thed
04-14-02, 08:07 AM
Royal Astronomical Society Press Notice
Date: 4 April 2002
EMBARGOED FOR RELEASE 7 am BST WEDNESDAY 10 APRIL 2002
Ref. PN 02/22 (NAM 16)
Issued by: RAS Press Officers
Peter Bond (Except 8 - 12 April)
Tel: +44 (0)1483-268672
Fax: +44 (0)1483-274047
Mobile phone: +44 (0)7711-213486
E-mail: PeterRBond@cs.com
AND
Dr Jacqueline Mitton (Except 7 - 13 April)
Tel: +44 (0)1223-564914
Fax: +44 (0)1223-572892
Mobile phone: +44 (0)7770-386133
E-mail: jmitton@dial.pipex.com
National Astronomy Meeting Press Room phones (9 -12 April only):
+44 (0)117 928-4337 +44 (0)117 928-4338
+44 (0)117 954-5913 +44 (0)117 928-7901
RAS Web site: http://www.ras.org.uk
UK National Astronomy Meeting Web site:
http://www.star.bris.ac.uk/nam/index.html
CONTACT DETAILS ARE LISTED AT THE END OF THIS RELEASE
************************************************** ***********
UK ASTRONOMERS SURVEY GALACTIC GRAVEYARD
An unprecedented source of planetary nebulae, the disk-like relics of
elderly, dying stars, has been discovered in the southern part of our
Milky Way galaxy.
With about 1000 planetary nebulae found so far and many more still to
be discovered, the number of aged stars in their death throes revealed
by the new survey is rapidly overtaking the entire population
discovered over the entire sky during the last 75 years.
The cosmic graveyard is revealed in deep survey images taken in
"H-alpha" light with the UK Schmidt Telescope at the Anglo-Australian
Observatory (AAO/UKST) in New South Wales, Australia. The survey was
led by Quentin Parker (Institute for Astronomy, Royal Observatory
Edinburgh) and Steven Phillipps (University of Bristol)
Dr. Parker will be showing the colourful new images obtained during his
survey to the UK National Astronomy Meeting in Bristol on Wednesday 10
April 2002, and explaining their significance for improving our
understanding of star formation and evolution.
"So far we have identified 1000 new planetary nebulae from visual scans
of 70 percent of the southern Galactic plane," said Parker. "This number
is now increasing rapidly as the plates are systematically scrutinised
by the SuperCOSMOS facility at the Royal Observatory, Edinburgh, so
that more compact, fainter candidates are being found."
According to Parker, the doubling of the known population of planetary
nebulae will have a significant impact on many aspects of research
into stellar evolution and Galactic structure.
"Finding evolved planetary nebulae and their central stars can help
us understand stellar evolution during the critical transition phase
between the nebula and a white dwarf," he said. "There is a currently
a severe paucity of observational data of evolved planetary nebulae
which our new catalogue should help address."
The highlights from the new sample include identification of some rare
and unusual objects:
* 8 Wolf-Rayet stars (exceptionally hot stars rich in carbon or
nitrogen) have been discovered at the centres of new planetary
nebulae from follow-up spectroscopy. They include what may be the
first nitrogen-rich central star yet found in our Galaxy. Only 56
Wolf-Rayet stars are currently known.
* The discovery of several halo planetary nebulae travelling at more
than 300 km/s towards the Galactic centre.
* The discovery of a planetary nebula in an old open star cluster.
This is an extremely rare and valuable find as the known cluster
(and hence planetary nebula) distance enables accurate estimates of
planetary nebula parameters.
* The identification of large numbers of evolved planetary nebulae,
many with angular sizes from 100 arcseconds to 8 arcminutes.
* The discovery of several close pairs of planetary nebulae, with
separations of less than 2 arcminutes.
* The discovery of additional shells, ansae ("handle-shaped" clouds)
and lobes around many known planetary nebulae. This may help to
solve the problem of missing mass in planetary nebulae, since they
provide evidence of previous episodes of material being ejected
into space. Their new angular dimensions should lead to
re-evaluation of many distance estimates.
* The discovery of two faint equidistant lobes either side of the
well known butterfly-like planetary nebula NGC 2899, probably
making this object one of the largest and closest planetary nebulae
to the Sun.
* The discovery of several hundred planetary nebulae in the Galactic
Bulge region -- the densely populated region of stars close to the
centre of the Galaxy.
NOTES FOR EDITORS:
Studies of planetary nebulae are essential for improving understanding
of the later evolution of low mass stars like our own Sun and of
stellar evolution in the critical phase prior to the creation of small,
dead stars known as white dwarfs. They provide vital probes for
studying processes of nucleosynthesis inside stars, abundances of
chemical compounds and chemical enrichment of interstellar space,
acting as powerful indicators of our Galaxy1s star formation history.
Planetary nebulae are also excellent tracers for Galactic Bulge
dynamical studies because they are less affected by metallicity bias
than other tracers and have strong emission lines permitting accurate
velocity determinations.
The AAO/UKST H-alpha Survey was carried out using a filter that reveals
hot, hydrogen-rich clouds in the Galactic plane. It uses the world's
largest optical interference filter for astronomy and covers a swathe
approximately 20 degrees wide along the Galactic plane. This provides
an unprecedented combination of coverage, resolution and sensitivity
that make it superior to any previous survey of this type.
CONTACT DETAILS:
During the UK National Astronomy Meeting (9 - 12 April) Dr. Parker can
be contacted via the NAM press office (see above).
Normal contact details:
Dr. Quentin A Parker
Institute for Astronomy
Royal Observatory
Edinburgh
EH9 3HJ
Tel: +44 (0)131-668-8378 (switchboard): +44 (0)131-668-8100
Mobile: +44 (0)7714-143273
Fax: +44 (0)131-662-1668
E-mail: qap@roe.ac.uk
URL: http://www.roe.ac.uk/ifa/people/
From 16 April 2002 Dr. Parker can be contacted at:
Dept. of Physics
University of Macquarie
Sydney
NSW 2109
Australia
E-mail: qap@physics.mq.edu.au
FURTHER INFORMATION AND AN H-ALPHA IMAGE OF THE VELA SUPERNOVA REMNANT
CAN BE FOUND ON THE WEB AT:
http://www-wfau.roe.ac.uk/sss/halpha/hapr.html
DETAILS OF THE H-ALPHA SURVEY CAN BE FOUND ONLINE AT:
http://www.roe.ac.uk/wfau/halpha/halpha.html
OTHER IMAGES OF PLANETARY NEBULAE AND BACKGROUND INFORMATION CAN BE FOUND
AT:
http://www.astro.washington.edu/balick/WFPC2/index.html
Date: 4 April 2002
EMBARGOED FOR RELEASE 7 am BST WEDNESDAY 10 APRIL 2002
Ref. PN 02/22 (NAM 16)
Issued by: RAS Press Officers
Peter Bond (Except 8 - 12 April)
Tel: +44 (0)1483-268672
Fax: +44 (0)1483-274047
Mobile phone: +44 (0)7711-213486
E-mail: PeterRBond@cs.com
AND
Dr Jacqueline Mitton (Except 7 - 13 April)
Tel: +44 (0)1223-564914
Fax: +44 (0)1223-572892
Mobile phone: +44 (0)7770-386133
E-mail: jmitton@dial.pipex.com
National Astronomy Meeting Press Room phones (9 -12 April only):
+44 (0)117 928-4337 +44 (0)117 928-4338
+44 (0)117 954-5913 +44 (0)117 928-7901
RAS Web site: http://www.ras.org.uk
UK National Astronomy Meeting Web site:
http://www.star.bris.ac.uk/nam/index.html
CONTACT DETAILS ARE LISTED AT THE END OF THIS RELEASE
************************************************** ***********
UK ASTRONOMERS SURVEY GALACTIC GRAVEYARD
An unprecedented source of planetary nebulae, the disk-like relics of
elderly, dying stars, has been discovered in the southern part of our
Milky Way galaxy.
With about 1000 planetary nebulae found so far and many more still to
be discovered, the number of aged stars in their death throes revealed
by the new survey is rapidly overtaking the entire population
discovered over the entire sky during the last 75 years.
The cosmic graveyard is revealed in deep survey images taken in
"H-alpha" light with the UK Schmidt Telescope at the Anglo-Australian
Observatory (AAO/UKST) in New South Wales, Australia. The survey was
led by Quentin Parker (Institute for Astronomy, Royal Observatory
Edinburgh) and Steven Phillipps (University of Bristol)
Dr. Parker will be showing the colourful new images obtained during his
survey to the UK National Astronomy Meeting in Bristol on Wednesday 10
April 2002, and explaining their significance for improving our
understanding of star formation and evolution.
"So far we have identified 1000 new planetary nebulae from visual scans
of 70 percent of the southern Galactic plane," said Parker. "This number
is now increasing rapidly as the plates are systematically scrutinised
by the SuperCOSMOS facility at the Royal Observatory, Edinburgh, so
that more compact, fainter candidates are being found."
According to Parker, the doubling of the known population of planetary
nebulae will have a significant impact on many aspects of research
into stellar evolution and Galactic structure.
"Finding evolved planetary nebulae and their central stars can help
us understand stellar evolution during the critical transition phase
between the nebula and a white dwarf," he said. "There is a currently
a severe paucity of observational data of evolved planetary nebulae
which our new catalogue should help address."
The highlights from the new sample include identification of some rare
and unusual objects:
* 8 Wolf-Rayet stars (exceptionally hot stars rich in carbon or
nitrogen) have been discovered at the centres of new planetary
nebulae from follow-up spectroscopy. They include what may be the
first nitrogen-rich central star yet found in our Galaxy. Only 56
Wolf-Rayet stars are currently known.
* The discovery of several halo planetary nebulae travelling at more
than 300 km/s towards the Galactic centre.
* The discovery of a planetary nebula in an old open star cluster.
This is an extremely rare and valuable find as the known cluster
(and hence planetary nebula) distance enables accurate estimates of
planetary nebula parameters.
* The identification of large numbers of evolved planetary nebulae,
many with angular sizes from 100 arcseconds to 8 arcminutes.
* The discovery of several close pairs of planetary nebulae, with
separations of less than 2 arcminutes.
* The discovery of additional shells, ansae ("handle-shaped" clouds)
and lobes around many known planetary nebulae. This may help to
solve the problem of missing mass in planetary nebulae, since they
provide evidence of previous episodes of material being ejected
into space. Their new angular dimensions should lead to
re-evaluation of many distance estimates.
* The discovery of two faint equidistant lobes either side of the
well known butterfly-like planetary nebula NGC 2899, probably
making this object one of the largest and closest planetary nebulae
to the Sun.
* The discovery of several hundred planetary nebulae in the Galactic
Bulge region -- the densely populated region of stars close to the
centre of the Galaxy.
NOTES FOR EDITORS:
Studies of planetary nebulae are essential for improving understanding
of the later evolution of low mass stars like our own Sun and of
stellar evolution in the critical phase prior to the creation of small,
dead stars known as white dwarfs. They provide vital probes for
studying processes of nucleosynthesis inside stars, abundances of
chemical compounds and chemical enrichment of interstellar space,
acting as powerful indicators of our Galaxy1s star formation history.
Planetary nebulae are also excellent tracers for Galactic Bulge
dynamical studies because they are less affected by metallicity bias
than other tracers and have strong emission lines permitting accurate
velocity determinations.
The AAO/UKST H-alpha Survey was carried out using a filter that reveals
hot, hydrogen-rich clouds in the Galactic plane. It uses the world's
largest optical interference filter for astronomy and covers a swathe
approximately 20 degrees wide along the Galactic plane. This provides
an unprecedented combination of coverage, resolution and sensitivity
that make it superior to any previous survey of this type.
CONTACT DETAILS:
During the UK National Astronomy Meeting (9 - 12 April) Dr. Parker can
be contacted via the NAM press office (see above).
Normal contact details:
Dr. Quentin A Parker
Institute for Astronomy
Royal Observatory
Edinburgh
EH9 3HJ
Tel: +44 (0)131-668-8378 (switchboard): +44 (0)131-668-8100
Mobile: +44 (0)7714-143273
Fax: +44 (0)131-662-1668
E-mail: qap@roe.ac.uk
URL: http://www.roe.ac.uk/ifa/people/
From 16 April 2002 Dr. Parker can be contacted at:
Dept. of Physics
University of Macquarie
Sydney
NSW 2109
Australia
E-mail: qap@physics.mq.edu.au
FURTHER INFORMATION AND AN H-ALPHA IMAGE OF THE VELA SUPERNOVA REMNANT
CAN BE FOUND ON THE WEB AT:
http://www-wfau.roe.ac.uk/sss/halpha/hapr.html
DETAILS OF THE H-ALPHA SURVEY CAN BE FOUND ONLINE AT:
http://www.roe.ac.uk/wfau/halpha/halpha.html
OTHER IMAGES OF PLANETARY NEBULAE AND BACKGROUND INFORMATION CAN BE FOUND
AT:
http://www.astro.washington.edu/balick/WFPC2/index.html