Na Kilo Hoku o Mauna Kea
On
June 6, 2003
“The Universe Tonight’
Presents
GALAXY BIRTH, DEATH
AND REINCARNATION
By
Dr. Michael West
Department of Physics & Astronomy
University of Hawaii
at Hilo
The June presentation of the popular “The Universe Tonight” program will be presented at the Mauna Kea Visitor Information Station off Saddle Road.
The Mauna Kea Program will be held on Saturday June 7, 2003 at the Onizuka Center for International Astronomy, located at the 9,300-foot level of Mauna Kea. The presentation will begin at 6p.m. and stargazing with portable astronomical telescopes will follow after sunset.
Please
Note
In addition to The Universe
Tonight astronomy lecture a free musical performance will also be offered.
“Strings Under the Stars”, a free musical
performance will be featured Saturday evening, June 7, at Hale Pohaku visitor
center. Students from O’ahu and the Big Island will offer a varied selection of
folk songs, light classics, fiddle tunes, and Hawaiian music on violin, viola
and cello. The musical portion of the evening’s program will begin at 5:30 pm
and continue at 7pm, following the regularly scheduled “Universe Tonight”
presentation. Together with the star gazing program that begins at 6 p.m., this
will be a wonderful opportunity to enjoy the best of music and astronomy in one
great setting.
The Visitor Information Station can be reached from Hilo, Waimea and Kona via Saddle Road. Seating is limited and will be provided on a first-come first-serve basis.
The Universe Tonight is presented the first Saturday of each month at the Visitor Information Station. A special speaker from a different Mauna Kea observatory shares recent observations and discoveries with the general public.
For more information on programs at the Mauna Kea Visitor Information Station visit the Web site www.ifa.hawaii.edu/info/vis or call (808) 961-2180.
GALAXY BIRTH, DEATH
AND REINCARNATION
Dr. Michael West,
Countless billions of
galaxies are scattered like snowflakes throughout the cosmos. These
galaxies are home to stars, planets, gas, dust and invisible dark matter, all
held together by gravity.
Understanding how and when
galaxies came into existence is one of the major goals of astronomical
research. Telescopes around the world, including those on Mauna Kea, peer
at galaxies night after night, hoping to unlock the secrets of their
origin. Yet nearly a century after Edwin Hubble first deduced the true
nature of galaxies as distant "island universes", their origin remains one
of the great-unsolved mysteries of modern astronomy.
One way
that astronomers study the history of galaxies is by observing far away
ones. Because light travels at a fixed speed of 186,000 miles per second,
we see objects as they looked in the past. Light from the Sun takes 8
minutes to reach Earth, and so we see the Sun as it appeared 8 minutes
ago. Similarly, light from distant galaxies takes millions or billions of
years to reach Earth, and so we see them, as they appeared in their infancy
millions or billions of years ago. By observing galaxies over a wide range
of distances, astronomers are able to look back in time to see how galaxies were
in the past. In principle, it should even be possible to witness the birth
of the very first galaxies by looking sufficiently far into space.
Yet while much of current
astronomical research is focused on the question of galaxy formation, a growing
body of evidence suggests that galaxies can also be destroyed, and many may have
already met their demise. For example, large galaxies have been observed
to devour smaller ones, and astronomers now think that many large galaxies may
have grown to their present sizes by cannibalizing other galaxies.
Even our home galaxy, the Milky Way, is a cannibal that would make Hannibal
Lecter proud, as it is currently making a meal of an unfortunate smaller galaxy
called the Sagittarius dwarf that strayed too close and got caught in its
gravitational grip. It is likely that the Milky Way as already snacked on
dozens or perhaps hundreds of smaller galaxies during its lifetime, inheriting
their stars in the process.
Even without the threat from
cosmic cannibals, galaxies face plenty of perils. A sudden gust of gravity
from a passing galaxy, for example, can rip stars loose, sending them careening
off into distant space. In some cases entire galaxies may be disrupted by
violent collisions with neighbors. As galaxies are destroyed, their
contents are strewn into space, resulting in an ever-growing sea of
intergalactic stars, gas, and other cosmic flotsam and jetsam. No longer
part of any individual galaxy, these free-floating stars and other objects
wander through space like cosmic vagabonds.
For the past few years my
collaborators and I have been conducting a census of this intergalactic debris
using Keck, Subaru, Canada-France-Hawaii and University of Hawaii telescopes on
Mauna Kea, as well as the Hubble Space Telescope. Because this
intergalactic material is composed of the accumulated remains of shredded
galaxies, we hope to be able to learn more about the numbers and types of
galaxies that have been destroyed over the history of the universe.
But nature recycles. The
history of the universe is essentially a tale of atoms being continuously
rearranged in new ways. Despite illusions, no object is permanent, it is a
flowing event. Galaxies are no exception to this rule.
Astronomers now know that some of the intergalactic material made from the
remains of destroyed galaxies is eventually incorporated into other
galaxies. And in some cases, whole new generations of galaxies have been
seen to form from material torn from other galaxies during collisions. The
births and deaths of galaxies appear to be intertwined.
-----------------------------------------------------------------------
Michael West
Department of Physics & Astronomy
University of Hawaii at Hilo
808-974-7744
west@astro.uhh.hawaii.edu
TUTA030525UHHa