Scientists Discovered Halo Around Andromeda Galaxy
Scientists Discovered Halo Around Andromeda Galaxy
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Yet another remarkable discovery has been made by NASA’s Hubble Space Telescope in its long voyage into the space. Scientists has been able to map a halo surrounding our closest spiral galaxy Andromeda (2.5 million light years from earth) extended about half way (1.3 million light year) to our home galaxy. So, to some extent this halo is currently overlapping with our own galactic halo. Current findings suggest that the halo of Andromeda is of shell structure with two prominent distinct shell of gaseous plasma.
Context
Scientists probed the light form more than 40 quasars scattered in the background of Andromeda, to study the halo of Andromeda. They used the program called Project Absorption Map of Ionized Gas in Andromeda, to map the light from quasars. Scientists observed the quasar light is absorbed in the halo and the pattern of absorption is different in different region.
UV lights coming from the quasars can not be studied from any ground stations on Earth, since earth atmosphere absorbs UV ray. The scientists used the Hubble’s Cosmic Origin Spectrograph technique to study the UV light from the background quasars of Andromeda.
The illustration shows the location of the 43 quasars in the background of Andromeda’s gaseous halo
Credits: NASA, ESA, and E. Wheatley (STScI)
Why study of galactic halo important??
Well the question may arise in your mind why do scientists study the halo? The reason is
pretty obvious – Galactic Halo is basically carrying the seed of future galactic phenomena like – ‘Star Formation’.
What do you think, where this huge amount of gas came from?
The answer lies in the violent incidents of the galaxy – Novae & Supernovae explosions. This gas contains the history of nucleo-synthesis mechanisms in the heart of the stars died long ago.
Also halo of a galaxy is the practical gravitational sphere of influence of the galaxy.
Brief Notes
Halo – Galactic halo basically an extensive envelope of plasma of very rarified gas and ionized gas. Halo of galaxies contains the vast majority of mass, but the exact mass of any halo is unknown. EM radiation is easily absorbed or scattered by this gaseous plasma.
Andromeda – It is the closest spiral neighbor to Milky Way. It is the most distant object to be seen by naked eyes in clear night sky. Andromeda is also known as M31, contains about over 1 trillion stars (Milky way – 250 Billion). Interesting fact is that in a few billion years (nearly 4 billion years) in the future Andromeda will merge with our own Milky Way galaxy in a violent yet beautiful cosmic dance.
References- NASA, Harvard Center for Astrophysics
Author Link: Sourav Sadhukhan
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