ALFA logo      +      3D logo

Adaptive optics with a Laser For Astronomy
3D integral field spectroscopy
3D is an instrument built by MPE which allows the observer to obtain a spectrally resolved image. Details can be found on the 3D homepage. An Aperture Interchange Module (AIM) allows 3D to be used with ALFA and provides 2 pixel scales: 0.07" for diffraction limited observing, and 0.25" for wide-field mode (giving a 4"x4" field). In either case spectra covering the H or K bands are simultaneously obtained with a resolution of R=1000 (or part of each band at R=2000).

The results described here are due to a productive collaboration between the ALFA and 3D teams. We are particularly grateful to S. Anders, N. Thatte, L. E. Tacconi-Garman, F. Eisenhauer, and M. Tezca.

Objects observed include:
1998 HEI 7 0.26" binary - the first result, described below
1999 T Tau intermediate mass young stellar binary object
BD +31 643 binary system with dust disk
NGC 1161 LINER galaxy
G 45.45 +0.06 ultra compact HII region
MWC 1080 Herbig Ae/Be star with companion 0.75" away and 3.3mag fainter
NGC 1068 archetypal Seyfert 2 galaxy

binary star HEI 7

This is the first diffraction limited spectroscopy ever obtained. The data were obtained on the 3.5-m telescope at the German-Spanish Astronomical Centre at Calar Alto in southern Spain during August 1998.

image of PSF reference
image of HEI 7
HD 183051    HD 183051
Download a postscript figure of these images

Each of the K-band (2.2 micron) images above is 1.2" on a side. The PSF reference (left) shows a diffraction limited core and bits of the first ring. The binary (right) has an extra component above and to the right of the main star - the secondary star, 3 magnitudes (a factor of 10) fainter.

Spectra of the 2 components of HEI 7
HEI7 spectra
Download a postscript figure of these spectra

The spectra of the primary star (green) and secondary (red) are shown above. There are some similarities such as the Mg absorption at 2.28 microns But definite differences can also be seen, even though the spectra were extracted from stars only 0.26" apart: the Ca line at 2.26 microns and first CO bandhead at 2.29 microns.

This result is very encouraging, and provides a glimpse of the possibilities that such techniques will open up.

Data reduced & figures drawn by N. Thatte