No X-rays from WASP-18

Pillitteri, I.; Wolk, S. J.; Sciortino, S.; Antoci, V.

doi:10.1051/0004-6361/201423579

Cited by 47 publications

(59 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The strong tides generated on the star by such a massive and close-in planet might significantly affect the stellar dynamo and remarkably reduce its activity. On the other hand, evidence for hot Jupiters spinning up their hosts was found by Poppenhaeger & Wolk (2014) in CoRoT-2 and possibly HD 189733.…”

Section: Discussionmentioning

confidence: 99%

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

Lanza

2014

A&A

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 99%

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

Lanza

2014

A&A

View full text Add to dashboard Cite

show abstract

“…55 Cnc b and GJ 436 b have proven to be suitable targets for Lyα transit observations, thus, we included them in our analysis. The sample was scanned for previous X-ray observations: WASP-18 was not detected in a dedicated X-ray observation (Pillitteri et al 2014) and WASP-43 has been analyzed by Czesla et al (2013). The remaining seven host stars did not have any prior X-ray observation and unrestrictive ROSAT upper limits.…”

Section: Target Selectionmentioning

confidence: 99%

High-energy irradiation and mass loss rates of hot Jupiters in the solar neighborhood

Salz

Schneider

Czesla

et al. 2015

A&A

View full text Add to dashboard Cite

Giant gas planets in close proximity to their host stars experience strong irradiation. In extreme cases photoevaporation causes a transonic, planetary wind and the persistent mass loss can possibly affect the planetary evolution. We have identified nine hot Jupiter systems in the vicinity of the Sun, in which expanded planetary atmospheres should be detectable through Lyα transit spectroscopy according to predictions. We use X-ray observations with Chandra and XMM-Newton of seven of these targets to derive the highenergy irradiation level of the planetary atmospheres and the resulting mass loss rates. We further derive improved Lyα luminosity estimates for the host stars including interstellar absorption. According to our estimates WASP-80 b, WASP-77 b, and WASP-43 b experience the strongest mass loss rates, exceeding the mass loss rate of HD 209458 b, where an expanded atmosphere has been confirmed. Furthermore, seven out of nine targets might be amenable to Lyα transit spectroscopy. Finally, we check the possibility of angular momentum transfer from the hot Jupiters to the host stars in the three binary systems among our sample, but find only weak indications for increased stellar rotation periods of WASP-77 and HAT-P-20.

show abstract

“…It may be that selection biases (acting primarily at low M P /a 2 ) and cumulative tidal influences (relevant primarily at high M P /a 2 ) combine to mimic the statistical signature of star-planet interaction. Of course, these effects do not rule out magnetic recombination events producing enhanced activity, 22 but they 21 WASP-18 experiences significant tidal effects from the planet (Arras et al 2012) and may also be spun-up, although it is still inactive (see Miller et al 2012, Pillitteri et al 2014b, and references therein).…”

Section: Cumulative Tidal Effects In Extreme Systemsmentioning

confidence: 99%

“…However, even in the best candidate systems, any signatures seem to be transient (Shkolnik et al 2008). 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).…”

mentioning

confidence: 96%

A Comprehensive Statistical Assessment of Star-Planet Interaction

Miller

Gallo

Wright

et al. 2015

ApJ

View full text Add to dashboard Cite

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.

show abstract

No X-rays from WASP-18

Cited by 47 publications

References 60 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

High-energy irradiation and mass loss rates of hot Jupiters in the solar neighborhood

A Comprehensive Statistical Assessment of Star-Planet Interaction

Contact Info

Product

Resources

About