In the dark starry night somewhere out there is a small faint light in the sky
among millions of stars that shine upon us this light is so faint that perhaps our most
recognized astronomers ignored it first but an amateur Stargazer got curious about this
little dust Among the Stars that turn out to be an ancient Galaxy hiding in our neighborhood
What secrets is this galaxy Holding On Us what would we find out about the early Universe
in this fossil of the past would it be able to help us solve the mystery of dark matter
welcome to Factnomenal and today let's learn more about Pegasus 5 the ultra
faint dwarf Galaxy that could be among the earliest of galaxies that are ever found
if there was an astronomical version of where's Waldo skywatcher Giuseppe Donatello would have
been the champion of that game his Keen Eye managed to find an entire galaxy that somehow
everybody else missed in the archival data from a US Department of energy camera designed
to hunt for dark energy the incredibly faint and small Pegasus 5 which can be seen as a dim cloud
of stars in the center of the image here is a companion to the much larger Andromeda Galaxy
Donatello was able to spot the Galaxy and the data gathered by the Victor M Blanco 4 meter telescope
at the Cerro tololo inter-american observatory in Chile the amateur astronomer was taking part in a
search for dwarf galaxies that are satellites to the Andromeda galaxy when he spotted the ever so
elusive Pegasus 5. Andromeda is a massive spiral galaxy similar to our own Milky Way but a bit
bigger located nearly two and a half million light years away from the Milky Way the Galaxy
dominates this small clutch of galaxies that we call the local group along with the Milky Way
in a way you can say Andromeda is the king and the Milky Way is the queen Galaxy of this local group
and both of these galaxies are surrounded by dozens if not more of smaller galaxies
that could be termed as companions or satellites of their parent Galaxy
even with the help of a smallish telescope you can spot a couple of dwarf galaxies near
the center of the local group these galaxies would be M32 and NGC 205
this isn't the first time an ultra faint dwarf galaxy has been discovered because of the data
collected by the dark energy can local volume exploration or delve survey earlier this year a
group of astronomers led by William cherny of the University of Chicago Illinois also found a ufd
that was dubbed Pegasus 4. and it turned out to be a satellite of the Milky Way galaxy Pegasus 4 lies
at the very Northern edge of the sky accessible to the dark energy camera in a region previously
covered at a shallower depth by the Sloan digital Sky survey and a few others Pegasus 4 and Pegasus
5 both are compact old Ultra faint Stellar systems Pegasus 5 is much much fainter however the Desi
Legacy Imaging survey covered the Northern Hemisphere Sky which constitutes 14 000 Square
degrees which is nearly a third of the entire Sky of the entire Earth as Pegasus 5 appeared very dim
over the density of light a team of astronomers decided to take this matter to the massive Gemini
8.1 meter telescope so that they can capture some deeper images to study the Galaxy better
according to the Gemini telescope's observations Pegasus 5 appears to be a
very dinky looking Galaxy and is probably no larger than a few hundred light years
in wave which makes it at least a hundred times smaller than the Milky Way which for
comparison is a hundred and twenty thousand light years in diameter another thing that
makes Pegasus 5 diminutive and super hard to spot is the lack of light it is emitting
the super faint super dim dwarf galaxy has a total Luminosity of 26 000 Suns for an entire galaxy
that is super low because even a single massive star has more brightness than that however it
is still a lot more than Pegasus 4 which only glows four and a half thousand times the Sun
with the help of the Gemini telescope data on the Galaxy astronomers managed to observe individual
stars in the galaxy this helped them determine two important characteristics of the dwarf Galaxy
its age and distance but before we get to that let's talk about the stars that call Pegasus 5
their home well to be frank there is a reason astronomers are calling Pegasus 5 a fossil of
a galaxy rather than a proper Galaxy Pegasus 5 is more of a hospice of stars rather than a home
the stars that are the denizens of this dwarf Galaxy are extremely old ancient in fact they
are so old that they have no trace of heavy elements in them this sets their birth date around
the time when the universe was still young and was almost entirely made of hydrogen and helium
this was the period when elements Like Oxygen and iron were made inside stars that exploded
at the ends of their lives and Scattered those Elements which were then incorporated into later
generations of stars by measuring the amounts of these elements we can measure the star's ages and
also the age of Pegasus 5. but this method would require further study of this ever so shy Galaxy
but we do have an estimate for now using a different technique scientists derive that
Pegasus 5 should be nearly 12.5 billion years old that puts the little Galaxy not so far from The
Big Bang itself that's very Vital Information about this not so significant looking Galaxy
an important detail about the early universe is that during that period the gas was so dense all
over that it made the universe opaque to light but as the universe kept expanding and the first
stars were born they created a huge flood of ultraviolet light that stripped electrons off the
hydrogen atoms and made the universe transparent this phase of the evolution of the universe is
called the Epic of reionization but why is that information relevant in the case of Pegasus 5.
well that blast of UV light would have sucked the gas right out of the small galaxies at the time
and astronomers think that would have quenched any Star formation in galaxies like Pegasus 5.
so seeing 12.5 billion year old stars in Pegasus 5 means it might be a remnant of
that era a fossil from reionization and that is why this galaxy makes a very tempting Target
for astronomers who want to understand that difficult to observe time in Cosmic history
also Pegasus 5 lies nearly 2.3 million light years from the earth which makes it about 850 000 light
years from the center of the Andromeda galaxy and this is where things get exciting for the future
the existence of Pegasus 5 so far from Andromeda implies that there should be
more Ultra faint dwarf galaxies out there as far from Andromeda as Pegasus 5 is
models of how galaxies form predict there should be hundreds of small faint galaxies
orbiting Andromeda but only a few dozen have been found so the existence of Pegasus 5 should be
able to solve the dwarf Galaxy problem and that would make the universe make more sense to us
and if we found them we would be able to get closer to the answer to the question where
do we come from what do you think thanks for watching fact nominal please share and like the
video If you enjoyed it we will be back with yet another video exploring our universe soon