[1][2] On November 14, 2018, the Red Dots project announced that Barnard's star hosts an exoplanet at least 3.2 times as massive as Earth, though this does not match either of the planets he had claimed.

His younger brother Jacob van de Kamp was also a successful scientist: an organic chemist, who spent most of his career in the United States.

In 1923 he left for the Leander McCormick Observatory at the University of Virginia for a year's residence supported by the Draper Fund of the National Academy of Sciences.

There he assisted Samuel Alfred Mitchell with his extensive stellar parallax program and Harold Alden with the lengthy Boss star project.

[6] Van de Kamp returned to McCormick on October 1, 1925, to take up the position left vacant by Harold Alden, who had just taken up the directorship of the Yale University Observatory Southern Station in Johannesburg, South Africa.

While at Sproul Observatory, he made astrometric measurements of Barnard's Star and in the 1960s reported a periodic "wobble" in its motion, apparently due to planetary companions.

[9][10][11] In 1973 astronomers George Gatewood of the Allegheny Observatory and Heinrich Eichhorn of the University of Florida, using data obtained with improved equipment on the 30-inch Thaw Refractor telescope, did not detect any planets but instead detected a change in the color-dependent image scale of the images obtained from the 24-inch refractor telescope at the Sproul Observatory used by Van de Kamp in his study.

[13] Wulff Heintz, Van de Kamp's successor at Swarthmore and an expert on double stars, questioned his findings and began publishing criticisms from 1976 onwards; the two are reported to have become estranged because of this.

[4] In August 2024, by using data from ESPRESSO spectrograph of the Very Large Telescope, the existence of an exoplanet with a minimum mass of 0.37±0.05 M🜨 and orbital period of 3.15 days was confirmed.

From the 1940s on Van de Kamp and his staff made similar claims of planetary systems around the nearby stars Lalande 21185, 61 Cygni, and many others, based on the same flawed photographic plates.