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European Space Agency

Press Release

The mysterious 'Garden-sprinkler' nebula

22 May 2003
 
There are many mysterious objects seen in the night sky which are not
really well understood. For example, astronomers are puzzled by the
'jets' emerging from planetary nebulae. However, the S-shaped jet
from Henize 3-1475 is the most perplexing of all.
 
'Jets' are long outflows of fast-moving gas found near many objects
in the Universe, such as around young stars, or coming from black
holes, neutron stars, and planetary nebulae, for example. The
NASA/ESA Hubble Space Telescope has imaged the young planetary nebula
Henize 3-1475 and its bizarre jet. Astronomers have nicknamed it the
'Garden-sprinkler' Nebula.

The origin of jets in the Universe is unclear, but they appear to
originate in small regions of space where even Hubble's sharp vision
cannot penetrate. To produce a jet, you require some sort of nozzle
mechanism. So far, these theoretical 'nozzles' remain hidden by dust
that obscures our view of the centres of planetary nebulae.

Despite decades of intense effort, there is no single example of a
jet whose origin is clearly understood. The curious S-shape and
extreme high speed of its gaseous outflow gives Henize 3-1475 a
special place in the study of planetary nebulae.

Henize 3-1475 is located in the constellation of Sagittarius around
18 000 light-years away from us. The central star is more than 12 000
times as luminous as our Sun and weighs three to five times as much.
With a velocity of around 4 million kilometres per hour, the jets are
the fastest ever discovered. Scientists are also intrigued by the
converging, funnel-shaped structures that connect the innermost
'knots' and the core region.

A group of international astronomers led by Angels Riera from
Universitat Politècnica de Catalunya, Barcelona, Spain, have combined
observations from Hubble's Wide Field and Planetary Camera 2, the
Space Telescope Imaging Spectrograph and ground-based telescopes.
Their work suggests that the nebula's S-shape and hypervelocity
outflow is created by a central source that ejects streams of gas in
opposite directions and precesses once every 1500 years. It is like
an enormous, slowly rotating garden sprinkler.

The flow is not smooth, but rather episodic with an interval of about
100 years, creating clumps of gas moving away at velocities up to 4
million kilometres per hour. The reason for these intermittent
ejections of gas is not known. It may be due to either cyclic
magnetic processes in the central star (similar to the Sun's 22-year
magnetic cycle), or to interactions with a companion star.
 
Notes for editors
 
For broadcasters, animations of Henize 3-1475 are available from
http://www.spacetelescope.org/video/heic0308_vnr.html

More info about Henize 3-1475 

The colour image is composed of five different exposures with
Hubble's Wide Field and Planetary Camera 2 through the following
filters: a wide blue filter (500 seconds), oxygen (800 seconds) shown
in green, hydrogen-alpha (830 seconds) shown in yellow-orange, a
singly ionised sulphur filter (1200 seconds) shown in orange-red and
a wide red filter shown in red.

The composite image was constructed with data from the ESO/ST-ECF
Science Archive. The original Hubble exposures were obtained by J.
Borkowski, (North Carolina State University, United States), J.
Harrington, (University of Maryland, United States), J. Blondin
(North Carolina State University, United States), M. Bobrowsky
(Challenger Center for Space Science, United States), M. Meixner
(Space Telescope Science Institute, United States), and C. Skinner
(Space Telescope Science Institute, United States).

The Hubble Space Telescope is a project of international cooperation
between ESA and NASA.

 
For more information, please contact:
 
Angels Riera
Universitat Politecnica de Catalunya
Barcelona, Spain
Tel. +34 93 896 77 39 (Monday, Wednesday, Thursday)
Tel. +34 93 402 11 27 (Tuesday and Friday)
E-mail: angels.riera{at}upc.es 

Pedro Garcia-Lario
European Space Agency ISO Data Centre
Villafranca, Spain
Phone: +34 91 813 1389
E-mail: pedro.garcia.lario{at}esa.int 

Lars Lindberg Christensen
Hubble European Space Agency Information Centre
Garching, Germany
Tel: +49 89 3200 6306 (089 within Germany)
Cellular (24 hr): +49 173 3872 621 (0173 within Germany)
E-mail: lars{at}eso.org

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