Artist’s impression of a “hot Jupiter”. Credit: Ricardo Cardoso Reis (CAUP)
Astronomers have detected a new “hot Jupiter” exoplanet orbiting a nearby T Tauri star known as TAP 26. The newly detected alien world, designated TAP 26 b, is about 66% more massive than Jupiter and is orbiting its parent star approximately every 10 days. Located 480 light years away, TAP 26 belongs to the T Tauri class of variable pre-main-sequence stars. With a mass similar to that of the sun, TAP 26 has a radius of 1.17 solar radii and is about 17 million years old.
Such young forming T Tauri stars could provide important information about the formation and early evolution of planetary systems. Thus, detecting “hot Jupiters” around these objects and determining orbital properties could help astronomers understand how they form and migrate, offering crucial insights on physical processes responsible for generating such planets.
With this aim in mind, a team of astronomers led by Liang Yu of the Toulouse University in France, has observed TAP 26 between November 2015 and January 2016 using the the 3.6-meter Canada-France-Hawaii Telescope (CFHT) in Hawaii. The campaign, which utilized CFHT’s Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS), was carried out under the Magnetic Topologies of Young Stars and the Survival of close-in massive Exoplanets (MaTYSSE) program.
By implementing 3 different methods, the researchers managed to detect a planet radial velocity signal in TAP 26’s spectrum. The discovery is based on the analysis of 29 unpolarised and circularly polarised spectra collected over a timespan of 72 days. “We report the detection of a hot Jupiter around TAP 26 using 3 different methods, 2 using Zeeman-Doppler Imaging (ZDI) and one Gaussian-Process Regression (GPR), with a false-alarm probability smaller than 6 10−4,” the paper reads.
The newly detected planet has a mass of 1.66 Jupiter masses and is circling its parent star at a distance of nearly 0.1 AU. With its short orbital period, huge mass and proximity to its host star, TAP 26 b was classified as a “hot Jupiter.” The so-called “hot Jupiters” are gas giant planets, similar in characteristics to the solar system’s biggest planet, with orbital periods not longer than 10 days. They have high surface temperatures, as they orbit their parent stars very closely. More detailed characteristics of TAP 26 b are expected to be determined by further observations, in particular including more regular temporal sampling.
The team created surface brightness and magnetic maps of TAP 26, revealing the presence of cool spots and warm plages totaling up to 12% of the stellar surface. They found that the star’s photospheric temperature is about 4,620 K and its maximum V magnitude is equal to 12.16. Moreover, based on the observational data, the scientists assume that TAP 26 dissipated its accretion disc very early and its magnetic field started to evolve into a complex topology.
http://phys.org/news/2017-01-hot-jupiter-nearby-variable-star.htmljCp
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