Making the invisible visible
New workhorse for the world's largest optical telescope
(Tucson, Ariz.) - The Large Binocular Telescope (LBT) partners in Germany, the U.S.A. and Italy are pleased to announce that the first of two new innovative near-infrared cameras/spectrographs for the LBT is now available to astronomers for scientific observations at the telescope on Mt. Graham in south-eastern Arizona. After more than a decade of design, manufacturing and testing, the new instrument, dubbed LUCIFER 1, provides a powerful tool to gain spectacular insights into the universe, from the Milky Way up to extremely distant galaxies. LUCIFER 1 has been built by a consortium of German institutes and will be followed by an identical twin instrument that will be delivered to the telescope in early 2011.
LUCIFER's innovative design allows astronomers to observe in unprecedented detail, for example, star forming regions which are commonly hidden by dust clouds. The instrument provides unrivaled flexibility, with features such as a unique robotic arm that can replace multi object spectroscopic (MOS) masks within the instrument's extreme sub-zero environment.
Pushing the limits
LUCIFER and its twin are mounted at the focus points of the LBT's two giant 8.4-meter (27.6 foot) diameter telescope mirrors. Each instrument is cooled to a chilly -213 degrees Celsius in order to observe in the near-infrared (NIR) wavelength range. Near-infrared observations are essential for understanding the formation of stars and planets in our galaxy as well as revealing the secrets of the most distant and very young galaxies.
LUCIFER is a remarkable new multi-purpose instrument with great flexibility combining a large field of view with a high resolution. It provides three exchangeable cameras for imaging and spectroscopy in different resolutions according to observational requirements. Besides its outstanding imaging capability which presently makes use of 18 high-quality filters, LUCIFER allows the simultaneous spectroscopy of about two dozen objects in the infrared through laser-cut slit-masks. For highest flexibility the masks can be changed even at the cryogenic temperatures, through the innovative development of a unique robotic mask grabber which places the individual masks with absolute precision into the focal plane.
"Together with the large light gathering power of the LBT, astronomers are now able to collect the spectral fingerprints of the faintest and most distant objects in the universe." says Richard Green, the Director of the LBT. "After completion of the LBT adaptive secondary mirror system to correct for atmospheric perturbation, LUCIFER will show its full capability by delivering images with a quality that are otherwise only obtained from space-based observatories."
Where stars are born
"Already the very first LUCIFER observations of star forming regions are giving us a hunch for the enormous potential of the new instrument," said Thomas Henning, the chair of the German LBT-Partners.
Image one (by Arjan Bik) is a snapshot of a stellar nursery in our home galaxy, the Milky Way: a high-mass star forming region inside the giant molecular cloud S255, about 8,000 light-years away from Earth (1 light-year is roughly 10 trillion kilometers). Such clouds are typically opaque to visible light. However, infrared light can penetrate the dust, so that the LUCIFER image reveals the cluster of newly born stars and its complex environment in all their splendour.
Image two (by Anna Pasquali) shows the faint irregular dwarf galaxy NGC 1569, located 6.2 million light-years from Earth. This galaxy contains several large stellar clusters with episodic star formation at a rate of more than 100 times faster than we observe in our own galaxy. In visible light, the core of the galaxy shows only three large stellar clusters, each containing more than one million stars. With LUCIFER it became possible to peer through the cosmic dust and to reveal many more compact star forming regions.
An outstanding success for German institutes
Image three (by Jaron Kurk) is a cut-out of a multi-object spectrum obtained with LUCIFER showing the tell-tale signs of gas heated by young stars at unimaginable distances of billions of light-years. Such a spectrum is the decomposition of light into its different wavelengths (colors). At certain wavelengths, emission lines can be found depending on the chemical composition and physical conditions of an object. They are fingerprints for the investigation of what goes on in stars and galaxies. For distant galaxies, the most interesting lines are found in the near-infrared, where observations were less efficient until now. With LUCIFER and the LBT, large samples of galaxies can now be studied using its multi-object capability.
The instruments have been built by a consortium of five German institutes led by the Center for Astronomy of Heidelberg University (Landessternwarte Heidelberg, LSW) together with the Max Planck Institute for Astronomy in Heidelberg (MPIA), the Max Planck Institute for Extraterrestrial Physics in Garching (MPE), the Astronomical Institute of the Ruhr-University in Bochum (AIRUB) as well as the University of Applied Sciences in Mannheim (Hochschule Mannheim).
Walter Seifert (LSW), Nancy Ageorges (MPE) and Marcus Jütte (AIRUB), responsible for the successful commissioning, spent more than half a year in several runs at the LBT site to make the telescope/instrument combination work efficiently. Holger Mandel, the PI of LUCIFER said: "From the very beginning, there was a uniform excitement about the promise of this instrument for world-beating science. Now, the amazing results speak for themselves."
The Large Binocular Telescope (LBT) is a collaboration among the Italian astronomical community (National Institute of Astrophysics - INAF), The University of Arizona, Arizona State University, Northern Arizona University, the LBT Beteiligungsgesellschaft in Germany (Max-Planck-Institut für Astronomie in Heidelberg, Zentrum für Astronomie der Universität Heidelberg, Astrophysikalisches Institut in Potsdam, Max-Planck-Institut für Extraterrestrische Physik in Munich, and Max-Planck-Institut für Radioastronomie in Bonn), The Ohio State University and Research Corporation (Ohio State University, University of Notre Dame, University of Minnesota, and University of Virginia).
Dr. Holger Mandel
Tel: (0|+49) 6221 - 541 734
Dr. Klaus Jäger
Max-Planck-Institut für Astronomie Heidelberg
Tel: (0|+49) 6221 - 528 379
Dr. Walter Seifert
Tel: (0|+49) 6221 - 541 732
Prof. Dr. Thomas Henning
Max-Planck-Institut für Astronomie Heidelberg
Tel: (0|+49) 6221 - 528 201
Dr. Markus Pössel
Max-Planck-Institut für Astronomie Heidelberg
Tel: (0|+49) 6221 - 528 261
Dipl.-Phys. Axel M. Quetz
Max-Planck-Institut für Astronomie Heidelberg
Tel: (0|+49) 6221 - 528 273
LARGE BINOCULAR TELESCOPE CORPORATION
LBT Project Office/USA
University of Arizona
Tucson, AZ 85721 USA
Osservatorio Astrofisico di Arcetri
Largo Enrico Fermi, 5
50125 Firenze, ITALY
Image 1. Star Cluster S255 (by Arjan Bik):
Image 4a: LUCIFER in the LBTO-lab during re-integration tests. The MOS-masks (to the right) and the shutter (center) are clearly visible
This is a snapshot of a stellar nursery in our own Milky Way, a high-mass star forming region inside the giant molecular cloud S255, at a distance of about 8000 light-years away from Earth. Such clouds are typically opaque to visible light: however, the infrared light can penetrate the dust and therefore the LUCIFER image reveals the cluster of newly born stars inside the cloud and its complex environment. Apart from the bright central cluster, several other sites of star formation can be seen. The oldest stars in this area are the bright blue stars in the eastern and western corners of the image. These stars have blown large bubbles of ionized Hydrogen in their cosmic neighborhood. They also compressed the dust cloud and triggered new star formation in particular in the bright cluster in the center of the image. This cluster harbours lots of young massive and lower mass stars. Some of these young stars are powering heavy outflows (visible in green), which indicates that these stars are still forming. South of the bright cluster nothing is present in the LUCIFER image, indicating that the very young objects in this region are still hidden inside the molecular cloud. Only in a million years or so these regions become observable at the wavelengths accessible to LUCIFER.
Technical data: Combination of three exposures in three different near-infrared filters. Blue: H-band (7 min), Green: H2 (50 min), Red: K-band (12 min).
Image 6:LUCIFER main commissioning team. From left to right: Volker Knierim (AIRUB), Nancy Ageorges (MPE), Werner Laun (MPIA), Michael Lehmitz (MPIA), Peter Buschkamp (MPE), Kai Polsterer (AIRUB), Marcus Jütte (AIRUB), Walter Seifert (LSW)
The average seeing during the observations was 0.6 arcsec. The total area covered in the image is 5.7 times 4.8 arc minutes corresponding to 13 light-years times 11 light-years at a distance of 7800 light-years.
Image 2a and b. Starburst Galaxy NGC 1569 (by Anna Pasquali)
Image 7: Detailed view of the MOS unit with the robot grabbing a mask from the storage magazine; please note the set of slitlets in the metallic film for the different objects in the field of view.
These two false color images show the starburst galaxy NGC 1569, which is forming stars at a rate that is 100 times faster than what is typically observed in our own galaxy, the Milky Way. The left image (2a) taken with three broader near-infrared filters illustrates well the sharp vision of LUCIFER, showing fine details even in an object located 6.2 million light-years from Earth. In classical optical images, only three large stellar clusters are visible. But using LUCIFER's high resolution camera in combination with a special set of filters it became possible to peer through the cosmic dust and to detect many more young star forming regions, bright in red, while a supernova remnant can be found at the bright blue region (right image 2b). This image shows impressively the power of the new instrument for near-infrared observations together with one of the world largest telescopes, especially for detecting diffuse, faint gas as tracer for stellar nurseries in nearby galaxies.
Technical data: Both images are a combination of three exposures in three different near-infrared filters. Left: K band (38 min), FeII+continuum (60 min) and Brγ+continuum (36 min). Right: Blue: [FeII] line at 1.64 micron (60 min), Green: K-band (38 min), Red: Brγ at 2.16 micron (36 min).
The average seeing during the observations was 0.4 arcsec. The total area covered in image 2a is roughly 3 arcmin x 1.5 arcmin, equivalent to about 5500 light-years x 2600 light-years at a distance of about 6.2 million light-years.
Image 3. MOS spectra of very distant star forming galaxies (by Jaron Kurk)
A LUCIFER multi object spectrogram in the K-band wavelength region of the near infrared. Only the wavelength range from 2.14 to 2.29 micron of seven spectra in one MOS mask is shown. The complete frame is a stack of 42 exposures, each lasting five minutes, and contains fifteen slitlets, one arcsec wide, and ten arcsec long, on average. The spectra have been put on a common wavelength scale. The vertical lines are due to noise that remains after subtraction of atmospheric lines from molecules in the Earth's atmosphere. Additionally, characteristic signatures of hydrogen, nitrogen, and sulphur in distant, star forming, galaxies have been observed. The detected elements and the redshifts of the galaxies are indicated. These emission lines are extremely faint and can only be seen after several hours of integration time with an eight meter telescope, like the LBT. With LUCIFER up to twenty objects can be observed in one single exposure.
Additional Technical Background
- LUCIFER is an acronym for: Large Binocular Telescope Near-infrared Utility with Camera and Integral Field Unit for Extragalactic Research)
- LUCIFERs three exchangeable cameras are available for direct imaging, long-slit-spectroscopy and multi-object-spectroscopy. Two of them are optimized for seeing-limited conditions, a third camera for diffraction-limited cases will be used after completion of the LBT adaptive secondary mirror system.
- Using a four Mega-pixel Hawaii2-camera the instrument covers a comparatively large field of view of 4 x 4 arc minutes (about 1/50th of the full moon on sky).
- According to observational requirements, presently a set of five broad-band filters (z, J, H, K, Ks), 12 medium and narrow-band filters and three different high-resolution spectroscopic gratings are available.
- A special feature of LUCIFER are 10 fixed and up to 22 exchangeable masks which can be used for longslit and multi-object spectroscopy (MOS). This multiplex-technology developed at MPE allows the spectroscopy of about two dozen objects simultaneously and reduces the costs per photon and observing time at the telescope dramatically. All laser-cutted MOS-masks are stored in a separate magazine which can be replaced with new masks at fully cryogenic temperatures using an external cryostat and a vacuum interlock to the main instrument. This work can be done within a few hours during a normal service-interval in day-time and avoids a several days lasting warming-up and cooling-down cycle of the complete LUCIFER-instrument, preserving valuable observing time.
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