عالم فيزياء سوداني بجامعة الخرطوم يكتشف كوكبا جديدا

Quote: An Earth-Sized Planet in the Habitable Zone of a Cool Star Elisa V. Quintana1,2,*, Thomas Barclay2,3, Sean N. Raymond4,5, Jason F. Rowe1,2, Emeline Bolmont4,5, Douglas A. Caldwell1,2, Steve B. Howell2, Stephen R. Kane6, Daniel Huber1,2, Justin R. Crepp7, Jack J. Lissauer2,8, David R. Ciardi9, Jeffrey L. Coughlin1,2, Mark E. Everett10, Christopher E. Henze2, Elliott Horch11, Howard Isaacson12, Eric B. Ford13,14, Fred C. Adams15,16, Martin Still3, Roger C. Hunter2, Billy Quarles2, Franck Selsis4,5 1SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043, USA. 2NASA Ames Research Center, Moffett Field, CA 94035, USA. 3Bay Area Environmental Research Institute, 596 1st Street, West Sonoma, CA 95476, USA. 4University of Bordeaux, Laboratoire d'Astrophysique de Bordeaux, UMR 5804, F-33270, Floirac, France. 5CNRS, Laboratoire d'Astrophysique de Bordeaux, UMR 5804, F-33270, Floirac, France. 6San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA. 7University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556, USA. 8Department of Geological and Environmental Sciences, Stanford University, 450 Serra Mall, Building 320, Stanford, CA 94305, USA. 9NASA Exoplanet Science Institute, California Institute of Technology, 770 South Wilson Avenue, Pasadena, CA 91125, USA. 10National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA. 11Southern Connecticut State University, New Haven, CT 06515, USA. 12University of California, Berkeley, CA 94720, USA. 13Center for Exoplanets and Habitable Worlds, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA. 14Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802, USA. 15Michigan Center for Theoretical Physics, Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA. 16Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA. Abstract The quest for Earth-like planets is a major focus of current exoplanet research. Although planets that are Earth-sized and smaller have been detected, these planets reside in orbits that are too close to their host star to allow liquid water on their surfaces. We present the detection of Kepler-186f, a 1.11 ± 0.14 Earth-radius planet that is the outermost of five planets, all roughly Earth-sized, that transit a 0.47 ± 0.05 solar-radius star. The intensity and spectrum of the star’s radiation place Kepler-186f in the stellar habitable zone, implying that if Kepler-186f has an Earth-like atmosphere and water at its surface, then some of this water is likely to be in liquid form. EDITOR'S SUMMARY Starry Brightness The high photometric precision of NASA's Kepler observatory has enabled the detection of many planets because they cause slight dimming of their host stars as they orbit in front of them. From these data, Quintana et al. (p. 277) have spotted a five-planet system around a small star. Here, the outermost planet is only 10% larger than Earth and completes its 130-day orbit entirely within the habitable zone, where liquid water could exist on its surface. Similarly, Kepler can detect faint periodic brightenings, as Kruse and Agol (p. 275) have reported for the binary system KOI-3278. In this system, a white dwarf acts as a gravitational microlens when it passes in front of its Sun-like G-star companion every 88 days. The lensing effect allows the mass of the white dwarf to be estimated, which helps us to understand how similar binary systems may have evolved.