High-resolution optical imaging of the Frosty Leo nebula

Abstract:  High-resolution optical images have been obtained of IRAS 09371 1212 (the 'Frosty Leo' nebula). The images were taken with the Dominion Astrophysical Observatory/Canada-F rance-Hawaii Telescope (DAO/CFHT) High-Resolution Camera using broadband V and I filters and with an intermediate-band H-alpha filter. The red filters, particularly H-alpha show that the bipolar nebula is surrounded by a nearly spherical envelope of material approximately 30 sec in diameter. The high-resolution images allow a detailed study of changes in the nebular morphology with wavelength. The ansae remain stationary with wavelength, whereas the positions of the lobes and the position angle of the disk change with wavelength from the optical to the near infrared. These results suggest that the ejection process is colliminated by the disk, which has been processing with time. The possibility that the Frosty Leo nebula is not a post-asymptotic giant branch (AGB) star but a pre-main-sequence object formed in isolation from interstellar clouds is discussed.