The Red Rectangle


The Red Rectangle's Morphologies Revealed by Narrow-Band Imaging:

Vijh, U. P.; Witt, A. N.; York, D. G.; Dwarkadas, V. V.; Woodgate, B. E.; Palunas, P.

American Astronomical Society Meeting 206, #38.11; Bulletin of the American Astronomical Society, Vol. 37, p.491




The optical spectrum of the Red Rectangle (RR) nebula consists of several components of comparable intensities, and it is therefore possible to use narrow band imaging to attempt to isolate the morphological substructures where particular emissions are dominant. Extended Red Emission (ERE), the Blue Luminescence (BL), and the sharp red emission features are all comparable in intensity to the underlying dust-scattered radiation. The ERE band peaks near 670 nm (FWHM ˜ 180 nm) and is the primary cause of the red color and the peculiar appearance of the nebula at redder wavelengths. The carrier of the ERE is as yet unknown. The BL band has a peak near 380 nm (FWHM ˜ 45 nm), and has been attributed to fluorescence by neutral PAH molecules with 14-18 C atoms. The sharp red emission features are a set of relatively narrow emission bands due to as yet unidentified molecules. Some of these bands may be emission counterparts of corresponding diffuse interstellar bands. The almost edge-on geometry of the bipolar outflow of this proto-planetary nebula allows one to associate specific physical conditions, such as density, radiation field and ionization equilibrium, with specific nebular regions. The optically thick disk acts like a 0.1 arcsec wide coronographic decker, preventing direct star light and forward-directed scattered light from reaching the observer. This makes it possible to image the nebular emissions at exceptionally small angular offsets from the center of the nebula.

We will present new narrow band imaging data of the RR obtained at the Apache Point Observatory. These images show an almost mutually exclusive morphology of the BL and the ERE, which may allow us to constrain the physical state(s) of the different emitters.

This research has been supported by the National Science Foundation through Grant AST 0307307 to The University of Toledo. VVD's research is supported by NSF Award AST 0319261.

Optical Emission Band Morphologies of the Red Rectangle

Vijh, Uma P.; Witt, Adolf N.; York, Donald G.; Dwarkadas, Vikram V.; Woodgate, Bruce E.; Palunas, Povilas

The Astrophysical Journal, Volume 653, Issue 2, pp. 1336-1341. (ApJ Homepage)




We present narrowband images of the Red Rectangle (RR) Nebula that reveal the distinct morphologies of this intriguing nebula in different optical emission bands. The morphology of the RR nebula in blue luminescence (BL) and extended red emission (ERE) are almost mutually exclusive. We also present the optical detection of the circumbinary disk of the RR in the light of the BL. The total intensities from the two optical band emissions (BL and ERE) when summed over the nebula are of comparable magnitude. Their spatial distributions with respect to the embedded illumination sources lead us to suggest that they may be attributed to different ionization stages of the same family of carriers.