Andrew Yee
September 1st 05, 02:57 AM
ESO Education and Public Relations Dept.
--------------------------------------------------------------
Text with all links and the photos are available on the ESO
Website at URL:
http://www.eso.org/outreach/press-rel/pr-2005/phot-26-05.html
--------------------------------------------------------------
For immediate release: 24 August 2005
ESO Press Photo 26/05
Celestial Blast in Bleak Reticulum
ESO PR Photo 26/05
Supernova 2005dh and Spiral Galaxy NGC 1559
Caption: ESO PR Photo 26/05 is a colour-composite image of
the spiral galaxy NGC 1559 in the Reticulum constellation,
obtained with the multi-mode FORS1 instrument on ESO's 8.2m
VLT. The supernova, SN 2005df, is visible as the bright
star just above the galaxy. Many background galaxies can
also be seen in this image.
The southern Reticulum constellation [1] certainly isn't a
big hit for amateur astronomers. This tiny, bleak and
diamond-shaped constellation, not far on the sky from the
Large Magellanic Cloud, is often overlooked. But recently,
astronomers had a closer look at a galaxy situated inside it.
And more precisely at an exploding star hosted by the spiral
galaxy NGC 1559 [2].
On the night of August 4, 2005, Australian amateur astronomer
Reverend Robert Evans discovered a supernova just north of
the galaxy with his 0.31-m telescope. The supernova -- the
explosion of a star -- was of magnitude 13.8, that is, only
20 times fainter than the entire host galaxy. Being the 104th
supernova discovered in 2005, it received the name SN 2005df.
Noticeably, Evans had already discovered 2 other supernovae
in the same galaxy: in 1984 (SN 1984J) and in 1986 (SN 1986L).
The following night, astronomer Marilena Salvo and her
Australian colleagues classified the supernova as a somewhat
unusual type Ia supernova, caught probably 10 days before it
reached its maximum brightness. Such a supernova is thought
to be the result of the explosion of a small and dense
star -- a white dwarf [3] -- inside a binary system. As its
companion was continuously spilling matter onto the white
dwarf, the white dwarf reached a critical mass, leading to
a fatal instability and the supernova.
These are exactly a kind of supernovae in which Dietrich
Baade, Ferdinando Patat (ESO), Lifan Wang (Lawrence Berkeley
National Laboratory, USA), and their colleagues are
interested. In particular, they study the polarization
properties of this kind of supernova in order to learn more
about their asphericity, which holds important clues to the
detailed physics that governs this terminal catastrophe in
the life of such stars.
Having an accepted observing programme that uses the FORS1
multi-mode instrument on Kueyen, one of the four Unit
Telescopes of ESO's 8.2m Very Large Telescope at Cerro
Paranal, they triggered a Target of Opportunity request so
that on-duty astronomers at the VLT could observe this
supernova, which was done on August 6.
From a very first analysis of their data, Wang and his
colleagues found that SN 2005df resembles closely another
supernova they had studied before, SN 2001el, whose explosion
they showed was significantly asymmetric (see ESO PR 23/03).
NGC 1559 is a SBc(s)-type spiral galaxy [4] located about 50
million light-years away, that weighs the equivalent of about
10,000 million of suns, and is about 7 times smaller than our
Milky Way: on the sky, it measures about 4x2 arcmin2. Receding
from us at a speed of about 1,300 km/s, it is a galaxy of the
Seyfert type. Such galaxies are characterized by a bright
nucleus that radiates strongly in the blue and in the
ultraviolet. Astronomers think that about 2 solar masses of
gas per year are transformed into stars in this galaxy. Like
most galaxies, NGC 1559 probably contains a black hole in its
centre, which should have a mass that is equivalent to 300,000
suns.
Technical Information: ESO PR Photo 26/05 is a composite based
on four images taken with FORS1 on Kueyen (VLT) by Paul
Vreeswijk, Dominique Naef and Chris Lidman (ESO) for Dietrich
Baade, Ferdinando Patat, and Lifan Wang. The images were taken
through different filters: V, R, I, and a narrow-band filter
centred on the H-alpha line. The exposure time is 60 seconds
in the three broad-band filters (V, R and I) and 3 min in the
H-alpha filter. The field of view is 5.5 x 4.7 arcmin2. North
is up and East is to the left.
Notes
[1]: The Reticulum (the Reticule) was named by French
astronomer Nicolas Louis de La Caille (1713-1762), when
observing from the Cape between 1750 and 1754. He defined
14 new southern constellations, giving them the names of
scientific instruments -- e.g. the Telescope -- or names
taken from the fine arts -- e.g. the Sculptor. The reticule
was an instrument used to measure the position of stars.
[2]: "NGC" means "New General Catalogue" (of nebulae and
clusters) that was published in 1888 by J.L.E. Dreyer in
the "Memoirs of the Royal Astronomical Society".
[3]: White dwarfs are Earth-size, hot and extremely dense
stars that represent the end products of the evolution of
stars like the Sun.
[4]: SBc galaxies are characterized by the presence of stars
and HII regions in the bar and spiral arms, by the near
absence of a nuclear bulge, and the openness of the spiral
pattern. The "(s)" indicates that the spirals are attached
to the ends of the bar.
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Terhi Loukiainen, +358 9 7748 8385
Denmark: Dr. Michael Linden-Vørnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Prof. Massimo Capaccioli, +39-081-55 75 511
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
--------------------------------------------------------------
ESO Press Information is available on the WWW at
http://www.eso.org/outreach/press-rel/
--------------------------------------------------------------
(c) ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
--------------------------------------------------------------
--------------------------------------------------------------
Text with all links and the photos are available on the ESO
Website at URL:
http://www.eso.org/outreach/press-rel/pr-2005/phot-26-05.html
--------------------------------------------------------------
For immediate release: 24 August 2005
ESO Press Photo 26/05
Celestial Blast in Bleak Reticulum
ESO PR Photo 26/05
Supernova 2005dh and Spiral Galaxy NGC 1559
Caption: ESO PR Photo 26/05 is a colour-composite image of
the spiral galaxy NGC 1559 in the Reticulum constellation,
obtained with the multi-mode FORS1 instrument on ESO's 8.2m
VLT. The supernova, SN 2005df, is visible as the bright
star just above the galaxy. Many background galaxies can
also be seen in this image.
The southern Reticulum constellation [1] certainly isn't a
big hit for amateur astronomers. This tiny, bleak and
diamond-shaped constellation, not far on the sky from the
Large Magellanic Cloud, is often overlooked. But recently,
astronomers had a closer look at a galaxy situated inside it.
And more precisely at an exploding star hosted by the spiral
galaxy NGC 1559 [2].
On the night of August 4, 2005, Australian amateur astronomer
Reverend Robert Evans discovered a supernova just north of
the galaxy with his 0.31-m telescope. The supernova -- the
explosion of a star -- was of magnitude 13.8, that is, only
20 times fainter than the entire host galaxy. Being the 104th
supernova discovered in 2005, it received the name SN 2005df.
Noticeably, Evans had already discovered 2 other supernovae
in the same galaxy: in 1984 (SN 1984J) and in 1986 (SN 1986L).
The following night, astronomer Marilena Salvo and her
Australian colleagues classified the supernova as a somewhat
unusual type Ia supernova, caught probably 10 days before it
reached its maximum brightness. Such a supernova is thought
to be the result of the explosion of a small and dense
star -- a white dwarf [3] -- inside a binary system. As its
companion was continuously spilling matter onto the white
dwarf, the white dwarf reached a critical mass, leading to
a fatal instability and the supernova.
These are exactly a kind of supernovae in which Dietrich
Baade, Ferdinando Patat (ESO), Lifan Wang (Lawrence Berkeley
National Laboratory, USA), and their colleagues are
interested. In particular, they study the polarization
properties of this kind of supernova in order to learn more
about their asphericity, which holds important clues to the
detailed physics that governs this terminal catastrophe in
the life of such stars.
Having an accepted observing programme that uses the FORS1
multi-mode instrument on Kueyen, one of the four Unit
Telescopes of ESO's 8.2m Very Large Telescope at Cerro
Paranal, they triggered a Target of Opportunity request so
that on-duty astronomers at the VLT could observe this
supernova, which was done on August 6.
From a very first analysis of their data, Wang and his
colleagues found that SN 2005df resembles closely another
supernova they had studied before, SN 2001el, whose explosion
they showed was significantly asymmetric (see ESO PR 23/03).
NGC 1559 is a SBc(s)-type spiral galaxy [4] located about 50
million light-years away, that weighs the equivalent of about
10,000 million of suns, and is about 7 times smaller than our
Milky Way: on the sky, it measures about 4x2 arcmin2. Receding
from us at a speed of about 1,300 km/s, it is a galaxy of the
Seyfert type. Such galaxies are characterized by a bright
nucleus that radiates strongly in the blue and in the
ultraviolet. Astronomers think that about 2 solar masses of
gas per year are transformed into stars in this galaxy. Like
most galaxies, NGC 1559 probably contains a black hole in its
centre, which should have a mass that is equivalent to 300,000
suns.
Technical Information: ESO PR Photo 26/05 is a composite based
on four images taken with FORS1 on Kueyen (VLT) by Paul
Vreeswijk, Dominique Naef and Chris Lidman (ESO) for Dietrich
Baade, Ferdinando Patat, and Lifan Wang. The images were taken
through different filters: V, R, I, and a narrow-band filter
centred on the H-alpha line. The exposure time is 60 seconds
in the three broad-band filters (V, R and I) and 3 min in the
H-alpha filter. The field of view is 5.5 x 4.7 arcmin2. North
is up and East is to the left.
Notes
[1]: The Reticulum (the Reticule) was named by French
astronomer Nicolas Louis de La Caille (1713-1762), when
observing from the Cape between 1750 and 1754. He defined
14 new southern constellations, giving them the names of
scientific instruments -- e.g. the Telescope -- or names
taken from the fine arts -- e.g. the Sculptor. The reticule
was an instrument used to measure the position of stars.
[2]: "NGC" means "New General Catalogue" (of nebulae and
clusters) that was published in 1888 by J.L.E. Dreyer in
the "Memoirs of the Royal Astronomical Society".
[3]: White dwarfs are Earth-size, hot and extremely dense
stars that represent the end products of the evolution of
stars like the Sun.
[4]: SBc galaxies are characterized by the presence of stars
and HII regions in the bar and spiral arms, by the near
absence of a nuclear bulge, and the openness of the spiral
pattern. The "(s)" indicates that the spirals are attached
to the ends of the bar.
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Terhi Loukiainen, +358 9 7748 8385
Denmark: Dr. Michael Linden-Vørnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Prof. Massimo Capaccioli, +39-081-55 75 511
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
--------------------------------------------------------------
ESO Press Information is available on the WWW at
http://www.eso.org/outreach/press-rel/
--------------------------------------------------------------
(c) ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
--------------------------------------------------------------