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In the constellation of Andromeda, at a distance of 378 light years from Earth, there is a Delta Scuti type pulsating star, called WASP-33, that has a giant planet. Detected for the first time in 2006, thanks to its transits across the stellar disk, the planet was the first to be discovered around a variable star of this type.
Recent studies by a group of researchers of the Instituto de Ciencias del Espacio (IEEC-CSIC) at the University of Barcelona have investigated the system in great detail, and have discovered that the mass of the planet influences the stellar pulsations.
Delta Scuti variables are essentially dwarf Cepheids that show small luminosity variations, caused by both radial and non-radial pulsations, with very variable amplitudes and periods. In the case of WASP-33, the pulsations show a periodic variation that can be attributed to the presence of the planet, that at 4 times the mass of Jupiter and an orbital distance of only 3 million kilometres (orbital period of only 1.2 days), seems to alter the regular rhythm of the pulsations; the only example known to date.
Another reason for interest in this system is the unusual orbit of the planet: apart from being very inclined it is also retrograde with respect to the spin of the star. Understanding why will be fundamental to the understanding of this system.
Perhaps the most interesting aspect of the research carried out by the Catalan team is, however, the makeup of the investigative team, containing professional researchers (Ignasi Ribas and Juan Carlos Morales), a research student (Enrique Herrero) and an amateur astronomer (Ramón Naves), and using both professional and amateur observatories (Observatori Astroṇmic del Montsec and Observatori Montcabrer).
The results of the study were recently published in Astronomy & Astrophysics.
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