Text with all links and the photo is available on the ESO Website at

A new astronomical instrument, TIMMI2, has just been installed on the ESO
3.6-m telescope at La Silla. The first images have just been obtained and
hold great promise for future research programmes with this facility.

The Thermal Infrared MultiMode Instrument was built in a collaboration
between ESO and a consortium headed by the Jena University Observatory
(Germany). It detects infrared radiation in the 5-24 microns mid-IR
spectral region.

It is particularly well suited for observations of the complex processes
that take place in the innermost regions of star-forming clouds. It is
also a forerunner of a similar, but even more powerful instrument to be
installed at the 8.2-m VLT telescopes on Paranal during the next years.

Among the first images are some of the most penetrating, mid-infrared
views ever obtained of the central region of the Orion Nebula.

PR Photo 12a/01: Location of the BN/KL complex in the Orion Nebula.

PR Photo 12b/01: TIMMI2 photo of the BN/KL complex at wavelength
10.3 microns.

PR Photo 12c/01: TIMMI2 photo of the BN/KL complex at wavelength
20.0 microns.

PR Photo 12d/01: Composite “thermal” photo of the BN/KL complex.

PR Photo 12e/01: The TIMMI2 instrument at the ESO 3.6-m telescope.

Mid-infrared TIMMI2 images of a starforming region in Orion

  ESO PR Photo 12a/01                  ESO PR Photo 12b/01

  ESO PR Photo 12c/01                  ESO PR Photo 12d/01

Caption: A series of mid-infrared images of the BN/KL complex, a
star-forming region deep inside the Orion Nebula, was recently obtained
with ESO’s new Thermal Infrared MultiMode Instrument (TIMMI2), now
mounted at the Cassegrain focus of the 3.6-m telescope on La Silla. The
area is located close to the Trapezium cluster and is identified on a
near-infrared image (PR Photo 12a/01) obtained with the ISAAC instrument
at the 8.2-m VLT ANTU telescope (cf. ESO PR Photos 03a-d/01). The complex
itself is so heavily obscured by the dust cloud that it is not visible
at this wavelength. However, the dust is more transparent at longer
wavelengths and the complex is clearly seen on images obtained with
TIMMI2 at wavelengths of 10.3 microns (PR Photo 12b/01; with isophotes at
the brightest object) and 20.0 microns, (PR Photo 12c/01). They show in
some detail the structures around the compact sources and the extended
thermal emission from the dust. The ratio of these two photos (PR Photo
12d/01) illustrates how the temperature of the dust in this area varies.
The brighter areas are the hotter ones. Technical information about these
photos is available below.

A group of astronomers [1] has recently imaged a star-forming region in the
Orion Nebula with a new and powerful astronomical instrument, the Thermal
Infrared MultiMode Instrument (TIMMI2), now available at the La Silla
Observatory. In addition to being scientifically very interesting, these
observations also provide a demonstration of the impressive capabilities of
this new facility.

It has been known for some time that the “BN/KL Complex” is a site of
recent, massive star formation. It is located deep inside the Orion Nebula
(PR Photo 12a/01) and is observed as a cluster of infrared-emitting objects
and compact regions of ionized Hydrogen (“H II regions”), associated with
intricate interstellar dust filaments and circumstellar dust clouds. There
are also several hot and large stars in this heavily obscured area –
together they shine as bright as 100,000 suns.

It is a difficult task to identify the main sources of heating in this
region — the “heart” of the Orion BN/KL star-forming complex. For this,
a combination of sharp images (at 1 arcsec resolution or better) at
different wavelengths is required. This is now possible with ISAAC
near-infrared and TIMMI2 mid-infrared images that together show the
energy distribution of the individual sources.

The present TIMMI2 images of the BN/KL Complex were obtained at two
different wavelengths, 10.3 microns (PR Photo 12b/01) and 20.0 microns
(PR Photo 12c/01).

These mid-infrared photos are powerful tools for the astronomers’ attempts
to analyze the very early processes of star formation. They mainly show the
thermal radiation from the dust in the area that is heated by the UV and
visible light from the stars, and especially the comparatively warm, dense
dust cocoons around the very young stars. Contrarily, the slightly older
stars in this area have already blown away most of their dust shell and
can therefore be seen at shorter wavelengths, e.g. in the ISAAC image
(PR Photo 12a/01), but not in the TIMMI2 photos.

The dust clouds through which we can now look with TIMMI2 are extremely
dense. The obscuration in the visual region of the spectrum is enormous,
about 60 magnitudes (i.e., a factor of 10**24). No wonder that even the
largest telescopes cannot get through to those “hidden” objects in visual

The ratio between the TIMMI2 images (“20microns/10microns”; PR Photo 12d/01)

provides a temperature map of the dust in this region. The “hottest”
(brightest in this photo) areas mostly correspond to the cocoons around
the very young stars. With the excellent image sharpness (about 1 arcsec)
provided by TIMMI2, it was possible to identify ten new mid-infrared sources
on this photo. From the image ratio, dust temperatures of up to about 190 C
(460K) are measured.

The TIMMI2 instrument

ESO PR Photo 12e/01

Caption: The TIMMI2 instrument at the Cassegrain focus of the ESO 3.6-m
telescope at La Silla. It is here seen just before “first light” in
January 2001.

The new Thermal Infrared MultiMode Instrument (TIMMI2) (PR Photo 12e/01) is
a second-generation instrument for the ESO 3.6-m telescope on La Silla [2].
It is the most sensitive and most versatile instrument of its kind available
in the world and puts European astronomy at the forefront of research in
this field.

TIMMI2 is a combined camera and spectrometer that is able to register
radiation (“light”) in the mid-infrared spectral range from 5-24 microns.
It is the successor to the most productive TIMMI instrument that was used
at La Silla and decommissioned in 1998, cf. e.g., the reports about the
first observations of structures in the disk around the star Beta Pictoris
pointing to the presence of planets (article in Nature 369, p.628; 1994),
the impact of Comet SL-9 on Jupiter and also about Comet Hale-Bopp.

To achieve sufficient sensitivity for thermal radiation from celestial
objects, TIMMI2 must be cooled (as a normal camera for visible light must
be black inside and light-tight). It operates at -230 C and the detector
is kept at -260 C.

Mid-infrared astronomy is a very promising field

Quite apart from its own capabilities, TIMMI2 also represents an
important step towards the VLT Mid Infrared Spectrometer/Imager VISIR,
a similar, but even more advanced mid-infrared instrument for ESO’s Very
Large Telescope at Paranal. VISIR is now being constructed under ESO
contract at research institutes in France and the Netherlands. It is
planned to install it on the 8.2-m MELIPAL in 2002. The sensitivity will
be five times higher than that of TIMMI2 and it will produce images that
are twice as sharp. Until then, the ESO astronomers and engineers as well
as many visiting astronomers will have gained invaluable experience with
TIMMI2, ensuring them a fast and efficient entry into this largely
unexplored field of astronomy.

Mid-infrared observations like these are a most valuable tool for
studying the birth of stars and the formation of circumstellar disks and
planets. As such it is complementary to submm observations, e.g. with the
future ALMA facility.

Later, an extremely large telescope with similar instrumentation – like
the 100-m OWL for which a concept study is now underway at ESO — may be
used to image earth-size planets orbiting stars in our cosmic neighbourhood.


[1]: The team consists of Rolf Chini and Markus Nielbock (Astronomisches
Institut, Ruhr-Universitaet Bochum, Germany), Ralf Siebenmorgen and
Hans-Ulrich Kaeufl (ESO-Garching, Germany).

[2]: A more exhaustive description of TIMMI2 is available in the ESO
Messenger (No. 102, page 4).

Technical information about the photos

PR Photo 12a/01 covers an area of approx. 3 x 3 arcmin2. PR Photo 12b/01
shows an N-band (10.3 microns) mosaic image of the Orion BN/KL Complex,
composed of 80 co-added exposures, lasting a total of 3 min, obtained
with the 240 x 320 Raytheon detector array of the TIMMI2 camera. The
observations were made in the night of January 27-28, 2001. Individual
exposures have a scale of 0.2 arcsec/pixel and were taken with the
standard chopping and nodding technique with a nodding amplitude of 30
arcsec. The colours are displayed on a logarithmic intensity scale in
order to enhance the faintest structures. PR Photo 12c/01 shows a similar
Q-band (20.0 microns) mosaic, obtained with the same observing procedure.
Both photos show diffraction limited structures in a 30 x 42 arcsec2 sky
field. PR Photo 12d/01 shows the observed 20.0 microns to 10.3 microns
brightness ratio and hence the distribution of the colour temperature.
The lowest observed ratio corresponds to the highest temperature (a
de-reddened colour temperature of about 460 K, or +190 C); it occurs at
the location of the BN object.