[meteorite-list] VLT First Images of Comet Tempel 1 After Impact

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Jul 5 13:24:22 2005
Message-ID: <200507051723.j65HNYf12831_at_zagami.jpl.nasa.gov>

ESO Education and Public Relations Dept.

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Text with all links and the photos are available on the ESO
Website at URL:

http://deepimpact.eso.org/obseso8.html
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For immediate release: July 5, 2005 08:00 CEST

VLT First Images of Comet Tempel 1 After Impact

On the night of July 4, 2005, all ESO telescopes
continued their extensive observing campaign of
Comet Tempel 1. But this time, they were able to see
the effect of the impact on the comet. The astronomers
were clearly not disappointed.

The impact occurred at 07:52 CEST [0552 UTC] but
because the comet has already set in Chile at that
time, observers at the La Silla Paranal Observatory
could only start observing several hours later. The
first observations were done in the infrared by TMMI2
at the 3.6m telescope at La Silla, at 21:20 CEST
([1920 UTC] still daylight in Chile).

These first observations showed the comet to be 2 to
3 times brighter in the infrared than the day before
the impact. The coma is also much more extended than
it was until before the impact.

At sunset in Chile, all 7 telescopes of the La Silla
Paranal Observatory went into operations. The FORS2
multi-mode instrument on Antu, one of the 8.2m Unit
Telescope of the VLT array, took stunning images,
showing that the morphology of the comet had
dramatically changed: a new bright fan-like structure
was now visible.

The fan lies in the southern part of the image and
is rather bright and well defined. This feature is
an addition to those that were already visible during
the previous days, that seems to still be underlying
the new one. Behind this fan, the old coma from
yesterday is still present. The new structure is
about 15,000 km large, indicating that the matter
has been ejected with a speed of about 700 to
1,000 km/h.

Further observations during the week will study the
evolution of this fan, revealing if the probe has
activated a new region of the surface and how long
that region remains active.

The fan is visible through the reflection of sunlight
on dust grains. The fact that the big plume is not
uniform in colour probably indicates that different
dust size are traveling at different speeds.

Other telescopes have provided observations of the
comet as well. NACO took some images of the central
part of the coma, while UVES performed high-dispersion
spectroscopy of the comet, in order to compare with
the previous nights. First estimates indicate the
emission lines to be more pronounced by 10 to 20%.

At La Silla, the SOFI instrument at the NTT telescope,
imaged the comet in the near-infared. An image in the
J-band also shows the dust shell from the impact in
the south-western quadrant of the coma. The very inner
coma (indicated by the white box) shows on-going
enhanced activity compared to the pre-impact level.

The astronomers at the La Silla Paranal Observatory
will continue to observe Comet Tempel 1 for another
four days in order to monitor precisely its long-term
behaviour.

Note

[1]: Leading scientists of the ESO DI campaign:
H. Boehnhardt (MPI, Lindau, Germany), O. Hainaut (ESO),
H.U. Kaufl (ESO), H. Rauer (DLR, Germany).

Members of the ESO DI observing team on site:
N. Ageorges (ESO, Chile), S. Bagnulo (ESO, Chile),
L. Barrera (UMCE, Chile), H. Boehnhardt (MPS, Germany),
T. Bonev (Astr. Inst. Sofia, Bulgaria), O. Hainaut
(ESO, Chile), E. Jehin (ESO, Chile), H.U. Kaufl (ESO,
Germany), F. Kerber (ESO, Germany), J. Manfroid
(U.Li?ge, Belgium), O. Marco (ESO, Chile), E. Pompei
(ESO, Chile), C. Sterken (Vrije Universiteit Brussel,
Belgium), G.P. Tozzi (Obs. Arcetri, Italy), M. Weiler
(DLR, Germany)

Members of the ESO DI observing team not on site:
C. Arpigny (U.Li?ge, Belgium), A. Cochran (McDonald,
USA), C. Delahodde (Univ. Florida, USA), Y. Fernandez
(Univ. Hawaii, USA), D. Hutsemekers (U.Li?ge, Belgium),
H. Kawakita (Gunma, Japan), J. Knollenberg (DLR,
Germany), L. Kolokolova (Univ. Maryland, USA),
M. Kretlow (MPS, Germany), M. Kueppers (MPS, Germany),
E. Kuehrt (DLR, Germany), L. Lara (IAA, Spain),
J. Licandro (IAC, Spain), C. Lisse (Univ. Maryland,
USA), K. Meech (U.Hawaii, USA), R. Schulz (ESTEC, The
Netherlands), G. Schwehm (ESTEC, The Netherlands),
M. Sterzik (ESO, Chile), J.A. St?we (Leiden, The
Netherlands), I. Surdej (Univ. Li?ge, Belgium and
ESO, Garching), D. Wooden (Ames, USA), J.-M. Zucconi
(Besancon, France)
Received on Tue 05 Jul 2005 01:23:33 PM PDT