An international team of
astronomers has discovered that the nearby galaxy NGC 1277 was formed during
the cosmic dawn and has remained completely unaltered since then. Its identification
as a relic galaxy provides a unique window into the primitive Universe.
Researchers from the Subaru Telescope (Hawaii), the Instituto de Astrofísica de
Canarias and the Universidad Autónoma de Madrid (Spain) have recently focused
their attention on the nearby galaxy NGC 1277, located in the Perseus galaxy
cluster, because it presented most of the main characteristics for being a
relic galaxy of the early Universe: It is massive and very compact. They
analyzed data obtained from the Hubble Space Telescope and from deep
spectroscopic observations with the 4.2 m William Herschel Telescope (at the
Roque de los Muchachos Observatory, La Palma, Spain) and found that the galaxy
has remained unchanged from the time that the Universe was only two-thousand-million-years
old, about 15% of its current age.
For some unknown reason this
galaxy remained isolated from its surroundings at that point and has not
changed since then. It is a relic galaxy, suspended in time, and offers a
unique opportunity to look more closely at the features of the early Universe.
As principal investigator Dr. Ignacio Trujillo (Instituto de Astrofísica de
Canarias, Spain) pointed out, "Due to reasons we don't know, the
traditional sources of gas and stars that the rest of galaxies usually have
were shut down for this relic galaxy. Therefore, this object was left without
the flux of new material that forms stars and has remained as frozen in
time."
The discovery provides a new
opportunity to study properties of the primitive Universe in unprecedented
detail: its chemo-physical processes, its structures, and the dynamics that
formed the very first galaxies and groups of stars. Researcher Dr. Anna Ferré-Mateu
(Subaru Telescope, Hawaii) explained, "Finding a galaxy that has almost no
interaction with the rest and that is so close to us means that we can study
the properties of its form, its dynamics, and stellar populations with our
current telescopes with a precision that would be impossible if we wanted to
directly study the same object in the early Universe." Objects in the
early Universe are so far away that it is difficult to detect any light from
them. From the data that the researchers analyzed, they concluded that NGC 1277
is a very old, metal-rich galaxy, and it was formed in just a few million
years. This conclusion implies that the production of newborn stars in the
initial phase of galaxy formation was extremely high, around one thousand solar
masses per year. Dr. Trujillo commented, "The data obtained indicates that
the stars in massive galaxies formed much faster than we thought. If our
measurements are correct, the star formation rates in the early Universe were
one thousand times larger than those in our own galaxy now, where roughly one
Sun form every year."
This galaxy is also an object
with amazing dynamics; it contains a super-massive black hole in its center.
The stars located in its center move randomly, with velocities over 400 kilometers
per second (km/s), at the incredible speed of almost one and a half million
kilometers per hour; a rocket moving at this velocity would reach the moon in
15 minutes. The external region of this elliptical galaxy moves in a more
orderly way, with stars rotating at velocities of 300 km/s. As Dr. Trujillo
points out, "Usually the stars in galaxies do not present these two types
of stellar motions at the same times with such intensity." This finding
poses new, unimagined questions to be answered.
Dr. Ferré-Mateu regards this
research as just the beginning of more to come. She commented, "We are
already working in a more detailed analysis with larger telescopes than the one
used for this work, such as the 10.4 m Gran Telescopio de Canarias (GTC), in
Spain, the largest in the world, and with the 8 m Gemini North telescope in
Hawaii. This galaxy will also allow us to explore the capabilities of new
instruments mounted on the 8.2 m Subaru Telescope, which is also based in
Hawaii".
Credit: naoj.org
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