HUBBLE TELESCOPE REVEALS SWARM
OF GLITTERING STARS IN NEARBY GALAXY
Plait, Sally Heap and Eliot Malumuth
Deep in the heart of the Large Magellanic Cloud
(LMC; a small companion galaxy to our own Milky
Way) is a tremendous cloud of gas called the Tarantula
Nebula. For about the past five million years, the
Tarantula has been busily turning itself into stars.
Very busily-- just in its center, the nebula has
converted enough gas to form the mass equivalent
of 15,000 Suns, and far more are being formed over
the nebula as a whole. Because this is one of the
largest and closest star forming regions known,
it has long been subject to intense scrutiny by
Ground-based image by Gary
Bernstein and Megan Novicki (©
the University of Michigan and Lucent).
In February 1996, Drs.
Sally Heap and Eliot
Malumuth at NASA's Goddard Space Flight Center
pointed Hubble's Faint Object Spectrograph at the
core of the cluster to investigate the properties
of the very massive hot stars forming there. In
parallel, they also switched on Hubble's Wide Field
Planetary Camera 2 (WFPC2). The two instruments
worked at the same time: while the spectrograph
took data of the center of the nebula, WFPC2 took
numerous deep, multi-color images of the outskirts.
By taking observations far from the crowded center
of the nebula, fainter stars were more easily detected
since they were not overwhelmed by the much brighter
stars near the core. In this way, we can find out
more about how stars like our Sun are formed.
Dr. Philip Plait (also from GSFC) analyzed the
The top image (in the panel of 3 images) is of
the entire nebulosity complex and was taken by
Gary Bernstein and Megan Novicki of the University
of Michigan using a ground based telescope in Hawaii
(we thank them for graciously allowing the image
to be used here). The giant gas cloud spans the
roughly 1500 light year field of this image. The
bright center of the nebula can be seen in the center
left of the image. The star which eventually blew
up to become Supernova
1987A was born in this cloud, near the lower
right hand side of the image.
This image is not as deep as the Hubble image
(it had a much shorter exposure time) but it covers
a much larger area of the sky. The white outline
in the big picture represents the field of the next
image, which is a zoom in on the ``suburbs'' of
This smaller area of the nebula spans about 300
light years, and you can start to see some of the
individual fainter stars and details of the gas.
The outline of the Hubble image is shown in this
The field-of-view of the
Wide Field and Planetary Camera 2 is overlaid
on the ground-based image in the middle image
and the "Starfield in
the Large Magellanic Cloud" Hubble Heritage
image is detailed in the bottom.
For the third image, three Hubble WFPC2 images
have been combined to make a natural color picture
of the region. (Editor's note: details about color
assignments to black and white data can be found
technical information page and about specific
assignments for this image in its fast
facts table.)This picture represents the deepest
multi-color images ever taken in the LMC; over 10,000
stars can be seen in the image, including stars
as faint as 26th magnitude. The brightest stars
in the image are 10,000 times fainter than can be
seen with the unaided eye, and the faintest are
100 million times dimmer! At this distance, the
Sun itself would be about 23rd magnitude, and would
be lost in the wash of thousands of stars. In the
image are also sheets of nebular gas which are shaped
by their interaction with the light and winds from
nearby stars. Also visible are dark patches of interstellar
dust which block our view of the stars behind them.
In the Hubble image, stars as close together as
0.2 light years can be distinguished from each other.
That's 20 times closer than the Sun to its nearest
stellar neighbor, Proxima
Note the different colors of the stars. The brightest
stars are giants, much larger than the Sun, which
are hundreds or thousands of times brighter than
the Sun. They are bluish white or red- the red giants
are nearing the end of their short lives, and may
end as supernovae, or exploding stars. Fainter stars
come in all colors, most obviously blue or yellow,
and some fainter reddish stars can also be seen.
These stars are less massive and cooler than the
Sun, shining with a ruddy glow.
By studying such deep images, we hope to learn
more about what triggers star formation and why
it produces the kinds of stars it does. Understanding
stars is fundamental to understanding how our own
Sun behaves, how it affects us on Earth and possibly
even how other stars can form their own planets
and solar systems.