Paul Butler of the Carnegie Institution of Washington, who was involved in all three papers, said astronomers thought that one-third to one-half of all Sun-like stars harbored such super-Earths orbiting at scorching distances much closer than Mercury is to the Sun.

Image A bank of eight telescopes called MEarth on Mount Hopkins in Arizona monitors 2,000 red dwarf stars. Credit... Dan Brocious/Center for Astrophysics

In the 15 years since the first extrasolar planet was found, more than 400 have been detected. The field is getting more intense as dedicated planet-hunting instruments like the Kepler satellite from the National Aeronautics and Space Administration, due to report a new batch of such planets next month, get into the game.

Alan P. Boss, a planetary theorist at the Carnegie Institution of Washington, said of the planet hunters, “Give them a couple more years and they’re going to knock your socks off.”

Dr. Charbonneau’s planet, only 1.3 million miles from its home star, is distinguished by its relative coolness  a consequence of the dimness of GJ 1214, which puts out one three-hundredth of the Sun’s energy. He and his colleagues had set out to search for planets around such stars, noting that they are more numerous and that it is easier to discern planets around them.

His planet-hunting equipment is a bank of eight telescopes called MEarth, pronounced “mirth,” on Mount Hopkins in Arizona. Each telescope is only 16 inches in diameter, no bigger than those that grace the backyard of many amateur astronomers. They monitor the light of 2,000 nearby stars, looking for the regular blips caused when a planet passes by, or transits.

In May, Zachory Berta, a first-year graduate student of Dr. Charbonneau, called the group’s attention to blips in the Ophiuchus star that seemed to be happening every 1.6 days. If he was right, Mr. Berta said, the next transit would occur at 6 a.m. on May 13.

Dr. Charbonneau was in Washington later that day preparing for a State Department dinner when he got a group e-mail message that began: “We have a winner. Congrats Zach!”