Astronomers Have Discovered the Pleiades' Secret Stellar Family

"The sun wanders the Milky Way alone; our star orbits the galaxy's distant center without any stellar siblings. But it wasn't always this way. The solar system was very likely born in a tremendous gas cloud that also birthed thousands of other stars, forming a large, loosely bound stellar family called an open cluster. These stars may have remained enshrouded in that nebula for 10 million years or more, until their combined stellar winds and light pushed away the surrounding nebulosity."

"No longer embedded in the gas, the cluster gradually disintegrated as its internal motions flung away some of its members. Throw in collisions with other huge clouds of gas and dust, as well as interactions with the galaxy's gravitational field, and the cluster's fate was sealed: its stars dispersed, eventually mixing with the background field stars in the Milky Way."

"Our solar kin may be long lost, but that's not the case for all stars. Some groupings are younger than the sun's 4.6-billion-year ageand are still in the process of eroding away. Interestingly, we see such loose affiliations of stars (called associations) all over the sky, and they often share similar characteristics, such as age and velocity, through the galaxy. Astronomers now suspect that many of these scattered associations formed in the same gas cloud, where they were born as part of a single,"

The Sun likely formed within a dense gas cloud, creating thousands of stars in a loosely bound open cluster. These stars remained embedded in the nebula for perhaps ten million years until stellar winds and radiation cleared the gas. After gas removal, internal motions, collisions with other clouds, and Galactic tides caused the cluster to disintegrate and its stars to disperse. Some younger associations still show similar ages and velocities across the sky and may have originated from the same sprawling cloud. Dense central cores of clusters can remain gravitationally bound and survive as compact groups, preserving clues to formation and evolution.

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