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Occultation of IRC +10216

Last modified on November 18, 1998 by A. Richichi

An occultation of the carbon star IRC +10216 (aka CW Leo) was recorded from the ESO/La Silla observatory on November 11, 1998. This is the brightest and best studied carbon star, but also a very peculiar one with the central star being embedded in a thick dust envelope. Therefore, its energy is emitted mostly in the infrared wavelengths: in fact, IRC +10216 is the brightest object in the sky at 10 microns. Recent speckle observations (Weigelt et al. 1998 A&A,333,51, Haniff and Buscher 1998 A&A,334,5) are beginning to show the complex structure of the dust ``shell''.

A series of lunar occultations of this very interesting object has just begun. Offering very high angular resolution also at near and mid-infrared wavelengths, this technique holds the potential for a further step in the understanding of IRC +10216. The first of these occultations has been recorded at the ESO/La Silla 3.6m telescope by B. Stecklum) and H.U. Käufl) using the TIMMI mid-infrared camera. Occultations were observed before with this instrument: an example is the observation of the late-type giant Z Cnc, also showing the presence of cold dust.

Movies available

Taking advantage of 10 micron operation, Stecklum and Käufl managed to observe both the disappearance, and the reappearance, of IRC +10216 on November 11, 1998 (movies are 700Kb and 250Kb respectively). The data were obtained in a narrow filter centered at 10.52 microns, with a pixel size of 0.34 arcsec/pixel and a frame rate of 20Hz.

The occultation series of IRC +10216 is continuing, and the next opportunity will be from Europe on February 28, 1999. Observations will be attempted at the TNG and Calar Alto observatories. Here you can view ground track charts for the years 1998/1999 (obtained with a PC program written by B. Stecklum).

Note: A similar page, with a few more details, is maintained by B. Stecklum and is available here


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