Inhibition of giant-planet formation by rapid gas depletion around young stars

• Published in: Nature (London) 1995-02, Vol.373 (6514), p.494-496
• Main Authors: Zuckerman, B., Forveille, T., Kastner, J. H.
• Format: Article
• Language: English
• Subjects: Accretion; Astronomy; Astrophysics; Earth, ocean, space; Exact sciences and technology; Extraterrestrial Environment; Gases; Helium; Humanities and Social Sciences; letter; multidisciplinary; Planets; Pre-main sequence objects, young stellar objects (yso's) and protostars (t tauri stars, orion population, herbig-haro objects, bok globules, bipolar outflows, cometary nebulae, etc.); Science; Science (multidisciplinary); Space life sciences; Stars; Stars & galaxies
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/373494a0

ALTHOUGH stars form from clouds of gas and dust, there are insig-nificant amounts of gas around ordinary (Sun-like) stars. This suggests that hydrogen and helium, the primary constituents of planets such as Jupiter and Saturn, are not easily retained in orbit as a star matures. The gas-giant planets in the Solar System must therefore have formed rapidly. Models of their formation generally suggest that a solid core formed in ⩽10 6 yr, followed by the accretion of the massive gaseous envelope in ∼10 7 yr (refs 1–5). But how and when the gas of the solar nebula dissipated, and how this compares with the predicted timescale of gas-giant formation, remains unclear 6,7 , in part because direct observations of circumstellar gas have been made only for stars either younger or older than the critical range of 10 6 –10 7 yr (refs 8–15). Here we report observations of the molecular gas surrounding 20 stars whose ages are likely to be in this range. The gas dissipates rapidly; after a few million years the mass remaining is typically much less than the mass of Jupiter. Thus, if gas-giant planets are common in the Galaxy, they must form even more quickly than present models suggest.