Hubble reveals Andromeda has made contact with our galaxy
The Hubble Space Telescope mapped the halo of the Andromeda galaxy, revealing our galactic neighbor in a new light.
Halo… halo… halo… is there anybody out there?
The halo was found to possess a layered structure containing a pair of distinct nested shells of gas. Examination of this halo, which supplies material for the formation of stars, can reveal information about the birth and deaths of stars within the Andromeda Galaxy. The discovery of heavy elements, produced in the explosions of massivesupernovastars, reveals evidence for the deaths of vast numbers of behemoth stars.
“We find the inner shell that extends to about a half million light-years is far more complex and dynamic. The outer shell is smoother and hotter. This difference is a likely result from the impact of supernova activity in the galaxy’s disk more directly affecting the inner halo,” Dr.Nicolas Lehnerof the University of Notre Dame, describes.
The Andromeda Galaxy, also known as M31, is roughly the size of theMilky Way Galaxy. Containing roughly one trillion stars, this massive family of stars can be seen as a smudge in the sky each Autumn. If the halo were visible, the sight would dwarf all other targets in the sky.
Abner! Abner!
Astronomers set the sights of the Hubble Space Telescope’s Cosmic Origins Spectrograph (COS) on 43 quasars (highly-active galaxies) set behind the galactic halo, viewing light traveling through several regions of the cloud of plasma. Because the halo gives off just a small amount ofelectromagnetic radiation, studying light passing through the cloud makes it easier to study.
“Previously, there was very little information — only six quasars — within 1 million light-years of the galaxy. This new program provides much more information on this inner region of Andromeda’s halo,” explained co-investigator J. Christopher Howk of Notre Dame.
Andromeda is the only galaxy close enough and large enough for astronomers to study using this method. And only one telescope was capable of carrying out the tasks required for Project AMIGA (Absorption Map of Ionized Gas in Andromeda) — TheHubble Space Telescope.
The Milky Way is also likely to have its own halo, similar to the one seen around Andromeda. However, it is challenging to study our own halo from within its structure. Smaller halos have been seen around other, more distant galaxies, but this is the most detailed study of such a galactic halo ever conducted.
In four billion years, the Andromeda Galaxy and the Milky Way will collide — and it’s already come by for ahalo!
This article was originally published onThe Cosmic CompanionbyJames Maynard, founder and publisher of The Cosmic Companion. He is a New England native turned desert rat in Tucson, where he lives with his lovely wife, Nicole, and Max the Cat. You can read this original piecehere.
Astronomy News with The Cosmic Companionis also available as a weekly podcast, carried on all major podcast providers. Tune in every Tuesday for updates on the latest astronomy news, and interviews with astronomers and other researchers working to uncover the nature of the Universe.
Story byThe Cosmic Companion
Exploring the wonders of the Cosmos, one mystery at a time.Exploring the wonders of the Cosmos, one mystery at a time.
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