Astronomy and Astrophysics – Astronomy
Scientific paper
Mar 2001
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001eso..presp..12.&link_type=abstract
ESO Press Release, 03/2001
Astronomy and Astrophysics
Astronomy
Scientific paper
New Vistas with Powerful Thermal Infrared Instrument at La Silla
Summary
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 µm 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 µm . PR Photo 12c/01 : TIMMI2 photo of the BN/KL complex at wavelength 20.0 µm . 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 10a/01
ESO PR Photo 12a/01 [Preview - JPEG: 347 x 400 pix - 93k] [Normal - JPEG: 694 x 800 pix - 224k] [Hi-Res - JPEG: 2601 x 3000 pix - 1.4M]
ESO PR Photo 10b/01
ESO PR Photo 12b/01 [Preview - JPEG: 250 x 400 pix - 42k] [Normal - JPEG: 500 x 800 pix - 120k]
ESO PR Photo 10c/01
ESO PR Photo 12c/01 [Preview - JPEG: 250 x 400 pix - 78k] [Normal - JPEG: 500 x 800 pix - 200k]
ESO PR Photo 10d/01
ESO PR Photo 12d/01 [Preview - JPEG: 250 x 400 pix - 78k] [Normal - JPEG: 500 x 800 pix - 208k]
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 µm ( PR Photo 12b/01 ; with isophotes at the brightest object) and 20.0µm, ( 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 µm ( PR Photo 12b/01 ) and 20.0 µm ( 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 light!
The ratio between the TIMMI2 images ("20µm/10µm"; 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 10e/01
ESO PR Photo 12e/01 [Preview - JPEG: 400 x 347 pix - 144k] [Normal - JPEG: 800 x 694 pix - 320k] [Hi-Res - JPEG: 2048 x 1777 pix - 1.5M]
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 µm. 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 compl
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