Astronomers Spot New Details in the Faint Plumes of the Nearby Whirlpool Galaxy

Astronomers have discovered faint plumes extending from a nearby spiral galaxy, revealing unprecedented details about this object. The findings could tell researchers a bit more about spiral galaxies in general.

The spiral galaxy in question is named M51a, and is also known as the "Whirlpool Galaxy."  It's actually the first known spiral galaxy and was first identified in 1845. The whirlpool and its small companion, M51b, are both located in the hunting dogs constellation, Canes Venatici, which is located about 31 million light-years away.

In order to capture a better glimpse of this galaxy, the scientists essentially took a photograph made by a 20-hour exposure. This image revealed new details about the linear northwest plume, which is nearly 120,000 light-years long. In addition, the image revealed a lack of stars in a portion of the southeast tail.

"These features can be used in future modeling to understand the history of M51, when it and its companion galaxy first started to interact," said Aaron Watkins, one of the researchers, in a news release. "No professional astronomer we know of has ever taken such a deep image of this galaxy."

The northwest plume of the galaxy was seen in the 1970s, but now astronomers can see it in far more detail. It's dominated by older, redder stars and has little gas found in small patches. Due to the age of the stars and the length of the plume, the plume itself was probably created by the interaction of an outer disk of M51 with another galaxy about 200 million years ago.

The southern plume is stranger. It has no morphological similarities with the surrounding parts of M51 and no gas. It also has few stars and, thus, total light. It's possible that the plume could be the remnants of a third satellite or body in the M51 system.

The findings reveal a bit more about this galaxy system. Currently, scientists are now devising other ways to look at M51 to gather more details from the faint plumes.

The findings are published in The Astrophysical Journal Letters.

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