A funny thing happened to some astronomers who were using the Hubble
Space Telescope to study stars in a nearby cluster. They found something
hiding behind the cluster, a distant undiscovered galaxy millions of
light-years away! Welcome back to Launch Pad, I'm Christian Ready you're
friendly neighborhood astronomer. A team of astronomers using the Hubble Space
Telescope were investigating a nearby globular star cluster called NGC 6752.
Globular clusters are populations of older stars that are arranged in a
spherical or globular shape, hence the term "globular cluster". These clusters
orbit our galaxy in a halo surrounding the Milky Way. Each cluster contains
upwards of tens of thousands all the way up to a million stars each. The stars in
these clusters are pretty old; they're at least the second generation of stars
born in the universe and there may even be some first generation stars still
hiding in there. Most of the stars in these clusters have long since died out,
leaving behind their now exposed cores called
white dwarfs. A team of astronomers led by Dr. Luigi Bedin were using the
Hubble Space Telescope to understand how the white dwarfs in NGC 6752 cooled down
over time. Globular clusters are rich hunting grounds for white dwarfs, which
by their very nature are very faint stars. As the team were inspecting their
Hubble images however, they discovered a population of stars that were even
fainter than the faintest white dwarf in the cluster. The team immediately
suspected that this was in fact a distant galaxy. Specifically a spheroidal
dwarf galaxy. Dwarf spheroidal's Iike the Fornax dwarf shown here are
typically found as satellites to much larger galaxies. In fact, dwarfs galaxies
often crashed together in the early universe, building up over time the large
galaxies that we see today. So whenever these galaxies are found in isolation or
surrounding a larger galaxy, they're pretty much
fossil records of what the early universe was like. Dwarf spheroids resemble
globular clusters. After all, they're both, well...spheroidal in shape. But globular
clusters are much smaller and much more densely compact than dwarf spheroid
galaxies. But in order to confirm this new object was in fact a galaxy, the team
needed to figure out just how far away from Earth it really is. To do that they
examined each and every star in the background galaxy and compared each
star's color to its apparent brightness. This results in a diagram like we see
here called a color magnitude diagram. The cooler the star is, the redder it
appears, and the brightest and reddest stars are red giant stars. These are
stars that were once much like our Sun, but have since expanded several hundred
times their previous radius. Oh and by the way, we're gonna be talking about the
Sun's fate in an upcoming video so stay tuned.
Anyway, the red giant stars were of particular interest to the research team
because they have a fairly well-known luminosity. That is we know how bright
these stars really are. So by comparing their known luminosity to their apparent
brightness, the team are able to work out just how far away these red giants are
and therefore how far away the galaxy is. Turns out it's about 28 million light
years away. Sure enough the team did in fact find a
brand new galaxy, designated Bedin 1. Now we're gonna find out more about this
galaxy in just a moment, but first I want to thank my Patreon supporters for their
generous support: Patti Broussard, Neil from Crypto Cruising, Eric from Modern Day
Tech John Cannon, Erynn Wilson, and Gorothballion. And I want to welcome my
newest Patreon supporter Jennifer Brozeck. Thank you so much for your support, it
really helps a lot! Bedin 1 is about four degrees in the sky away from NGC
6744, a huge grand design spiral galaxy in the
constellation Pavo. That puts Bedin 1 about 2.1 million light years away from
NGC 6744, so it could mean that Bedin one is a
distant satellite to the larger galaxy, or more than likely it's a standalone
dwarf. The team didn't just work out this new galaxy's distance but they also
measured the galaxy's overall metallicity. In astronomy we define
anything that's heavier than helium as a metal, so yes oxygen is a metal...you're
breathing metal... Anyway, Bedin 1's low metallicity means
that this galaxy and its stars are very old. At least 10 billion but possibly as
old as 13 billion years. That puts Bedin 1 at about the very age of the
universe itself. Now dwarf spheroid galaxies like Bedin 1 may not be
resplendent with gorgeous spiral arms or bursts of star formation or wonderful
neat structures. But they are fundamental building blocks of our universe. By
making a complete census of each and every galaxy, no matter how small, we can
build up a much better understanding of the current present-day structure of the
universe. But by comparing our local universe with the most distant clusters
of galaxies we can compare the modern-day universe to the universe as
it appeared billions of years ago. That means that we can better understand not
just how the universe is put together today, but how it evolved over time. Now
that is really exciting stuff! So far it looks like Bedin 1 is the most
distant standalone dwarf galaxy yet discovered. That galaxy is a population
of stars, many of which were once just like our Sun but have since expanded
into red giants. Now if you'd like to learn more about how our Sun will one
day become a red giant and meet its fate, make sure that you subscribe and
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