Free Astronomy Magazine January-February 2019

7 JANUARY-FEBRUARY 2019 PLANETOLOGY tics with which the plates were taken: cu- riously, each time the objective lens was re- moved, cleaned and reassembled, the color- dependent image scale of the stellar images changed. It is for this reason that the same, presumed oscillations were then noticed also for many other stars, and it is again for this reason that van de Kamp and some of his collaborators were convinced they had al- ready discovered other planetary systems, later proved as non-existent. In spite of the evidence of equipment being responsible for the observed oscillations, van de Kamp advocated his discovery in special- ized magazines until the 1980s. By this time, the precision of other radial velocity meas- urements had imposed for the mass of the alleged planet a much lower limit than that calculated by van de Kamp, insufficiently small to produce the observed effects. In short, that planet did not exist. However, the interest of astronomers in Barnard’s Star has never diminished. Because of its proximity to our planet, it has continued to be a very studied object with astrometric, photometric and spectroscopic techniques. The last two decades of data, gathered in seven prestigious observatories, have merged into a study linked to the Red Dots project (which in 2016 produced the discov- ery of Proxima Centauri b). This collective study has now made real the original illusion of van de Kamp through the discovery of a planet in orbit around Barnard’s Star. The achievement was realized thanks to the synergy of about sixty researchers, belong- ing to about thirty scientific institutes, who combined almost 800 measurements of ra- dial velocities, all performed using high-res- olution spectral lines of the star. T his wide-field image shows the surroundings of the red dwarf known as Bar- nard’s Star in the constellation of Ophiuchus (the Serpent-Bearer). This picture was created from the material forming part of the Digi- tized Sky Survey 2. The center of the image shows Barnard’s Star captured in three different expo- sures. The star is the fastest mov- ing star in the night sky and its large apparent motion can be seen as its posi- tion changes be- tween successive observations — shown in red, yel- low and blue. [ESO/Digitized Sky Survey 2. Davide De Martin E – Red Dots]