MOVES - II. Tuning in to the radio environment of HD189733b

被引:30
作者
Kavanagh, R. D. [1 ]
Vidotto, A. A. [1 ]
Fionnagain, D. O. [1 ]
Bourrier, V. [2 ]
Fares, R. [3 ,4 ]
Jardine, M. [5 ]
Helling, Ch. [6 ]
Moutou, C. [7 ]
Llama, J. [8 ]
Wheatley, P. J. [9 ]
机构
[1] Univ Dublin, Sch Phys, Trinity Coll Dublin, Dublin 2, Ireland
[2] Observ Univ Geneve, Chemin Maillettes 51, CH-1290 Versoix, Switzerland
[3] United Arab Emirates Univ, Phys Dept, POB 15551, Al Ain, U Arab Emirates
[4] Univ Southern Queensland, Ctr Astrophys, Toowoomba, Qld 4350, Australia
[5] Univ St Andrews, Sch Phys & Astron, SUPA, North Haugh, St Andrews KY16 9SS, Fife, Scotland
[6] Univ St Andrews, Ctr Exoplanet Sci, St Andrews KY16 9SS, Fife, Scotland
[7] CNRS CFHT, 65-1238 Mamalahoa Highway, Kamuela, HI 96743 USA
[8] Lowell Observ, 1400 W Mars Hill Rd, Flagstaff, AZ 86001 USA
[9] Univ Warwick, Dept Phys, Coventry CV4 7AL, W Midlands, England
基金
瑞士国家科学基金会; 欧洲研究理事会;
关键词
MHD-stars: individual (HD189733); stars: low-mass; stars: planetary systems; stars:; winds; outflows; CYCLOTRON MASER INSTABILITY; MAGNETOSPHERE INTERACTION; MAGNETIC CYCLES; TAU BOOTIS; STAR; WIND; SPECTRUM; VARIABILITY; EXOPLANETS; RADIATION;
D O I
10.1093/mnras/stz655
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present stellar wind modelling of the hot Jupiter host HD189733, and predict radio emission from the stellar wind and the planet, the latter arising from the interaction of the stellar wind with the planetary magnetosphere. Our stellar wind models incorporate surface stellar magnetic field maps at the epochs 2013 June/July, 2014 September, and 2015 July as boundary conditions. We find that the mass-loss rate, angular momentum loss rate, and open magnetic flux of HD189733 vary by 9 per cent, 40 per cent, and 19 per cent over these three epochs. Solving the equations of radiative transfer, we find that from 10 MHz-100 GHz the stellar wind emits fluxes in the range of 10(-3)-5 mu Jy, and becomes optically thin above 10 GHz. Our planetary radio emission model uses the radiometric Bode's law, and neglects the presence of a planetary atmosphere. For assumed planetary magnetic fields of 1-10 G, we estimate that the planet emits at frequencies of 2-25 MHz, with peak flux densities of 10(2) mJy. We find that the planet orbits through regions of the stellar wind that are optically thick to the emitted frequency from the planet. As a result, unattenuated planetary radio emission can only propagate out of the system and reach the observer for 67 per cent of the orbit for a 10 G planetary field, corresponding to when the planet is approaching and leaving primary transit. We also find that the plasma frequency of the stellar wind is too high to allow propagation of the planetary radio emission below 21 MHz. This means a planetary field of at least 8 G is required to produce detectable radio emission.
引用
收藏
页码:4529 / 4538
页数:10
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