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Description
In this paper we present MASCARA-2 b, a hot Jupiter transiting the m_V_=7.6 A2 star HD 185603. Since early 2015, MASCARA has taken more than 1.6 million flux measurements of the star, corresponding to a total of almost 3000 hours of observations, revealing a periodic dimming in the flux with a depth of 1.3%. Photometric follow-up observations were performed with the NITES and IAC80 telescopes and spectroscopic measurements were obtained with the Hertzsprung SONG telescope. We find MASCARA-2 b orbits HD 185603 with a period of 3.474119^+0.000005^_-0.000006_ days at a distance of 0.057+/-0.006AU, has a radius of 1.83+/-0.07R_J_ and place a 99 % upper limit on the mass of <17M_J_. HD 185603 is a rapidly rotating early-type star with an effective temperature of 8980^+90^_-130_K and a mass and radius of 1.89^+0.06^_-0.05_M_sun_, 1.60+/-0.06R_sun_, respectively. Contrary to most other hot Jupiters transiting early-type stars, the projected planet orbital axis and stellar spin axis are found to be aligned with {lambda}=0.6+/-4{deg}. The brightness of the host star and the high equilibrium temperature, 2260+/-50K, of MASCARA-2 b make it a suitable target for atmospheric studies from the ground and space. Of particular interest is the detection of TiO, which has recently been detected in the similarly hot planets WASP-33 b and WASP-19 b.
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