Hubble telescope spots giant halo around the Messier 31 galaxy

During a recent study using NASA’s much talked about Hubble Space Telescope, a group of scientists led by the University of Norte Dame astrophysicist Nicolas Lehner has spotted a massive halo of gas around Andromeda. For those who don’t know: Andromeda is the closest major galaxy to our planet.

The halo stretches for around a million light years from the Andromeda Galaxy and covers almost 50% of our home galaxy Milky Way. This discovery will allow astronomers to gather further knowledge about the kind of changes the structure of huge spiral galaxies like Andromeda and Milky Way has undergone.

Lehner, who was leading the research team, said halos are gaseous atmospheres the galaxies have. He added that the characteristics of these halos decided at what rate stars will be formed in a particular galaxy. The mass of the gas in the halo around Andromeda, according to the scientists, is at least 50 percent of the mass of the stars the galaxy possesses.


Researchers also refer to the Andromeda as M31 or Messier 31. The M31 is the biggest galaxy in the Local Group, of which our home galaxy Milky Way is also a part. The group is home to around 45 more known galaxies.

Right now, Andromeda houses around a trillion stars, which is two times more than the number of stars present in Milky Way. In addition, primarily due to the larger number of stars it possesses, the Andromeda Galaxy is 25% brighter than our home galaxy. The distance between the two galaxies is approximately 2.5 million light-years.

The study conducted by Lehner and his team demonstrated that the newly discovered Halo is one of the most important features of Andromeda. Its diameter is hundred times bigger than the moon’s diameter. However, the gas constituting the halo is invisible. Thus, for finding and studying the halo, researchers had to look at the luminous objects in its background; the light emitted by those objects is affected by the gas forming the halo.

You can read the entire paper in this week’s edition of the widely read science journal The Astrophysical Journal. Lehner has University of Wisconsin Madison’s Bart Wakker as his co-author for the study.