Proprioception of Knee Joint in Athletes and Non-Athletes Obese

Moravveji, Hajar; Ghanbari, Ali; Kamali, Fahimeh

doi:10.5539/gjhs.v9n2p286

Cited by 15 publications

(11 citation statements)

References 29 publications

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“…With the lowering of the detection threshold in observations, especially using data from space, different studies show that hybridity is very common among β Cep stars (Balona et al 2011;Pigulski et al 2016;Daszyńska-Daszkiewicz et al 2018;Walczak et al 2019). This is confirmed by recent theoretical calculations, in which the extent of the g-mode instability domain is large in the upper part of the main sequence (Walczak et al 2015;Moravveji 2016;Szewczuk & Daszyńska-Daszkiewicz 2017).…”

Section: Second Iteration Of Ensasupporting

confidence: 75%

Ensemble asteroseismology of pulsating B-type stars in NGC 6910

Moździerski

Pigulski

Kołaczkowski

et al. 2019

A&A

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Asteroseismology offers the possibility of probing stellar interiors and testing evolutionary and seismic models. Precise photometry and spectroscopy obtained during multi-site campaigns on young open clusters allows discovering rich samples of pulsating stars and using them in a simultaneous seismic modelling called ensemble asteroseismology. The aim of this study is to obtain the age of the open cluster NGC 6910 by means of ensemble asteroseismology of the early-type pulsating members, to derive their stellar parameters, and to classify the excited modes. We used time-series analysis, performed photometric and spectroscopic mode identification, and calculated grids of evolutionary and seismic models to apply the procedure of ensemble asteroseismology for nine pulsating members of NGC 6910. With two iterations of the procedure of ensemble asteroseismology applied to nine pulsating stars we derived an age of 10.6 +0.9 −0.8 Myr for NGC 6910. We also identified the degree l for 8 of 37 modes detected in these stars and classified all modes in terms of p, g, and mixed-mode pulsations. Of the nine pulsating stars examined in the paper, eight are β Cep stars, including three that are hybrid β Cep and slowly pulsating B-type (SPB) pulsators, and one is an SPB star. Interestingly, the least massive β Cep star, NGC 6910-38, has a mass of about 5.6 M . The present theory does not predict unstable p modes in B-type stars with such a low mass. The g modes with relatively high frequencies (> 3.5 d −1 ), observed in three members of the cluster, are also stable according to seismic modelling. Both findings pose a challenge for theoretical calculations and prompt a revision of the opacities. The procedure of ensemble asteroseismology was found to be successful for NGC 6910 and χ Per on the basis of pulsating B-type stars and can therefore be applied to other young open clusters that are rich in such stars.

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Section: Second Iteration Of Ensasupporting

confidence: 75%

Ensemble asteroseismology of pulsating B-type stars in NGC 6910

Moździerski

Pigulski

Kołaczkowski

et al. 2019

A&A

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“…The chemical mixture was taken to be the solar one from Asplund et al (2009). We used the opacity tables from Moravveji (2016). Further, we relied on the Ledoux criterion to determine the convection boundaries and adopted the mixing length theory by Cox & Giuli (1968), with mixing length parameter α mlt =2.0 based on the solar calibration by Christensen-Dalsgaard et al (1996).…”

Section: Setupmentioning

confidence: 99%

“…This method was a necessary complication compared to the modelling of Kepler stars because no obvious independent period spacing pattern spanning several consecutive radial orders could be identified for HD 43317. Hence the straightforward method for mode identification using the technique employed by Van Reeth et al (2015, 2016 was not possible for our CoRoT target star.…”

Section: Setupmentioning

confidence: 99%

Forward seismic modeling of the pulsating magnetic B-type star HD 43317

Buysschaert

Aerts

Bowman

et al. 2018

A&A

124

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The large-scale magnetic fields detected at the surface of about 10 % of hot stars extend into the stellar interior, where they may alter the structure. Deep inner regions of stars are only observable using asteroseismology. Here, we investigated the pulsating magnetic B3.5V star HD 43317, inferred its interior properties and assessed whether the dipolar magnetic field with a surface strength of B p = 1312 ± 332 G caused different properties compared to those of non-magnetic stars. We analysed the latest version of the star's 150 d CoRoT light curve and extracted 35 significant frequencies, 28 of which were determined to be independent and not related to the known surface rotation period of P rot = 0.897673 d. We performed forward seismic modelling based on non-magnetic, nonrotating 1D MESA models and the adiabatic module of the pulsation code GYRE, utilizing a grid-based approach. Our aim was to estimate the stellar mass, age, and convective core overshooting. The GYRE calculations were done for uniform rotation with P rot . This modelling was able to explain 16 of the 28 frequencies as gravity modes belonging to retrograde modes with ( , m) = (1, −1) and (2, −1) period spacing patterns and one distinct prograde (2, 2) mode. The modelling resulted in a stellar mass M = 5.8 +0.1 −0.2 M , a central hydrogen mass fraction X c = 0.54 +0.01 −0.02 , and exponential convective core overshooting parameter f ov = 0.004 +0.014 −0.002 . The low value for f ov is compatible with the suppression of near-core mixing due to a magnetic field but the uncertainties are too large to pinpoint such suppression as the sole physical interpretation. We assessed the frequency shifts of pulsation modes caused by the Lorentz and the Coriolis forces and found magnetism to have a lower impact than rotation for this star. Including magnetism in future pulsation computations would be highly relevant to exploit current and future photometric time series spanning at least one year, such as those assembled by the Kepler space telescope and expected from the TESS (Continuous Viewing Zone) and PLATO space missions.

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“…PG 1610+062 lies right inside the instability domain of slowly pulsating B (SPB) stars (see, e.g., Moravveji 2016) and is thus expected to pulsate if it is a MS star. The ATLAS variable star catalog (Heinze et al 2018) indeed classifies it as a candidate variable star.…”

Section: Light Curvementioning

confidence: 99%

PG 1610+062: a runaway B star challenging classical ejection mechanisms

Irrgang

Geier

Heber

et al. 2019

A&A

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Hypervelocity stars are rare objects, mostly main-sequence (MS) B stars, traveling so fast that they will eventually escape from the Milky Way. Recently, it has been shown that the popular Hills mechanism, in which a binary system is disrupted via a close encounter with the supermassive black hole at the Galactic center, may not be their only ejection mechanism. The analyses of Gaia data ruled out a Galactic center origin for some of them, and instead indicated that they are extreme disk runaway stars ejected at velocities exceeding the predicted limits of classical scenarios (dynamical ejection from star clusters or binary supernova ejection). We present the discovery of a new extreme disk runaway star, PG 1610+062, which is a slowly pulsating B star bright enough to be studied in detail. A quantitative analysis of spectra taken with ESI at the Keck Observatory revealed that PG 1610+062 is a late B-type MS star of 4-5 M with low projected rotational velocity. Abundances (C, N, O, Ne, Mg, Al, Si, S, Ar, and Fe) were derived differentially with respect to the normal B star HD 137366 and indicate that PG 1610+062 is somewhat metal rich. A kinematic analysis, based on our spectrophotometric distance (17.3 kpc) and on proper motions from Gaia's second data release, shows that PG 1610+062 was probably ejected from the Carina-Sagittarius spiral arm at a velocity of 550 ± 40 km s −1 , which is beyond the classical limits. Accordingly, the star is in the top five of the most extreme MS disk runaway stars and is only the second among the five for which the chemical composition is known.

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Proprioception of Knee Joint in Athletes and Non-Athletes Obese

Cited by 15 publications

References 29 publications

Ensemble asteroseismology of pulsating B-type stars in NGC 6910

Ensemble asteroseismology of pulsating B-type stars in NGC 6910

Forward seismic modeling of the pulsating magnetic B-type star HD 43317

PG 1610+062: a runaway B star challenging classical ejection mechanisms

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