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For immediate release: 19 December 2003

ESO Press Photos 33a-c/03

Three Dusty Beauties

New Portraits of Spiral Galaxies NGC 613, NGC 1792 and NGC 3627

Not so long ago, the real nature of the "spiral nebulae",
spiral-shaped objects observed in the sky through telescopes, was
still unknown. This long-standing issue was finally settled in
1924 when the famous American astronomer Edwin Hubble provided
conclusive evidence that they are located outside our own galaxy
and are in fact "island universes" of their own.

Nowadays, we know that the Milky Way is just one of billions of
galaxies in the Universe. They come in vastly different shapes --
spiral, elliptical, irregular -- and many of them are simply
beautiful, especially the spiral ones.

Astronomers Mark Neeser from the Universitäts-Sternwarte München
(Germany) and Peter Barthel from the Kapteyn Institute in
Groningen (The Netherlands) were clearly not insensitive to this
when they obtained images of three beautiful spiral galaxies
with ESO's Very Large Telescope (VLT). They did this in twilight
during the early morning when they had to stop their normal
observing programme, searching for very distant and faint
quasars.

The resulting colour images (ESO PR Photos 33a-c/03) were
produced by combining several CCD images in three different
wavebands from the FORS multi-mode instruments.

The three galaxies are known as NGC 613, NGC 1792 and NGC 3627.
They are characterized by strong far-infrared, as well as radio
emission, indicative of substantial ongoing star-formation
activity. Indeed, these images all display prominent dust as
well as features related to young stars, clear signs of
intensive star-formation.

NGC 613

PR Photo 33a/03 of the barred spiral galaxy NGC 613 was
obtained with the FORS1 and FORS2 multi-mode instruments (at
VLT MELIPAL and YEPUN, respectively) on December 16-18, 2001.
It is a composite of three exposures in different wavebands,
cf. the technical note below. The full-resolution version of
this photo retains the original pixels. Note the many arms
and the pronounced dust bands. North is up and East is left.

NGC 613 is a beautiful barred spiral galaxy in the southern
constellation Sculptor. This galaxy is inclined by 32 degrees
and, contrary to most barred spirals, has many arms that give
it a tentacular appearance.

Prominent dust lanes are visible along the large-scale bar.
Extensive star-formation occurs in this area, at the ends of
the bar, and also in the nuclear regions of the galaxy. The
gas at the centre, as well as the radio properties are
indicative of the presence of a massive black hole in the
centre of NGC 613.

NGC 1792

PR Photo 33b/03 shows the starburst spiral galaxy NGC 1792.
Note the numerous background galaxies in this sky field. North
is up and East is to the left.

NGC 1792 is located in the southern constellation Columba (The
Dove) -- almost on the border with the constellation Caelum
(The Graving Tool) -- and is a so-called starburst spiral galaxy.
Its optical appearance is quite chaotic, due to the patchy
distribution of dust throughout the disc of this galaxy. It is
very rich in neutral hydrogen gas -- fuel for the formation of
new stars -- and is indeed rapidly forming such stars. The galaxy
is characterized by unusually luminous far-infrared radiation;
this is due to dust heated by young stars.

M 66 (NGC 3627)

PR Photo 33c/03 of the spiral galaxy M 66 (or NGC 3627). North
towards upper left, West towards upper right.

The third galaxy is NGC 3627, also known as Messier 66, i.e. it
is the 66th object in the famous catalogue of nebulae by French
astronomer Charles Messier (1730 - 1817). It is located in the
constellation Leo (The Lion).

NGC 3627 is a beautiful spiral with a well-developed central
bulge. It also displays large-scale dust lanes. Many regions
of warm hydrogen gas are seen throughout the disc of this galaxy.
The latter regions are being ionised by radiation from clusters
of newborn stars. Very active star-formation is most likely
also occurring in the nuclear regions of NGC 3627.

The galaxy forms, together with its neighbours M 65 and
NGC 3628, the so-called "Leo Triplet"; they are located at a
distance of about 35 million light-years. M 66 is the largest
of the three. Its spiral arms appear distorted and displaced
above the main plane of the galaxy. The asymmetric appearance
is most likely due to gravitational interaction with its
neighbours.

Technical Information: The images were taken by Mark Neeser
(Universitäts-Sternwarte München, Germany) and Peter Barthel
(Kapteyn Astronomical Institute, Netherlands) during twilight
on the nights of 16-18 December 2001 with the FORS multi-mode
instruments attached to the VLT-MELIPAL (FORS1) or VLT-YEPUN
(FORS2). Each galaxy was observed in three different wavebands
for up to 300 seconds per waveband, and the image obtained in
each waveband was associated to a colour: B (blue), V (green)
and R (red). Neeser and Barthel also performed the first stage
of the image processing; further processing and colour-encoding
was made by Hans-Herman Heyer and Henri Boffin (ESO).

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