet in a 0.94 d period, shows no evidence for planet-linked activity (Miller et al 2012;Pillitteri et al 2014b); such interaction must be either absent, only rarely present, or 8 We ignore the distinction between M P and the minimum mass of explanets derived from radial velocity work, since the sin i inclination term is unknown for most of these systems but provides a typical correction of only ∼15% (Wright & Gaudi 2013). rendered inefficient by an extremely weak stellar magnetic field 9 Shkolnik et al 2013; but see also Miller et al 2012).…”

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confidence: 99%

A Comprehensive Statistical Assessment of Star-Planet Interaction

Miller

Gallo

Wright

et al. 2015

ApJ

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We investigate whether magnetic interaction between close-in giant planets and their host stars produce observable statistical enhancements in stellar coronal or chromospheric activity. New Chandra observations of 12 nearby (d < 60 pc) planet-hosting solar analogs are combined with archival Chandra, XMM-Newton, and ROSAT coverage of 11 similar stars to construct a sample inoculated against inherent stellar class and planet-detection biases. Survival analysis and Bayesian regression methods (incorporating both measurements errors and X-ray upper limits; 13/23 stars have secure detections) are used to test whether "hot Jupiter" hosts are systematically more X-ray luminous than comparable stars with more distant or smaller planets. No significant correlations are present between common proxies for interaction strength (M P /a 2 or 1/a) versus coronal activity (L X or L X /L bol ). In contrast, a sample of 198 FGK main-sequence stars does show a significant (∼ 99% confidence) increase in X-ray luminosity with M P /a 2 . While selection biases are incontrovertibly present within the main-sequence sample, we demonstrate that the effect is primarily driven by a handful of extreme hot-Jupiter systems with M P /a 2 > 450 M Jup AU −2 , which here are all X-ray luminous but to a degree commensurate with their Ca II H and K activity, in contrast to presented magnetic star-planet interaction scenarios that predict enhancements relatively larger in L X . We discuss these results in the context of cumulative tidal spin-up of stars hosting close-in gas giants (potentially followed by planetary infall and destruction). We also test our main-sequence sample for correlations between planetary properties and UV luminosity or Ca II H and K emission, and find no significant dependence.

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An Ultraviolet Investigation of Activity on Exoplanet Host Stars

Cited by 72 publications

References 70 publications

Observed spectral energy distribution of the thermal emission from the dayside of WASP-46b

Observed spectral energy distribution of the thermal emission from the dayside of WASP-46b

Indications for an influence of hot Jupiters on the rotation and activity of their host stars

A Comprehensive Statistical Assessment of Star-Planet Interaction

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