Hubble data links Andromeda’s star formation decline to smaller neighbor galaxy

Astronomers have found that the Andromeda galaxy's ability to forge new stars has dropped sharply over the last 40 million years, with a smaller neighboring galaxy emerging as the prime suspect behind the slowdown.

A Catalog of 200 Million Stars

Using observations from the Hubble Space Telescope, a research team led by Tobin Wainer, a graduate student at the University of Washington, analyzed data from two surveys covering two-thirds of Andromeda's disk. The effort produced a catalog of 200 million stars, which researchers divided into a grid of squares 300 light-years to a side, reconstructing the star formation history of each section based on stellar color.space+1

The results trace a steady decline: around 500 million years ago, Andromeda converted the equivalent of one solar mass of gas and dust into new stars each year. By 40 million years ago, that rate had fallen to about half a solar mass per year. Today, it stands at roughly one-fifth.newsbytesapp+1

M32: The Most Likely Suspect

The decline is not uniform across the galaxy. The most pronounced drop in star formation begins about 60 million years ago on the side of Andromeda closest to M32, a compact satellite galaxy located just 16,000 light-years away. Astronomers believe M32 may be the remnant core of a spiral galaxy that lost its arms, possibly during a past collision with Andromeda.english.pravda+1

"We can't explicitly say that we are seeing a decrease in star formation because of M32. But it's right there, and it's definitely the most likely suspect," Wainer said in a statement, as reported by Space.com.space

What Comes Next

While the connection between M32 and the slowdown remains unconfirmed, astronomers expect new data from the Nancy Grace Roman Space Telescope, scheduled to launch in late August, to provide broader coverage of Andromeda than Hubble could achieve and help determine whether the smaller galaxy's gravitational influence is truly to blame.ua+1