As the nearest spiral galaxy to our Milky Way, the Andromeda is often considered by scientists as our galactic big sister. The massive Andromeda galaxy, or M31, is located around 2.5 million light-years away.
On Tuesday, Jan. 5, NASA released high-quality images of the Andromeda that were captured through the Nuclear Spectroscopic Space Telescope Array (NuSTAR).
The NuSTAR is capable of scanning X-ray emissions with the highest energies which the universe can generate. Because of Andromeda's relative closeness, the NuSTAR can study the spiral galaxy's X-ray emissions in fine detail.
How The NuSTAR Discovery Affects Current Knowledge About The Universe
NASA's observatory in Maryland zoomed in on the Andromeda and observed 40 X-ray binaries. These are intense X-ray sources made up of two stellar objects: either a black hole or a neutron star and a companion star.
As X-ray binaries orbit one another, the star's plasma is sucked and pulled away by the neutron star or the black hole. Gas from the plasma undergoes intense and rapid heating. This enables the emission of high-energy X-rays.
"Andromeda is the only large spiral galaxy where we can see individual X-ray binaries and study them in detail in an environment like our own," said Daniel Wik, an assistant research scientist at NASA's Goddard Space Flight Center.
Wik said their findings will help experts further understand the role of X-ray binaries in the formation and evolution of the universe. These extreme energies may have played a role in heating the intergalactic bath of gas where the first galaxies materialized.
Aside from that, scientists can also study whether X-ray binaries are mainly composed of neutron stars or black holes and how their radiation compares with emissions from more distant galaxies, which are harder to see.
Ann Hornscheimer, one of the lead investigators of the NuSTAR Andromeda research, said by observing local populations of black holes and neutron stars with NuSTAR, scientists can figure out the amount of power coming out from these stellar systems.
The NuSTAR findings, which were presented at the 227th annual meeting of the American Astronomical Society, can also help scientists understand how the Andromeda galaxy differs from the Milky Way.
Caltech's Fiona Harrison, a co-investigator of the NuSTAR research, said intense stellar populations located in the Andromeda galaxy may tell scientists about the history of the forming stars within it, and how it may be different from the stars in our own galactic neighborhood.
The Andromeda Galaxy
The Andromeda is enveloped in a massive halo of gas, an atmosphere that is a thousand times more massive and six times larger than what scientists had predicted.
"Halos are the gaseous atmospheres of galaxies. The properties of these gaseous halos control the rate at which stars form in galaxies," said University of Notre Dame astrophysicist Nicolas Lehner.
The Andromeda galaxy contains more than 1 trillion stars, a number twice the stars present in the Milky Way. This stellar galaxy ranks as the largest of our own local group of galaxies and is the most distant object that is visible to the naked human eye.
The Sun Seen In High-Energy X-Ray
Aside from the Andromeda galaxy, NASA's NuSTAR has also detected and captured images of the sun in high-energy X-ray in December 2014.
Because the NuSTAR can see beyond the farthest of our own galaxy, scientists have long considered the space telescope as an ideal candidate in studying our sun.
"NuSTAR will give us a unique look at the sun, from the deepest to the highest parts of its atmosphere," said David Smith, a solar physicist and member of the NuSTAR research team in California.
Smith coordinated with Harrison to safely look for faint X-ray flashes in the sun. Although the sun is much too bright for space telescopes, the NuSTAR can look at the sun in higher-energy X-ray realms where the sun is not as bright.
Combined with an infrared image taken by NASA's Solar Dynamics Observatory, the X-ray image revealed solar activity such as sunspots and flares.
The NuSTAR continues to observe the universe and detect black holes, neutron stars, remnants of supernovas and other celestial objects.
