An Extraordinary Journey to the Mysterious Galaxy of Andromeda – Since the dawn of mankind, the cosmos has never ceased to amaze anyone who looks up to the sky. The starry nights move, subjugate, transport and fascinate the lovers of the stars, the lovers quite simply. The discoveries follow one after the other, some confirming old hypotheses, others, breaking assumptions, exposing us to more and more unresolved mysteries. If we have begun to understand the functioning of our galaxy, the Milky Way, we also know that it occupies only an insignificant part of the space that surrounds us. The universe is so vast that the observation of its horizon is still inaccessible to our most sophisticated instruments. Nevertheless, we offer you the possibility to discover, beyond our solar system, a neighboring galaxy, just as wonderful and spectacular.
The Andromeda Galaxy: – The immense diameter of approximately 200,000 light-years gives the Andromeda Galaxy, the place of first galaxy by size in the Local Group, our Milky Way then taking the second position. The Andromeda Galaxy is the closest spiral galaxy to our own and contains nearly a thousand billion stars, about twice as many as the Milky Way. However, its total mass is estimated to be around 1,230 billion solar masses compared to 1,900 solar masses for our galaxy.
If these two galaxies have similar masses, the density of stars in the Andromeda Galaxy is higher. This is why its luminosity is 25% higher than that of the Milky Way. The total luminosity of the Andromeda Galaxy is estimated at 26 billion times the solar luminosity. However, the Milky Way has three to five times more star formation than the Andromeda Galaxy. The latter seems to have reached a certain state of rest. But if this rest is related to its production of stars, the galaxy is well in motion. Starting from the galactic center, the speed of stars increases to 225 km/s before decreasing to 50 km/s at 7000 light-years, then increases again to 250 km/s at 33 000 light-years before decreasing to 200 km/s at 80 000 light-years. We can then deduce that the total mass of the Andromeda galaxy increases linearly up to 45 000 light-years from the center, then more slowly beyond this distance. The mass of the core is then estimated at six billion solar masses. It is certain that the Andromeda Galaxy contains millions, even billions of planets orbiting its many stars. However, current technology, although already very advanced, does not allow us to observe non-luminous stars, distant more than 2.5 million light-years from our solar system.
But astronomers are competing with ingenuity and do not cease to observe our galactic neighbor. Moreover, an object seems to have been spotted during a microlensing event in 1999. What if it was indeed a planet? This confirmation would make the headlines in scientific journals worldwide. Indeed, it would be the first extragalactic planet officially discovered, all the planets listed to date being part of our Milky Way. This hypothetical planet, distant of 2 185 247 light-years from our Galaxy, has been named PA-99-N2. Its mass is estimated at 6.34 masses of Jupiter, or more than 2015.5 times the mass of Earth. Imagine that this planet orbits in a habitable zone. Do you think that a life form could be discovered there?