Best Galaxy For Life: Ellipticals For The Win
The latest evidence from astrobiology reveals that elliptical galaxies may be the best galaxies to look for extra-terrestrial life.
Astrobiology seems like a branch of science that’s a bit premature doesn’t it? It’s kinda like an artificial intelligence psychiatrist. Astrobiologists however, don’t need to solely focus on the biology of as of yet undiscovered extra-terrestrials however.
This is how NASA’s website describes this science:
“Astrobiology is the study of the origin, evolution, distribution, and future of life in the universe. This multidisciplinary field encompasses the search for habitable environments in our Solar System and habitable planets outside our Solar System, the search for evidence of prebiotic chemistry and life on Mars and other bodies in our Solar System, laboratory and field research into the origins and early evolution of life on Earth, and studies of the potential for life to adapt to challenges on Earth and in space
These guys then have a lot more on their plates than you may have imagined. Determining where life as we know it could exist in the universe has long been one of my favorite parts of their jobs. They done quite a bit the past decade or so in learning about the habitable zones around stars. They’ve now taken a step back and increased the size of those zones to encompass not just stars but whole galaxies.
This new perspective was taken up by researchers in Universities that use a shit-ton of words to fully enumerate like the Institute for Computational Cosmology, Department of Physics, University of Durham, the UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, and the Consortium for Fundamental Physics, Lancaster University, earth, sol system, Milky Way.
In order to determine which galaxy types are most conducive to life, you need to come up with the factors to choose that increase the odds maximally. They pared their list down to just 3 criteria:
- The number of stars that could host life
- The amount of the appropriate elements available for planets and life-forms
- The amount of supernovas
Once these factors were decided upon, the next step was to examine as many galaxies as possible and start ranking them. The cool thing is that they didn’t even have book time on a telescope. The arduous work of cataloging 150,000 galaxies based on these exact criteria was already done. Thank you Sloan Digital Survey.
When it was all said and done, it turns out that spiral galaxies like our Milky Way was not at the top of the list. The winner was giant elliptical galaxies.
Elliptical galaxies are one of the three top-tier types of galaxies along with the Spirals (yayyy) and Lenticulars. Other schemes include types like irregulars galaxies as well. Ellipticals have never been favorites to look at though, mainly because they have no structure. They’re essentially spherical blobs of stars like globular clusters on galactic steroids. The giant ellipticals though are generally big (some have more than a trillion stars). They also have a tremendous amount of metal in them that could be put to use creating planets and life. They also have far fewer supernovas than other galaxies.
These galaxies aren’t just slightly better abodes of life. If you look at an elliptical that’s at least twice the size of our galaxy and has one tenth the supernova rate we do, it could potentially host 10,000 times the number of earth-like habitable worlds that we do.
Not bad for the ugly ducklings of the universe.
Abstract: Astrophysical Journal Letters
Image Credit: http://www.dailygalaxy.com/my_weblog/2015/07/an-entire-spiral-galaxy-fell-through-the-center-of-maasive-elliptical-galaxy-m87-eso.html