|
Virgin Galactic's Private Spaceship Makes First Crewed Flight
Virgin Galactic's VSS Enterprise has made its first flight with a
crew onboard this month. The private suborbital spaceship built for
space tourism tested all of the spacecraft's systems and functions
during the 6-hour, 12-minute flight.
http://tinyurl.com/36hbrp9
Hop on Board the Lunar Elevator!
Are Virgin Galactic's private spacecraft obsolete before
they're even completed? At least one entrepreneur believes a space
elevator from the surface of the Moon could be built within a decade.
http://tinyurl.com/25zttey
Hubble's Successor - How Does it Compare?
The James Webb Space Telescope (JWST) is scheduled for launch
in 2014 and will in many ways replace the Hubble Space Telescope as the
world's premier observatory. It will study the history of our Universe
from the Big Bang to the formation of solar systems capable of
supporting life. But how different is JWST to Hubble? This interactive
programme will give you an idea...
Scary, Record-Breaking Star
- David Britten
Astronomers
announced details last month of the most massive stars yet discovered.
The largest, designated R136a1, is 10 million times brighter than the
Sun. If we could replace our Sun with this star, it would outshine the
Sun the same as the Sun outshines the Full Moon. Its powerful
ultraviolet radiation would sterilize the Earth, and its gravity would
speed up the Earth and shorten our year to just 3 weeks.
The
announcement prompted a flurry of incorrect and misleading headlines,
news items and talkback. The most common mistake was confusing size
with mass, calling this the 'largest' or 'biggest' star.
Mars
would orbit inside the surface of the supergiant star Betelgeuse, which
'weighs' about 20 Suns (solar masses). It is a 'very big' or 'very
large' star. The new star, RMC136a1, is more than 100 times more
massive than Betelgeuse, at around 265 solar masses.
R136a1
started out at nearly 320 solar masses and has shed nearly a fifth of
its weight since then. More massive stars burn hotter than less massive
stars, and R136a1 is so extreme that it emits 50 times more energy than
the entire Orion nebula.
People
were asking why this star hadn't been found before now - if it's so
incredibly large and bright, how could astronomers miss it?! The answer
is that closer stars are easier to observe than more distant objects in
space, but there are no stars this large near the Sun. The nearest
mega-stars are thousands of light-years away (thousands to hundreds of
thousands of trillions of kilometres!).
Supermassive
stars only form in the most dense of star clusters. R136a1 is part of
the star cluster RMC136, which lies 165,000 light-years distant in the
Tarantula nebula, which is in the Large Magellanic cloud.
Observing
individual stars in this distant dwarf galaxy has not been possible
until very recently. The key to revealing the stars in this cluster was
using infrared instruments on the VLT (Very Large Telescope) in Chile.
The VLT has four 8.2m telescopes that can combine their light in
various ways to greatly improve the sharpness of stellar images.
Supermassive
stars are so bright and give off such huge clouds of hot gases that
observations of their temperature and brightness are very difficult. It
can even be difficult to tell whether these are single supermassive
stars or multiple star systems, which may comprise two or more massive
stars orbiting closely together, or there may be a supermassive star
with one or more companions.
It seems certain, though, that this record star is unlikely to be beaten any time soon.
Left: Wide-field view of the Tarantula nebula in the Large Magellanic
Cloud. Middle: Zoomed-in view of boxed area in visible light. Right:
Near-infrared close-up view showing details of the stars in the RMC136
cluster.
|
