Reference : A compact system of small planets around a former red giant star
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
A compact system of small planets around a former red giant star
Charpinet, Stéphane mailto [Institut de Recherche en Astrophysique et Planétologie (IRAP) > > > >]
Fontaine, Gilles mailto [Université de Montréal - UdeM > Département de Physique > > >]
Brassard, Pierre mailto [Université de Montréal - UdeM > Département de Physique > > >]
Green, Elizabeth M. mailto [University of Arizona > > > >]
Van Grootel, Valérie mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie >]
Randall, Suzanna K. mailto [European Southern Observatory (ESO) > > > >]
Silvotti, Roberto mailto [INAF-Osservatorio Astronomico di Torino > > > >]
Baran, Andrzej mailto [Mt. Suhora Observatory > > > >]
Ostensen, Roy H. mailto [Katholieke Universiteit Leuven - KUL > Instituut voor Sterrenkunde > > >]
Kawaler, Steve D. mailto [Iowa State University > > > >]
Telting, John H. mailto [Nordic Optical Telescope > > > >]
Nature Publishing Group
Yes (verified by ORBi)
United Kingdom
[en] Planets that orbit their parent star at less than about one astronomical unit (1AU is the Earth-Sun distance) are expected to be engulfed when the star becomes a red giant. Previous observations have revealed the existence of post-red-giant host stars with giant planets orbiting as close as 0.116AU or with brown dwarf companions in tight orbits, showing that these bodies can survive engulfment. What has remained unclear is whether planets can be dragged deeper into the red-giant envelope without being disrupted and whether the evolution of the parent star itself could be affected. Here we report the presence of two nearly Earth-sized bodies orbiting the post-red-giant, hot B subdwarf star KIC 05807616 at distances of 0.0060 and 0.0076AU, with orbital periods of 5.7625 and 8.2293 hours, respectively. These bodies probably survived deep immersion in the former red-giant envelope. They may be the dense cores of evaporated giant planets that were transported closer to the star during the engulfment and triggered the mass loss necessary for the formation of the hot B subdwarf, which might also explain how some stars of this type did not form in binary systems.

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