Free Astronomy Magazine September-October 2021

7 SEPTEMBER-OCTOBER 2021 ASTRO PUBLISHING first study showed that double stars can host planets like single ones, provided that the two stars are far enough apart that they do not pre- vent the formation of the planets themselves. This first study was con- firmation that there could be many more Earth-sized planets than those discovered up to that point. In more recent years, this line of re- search has recorded several other contributions from various teams, including the most recent and sig- nificant one by Kathryn Lester (NASA Ames Research Center) and collaborators. This team employed speckle imaging with both Gemini (North and South) and WIYN tele- scopes to study over 500 candidate planet-hosting stars already ob- served by the Transiting Exoplanet Survey Satellite (TESS). The researchers’ ground-based ob- servations reached angular resolu- tions between 20 milliarcseconds and 1.2 arcseconds, corresponding to spatial resolutions between just under 10 and about 500 AU, a much T he design of the “Zorro” speckle imaging device used by Lester’s team. A pickoff mirror deflects the light coming from the tertiary mirror, redirecting it into Zorro. Inside Zorro, the light is split by a dichroic into red and blue channels and their light is sent to respective cameras equipped with electron-multiplying CCDs. [Dr. Nic Scott/NASA Ames] N ASA machinist Emmett Quigley doing work on a part for the speckle instru- ment in Chile. Dr Steve Howell is in the background. [NASA] evaluate the influence a companion star can have on the formation, evo- lution and survival of planets. Theo- retical studies have suggested that a stellar companion can distort the protoplanetary disk of the primary star (or vice versa), removing mate- rial from the formation of the plan- ets. Later, the bulky presence can favor the migration of gas giants and eventually disperse smaller plan- ets. Overall, fewer companion stars could be expected to be found at distances of less than 100 AU around stars with a planetary system, com- pared to pairs without planets. And so it was. Lester’s team found that 73 stars in the sample examined with Gemini telescopes and 18 observed with WIYN are binary systems. larger range than that of previous studies. This allowed the team to