The surroundings of the interacting galaxy NGC 5291
The interacting galaxy NGC 5291 in the constellation of Centaurus
Wide-field view of the sky around the interacting galaxy NGC 5291
The surroundings of the interacting galaxy NGC 5291 (annotated)
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Zooming in on the interacting galaxy system NGC 5291
The spectacular aftermath of a 360
million year old cosmic collision is revealed in great detail in new
images from ESO’s Very Large Telescope at the Paranal Observatory. Among
the debris is a rare and mysterious young dwarf galaxy. This galaxy is
providing astronomers with an excellent opportunity to learn more about
similar galaxies that are expected to be common in the early Universe,
but are normally too faint and distant to be observed by current
telescopes.
NGC 5291, the
hazy, golden oval dominating the centre of this image, is an elliptical
galaxy located nearly 200 million light-years away in the constellation
of Centaurus (The Centaur). Over 360 million years ago, NGC 5291 was
involved in a dramatic and violent collision as another galaxy
travelling at immense speeds barrelled into its core. The cosmic crash
ejected huge streams of gas into nearby space, which later coalesced
into a ring formation around NGC 5291 [1].
Over time, material in this ring gathered and collapsed into dozens
of star-forming regions and several dwarf galaxies, revealed as pale
blue and white regions scattered around NGC 5291 in this new image from
the FORS instrument, mounted on the VLT.
The most massive and luminous clump of material, to the right of NGC
5291, is one of these dwarf galaxies and is known as NGC 5291N.
The Milky Way, like all large galaxies, is believed to have formed
through the build-up of smaller dwarf galaxies in the early years of the
Universe. These small galaxies, if they have survived on their own up
to the present day, now normally contain many extremely old stars.
Yet NGC 5291N appears to contain no old stars. Detailed observations with the MUSE spectrograph [2]
also found that the outer parts of the galaxy had properties typically
associated with the formation of new stars, but what was observed is not
predicted by current theoretical models. Astronomers suspect that these
unusual aspects may be the result of massive collisions of gas in the
region.
NGC 5291N doesn’t look like a typical dwarf galaxy, but instead it
shares a striking number of similarities with the clumpy structures
present within many of the star-forming galaxies in the distant
Universe. This makes it a unique system in our local Universe and an
important laboratory for the study of early gas-rich galaxies, which are
normally much too distant to be observed in detail by current
telescopes.
This unusual system has previously been observed by a wide range of ground-based facilities, including ESO’s 3.6-metre telescope at the La Silla Observatory [3].
However, the capabilities of MUSE, FORS and the Very Large Telescope
have only now allowed some of the history and properties of NGC 5291N to
be determined.
Future observations, including those by ESO’s European Extremely Large Telescope (E-ELT), may allow astronomers to further unravel this dwarf galaxy’s remaining mysteries.
Notes
[1] NGC 5291 is currently also interacting more gently with
MCG-05-33-005 — or the Seashell Galaxy — the unusual comma-shaped galaxy
appearing to leech off NGC 5291’s luminous core.
[2] NGC 5291N was observed using integral field spectrography
during MUSE’s first Science Verification run. Integral field
spectrography collects a spectrum at every point on the sky, providing a
powerful three-dimensional view of the target. The MUSE observations
revealed unexpected oxygen and hydrogen emission lines in the outskirts
of NGC 5291N.
[3] NGC 5291 was studied by
astronomers using ESO’s 3.6-metre telescope at the La Silla Observatory
back in 1978. These observations revealed large amounts of material in
the intergalactic space around the galaxy, which we now know to be the
star-forming regions and several dwarf galaxies created from the
collapse of the galaxy’s gaseous ring.
More Information
This research was presented in a paper entitled “Ionization processes
in a local analogue of distant clumpy galaxies: VLT MUSE IFU
spectroscopy and FORS deep images of the TDG NGC 5291N”, by J. Fensch et
al., to appear in the journal Astronomy & Astrophysics.
The team is composed of J. Fensch (Laboratoire AIM Paris-Saclay,
CEA/IRFU/SAp, Universite Paris Diderot, Gif-sur-Yvette, France [CEA]),
P.-A. Duc (CEA) , P. M. Weilbacher (Leibniz-Institut für Astrophysik,
Potsdam, Germany), M. Boquien (University of Cambridge, United Kingdom;
Universidad de Antofagasta, Antofagasta, Chile) and E. Zackrisson
(Uppsala University, Uppsala, Sweden).
ESO is the foremost intergovernmental astronomy organisation in
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operates three unique world-class observing sites in Chile: La Silla,
Paranal and Chajnantor. At Paranal, ESO operates the Very Large
Telescope, the world’s most advanced visible-light astronomical
observatory and two survey telescopes. VISTA works in the infrared and
is the world’s largest survey telescope and the VLT Survey Telescope is
the largest telescope designed to exclusively survey the skies in
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building the 39-metre European Extremely Large Telescope, the E-ELT,
which will become “the world’s biggest eye on the sky”.
Links
Contacts
Jérémy Fensch
Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp, Universite Paris Diderot
Gif-sur-Yvette, France
Email: jeremy.fensch@gmail.com
Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp, Universite Paris Diderot
Gif-sur-Yvette, France
Email: jeremy.fensch@gmail.com
Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Source: ESO
